20-yr Old Tamarack Attic Fan - Troubleshooting Crouzet Synchronous Motor, Etc.

[attticfan]

Hi All,

Let me open by explaining that I am a novice when it comes to troubleshooting failed electrical appliances/components.

That said, this is my first time posting and I'm looking forward to whatever assistance folks are able to provide.

I am the owner (and original installer) of a no-longer-supported c.1998 Tamarack Technologies Inc. "HV500" Whole House Cooler (a.k.a "high efficiency attic fan") which, sadly, has ceased operating. The unit consists of a power relay, a synchronous motor (which is connected to two countering rotating pusher arms that, when operated, open and close the insulated hatch and actuate two limit switches, one of which cuts power to the hatch motor and sends power to the fan while the other of which, I believe, cuts power to the power relay to shut everything off), the aforementioned limit switches and the aforecited fan, all housed in a custom two-piece molded plastic (I'm guessing PVC) enclosure. Note: the above supplied links point to the currently available replacement components and don't necessarily detail the currently installed components. For instance, the synchronous motor currently installed in the unit was long ago discontinued which prevented me from supplying a link to it (so I supplied a link to the modern-day comparable part).

Having removed the unit from the attic, disassembled it, cleaned it, researched the availability of replacement components and done my best to test the existing components (all of which, I might add, are readily available off-the-shelf analog parts) I have determined the following:

• when everything is connected and the hatch in the 'closed' position (which results in one pusher arm pressing on one of the two limit switches) and I send power to the power relay, it actuates but nothing else happens;
• when everything is connected and the hatch is the 'open' position (which results in one pusher arm pressing on the other of the two limit switches) and I send power to the power relay, it actuates but nothing else happens;
  
• the fan, when isolated from the rest of the unit's electrical system and supplied independently with power, runs normally;
• the synchronous motor, when isolated from the rest of the unit's electrical system and supplied independently with power, runs but no longer has enough strength, via the 1RPM reduction gearbox (which I opened and all the nylon gears are in place and in excellent condition), to drive the interconnected pusher arms. IOW the motor runs but is not strong enough to oppose the weight of the hatch. However, if I lay the unit on its side (thus unloading the gravitational weight of the hatch from the motor) the motor is able to actuate the pusher arms and the hatch opens and closes.
• Both limit switches show continuity (or not depending on the position of the limit switch) implying to me that they are both functioning properly.

Note - I do not have the unit's electrical diagram and nor is one available. The unit was not supplied with one and Tamarack, which came under new ownership more than a decade ago, disavows any knowledge of this particular unit.

As I recall, the way that this unit is supposed to operate is that when the wall-mounted switch is toggled to the "on" position, the power relay energizes thus sending power to the synchronous motor which then activates to open the insulated hatch (the action of which, in the first second or two of operation, results in the de-actuation of one of the two limit switches, what I'll call Limit Switch "A"). When the hatch reaches the open position, the other limit switch (what I'll call Limit Switch "B") is actuated which simultaneously cuts power to the hatch motor while also sending power to the fan, the latter of which turns on [and cools our two story house via chimney effect - by drawing cooler outdoor air in through open windows and doors (which we open around dusk) - and also by pressurizing the attic (which causes hot air in the attic to be evacuated though the vents in each gable end]. Then, when the wall-mounted switch is toggled to the "off" position, the fan immediately shuts off (not sure what the power relay does in this moment) and the synchronous motor re-activates, this time closing the insulated hatch (the action of which, in the first second or two of operation, results in the deactivation of Limit Switch "B"). When the hatch reaches the closed position, this action, via the position of the pusher arms, results in the actuation of Limit Switch "A", the latter of which must then cut power to the power relay, thus removing power from the entirety of the unit. What I can't work out is exactly how Limit Switch "B" is able to force the power relay to cut power to the fan and synchronous motor, etc. but then allows the power relay to re-energize when the wall mounted switch is toggled back to the 'on" position.

Anyways, my question is: which - in terms of the existing components - do I need to replace? Without understanding the related PFM, it seems obvious that the synchronous motor needs to be replaced. However, do I also need to replace the power relay and/or one or both of the limit switches? The only component that makes any sense to me (again, as a novice) is the fan. When I power it up on its own, it works fine - so, I'm guessing that it doesn't need to be replaced. Does the power relay "sense" the problem with the synchronous motor and, accordingly, not send power to it? Is it "smart" enough to be able to function in this way? If so, do I only, therefore, need to replace the synchronous motor in order to return this unit to fully operable status?

Hoping someone with a better handle on the world of electricity and analog components can help me troubleshoot this (very effective and very much missed) appliance.

Thanks, in advance, for your kind assistance.

And, because a photo is worth a thousand words, please see the following images (Note: the Wago Lever Nuts are my addition - I upgraded from the original wire nuts - and the scary-looking makeshift test-bed power supply cord was unplugged while I took pictures):

 

[73's de Edd]

Sir atticfanman . . . . .

THOROUGH initial info + GOOD photo coverage.

So it looks like the problem is the units shutter / door driver motor.
I see the white and blue power wires . . . . .I also looked and saw no associative capacitor being used, for this unit.
I saw a "GLORIFIED" clock motor and its 1 RPM output drive shaft . . . . . . BUT not attached to a non taxing, mere seconds hand of a clock .
BUT . . . instead, I fully see, a somewhat more challenging LOAD.
They needed to get down from the sync motors given 1800 rpm to a 1 rpm . . . so QUITE an intermediate gear trains ratio transitioning was required.

Now if you EVER tore down an old mechanical clock . . . BIG BEN . . . . as a kid, you would find turning the first gears in the train to make the END gears move . . . . v...e...r...i...l...y s l o w ly was a piece of cake , but the other direction was somewhat limited by the gear you chose and the loading down of the WHOLE gear train.

By your units described operation, I think that your situation is being related to the friction / loading of the whole gear train.
But the factor possibly and likely being the time related " tightness" of the internal lube.

So o o o o o my first attempt of that confirmation, would be to hook up and position the unit in the position where you found most success in a complete opening / closing cycle.

Then wrap any potential heat sensitive wiring, plastic, etc. . . . with an aluminum foil wrap. Then either use a heat gun or commandeer Mamma Cass's hair dryer, used in hottest mode, to heat up the gear case housing to a very -very HOOOTTTTTTTTT coffee like temperature.
While still hot, see if it might THEN readily execute a test cycle. If so, you can then do an additional finger pinch type of loading down of the shaft, to check for, there now even being a slight reserve of drive potential .
If so, the now freeness of the whole gear train, suggests of the timely hardening of its internal lube.

In getting access for further inspection of that internl grease packing . . . . (I've been there) . . . . usually the steel metal end plate, supporting the gear trains output shaft, has it being inserted / pressed down into the molded housing and is soldered in with a surrounding seam.
(I can see that the housing is not being one of the later versions , pot metal housings.)

Investigate all !

73's de Edd . . . . .


Prayer: . . . . . . "Oh Lord, give me patience . . . . . . but give it to me . . . RIGHT NOW ! . . ."

 

[attticfan]

@73's de Edd - Thanks so much for your reply! And my apologies for any confusion regarding the gearbox. Regarding it, I tried to make it clear that I had a look inside when I removed the motor to look more closely at it (and the gear box). The cover for the gear box is plastic and pops off easily. The gears inside (there are several) are all made of nylon/plastic and everything turns smoothly when spun by hand. I made sure to mark the resting position of the flat on the spindle before I opened the gear box to ensure that I would be able to return it to the correct position before reinstalling the motor. And you're right, the reduction gearing is quite pronounced. But the gear box and the gears/teeth are immaculate; even the original factory grease is intact - it hasn't separated. I did power the motor/gearbox when I had it out and I waited a full minute for the spindle to make a complete rotation. However, I didn't try to load the spindle in this condition. I suppose I could have held the motor in one hand and with the other (and a wrench bearing down on the flat on the spindle) tried to prevent the spindle/axle from rotating. But I don't think I'd realized at that point that laying the unit on its side (IOW un-loading the weight of the hatch from the motor) allowed the hatch to open and close. Said another way, I think I figured this out only after I'd already reinstalled the motor and gear box assembly.

Now, I guess another question is: is there a failure mode in a small synchronous motor of this type that can limit its original ability to offset the weight of the hatch? Not knowing, I assume that if an electric motor runs when powered then all is fine. But perhaps a motor like this can fail partially such that when unloaded it runs normally (or at least appears to run normally) but then, when loaded, it bogs down and will refuse to move what, in the past, it was able to move. I don't know - this is where my knowledge of these things runs out.

So, on another front, any thoughts on the matter of the power relay? I have to admit here again that having looked up the purpose and function of a relay ("A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current.") I can't figure out what purpose/function it serves in this particular assembly. That said, I am able discern that it's a rather complex relay (the orange and red hot wires emanating from it and the presence of the two limit switches - one or both of which must work in conjunction with the relay to make everything operate in the correct order together lead me to this conclusion). I've already figured out that the unit, when wired back in the circuit that powers it must always be hot and that the wall switch isn't shutting power on and off to the unit but instead that it's the relay that must be the device that acts in this regard. Otherwise, toggling the wall switch to the 'off' position wouldn't allow the hatch motor to continue to operate after the fan shuts off (which it does since the hatch needs to close all the way in order to seal the living space off from the attic in between uses and, most importantly, from the freezing temps in the attic during the winter months). But I digress.

OK, I'll order a replacement synchronous motor. However, I'm still unsure if I also need to replace the relay and/or one or both of the limit switches.

Sir atticfanman . . . . .

THOROUGH initial info + GOOD photo coverage.View attachment 45696

So it looks like the problem is the units shutter / door driver motor.
I see the white and blue power wires . . . . .I also looked and saw no associative capacitor being used, for this unit.
I saw a "GLORIFIED" clock motor and its 1 RPM output drive shaft . . . . . . BUT not attached to a non taxing, mere seconds hand of a clock .
BUT . . . instead, I fully see, a somewhat more challenging LOAD.
They needed to get down from the sync motors given 1800 rpm to a 1 rpm . . . so QUITE an intermediate gear trains ratio transitioning was required.

Now if you EVER tore down an old mechanical clock . . . BIG BEN . . . . as a kid, you would find turning the first gears in the train to make the END gears move . . . . v...e...r...i...l...y s l o w ly was a piece of cake , but the other direction was somewhat limited by the gear you chose and the loading down of the WHOLE gear train.

By your units described operation, I think that your situation is being related to the friction / loading of the whole gear train.
But the factor possibly and likely being the time related " tightness" of the internal lube.

So o o o o o my first attempt of that confirmation, would be to hook up and position the unit in the position where you found most success in a complete opening / closing cycle.

Then wrap any potential heat sensitive wiring, plastic, etc. . . . with an aluminum foil wrap. Then either use a heat gun or commandeer Mamma Cass's hair dryer, used in hottest mode, to heat up the gear case housing to a very -very HOOOTTTTTTTTT coffee like temperature.
While still hot, see if it might THEN readily execute a test cycle. If so, you can then do an additional finger pinch type of loading down of the shaft, to check for, there now even being a slight reserve of drive potential .
If so, the now freeness of the whole gear train, suggests of the timely hardening of its internal lube.

In getting access for further inspection of that internl grease packing . . . . (I've been there) . . . . usually the steel metal end plate, supporting the gear trains output shaft, has it being inserted / pressed down into the molded housing and is soldered in with a surrounding seam.
(I can see that the housing is not being one of the later versions , pot metal housings.)

Investigate all !

73's de Edd . . . . .


Prayer: . . . . . . "Oh Lord, give me patience . . . . . . but give it to me . . . RIGHT NOW ! . . ."

 

[73's de Edd]

Sir atticfanman . . . . .

A CONTINUANCE . . . . . . . . . .

I can't see all that I REALLY need to see, nor can I actually put my hands on it and make it go whiz-bang-whir r r r r .
Harvesting what I can see, with your " Crouton " motor having only a white and blue power wire, this is definitely being a uni-direction motor.
The oval cut in the housing for clearance of the lid lift actuator arm, confirms that there is having to be some side to side movement of the actuator arm; therefore, with it not moving in a very tight/ in and out linear action.
Therefore with a rotary action creating a end to end linear action, it must depend upon 1/2 of a rotation to move the drive rod to one directions limit and then the other half rotation cauises the drive rod to finish the other linear movement in the opposite direction. Thetreby permitting the use of a unidirectional motor. . . . . . no reversing required.

From your next to the last photo I am seeing a side by side fiber glass actuator rod pair that constitutes the lift rod(s) for the lid. This view only lets me see the closer rod.
You can see that the units very last action completed was for the drive motor to have been LOWERING the lid (all downhill coasting, wih gravity assist . . . whe e e e e e e . . . . no effort required ).
After it reached the point where the closest rod, centered upon the lever of the nearer microwitch, had reached its extreme, the power to the driving motor was cut off.
There you then have a turned off dormant system with the units attic door closed and the companion ventilating fan also turned off.

Then, you later come along and turn on the unit ( or a thermostat activates the unit, if so being incorporated) and the " Crouton " motor starts its cycle to LIFT the units attic door and have the main ventilating fan, blowing the rooms ceiling levels hot air up into the attic.
Then at the extreme limit of engagement of the actuator arm, is where the other limit switch stops the drive motor.
Then the attic main ventilator fan runs, sucking out the hot air . . . . . . . . . UNTIL ?

NOW I need some examination by you, for passing forward, some unviewable mechanical aspects of its operation.

I can see the 1 RPM rotating " Crouton " motors shaft end, but needing to convert a rotory movement to a linear . . . . no . . . make thet a quasi -linear back and forth movement.
I could do that with an eccentric cam, a connecting rod, a Geneva wheel or a set of opposed cams
I can't see how the NOW HIDDEN fiberglass shaft gets that opposite direction push on its associated microswitch when being at its extreme door lift position, ready for its power shut off.

AL FIN . . . . .

In your second photo down, with the unit being in its normal install position and your hand on the right side .
The units other side, exactlly opposite of your hand, is where there must be a piano hinge.
The closer the lift rods are installed to that hinge, the higher the door will lift within the structured movement limits of the lift rods..
Likewise, the further the lift is made from the hinge the less the lid will rise up, when at lift rod limits.
Two situations there :
The position closest to the hinge requires more mechanical effort to lift, while the more distant placement of the lid lifts, has the need decreased.
WITH the lower lift consideration, that the volume of the opening of the lids venting area then being provided, must exceed the area or the ventilating fan venturi exhaust.

When you had the whole unit resting on its side, such that the lid thereby had no gravitational restraint working against it, in either its opening or closing.
Could you REPEATEDLY turn the unit on and have the lid swing to its open position, then could you turn off power and have the lid close and be ready for your next operational demand ?

IF SO . . . . . your relay, and limit switches are all good, adjusted, and operating properly.

Since . . . the RELAY working in conjunction with the two limit swtches is tasked to detect that you have just switched on the wall power to the unit, then it powers up the "Crouton " motor to lift the lid, when the lid reaches its extreme limit , that then mechanically trips the limit microswitch, the " Crouton " motor stops and the ventilating fan runs . . . .and runs . . .and runs.

Should you come along and turn off the unit, it reacts with the relay, both holding AC power on and simultaneously turning on the " Crouton " motor, for it to lower the lid (so easy . . .much too easy ) and when that lift / (lowering rod) reaches its extreme limit it trips its microswitch to totally cut off power . . . . . until . . . . . . . .?

Now if all operations cycle flawlessly, I probably can suggest a mechanical fix for $3-5 or EURO ***. . . . . vice a pricey synchrous motor purchase

BTW . . . . . I can see the massive but vewy vewy light block of foam on top and suspicion it being contact cemented to an alum-i-ni-ninny-yum-yum plate on the bottom.
OR if the bottom plate was made of 1/8 inch thin masonite (or ersatz masonite, that is made with pressed paper) being bonded to the foam . . . . . . that unit would be as light as a popcorn fart.
Therefore the lid not being so weighty afterall, but, since its is hinge mounted , that precludes an easy lift off, for an actual and valid weight assessment.

***
If this a problem of lid weight, a mounted stretch spring aligned vertically just above the center of axis of lift of the lids connection to the push/pull rods that has its spring end mounted to an added aluminum support beam. The spring action pull would be selected so that the continual lifting action i is continually imposing, is being just somewhat short of starting to pull up the lid by itself.
Thereby that continual spring "prelift" pull, will tequire a much lower lifting action by the motor.

Question . . . . is there just a flat surface to surface closure of the lid, or is some sealing / weatherstripping being incorporated ?



Thaaaaasssssit . . . . .




73's de Edd . . . . .

If the world were a more logical place, men riding horses ( Ouch . . . . .Ouch . . . . .Ouch . . . . .Ouch . . . . . .Ouch . . . .Ouch . . . . Ouch ) . . . . . would be riding them sidesaddle, instead.

 

[attticfan]

My responses appear in red below:

Sir atticfanman . . . . .

A CONTINUANCE . . . . . . . . . .

You are correct. In this assembly, the motor driveshaft rotates in only one direction (clockwise). What I realize now is that you can't see the stubby aluminium actuator arm, which (in the photos that I originally included) is hiding behind the plastic actuator arm (which is visible). They rotate around each other as the motor goes through its motions and when the hatch is in the 'closed' position they are in-line with each other (as shown in the photos). See photo below for better detail.

From your next to the last photo I am seeing a side by side fiber glass actuator rod pair that constitutes the lift rod(s) for the lid. This view only lets me see the closer rod.

Yes. In the photos I included with my original post, the stubby aluminium "opener" arm is hidden behind the "closer" arm. Here's a better photo (taken prior to my having cleaned the unit and before I swapped out the wire nuts for lever nuts - my apologies for the fact that the photo is upside down - the forum software struggles with the orientation of some my photos):

You can see that the units very last action completed was for the drive motor to have been LOWERING the lid (all downhill coasting, wih gravity assist . . . whe e e e e e e . . . . no effort required ).
After it reached the point where the closest rod, centered upon the lever of the nearer microwitch, had reached its extreme, the power to the driving motor was cut off.

Correct.

There you then have a turned off dormant system with the units attic door closed and the companion ventilating fan also turned off.

Yes, but with one crucial caveat. The fan shuts off immediately when the wall switch is toggled to the "off' position. However, and this is the part of the sequence I don't understand, after the wall switch is toggled to the 'off' position, the hatch motor continues to operate until the hatch is pulled tightly closed and the applicable limit switch is contacted (which is what removes power from the hatch motor).

Then, you later come along and turn on the unit ( or a thermostat activates the unit, if so being incorporated) and the " Crouton " motor starts its cycle to LIFT the units attic door and have the main ventilating fan, blowing the rooms ceiling levels hot air up into the attic.

Yes, but with one crucial caveat: the fan doesn't turn on until the hatch reaches the fully 'open' position. At that moment, the hatch motor shuts off and the fan turns on.

Then at the extreme limit of engagement of the actuator arm, is where the other limit switch stops the drive motor.
Then the attic main ventilator fan runs, sucking out the hot air . . . . . . . . . UNTIL ?

Correct. The fan doesn't turn on until the hatch reaches the fully 'open' position (and the applicable limit switch is contacted).

NOW I need some examination by you, for passing forward, some unviewable mechanical aspects of its operation.

I can see the 1 RPM rotating " Crouton " motors shaft end, but needing to convert a rotary movement to a linear . . . . no . . . make that a quasi -linear back and forth movement.
I could do that with an eccentric cam, a connecting rod, a Geneva wheel or a set of opposed cams
I can't see how the NOW HIDDEN fiberglass shaft gets that opposite direction push on its associated microswitch when being at its extreme door lift position, ready for its power shut off.

Again, my apologies. The images I originally included don't show the stubby aluminium "opener" arm - it is hidden behind the plastic "closer" arm. See the photo above for additional detail.

AL FIN . . . . .

In your second photo down, with the unit being in its normal install position and your hand on the right side .
The units other side, exactlly opposite of your hand, is where there must be a piano hinge.
The closer the lift rods are installed to that hinge, the higher the door will lift within the structured movement limits of the lift rods..
Likewise, the further the lift is made from the hinge the less the lid will rise up, when at lift rod limits.
Two situations there :
The position closest to the hinge requires more mechanical effort to lift, while the more distant placement of the lid lifts, has the need decreased.
WITH the lower lift consideration, that the volume of the opening of the lids venting area then being provided, must exceed the area or the ventilating fan venturi exhaust.

When you had the whole unit resting on its side, such that the lid thereby had no gravitational restraint working against it, in either its opening or closing.
Could you REPEATEDLY turn the unit on and have the lid swing to its open position, then could you turn off power and have the lid close and be ready for your next operational demand ?

Not entirely. The hatch motor, at least in its present state, is not able to push past the two 'top dead center" positions. IOW were it working normally, it would be able to push through these two positions. When testing as part of the troubleshooting, I had to provide the additional force neccessary to assist the motor to make it through these two "restrictions". Moreover, something I didn't include earlier is the fact that the motor can't even hold the hatch open when the hatch is going through the closing portion of its travel. The weight of the hatch just totally overpowers the motor and it slams shut (not sure if the weight of the hatch forces the motor to run in reverse or if one or more of the nylon gears slip). All the more reason (I assume) to replace the motor.

IF SO . . . . . your relay, and limit switches are all good, adjusted, and operating properly.

Since . . . the RELAY working in conjunction with the two limit swtches is tasked to detect that you have just switched on the wall power to the unit, then it powers up the "Crouton " motor to lift the lid, when the lid reaches its extreme limit , that then mechanically trips the limit microswitch, the " Crouton " motor stops and the ventilating fan runs . . . .and runs . . .and runs.

Under normal operating conditions, this is correct. As it currently stands, however, when the wall switch is toggle to the 'on' position, the relay "clicks" (the sound of the electromagnet pulling the contactor over) but then nothing else happens. And the same thing goes regardless of whether or not either one of the limit switches in being actuated. When I send power to the relay, and the "click" occurs, and then I manipulate each limit switch manually, there is no change - nothing else happens under either scenario.

Should you come along and turn off the unit, it reacts with the relay, both holding AC power on and simultaneously turning on the " Crouton " motor, for it to lower the lid (so easy . . .much too easy ) and when that lift / (lowering rod) reaches its extreme limit it trips its microswitch to totally cut off power . . . . . until . . . . . . . .?

Now if all operations cycle flawlessly, I probably can suggest a mechanical fix for $3-5 or EURO ***. . . . . vice a pricey synchronous motor purchase

BTW . . . . . I can see the massive but vewy vewy light block of foam on top and suspicion it being contact cemented to an aluminium plate on the bottom.
OR if the bottom plate was made of 1/8 inch thin masonite (or ersatz masonite, that is made with pressed paper) being bonded to the foam . . . . . . that unit would be as light as a popcorn fart.
Therefore the lid not being so weighty after all, but, since its is hinge mounted , that precludes an easy lift off, for an actual and valid weight assessment.

Yes, the hatch does have some modest weight to it, though it consists only of the weight of a) the plastic lid, b) the full-dimension open cell foam gasket (which air seals the hatch) and c) the full-dimension 2" thick aluminium-tape-covered closed cell foam 'top' (which insulates the hatch). In this respect, it is quite lightweight, all things being equal. Plus, before the unit failed, the motor worked flawlessly for over a decade. So, if I can get another decade-plus from a replacement motor, then that's a small price to pay for having been able to refurbish the unit myself.

***
If this a problem of lid weight, a mounted stretch spring aligned vertically just above the centre of axis of lift of the lids connection to the push/pull rods that has its spring end mounted to an added aluminium support beam. The spring action pull would be selected so that the continual lifting action i is continually imposing, is being just somewhat short of starting to pull up the lid by itself.
Thereby that continual spring "prelift" pull, will require a much lower lifting action by the motor.

While I see the benefit of this approach., I'd rather just replace the motor (and any other faulty components) so as to minimize the overall complexity. Moreover, this unit doesn't owe me anything - my cost back in 1998 was under $300 (current models run over $700) so even with the cost of replacement parts I am well ahead of the game. Plus, I don't have to reframe a larger opening which is what I would need to do to install one of Tamarack's current models. And, it goes without saying, that now that I've seen the guts and build quality of one of these units, I certainly wouldn't pay the going asking price for a new one - I'm not going to participate in my own highway robbery! Plus, I have a feeling that the current models likely rely on a circuit board or two - I'd like to stick with my current unit given its relance instead on analog components that I can troubleshoot (poorly!) and easily replace. This model allows me to basically future-proof this installation.

Question . . . . is there just a flat surface to surface closure of the lid, or is some sealing / weather stripping being incorporated ?

I believe I answered this question above. That said, here are some additional photos that show a) the (slowly disintegrating) EPDM, full-dimension sponge foam gasket (which airseals the hatch to the body of the unit), b) the piano hinge that the hatch pivots on and c) how the whole thing goes together when fully assembled (note - years ago I crudely painted the face of the unit black so that it was less noticeable behind the white steel grate that hides it from view):

When assembled, the whole thing is held together with steel pop rivets and the areas where the two halves sandwich together are covered by simple vinyl moldings that slip over the joints - pretty basic stuff.

Thanks again for your kind assistance!



[Mod note ... major edit to fix the quoting and other issues]

 

[attticfan]

In the interest of moving this discussion along I drew up a rough wiring diagram:


The big blue component is the relay; the red donut is the fan; the two yellow rectangles are the limit switches; the orange cubes are the lever nuts; and the purple cylinder is the hatch motor. The layout of the posts on the relay and limit switches mimic real life. You will note that one of the posts on the relay is unused (this is for supplying power to an optional LED indicator that can be mounted in the wall switch cover plate) as is one of the posts on one of the two limit switches. This also mimics real life. The color of the various wires also mimics real life. The relative placement of the limit switches also mimics real life. To lessen the complexity of the image I omitted the various ground wires.

My apologies for not providing this before now. Hopefully this helps!

Also, I thought I'd provide some results of additional troubleshooting:

• With it isolated from the rest of system and powered up independently, I measured the voltage across the hatch motor. My multimeter shows 123V. This leads me to believe that the problem with the hatch motor lies in the gear box. As has been suggested to me elsewhere, I believe that either/or the pinon or the gear on the output shaft (both of which are press-fit - there are no mechanical fasteners like grub screws or flats on the driveshaft) is/are slipping.
• With everything connected but the orange wire removed from its respective post on the relay, I supplied power to the relay and then checked the voltage at the open post. It measured 1 volt. I'm assuming that the value here should be ~120V. If so, then this indicates, I guess, that the relay is bad. BTW this conditions remains regardless of how I manually manipulate the two limit switches

I also thought I'd show the relay under the two scenarios of "unpowered" and "powered".

Here is "unpowered":



...and here it is "powered":



Anyone have any additional thoughts?

 

[attticfan]

As has been pointed out to me elsewhere, part of the problem lies in a wiring mistake (mine). Accordingly, here is the corrected wiring graphic (the change is the inclusion of a red wire between the free post on the relay and the hot feed):



Wiring this correctly results in the opening sequence functioning normally. Now, when power is applied to the relay, it clicks and then the hatch motor turns on. Of course, sSince the hatch motor is unable (likely because of a slipping gear(s)) to operate the hatch it's clear that I need to replace it. However, when I manually move the hatch to the full open position and ensure that the stubby aluminum operator arm actuates the left limit switch, the hatch motor turns off and the fan turns on (!). This, of course, is music to my ears!

On a related note, it has also been made clear to me that the wall switch is not your normal light switch. Here's what it looks like:





Until I know more I'm working off the assumption that, as wired, the appliance is always "hot" and that this switch is what's behind the ability of the fan to turn off and the hatch motor to restart (and, ultimately, for the hatch motor to turn off again once the right limit switch is actuated) after the wall switch is toggled to the position shown in the above photo (which I've always thought of as "off" but which isn't actually so). IOW contrary to my poor understanding, it's not a simple "on/off" switch.

 

[73's de Edd]

ACH HIMMEL . . . . . .Icht bin der attticfanman ! . . . . .


Back when you submitted the initial pics of the lift mechanism for the door, it appeared to have two like rods being side by side.
Now, your latest photo totally clarifys that situation.
Now, one sees a length of 1/4 in metal bar stock that is being symmetrical in length from a central point, where it then uses opposing set screws to connect the motor drive train shaft at that point to what we will now call the . . . ." Rotating bar " . . . . and one end of that Rotating bar, gets connected to a rod that lifts the attic door of the unit . Let's call that the " Lift rod "
Notice that the ends of the Rotating bar are rounded, so that the one that is not conneted to the Lift rod is able to roll onto and off of the lever of the microswitch that is being the closest to the motor. The Lift rod has the same rounding, such that its its end can roll onto and off of the lever of the microswitch that is located the fartherest from the motor.
Now the relay used in the unit, initially serves to detect that you have just switched on the downstairs power switch. Its contacts then work in conjunction with the two limit switches to . . . . .
Initiate a door lift operation upon your switching on the unit at the wall.
The synchronous drive motor is wired in series with both of the limit switches, but when the unit stopped after its last door closing cycle the Lift rod ended up stopped on top of the " lift limit" switch and that stopped the system by disrupting motor power, so you currently have that being an open switch. BUT since you just turned on the wall switch, the relay powers up and closes a relay contact which jumps across the opened limit switch to initially get the motor running.
The Rotating bars CCW movement of the Lift rod then moves it off of its limit switch and the unit continues running.
At the 180 degree rotation point of the Rotating bar, it rolls upon the opposite limit switch and it opens power and that stops synchronous motor movement.
That is then being the positional situation, and while being there, your tornadic attic ventilating fan runs .
That is UNTIL you decide to turn off the power at the wall, ( but NOT really) as the relay is overiding and being the actual power control, as it now needs to use a set of its contacts to jump the far sides disabled limit switch to initially get the synchronous motor running again. With the motor now running it then continues CCW for its complation of its second 180 degree rotation to then have the Lift rod roll upon the closest limit switch. Power is THEN shut down.
It is then awaiting the next time you want to activate the unit .

Sooooooooo if you were to take loose that hairpin clip that connects one end of the Rotating bar to the Lift rod and swing the lift rod free, you would have no load being placed upon the drive mechanism.
IF you haven't already done this, power up and cycle the unit thru a lift and power down to get a complete operating cycle..
I am expecting it to work flawlessly, confirming no relay or limit switch problems. If not, we solve.

Now after a reconnect of the Rotating bar to the Lift rod , and the WHOLE UNIT being in the same plane as its attic mounted situation, in its having to lift the door, try out the system. It failed/ stalled right quickly , didn't it ?
If so, now the CRUX of your problem is surely going to be within the first 90 degrees of rotation of the Rotating bar after a power turn on,
Once the door is lifted its a downhill coasting situation on required mechanical demands after that.
PLUS after seeing the door opened and their lifting point mounting of the Lift rod to the door . . . . . I can see the hefty power being needed to lift the door..
Its a mechanical equivalency akin to you initially lifting a 10 lb weight vertically, with it in close to your body, versus lifting it again for an equal vertical distance, but while being held way out at arms length.
I an now thinking of two potentially changing mechanical aspects between 20 years ago and the present situation.
You told me of the capability of making a visual inspection of the gear train within the housing attached to the synchronous drive motor. With you being able to see all of them, I would only suspect tem of placing a dabbing on of a clinging grease to the gear train.
Plus, I just want to think that the 1800 rpm of the motor rotor and the internal gear train enclosed within the motor housing, which is probably dropping down to ~ 60 rpm and your external geat train, as examined, is dropping on down to your final 1 rpm.
So there is still possibility of 20 yrs of " time tightened " / viscosity increased internal grease within the motor housings divide by 30 internal gear train.
Therefore, have you tried the hair dryer heat to only the MOTOR housing, to see if any improvement in easier operation is acquired. ? ? ?
The other consideration is being the piano hinge on the door, there is a lot of surfactal area between the individual segments and the central rod.
Do you detect any undue friction when flexing the door between positions , with a disconnected door ? Rust- aluminum galling / oxidation-needing oiling ?

And finally, after seeing the whole systems mounting situation, I believe that I would try a counterweight at the point on the other side of the door of the mounting of the Lift rod .
A small nylon rope would connect to an eye screw at that point, and go straight up to a cross rafter , being straight vertically above it, where a pulley is mounted and has that rope threaded thru it. The rope drops down and has an appropriately connected counterrweight connected to the rope end.
If that weight should go down as far as to approach your unit, you would want to just mount another pulley to the side and loop the rope thru that pully so that your weight would be dropping down and thereby being a bit remoted from your main unit.
My initial test weight evaluation would be a gallon empty poly milk container and you just add water to trim weight as needed. You want to adjust weight until the lifted door will just drop back down.
That constant weight assist will appreciably reduce the power needed by the motor for making the heavy first rotational 90 degrees of lifting .

If you are familiar with olde tyme sash / casement windows, they would have hidden hollow side compartments to the sides of the window.
Normally the combined window frame and contained glass weight would be quite a chore to lift up. HOWEVER , at the sides of the window, they had a pulley hidden away inside on either side and a rope gets nailed to the inner side of a hollow in the window frame proper and then routes up and over a top pulley and then the rope drops down and is connected to a "window sash" weight in the order of 18-22-25 pounds.
Now when a frail lady or kiddo attempts to lift / open that window, they have the gravity assist of both of those weights helping them . . . its so much easier.
(Until 60 yrs 3 mos 2 days and 11:20 min later, when the olde cotton rope rots away and drops a weight, then its quite an unbalanced situation, and herder'n heck to get that winderr up.. )

How about exploring all of those possibilities now.

ACCOMPLISHMENT ? . . . . . . is being a minimal cost solution of the situation .

I've priced those AMERIKANSKY made " clock motors " and currently they are looking at $40-60 for just that little motor itself.

73's de Edd . . . .

Did ya ever notice, how there are being fewer and fewer land lines being used for PlainOldTelephoneService . . . . as all are going wireless . . . . . . WELL . . .

Wireless birds on line

 

[attticfan]

@73's de Edd - Thanks for your further reply and my sincere apologies for not updating this thread sooner. Based on some excellent assistance that I received on another forum, I've learned something crucial and also decided how I'm going to proceed.

What I learned was that I made a crucial wiring error. Someone much smarter than me pointed out that there is a wire missing from the existing layout. My explanation for how this came to be is as follows:

"The appliance failed while I was out the country. My father arrived on scene and disconnected the wiring in the attic to render the unit inop. I then returned several years later and removed the unit from the attic. However, when I found the unit in the attic, the red wire that was connected to the "free" post on the relay was hanging all by itself in the junction box, un-wire-nutted, Meanwhile, my father had installed wire nuts on the remainder of the wires in the junction box (leading me, along with my poor knowledge of this kind of stuff) to falsely believe that the red wire served no purpose and that it was the wire that was intended to power the optional LED light that I could have installed (but didn't) on the wall switch plate back in 1998 (when I first roughed this unit in). Little did I know that the red wire (which I innocently removed about half way through this troubleshooting process to get it out of the way) was and is in fact necessary! I wired it all up correctly the first time around but the intervening years and choosing to involve another person in the mix coupled with my ineptitude resulted in this oversight. I'm feeling more than a little sheepish right now!"

As it was so expertly explained to me, "...there should be a permanent live connected to the relay common....the incoming white wire is neutral...[and]...the incoming black wire is live via the wall switch." And that, ladies and gentlemen, is why electrical geniuses like yourselves get paid the big bucks!

So, when I added the red wire back into the mix and applied power to the relay, presto!, the hatch motor fired up! When I then manipulated the hatch to the full open position and made sure the stubby aluminum operator arm actuated the left limit switch, presto!, the hatch motor shut off and the fan turned on! All music to my untrained ears!

Moving forward, while I have every reason to believe that the right limit switch also works normally, I can't confirm this until I've reinstalled the appliance in its previous location. After all, I'm relying on a length of Romex with a 5-15 plug festooned onto the end it as my power supply, not the fancy wall switch. Between that and how the relay and limit switches figure into everything is where all the magic happens. Again, as it was so expertly explained to me:

"The relay common needs to have power connected to it all the time. The wall switch just switches the power to the relay coil. (The black wire to the relay.... When the relay is energised it feeds the motor via the micro switch (with the orange wire.) until it is actuated by the mechanism. (The open position.) It then feeds the fan. When the relay is not energised it feeds the motor via the micro switch with the red wire so it then stops in the closed position."

What follows is my updated graphic which includes the until-now missing red wire (it's the one fitted to what, in my earlier graphic, was the unused post on the relay). Reinstalled in the attic and wired up correctly, this will be connected to the hot feed while the black wire will be connected to the white wire from the wall switch):



To complete the necessary wiring not shown above, a) the black wire from the wall switch will be connected, along with the red wire from the relay, to the black (hot) feed, b) the black wire from the relay will be connected to the white wire from the wall switch, c) the white wire from the relay will be connected to the white wire coming from the feed (neutral) and all the grounds will be tied up. I think I've got this correct!

Now, what I've decided is how I'm going to proceed with returning this appliance to service. To do so, I will be converting the hatch motor aspect of the system to DC using the combination of a geared 1RPM DC gear motor and an AC/DC transformer (more on the transformer in a bit). In comparison to the weak link that is the existing under-powered nylon geared AC motor (which appears to be the only "failed" component and which also happens to be rated for only .5Nm), the DC motor that will replace it features metal gears and a rating of 14.1Nm. Everyone on the other forum was encouraging me to go with a DC motor (now I know why!) and so I have. Also based upon the advice I was given on that other forum, I could have tried to stop what is likely a gear or gears slipping on its/their respective gear shaft(s) in the AC motor's gear box (using red locitite) but I'm opting instead to eliminate this weak link from rearing its head again in the future by instead installing and relying on a much stronger motor with metal gears that (I assume) are held fast to their respective shafts by more reliable mechanical means. To complete this retrofit, I have sourced an appropriately-spec'd (and confirmed-by-me to be UL-listed) AC/DC transformer.

Here's the wiring graphic that shows the DC motor and hardwired/panel mount AC/DC transformer in the mix:



For clarity, the green cube is the panel mount AC/DC transformer and the purple cylinder is the DC hatch motor.

So, that's that.

Since the transformer is coming on the slow boat direct from China, it will take some time to arrive. However, once it has arrived and once I've reinstalled the appliance in its spot and wired everything up correctly, I'll report back here with the results of my efforts. Hopefully, I haven't missed anything!

Thanks again for all of your kind assistance!

 

[73's de Edd]

Sir attticfanman . . . . .

I just had to re read your posts to get a mental refresh, and came up with THIS .
Which seems to totally explain the situation.

Moreover, something I didn't include earlier, is the fact that the motor can't even hold the hatch open when the hatch is going through the closing portion of its travel. The weight of the hatch just totally overpowers the motor and it slams shut (not sure if the weight of the hatch forces the motor to run in reverse or if one or more of the nylon gears slip)

If that unit reesponds in that manner, we have slippage, as that gear train WILL be providing enough braking power, so as to not let that door fall for 30 seconds EVEN if it could be in "gear rundown" mode, but I don't think that would even be possible due to developed friction / load down, between all of the meshed HIGH gearing ratios.
You mentioned , visibility of all of the final plasti gears. I believe that the fault will be with the very final two gears.
Not a teeth meshing problem, but being a slippage under loading type of situation.
Say that you will have a small teeth count pinion gear cut into a shaft, that then meshes into a larger and HIGHER tooth count rotary gear. I suspect that largest gear to be slipping on its inner axle.

Your option of the planetary geared train coupled into a low voltage DC motor should solve your problem forever, considering its intermittent duty.

The main fault of the present unit might be its 20 years in a somettimes . . . HOT . . . attic, along with the final gears fabrication mode and chemical composition / "decomposition" of manufacturing plastic choice.

Should you want to mark "TICK" mark references on the final gears with a BLUE Sharpie and then mechanically cycle the "rotating bar" up to the point of inducing slippage, and taking note of that point of slippage. That would pinpoint the exact area.
Then, if you want , I can walk you thru a repair of the slippage point with some water viscosity alpha cyanoacrylate . . . or, how you clazy Amellicans say . . .Sooper Glue and a clump of sodium bicarbonate.

SINCE , I suspect it might be a bit more of time, before your Chinee " Care Package " arrives.

VISUAL REFERENCING . . . . .



73's de Edd . . . . .


Take care to get what you like or you will be forced to like what you get.

 

[attticfan]

Well. the various replacement & new parts and associated tooling which I needed to effect the repair arrived in record time and I have since successfully repaired the appliance and reinstalled it in the attic. Everything is working again as it should!

So, anyone wishing to learn all the gory details is encouraged to visit the related thread located elsewhere on the web. I'd repeat it all here but it's just simpler to surf on over to the other forum. In my case, it took a village to repair this appliance and I simply could be more appreciative of all the help I received. Thanks again @73's de Edd for all your generous assistance!