Need help with obsolete Motorola components.

[Rowdy]

I'm trying to repair an old garage door opener, remote. It has three active components, a transistor ? (that appears to be open) (8632 BEC Motorola 830), somebody tell me they know what this is,
A diode 1N4736A is a 6.8V 1W zener. (tests front to back ratio 5.5 meg to open) - (circuit - 9V supply, 6.8kΩ 1.3mA current limiter, holds voltage at 6.7V) so it's fine,
and an (SC370524P Motorola DQD8825 - 18 pin DIP) - (it is directly off of a 20 pin gang DIP switch to set the code) ?.
I would estimate a manufact. date in the early 70's. I'll draw out the circuit and get voltage measurements at various nodes and test values of passive components. I hate it when information on a component is missing in action. I understand it on stuff from the 10's and 20's but this isn't that old, and proprietary data withheld should be against the law. Well in my opinion. A little insight, it worked fine until water dripped on it from a roof leak in my garage. Pfhitt. Yeah the leak is fixed, didn't know I had it til Pfhitt.

 

[davenn]

hi,
welcome

yup get some drawings and also some pics of the circuit board(s) both sides

cheers
Dave

 

[Minder]

Most likely a 2SC830, http://www.americanmicrosemi.com/information/spec/?ss_pn=2SC830
If testing a semi on the regular ohms scale usually result in a false reading, unless you have a semi test range,
M.

 

[Rowdy]

hi,
welcome

yup get some drawings and also some pics of the circuit board(s) both sides

cheers
Dave

Working on it

 

[Rowdy]

Most likely a 2SC830, http://www.americanmicrosemi.com/information/spec/?ss_pn=2SC830
If testing a semi on the regular ohms scale usually result in a false reading, unless you have a semi test range,
M.

We can eliminate that transistor as this one is an epitaxial not a power tr. Probably a couple of watts at best.

 

[Rowdy]

Well I tried, didn't know how it worked here, will get it better. The transistor says 8632 then BEC then the motorola symbol and then 830. Am working on drawing up the schematic or more like learning draftsight again been awhile. Working on it but this is a really busy time of year.

 

[shrtrnd]

This won't help, but it might be informative. I used to repair Stanley swing gates (but not for Stanley). All of their components were proprietary part numbers.
When I'd get really stuck the boss would call an authorized Stanley rep and a repairman would come out, fix the controller, and leave.
The repairman always replaced the Stanley proprietary part numbered parts with industry standard JEDEC part numbers.
My guess is that you have a proprietary part number from the garage door company.
Have you tried Googleing your make and model, and see if anybody has posted anything on your particular board?
I would think you have industry standard components, just with the company's proprietary part number on them.

 

[73's de Edd]

.
Sir Rowdy . . . .
Howdy . .podnah . . .

¿ Water has got in past its protective case and has caused damage ? . . . .UNLESS it was submerged ?
In that situation I would be checking that PB xmit switch and the integrity of the DIP programming switches.
Or if they are all now BONE DRY, since that's CMOS in the SC digital encoding chip.
Looking at the antenna stub and gauging relevant operating frequency, along with the utilization of its value of
emitter resistor that is being used.
I wouldn't hesitate a heartbeat in subbing in the Aerospace/Military "Golden Building Brick" . . . . the 2N2222 with
its TO-18 CBE leads being re-positioned accordingly.
If it works, but more range/power is needed . . .maybe a 1/10 mile instead of 50 feet, move to its big brother
the 2N2218/19 in its TO-5 casing.

But MAN that IS being one Snow white PCB, SURELY its a ceramic bisque ?

Did the OEM ROTAMOLA pass testing of the CB-BE forward conducting junctions / voltage test in the diode test
mode of your DVM ?

Yes, the SC370524P DIP Chip is being the producer of the serial digital code burst, that feeds modulation
to the base of that transistor thru the 22K /10 K resistors.

Can we assume that there is another one or two Xmitter's and that they still communicate with the house supereg receiver
OK ?

Waiting for feed back . . .

73's de Edd


.

 

[73's de Edd]

.

Sir Rowdy . . . .

INITIATE . .pat on back . . . .you makee velly-velly good fotie-grafs!

I have 1x'd and mirrored both of the boards sides, but with my closely looking at theboard
the very top resistor of a possible 3 has been clipped out.
I'm thinking that a further crypto-complexity can also be randomly initiated at the factory
with these resistors being frequency of operation related.
With our KNOWING that the dips are establishing the chosen digital stream coding.
Using a resistor/versus/ being clipping out of circuit and the possible cross combinations
could result in another 180 permutations of coding complexity.

But what I was initially marking up, was those resistors solder pads, and the bottom YELLOW
circled one seems to be floating, can you confirm that, and possibly the one above it.
A well as . . . . all of them . . . . over the board.

Also, it is now easy to see that the negative battery terminal is floating and that the transmit
switch will initiate a lit LED with its good contact.
But I think that an ohmmeter/voltmeter would have to be used to confirm that the tact switches
internal action is ALSO completing grounding for the electronics circuitry.

Mirrored 1:1x PCB Sides:




73's de Edd


.

 

[Rowdy]

.
Sir Rowdy . . . .
Howdy . .podnah . . .

¿ Water has got in past its protective case and has caused damage ? . . . .UNLESS it was submerged ?
In that situation I would be checking that PB xmit switch and the integrity of the DIP programming switches.
Or if they are all now BONE DRY, since that's CMOS in the SC digital encoding chip.
Looking at the antenna stub and gauging relevant operating frequency, along with the utilization of its value of
emitter resistor that is being used.
I wouldn't hesitate a heartbeat in subbing in the Aerospace/Military "Golden Building Brick" . . . . the 2N2222 with
its TO-18 CBE leads being re-positioned accordingly.
If it works, but more range/power is needed . . .maybe a 1/10 mile instead of 50 feet, move to its big brother
the 2N2218/19 in its TO-5 casing.

But MAN that IS being one Snow white PCB, SURELY its a ceramic bisque ?

Did the OEM ROTAMOLA pass testing of the CB-BE forward conducting junctions / voltage test in the diode test
mode of your DVM ?

Yes, the SC370524P DIP Chip is being the producer of the serial digital code burst, that feeds modulation
to the base of that transistor thru the 22K /10 K resistors.

Can we assume that there is another one or two Xmitter's and that they still communicate with the house supereg receiver
OK ?

Waiting for feed back . . .

73's de Edd


.

Hey Edd - Wow, pretty impressive, and fast. Ha I had a 2222 laying out on the bench just trying to finish the schematic to figure orientation correctly (hope). Yep appears to be a ceramic unit. What do you estimate the freq to be, I guessed around 3 meg but sounds like you can probably calculate a solid number, If you had the component values a walk in the park huh. OK ok I'm working on it, lot of irons in my fire. Oh, nope no other spare units, one of a kind.

I want to thank all of you for the input and I will get to individual responses this evening.

Well didn't know what CB or EB were but,- - Ha I guess I did. Was going over the circuit and the bec on the transistor jumped out at me duh. Here I was headed to figure from the circuit which was the base, etc and pnp or npn, - when it was in front of my face. I guess it is time to fess up. I didn't want to ever say anything about it but this makes it pretty obvious to me. I am or was an Electronic Engineer,(retired) but I had a stroke just a little over a year ago and am just getting back to somewhat of a normal function, or I thought I was. got a long ways to go I guess. Any way with that extra little tidbit in my pocket I will continue on and get back with more later this evening. Oh and yes on the testing the transistor, - - on the Ω scale it was open all around, but on the diode test I get B+ E - .782V forward drop and reverse open. B+ C- .780V reverse open. So I guess the T is good and an NPN. So it is now looking a lot like the CMOS bit it. Any one got any Ideas about a substitute for it. I guess it is time to start getting a look with a scope to see what I can find working or not. Later this evening, right. I started writing this about noon, it's now almost 7:00 PM. Maybe tomorrow?

 

[jeff d]

Rowdy if you want my board/remote(s) or any parts let me know. I've got one or two of these which I no longer have use for but was keeping around to play with someday (always looking to learn something new). Mine look identical (except for the button switch). I found this thread looking up the IC and since my wife would prefer I get rid of things and not take on any new silly research projects, they're yours if you want to harvesting parts or just to use.

My board is the revision F, looks like yours is G.

 

[Rowdy]

Rowdy if you want my board/remote(s) or any parts let me know. I've got one or two of these which I no longer have use for but was keeping around to play with someday (always looking to learn something new). Mine look identical (except for the button switch). I found this thread looking up the IC and since my wife would prefer I get rid of things and not take on any new silly research projects, they're yours if you want to harvesting parts or just to use.

My board is the revision F, looks like yours is G.

SOLD: I been looking high and low to find the IC or figure a replacement. So far nada. my email is [email protected]. let me know how much you want for them, the postage, etc and where to send the payment. You won't have to do the research I will in time post on here exactly how to build one of these units and the details of exactly how it works, If I don't die first. So just keep up with the thread and it will come. This guy Edd the NASA dude that has been helping me really knows more than he is putting out there. But eventually I think he will. And with help from guy's like you as well it will all come together. I would bet the rev diff - F - G - is Freq or possible code iterations. THANKS

 

[73's de Edd]

.


Sir Rowdy . . . . .


I thought that you might have picked up all of your marbles / cow chips and went on home.

Did you do any further looking into :

But what I was initially marking up, was those resistors solder pads, and the bottom YELLOW
circled one seems to be floating,

can you confirm that, and possibly the one above it ?
A well as . . . . all of them . . . . over the board.
They would be a QUICK fix.

Pee Ess . . .The F-G (H -I-J-K - ad infinitum) are just being sequential revisions that occur.



73's de Edd

 

[Rowdy]

Yes I did. The ones you had circled, don't look like they have a real problem but all solder joints will be reflowed as I will remove every component and test it and re solder. Sorry I'm not moving real fast, I have several projects I'm working on along with this one. I pulled the bank of switches last night, tested each one and they were fine but did find /create a problem. One leg on the bank severed at the board.

I am not understanding this site. When I wrote the above it was about four times as long but when I went to post it it says I need to login again. So I tried but it wouldn't accept my password. I kept trying till it locked me out. So I went on to some other projects. I was on when you posted about my cow chips but not for long. I just came back to the house and it let me log on. So lets see if I can re-create what I wrote that got left off.

I don't think I broke it but you never know. When I pulled the trigger on the suction on the de-soldering gun the pin disappeared. I don't have another bank of switches so I will graft another pin on there to make do. Now I'm trying to remember and from here I can't even reference your post to jog my memory. Why does it have me in a new area, appending a previous post? I'm not understanding this. I'll try more later, this is stupid.

 

[jeff d]

.
But what I was initially marking up, was those resistors solder pads, and the bottom YELLOW
circled one seems to be floating,
73's de Edd

Interesting that on my board the middle resistor is the only one on this board, the other was clipped out. I doubt I did that, unless I needed a 27k resistor with tiny leads (doesn't sound like something I'd do!) The 5.1M resistor is the only on my board in that group of three.

 

[73's de Edd]

.



Sir Rowdy . . . .



Somebody correct me if knowing that I am wrong, but seems like that serial digital stream security coding on single chip technology;
was initially developed by an individual or small team that used to work for the MOSTEK brain trust in Carrollton, Texas back in their initial
development time of their design slants on the very first 4 banger calculator chips and digital clock calendar chips, and the first LED
wristwatches *.
That was back in the very late 60's . . . . * I had one that I made, with it being a Pulsar knock off, using one of their chips.
Then all of the MOSTEK memory chips , telecommunications chips, musical tone chips, phone dialtone and dial tone decoders came on the scene.

It sort of then looks like Motorola might have absorbed in this SC370524P GDO # . . . (GARAGE DOOR OPENER) . . . coding system
on a single chip. # (Since we don't want to have another CB-BE brain fart. )

Then, their real usage came in with their micro flat pack version, used in FOB transmitters to cars alarm systems.

I was going to look up its applications and data sheets, but it seems like all old stock has been bought up by enterprising Chinese NOS magnates.

As per the presence /clipping of certain resistors, and the potential provision of there being up to three of them, I somehow still want to think that
it is being audio tone frequency related, in the selecting of a specific tone frequency, which is then sliced up as a serial digital burst at that audio frequency.
Then that final modulated RF signal is received at the house unit by a simple super-regenerative receiver and processed to its decoder for a final
confirmation of its validity to that transmit unit coding and then initiate door opening.( And flippin'on de lite bub. )

73's de Edd



.

 

[DonT2012]

Debugging one of these now. Two actually. One works, one doesn't. The cmos chip produces a repeating train of ten pulses which is sent to the base of the transistor. The dip switches determine the width of the pulses (single wide or half wide). The transistor on my remote is MPSH10 NPN Bipolar VHF/UHF Transistor (equiv NTE-229). The problem in my broken remote seems to be in the RF part of the circuit because the pulse train from the IC looks ok. Working on it...

 

[Rowdy]

Debugging one of these now. Two actually. One works, one doesn't. The cmos chip produces a repeating train of ten pulses which is sent to the base of the transistor. The dip switches determine the width of the pulses (single wide or half wide). The transistor on my remote is MPSH10 NPN Bipolar VHF/UHF Transistor (equiv NTE-229). The problem in my broken remote seems to be in the RF part of the circuit because the pulse train from the IC looks ok. Working on it...

Thank you for posting that info. I now have three of them that don't work. Can you post more info like A pic of the unit, values of those resistors, pulse width of those ten pulses in the train, and the PRF any and all info will help. What freq does your operating unit put out? I think these are all 300 meg. Maybe your unit freq drifted? Any way thanks and feel free to jump in with both feet. I'm still working on it as well, and will try to post soon compiling any info gleaned from everyone's input.

 

[DonT2012]

Here's a pic of my functional remote. Note that the LED circuit is not necessary and is absent from this unit. This one has a different P/N on the IC, however my other unit matches yours (SC370524P).



Waveforms below. Top waveform is output of the IC applied to the base of the NPN. Bottom waveform is the modulated signal at the jumper at the center of the printed spiral trace. Ground of my scope probe is connected to the battery negative terminal. I've set the switches on the dip switch to alternating on/off, so the pulse train consists of alternating wide/narrow pulses. The narrow pulse is 0.5ms. The wide pulse is 1.5ms. Pulse period is 2ms. Anyway, if your unit is producing a series of pulses like this, then the IC part of the circuit is probably OK.


My non-functional unit produces a modulated signal similar to the functional one. I don't have freq measurement capability above 100MHz. Agreed my unit might have drifted in frequency. If so, I'm at a dead end without an RF scope or frequency counter. I hope this info is helpful in your debug efforts... Don

 

[Dave.M]

Hi Rowdy, I found this thread searching for the description of the IC on the electronic-device I just found. It's the exact circuit board you were repairing fully equipped. If you're interested I would sell it to you, just let me know. I'm attaching two photos (front & rear) of the device. Regards, Dave