Another treadmill problem

[loungedebaldy]

OK. After about 50 pics and 2.5 hours of time this pic is about the best I could come up with. If this is not adequate I will go to the neighbors and try their camera. This pic is with a concave mirror.
http://imgur.com/O3DyKlv

 

[loungedebaldy]

I was in the city today and picked up a different multimeter and wouldn't you know it I got some different readings. I kind of figured that there was something wrong with the one I was using. Anyway, I hope you haven't given up on me, Kris. I would like to pursue this to the end. Whatever that will be. Here are the readings that I get with the new meter.
Pin 3 to ds pad is 1.67v
Pin 3 to pin 4 is 12v
Pin 3 to ds pin is 6.15v
ds pin to ds pad is 4.8v
Thanks

 

[KrisBlueNZ]

No, I haven't given up on you! I spend five days per fortnight with my partner, and she doesn't like it when I "waste time" online

I'm surprised by the differences in your multimeter readings, and confused by the measurements themselves. It seems that voltage is coming out of the daughter board on that pin, which is supposed to be a 5V supply voltage input to the daughter board.

My next suggestion is to replace the 78L05 regulator. It's one of those transistor-like devices on the main board. The "78L05" part number is standard and they should be available from any electronic component shop. If you have Radio Shack in Canada, they carry an equivalent called NTE977 - see http://www.radioshack.com/product/index.jsp?productId=12653586

When you've replaced it, don't solder up pin 2, and measure those voltages (pin 4, pin 2 pad, and pin 2 pin) again (relative to pin 3). I'm expecting to see about +5V on pin 2 pad with the new regulator.

At the moment, I suspect the fault is on the daughter board. I think the next step will be to remove it completely and take some very clear and well-lit photographs of it.

 

[loungedebaldy]

OK. Thanks Kris. I didn't doubt that you had a life beyond this forum and a wife and family that liked attention also.
Speaking of family. I have some coming from the city this weekend and will try to get someone to pick up the regulator and bring with them. Thanks for that input. I'll let you know how it goes. Also will check readings again tomorrow and hope they don't change again!

 

[loungedebaldy]

Happy New Year to all.

Well I finally got the regulator and am going to try install tomorrow. Will check those voltages and post when I have some results. Also was able to pick up a new camera so will try post some better picks of the daughter board.

 

[loungedebaldy]

OK. I installed the new regulator and these are the voltages that I get.
Pin 3 to ds pad is 5.1
Pin 3 to ds pin is 6.14
Pin 3 to pin 4 is 12

 

[KrisBlueNZ]

OK. It looks like something on the daughter board is feeding voltage from the 12V rail back onto the 5V rail. I really need to trace out the schematic (circuit diagram) of the daughter board.

How would you feel about desoldering and removing the daughter board, and posting it to me here in New Zealand? I'll PM you my address.

 

[loungedebaldy]

Here are a few pics of the daughter board after I removed it from the mother board. Hope they help

http://imgur.com/iDodewT
http://imgur.com/X5joIyB
http://imgur.com/TAnYVFt

 

[KrisBlueNZ]

Thanks for those pics. I'll see what I can find out from them.

In the meantime can you check the resistance between the +12V and +5V rails on the daughter board for me. With the daughter board removed, and your multimeter set for resistance, measure between pin 2 and pin 4 on the daughter board itself. Measure both ways round, and tell me both readings.

What make and model is your multimeter?

 

[loungedebaldy]

Thanks for those pics. I'll see what I can find out from them.

In the meantime can you check the resistance between the +12V and +5V rails on the daughter board for me. With the daughter board removed, and your multimeter set for resistance, measure between pin 2 and pin 4 on the daughter board itself. Measure both ways round, and tell me both readings.

What make and model is your multimeter?

This new multimeter is a Mastercraft 52-0052-2 auto ranging.

I took some readings after the daughter board was removed and they are.
3 to 2 = 5.1
3 to 4 = 12 These were with black on the 3 hole.
With black on 2 and red on 4 the reading was +6.91

Now I'm set for resistance and unplugged from mains the readings were 15.24 K ohm and the other way was 15.3 K ohm.

 

[KrisBlueNZ]

This new multimeter is a Mastercraft 52-0052-2 auto ranging.

OK. From my Googling, it seems like that's a cheap Chinese multimeter with a Mastercraft badge. It should be fine as long as you don't try to measure the resistance of the wall socket or something equally abusive.

I took some readings after the daughter board was removed and they are.
3 to 2 = 5.1
3 to 4 = 12 These were with black on the 3 hole.

Those are right, OK.

Now I'm set for resistance and unplugged from mains the readings were 15.24 K ohm and the other way was 15.3 K ohm.

Did you measure that on the main board? I need the readings between those pins on the daughter board. That's where I think the fault is.

 

[loungedebaldy]

It should be fine as long as you don't try to measure the resistance of the wall socket or something equally abusive.
Did you measure that on the main board? I need the readings between those pins on the daughter board. That's where I think the fault is.

Yes, I just can't seem to pass up a sale at Canadian Tire! Thanks for the tip about the wall socket. I might just have felt the need someday.

Oop! I should have known you meant the daughter board.
With blk on 2 and red on 4 = 7.7 M ohm.
With red on 2 and blk on 4 = 0.L

 

[KrisBlueNZ]

Well, I'm glad you got it on sale. I wouldn't pay more than $20 for a meter like that.

OK. Can you try the same measurements with the meter set to the diode range please?

 

[loungedebaldy]

Yes, it was under $20 just. Good thing I bought the better of the two that were on sale at the time.
I did do the diode test and both ways were 0L.

 

[loungedebaldy]

The diode test was OL both directions.