Re: PCB protecter? Waterproofing? How to service?
How can I definitively determine what I have? Is there a wiki page somewhere? Or photos? Or a test I can perform?
scampo77
Badcaps Veteran
Last Activity: 09-19-2016, 06:46 AM
Joined: 12-19-2010
Location: Montreal Quebec Canada
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PCB protecter? Waterproofing? How to service?
I have a circuit board that seems to be cast in nylon? Rubber? Polyester? It's a controller for a transmission. I have seen this in controllers for aviation and generators, more industrial applications and it's usually pretty hard kind of like plastic. For the first time, this compound seems gummy, all most like rubber I can pick at it and slowly remove pieces. Does anyone know if there is a chemical or heat process to remove this stuff? I need to service this board.
Any idea how to remove? or re apply this stuff? Or any idea where I can find out more about it? -
Re: What is telephony? where does the VCC come from?
Here is the work I have done while the site has been down....Leave a comment:
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Re: What is telephony? where does the VCC come from?
Boy am I ever happy this site is back up and running!! I cant seem to attach pictures, but at this point beggars cant be choosers. I have complex photos of my measurements at all ICs, and important transistors and I have measurements from the working corroded board and the failed non corroded board I would like to repair. Unfortunately I cant post photos right now.
Some progress while this site has been down, but mostly bad news.
I have found a different logic board from a donor assembly, I was using...Leave a comment:
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Re: What is telephony? where does the VCC come from?
GOOD NEWS!!
I found a damaged trace under one of the RJ11 jacks. (photo enclosed) this connected "B" terminal to the fuse. the huge trace I was chasing around turned out to be B+. It is de coupled by a cap and protected by a fuse (look on the previous post photos) I repaired the trace and now I have MUCH better voltages to work with.
Now the "B" terminal is B+ and I have much better voltages on the remote board (photo enclosed).
The inverter is still going into...Last edited by scampo77; 01-06-2016, 07:29 PM.Leave a comment:
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Re: What is telephony? where does the VCC come from?
I have found a second non functioning logic board, I have something I can poke and remove parts from to see traces better. please don't comment that the caps are corroded or the solder traces are bad. I am dissecting this one with the intention of throwing it away when I am done with it.
I have removed all of the RJ11 jacks on this donor board to better see the traces. this "B" port seems to go to the neighboring RJ11 port for the auto start module which I do not have hooked up. then it goes to a capacitor...Last edited by scampo77; 01-06-2016, 12:38 PM.Leave a comment:
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Re: What is telephony? where does the VCC come from?
cant I just put a NPN transistor in place of the 15H and see what happens? should I order new communication ICs for each end?
it makes sense that something in the remote side is causing the 4.5v to drop, when I unplug the remote the output voltage bounces back up to 4.5-5 and when I plug the remote back in, the voltage drops again to 3vLast edited by scampo77; 12-30-2015, 11:17 AM.Leave a comment:
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Re: What is telephony? where does the VCC come from?
On the main logic board at the rectifier, I have 5 ohms between the 2 pins on the right hand side, all other combinations have very high resistance.
the picture enclosed is the remote PCB with voltage measurments...Leave a comment:
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Re: What is telephony? where does the VCC come from?
I have no idea what this piece is or what to look for, I just see that there is a "+" and a "-", so I checked for ACV and found some. I have never seen ACV on a circuit board before...Leave a comment:
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Re: What is telephony? where does the VCC come from?
Bud, that photo you linked is the main logic board, I will try my best to label all the photos moving forward.Leave a comment:
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Re: What is telephony? where does the VCC come from?
if I measure for ACV on pins on B&C then I get about 2.5VAC and if I reverse the probes I get 3.5VAC, but its really bouncing around on my meter, It fluctuates by.25v up and down.
I tried to get some photos of the capacitors and also the ICs on the remote. the other 8 leg IC is labeled MTAK 2951 ACMC. sorry I tried to get as many photos as I could but they did not come out very well. These are all photos of the remote board, when I remove the phone cable, everything goes to 0...Last edited by scampo77; 12-28-2015, 05:39 PM.Leave a comment:
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Re: What is telephony? where does the VCC come from?
Measuring A+B together with my meter on ACV I am getting 2.5VAC. I have no way to scope this reading but I suspect you are onto something.
If you look on post #6 there is a photo of the remote board, I don't think there is any rectification circuits here, but I'm not 100% sure what I am looking for.Leave a comment:
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Re: What is telephony? where does the VCC come from?
so after throwing my hat in the air and kicking my cat across the room out of frustration, I came back and realized that my main logic board is not totally dead. I have power to most of the ICs I had before. I now have 4.25v at terminal D leaving the logic board and arriving at the remote board, The remote board is still not working.
I still have power to the 483ECN on the logic board, the only difference now is that I have 4.25v output to the red D circuit.Leave a comment:
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Re: What is telephony? where does the VCC come from?
The voltage defiantly drops to 0v on the remote board when I unplug the phone line. on the main logic board I get an unusual result, I get 4.2v when I unplug the remote and then I get 3v when I plug the rj11 in.
I have 0v on both sides of the F thing located below the 483ECN
while taking measurements for this photo. I moved the board someway that it didn't like and one of the big relays clicked and now everything is 0v, DAMMIT!!
now as soon as I connect the B+ it clicks the relay and...Leave a comment:
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Re: What is telephony? where does the VCC come from?
There is no other connectors, only these 4 conductors on the phone cord. I am pretty sure the power comes from this logic board leaving on the red "D" terminal.
I was wondering if I could just jam 5v to this D terminal, to see what happens? I don't know if this is a good idea or not.Leave a comment:
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Re: What is telephony? where does the VCC come from?
Please ignore post #17, the logic board slides into the inverter like a video card on a PC. I was trying to probe around a corner and I was measuring the wrong port. I have since pulled all of the tin heat shields apart. The previous post (#18) is actual measurements. Moving forward I will do my best to keep the letters and colors the same.
The IC on the remote pin has only 2V at pin 8 with my ground lead on pin5
I have enclosed photos of the micro controller on the remote board. before I started...Leave a comment:
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Re: What is telephony? where does the VCC come from?
Here are some more measurements and some more photos.
there is no loss between the output of the logic board and the input of the remote.
I have negative voltage at one pin, I do not know what this means.
the IC in the photo of the logic board has 483ECN and 0448 on it and also possibly SIPEX ?
the IC above it are LM393 and the one below it are LM358A.
on the photo labeled "back of logic" there is an image of terminal B -1.1v and its very close...Leave a comment:
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Re: What is telephony? where does the VCC come from?
C .25 vdc
D 3 vdc
A,B, Ground
E.F, 0 vdc
The connections are good between the remote and the logic board. I have 0 ohms straight across each lead
terminals E and F don't seem to do anything and terminal D doesn't seem to be strong enough to light up the remote. I think this is possibly the problem??...Leave a comment:
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Re: What is telephony? where does the VCC come from?
I seem to have 2 sets shorted, it appears to be by design, I can follow the traces. the other pins are free and clear of each other.
these female jacks have 6 pins
I have only replaced the 4 female jacks on the main unit and I have not replaced the female plug on the remote....Leave a comment:
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Re: What is telephony? where does the VCC come from?
Dammit!! No I am not!!! I had a problem with the original cable that came installed with this thing. It stopped working so I bought a new phone cable to replace it. It worked and lasted a few months. After 3 phone cables and all worked, I realized the female jack was corroded. I thought the corrosion was my problem. I pulled the unit from the vehicle and replaced the female jacks, now I am in this predicament where the new or old phone cords don't work.Leave a comment:
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