Circuit Board Repairs?
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Circuit Board Repairs?
Can anyone recommend a shop that does circuit board repairs? I have a courtesy light delay timer board which has a bad diode. I need a competent shop to properly diagnose and repair. Any help here will be appreciated.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Can you see a damaged component on the board? If so, why not just buy a pencil-type soldering iron and a couple of heat sink clips (to prevent excess heat getting to other parts) and doing it yourself. Take the board to a Radio Shack and they can probably sell you a suitable diode for the replacement. Just orient the banded end the same direction when you install it.
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Can you see a damaged component on the board? If so, why not just buy a pencil-type soldering iron and a couple of heat sink clips (to prevent excess heat getting to other parts) and doing it yourself. Take the board to a Radio Shack and they can probably sell you a suitable diode for the replacement. Just orient the banded end the same direction when you install it.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Radio shack is another source if you know what is bad on the board.
Willcox Inc.
Willcox Inc.
Last edited by Willcox Corvette; Jul 24, 2010 at 08:38 PM.
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Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
Unless you see some evidence of heat on the board underneath it, I wouldn't worry about the capacitors. To test a diode, just cut one lead loose [above the board...you can tack solder it back later if OK] then check the diode both directions with an ohmeter. One way should read low ohms; one way should be high resistance. If either way is shorted, it's bad. Look for any components that show signs of heating on the board and replace them with equivalent parts (but maybe higher wattage, if it's a resistor). Really, what have you got to lose? You have to remove it to replace it, anyway. And, if you don't do any damage during the repair and it doesn't work, you can still take it to a repair person. I think the odds are with you that you will be successful.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
I repair electronics for a living. Testing a diode is easy. usually you don't even need to take a lead loose. On your multimeter, there sould be a selection like this -->│--, an arrow pointing to a line with a line through it. this is the diode check selection. select this, then put the red lead on the lead part farthest from the line on the doide, and the black lead on the other lead, the reading should be about 0.5 to 0.7 volts. Now reverse the leads, the reading should be open, or no reading, that is to high for the meter to read. this denotes a good diode. if the front reading is below 0.4 V or the reverse reading is any read voltage, remove one lead and retest. If the reading remain the same, the diode is bad, if they are as good above with one lead removed then the diode is good.
Advanced
Joined: Apr 2006
Posts: 87
Likes: 0
From: Finly IN
That is primitive electonics.
I work on electronics as well. Boy that is primitive. It's difficult to make out the diodes, but I agree. It should conduct in one direction, and show an open/higher resistance in the other.
Another problem area is solder joints on older equipment. With age you will see the joint turn gray and flakey. Try touching the tip of your soldering iron to each joint. Usually resistors open or increase in value. Diodes and capacitors short.
Take a better picture of the diodes in question.
If you need it look at I'm certified as a soldering tech and work on multilayer boards for aviation related equipment. A local TV repair shop could fix that for you if you are uncertain. Possibly a local electronics shop class even.
Another problem area is solder joints on older equipment. With age you will see the joint turn gray and flakey. Try touching the tip of your soldering iron to each joint. Usually resistors open or increase in value. Diodes and capacitors short.
Take a better picture of the diodes in question.
If you need it look at I'm certified as a soldering tech and work on multilayer boards for aviation related equipment. A local TV repair shop could fix that for you if you are uncertain. Possibly a local electronics shop class even.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Those aren't diodes, thos are ceramic capacitors. the diode is the small black cylindircal device in the front with two leads and the silver line. t5hose type of caps don't usualy fail, they look dirty to me, not bad. i could replace every componant on the board in about 10 mins. i'll be happy to look at it if you'd like, i'll send my address later,, no charge. C.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Those "jobbies" are capacitors...and they are very unlikely to be bad. I really don't see any obvious heating on the board. If that board is really bad [keep in mind that your problem could be due to a defective tach head unit or a wiring issue, also], my guess is that it would be the integrated circuit or the transistor...but I doubt it. Without an obvious indication of heating or damage, it would be difficult to identify a faulty component without having a way to 'bench check' the board's function. If I were you, I'd rule out all of the other possibilities before attacking that board. You might be able to find a repair source who could check it out before deciding any repair is necessary.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
P.S. Isn't there also some sort of "filter" component in the wiring leading to that board? If so, I think that those go bad more frequently than the circuit board. They are also easier to fix. I seem to remember the circuit diagram for the filter unit being in the Forum archives somewhere.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
On the delayed timer there is not a inline filter! Unlike the tachometer, it is a direct timer board.
Willcox Inc.
Willcox Inc.
Thread Starter
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Those aren't diodes, thos are ceramic capacitors. the diode is the small black cylindircal device in the front with two leads and the silver line. t5hose type of caps don't usualy fail, they look dirty to me, not bad. i could replace every componant on the board in about 10 mins. i'll be happy to look at it if you'd like, i'll send my address later,, no charge. C.
YOUR THE MAN !
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Sorry about that. Somewhere between postings my brain went from "courtesy light" to " tachometer" problem. Please ignore the references to tach and filter. My comments about the circuit board and how to proceed remain the same, however.
Instructor
Joined: Aug 2006
Posts: 188
Likes: 1
From: Kamloops BC
I see 6 semiconductor parts on that circuit.
2 signal doides behind the cap in the circle
1 IC mc14069u hex inverter
1 zener diode?? with the blue stripe
1 rectifer diode wth the silver stripe
1 transistor ??
From my experience the transistors are the hardest to replace as the parts # is some sort of in house general motors #. You need to find a good part and figure out what it is NPN,PNP,gain,pinout or in some cases trace the circuit.
The timer you have shown does not look like the timer for a C3 ,is it from your 89? If so, you may have better luck asking your question in the C4 forum.
If you want I can look at your timer but sending stuff across the boarder is a PITA.
Cheers
Dale
2 signal doides behind the cap in the circle
1 IC mc14069u hex inverter
1 zener diode?? with the blue stripe
1 rectifer diode wth the silver stripe
1 transistor ??
From my experience the transistors are the hardest to replace as the parts # is some sort of in house general motors #. You need to find a good part and figure out what it is NPN,PNP,gain,pinout or in some cases trace the circuit.
The timer you have shown does not look like the timer for a C3 ,is it from your 89? If so, you may have better luck asking your question in the C4 forum.
If you want I can look at your timer but sending stuff across the boarder is a PITA.
Cheers
Dale
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Those aren't diodes, thos are ceramic capacitors. the diode is the small black cylindircal device in the front with two leads and the silver line. t5hose type of caps don't usualy fail, they look dirty to me, not bad. i could replace every componant on the board in about 10 mins. i'll be happy to look at it if you'd like, i'll send my address later,, no charge. C.