Printed Circuit Question 79 K10

79K10Step · Mar 10, 2024

My problem is left turn indicator light is not working. All other gauges and lights working fine as most are new. On the back of the Printed Circuit Board the copper ribbon wire has a break in it wide enough that I will need to make a jumper. Question is how can I attach a jumper to this copper ribbon - Solder another piece of ribbon - silicone glue that conducts etc... I have some old Circuit boards just trying to figure the best way to fix as the copper ribbons on the PCB are very thin?

GTX63 · Mar 10, 2024

I believe LMC has circuit boards for your truck in stock now for less than $60. I had a 1980 GMC with the same left signal indicator issue.

ChuckN · Mar 10, 2024

79K10Step said:
My problem is left turn indicator light is not working. All other gauges and lights working fine as most are new. On the back of the Printed Circuit Board the copper ribbon wire has a break in it wide enough that I will need to make a jumper. Question is how can I attach a jumper to this copper ribbon - Solder another piece of ribbon - silicone glue that conducts etc... I have some old Circuit boards just trying to figure the best way to fix as the copper ribbons on the PCB are very thin?

When I took apart my cluster to do the tach conversion, mine had a printed circuit failure at one point. He had taken a couple small screws drilled through the back of the green plastic, and homemade a couple terminals out of them, one on each side of the part that had gone bad. He put a jumper wire from one terminal screw the other other to bypass the broken part. It looked sketchy as hell. But it might have been fine.

I second the recommendation for just getting a new printed circuit. They’re cheap overall and if you are missing any gauges or a tach that you would like and are missing, would be an opportune time to do it since you’re already in there.

Rickf · Mar 10, 2024

If plan "A" (new printed circuit) isn't an option, then what about going directly from the plug to the bulb?

Kiely · Mar 10, 2024

An easier fix is to use copper foil like they use doing stained glass lamps. The back side is sticky so it is easy to get it to stick to the circuit boar. To completely secure the fix, solder a little spot on each end of the repair.

RustyPile · Mar 10, 2024

ChuckN said:
When I took apart my cluster to do the tach conversion, mine had a printed circuit failure at one point. He had taken a couple small screws drilled through the back of the green plastic, and homemade a couple terminals out of them, one on each side of the part that had gone bad. He put a jumper wire from one terminal screw the other other to bypass the broken part. It looked sketchy as hell. But it might have been fine.

I second the recommendation for just getting a new printed circuit. They’re cheap overall and if you are missing any gauges or a tach that you would like and are missing, would be an opportune time to do it since you’re already in there.

That would work very well only if the broken trace were a ground path.. The broken trace the OP has can't be repaired using that method.. I've repaired several broken traces by soldering a "bridge across the broken spot. Scrape the coating off down to shiny copper, but don't further damage the trace or cut through the plastic. Use a short piece of solid (not stranded) 20 - 28 gauge bare wire. Tin it very good and solder it across the break.. Don't use 100 watt "gun". A small 40 watt iron used for electronic work is best.

79K10Step · Mar 10, 2024

Thanks to all of you for the good suggestions. The reason I had not gone for the new circuit option was twofold - one the PCB's have many different options (knowing LMC has 78-80 w/out tach) excluding the obvious tach option which I don't have for example mine has 4wd indicator some don't mine has a clock some don't etc.. The second concern I have is attaching a new one and messing up something that works. I will try to jump it and if that fails I will go for a new one. I will not use my propane soldering iron or my strong electric one as suggested. A direct connection to the bulb from the plug may work also. Thanks again

GTX63 · Mar 10, 2024

I had an oil pressure gauge that wasn't reading on one of my trucks not long ago. I traced it to a bad Sending Unit Female Terminal/circuit board connection behind the gauge. So, with other jobs coming up and not wanting to tear the dash out again, I ran a wire from the main terminal attached to the gauge directly to the sending unit. Done and done.
Now, if I never get back to replacing that board and sell the truck, eventually someone else down the road will for whatever reason, have the dash opened up and have a "WTF" moment.

tadslc · Mar 20, 2024

GTX63 said:
I believe LMC has circuit boards for your truck in stock now for less than $60. I had a 1980 GMC with the same left signal indicator issue.

I bought one of those circuit boards from LMC and was very disappointed in the quality. Typical Chinese junk. After I installed it 1/2 the lights didn't work. Found nothing was really wrong with my old one so I just cleaned it up and reinstalled.
I'd do whatever it took to get your original board working.

Goldie Driver · Mar 20, 2024

If the PCB is torn this probably won't work. If not, it might.

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I did not know they made this stuff and did solder some stranded wire ( what I had) to repair mine.

I would agree the OE is thicker and better made.

GTX63 · Mar 21, 2024

tadslc said:
I bought one of those circuit boards from LMC and was very disappointed in the quality. Typical Chinese junk. After I installed it 1/2 the lights didn't work. Found nothing was really wrong with my old one so I just cleaned it up and reinstalled.
I'd do whatever it took to get your original board working.

I have access to enough donor vehicles that I can still go with used OE as a first choice. If I lived more urban or didn't have room for cadaver trucks, I'd use places like LMC or fill in the blank often, and yes, sometimes with a grain of salt. We used to joke in the old days about trucks built on a Monday vs Friday. The modern aftermarket supplier has a quality on par with Walmart. I have aftermarket electronic parts that has lasted for years and other stuff not so much. That is now the state of most consumables.

greyghost · Mar 27, 2024

aluminum duct tape hvac guys know...somebody makes repair kit for rear window defroster grid that i think is a conductive paint fixes broken grid lines ingenious product

bucket · Mar 27, 2024

greyghost said:
aluminum duct tape hvac guys know...somebody makes repair kit for rear window defroster grid that i think is a conductive paint fixes broken grid lines ingenious product

I believe it might be Permatex that offers the defroster repair kit.

Printed Circuit Question 79 K10

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