87ZTX

Hello TGO community, I'm having trouble, with the headlight module on my 90 formula daily driver, it works one light just fine, but not the other. So what I have tried is re soldering the cracked solder on the pin connectors. However it did not fix the issue. After re inspecting the module I noticed a wire or fusible link burned out right next to relay. So I soldered in a wire to test, worked great, but after a moment I heard a buzzing sound from module and the affected headlight automaticly reversed. Also it began to smoke a bit so I unplugged it quickly..
I'm wondering if where I put the wire if it should be a fusable link or something else. Will post pitures shortly.

87ZTX

broken connection

attempted fix

slightly burned on edge

Restrorob

iTrader: (7)

Off the cuff, I'd say that's a fusible link wire that melts should that "relay" short out. So it was likely already bad melting the link and is now toast.....

87ZTX

I came to that's same conclusion after I patched it, the realay started buzzing, so realized its a loss.
Luckily my local bone yard had a couple, picked one up for 20 bucks

BlackLightning

Sorry for the thread necromancy, but I'm having this exact same issue. (87 GTA, passenger side headlight wouldn't move with switch but could be jumped from the battery, melted fusible link on module board.) I did kind of the same thing as the OP here, took the board to an electronics shop and had them solder a fuse holder in place of the melted link with an 8 amp fuse. When I plugged it in I could hear some noises like the lights were trying to move. I unplugged it, put the lights up manually and then plugged it back in and both lights went down automatically. My memory is a little fuzzy here because of what happened next, I can't remember for sure if I actually tried to put the lights up again or not but I think I did and they wouldn't go up. Then when I flipped the switch back down there was a noise like the motor wasn't stopping. As I was trying to make sure it was the passenger side making the noise I noticed the module smoking and frantically unplugged it. When I opened it up I found the same scorching by that black rectangular component with the gold circle on it (where the arrow is in OP's #3 pic).

I know it's probably too much to expect the dude with 6 posts 8 years ago to still be around but has anybody else seen this problem before? Can I safely assume the board itself had a bad component or is there something else in the motor/wiring I need to look for? I don't want to spend $100 on a new module just to end up with it fried because the problem was somewhere else.

scooter

iTrader: (11)

Bumping a post such as you've done is actually beneficial, don't feel sorry for contributing or asking a legitimate question

The component you're referring to is some sort of transistor. If you look up the numbers listed on the body you might be able to find the same part, or the specs so you can replace with something equivalent.

BlackLightning

Thanks, google hasn't been much help with the numbers but I'm trying to figure out how all this stuff works so I can get a better idea what I'm looking at/for. Did anybody happen to save deadbird's circuit diagram from this thread? https://www.thirdgen.org/forums/elec...ml#post1570146

Also does anyone know the amperage of the headlight motors? Wondering if I need a lower amp fuse since the 8A didn't blow when the transistor was frying.

LAFireboyd

iTrader: (3)

Try contacting lonsal. He's a moderator on the Convertible forum here on TGO. He's also the man behind Top-Down Solutions, a 3rdgen vendor.

He's in SoCal and used to salvage headlight modules from junkyard cars. Then he'd refurbish/rebuild them and sell them. I don't see any on his website at the moment, so maybe he doesn't do it anymore. But he has in the past, so he is familiar with their innards and might be able to answer your questions.

BlackLightning

Thanks, I'll shoot him a DM. I've been going over the circuit board trying to figure out the specs on all the components, looks like Vettes and Lotuses used something similar for that transistor. I found this thread on a Lotus board: https://www.lotustalk.com/threads/li...r-help.123906/ They suggested this as a suitable replacement: https://media.digikey.com/pdf/Data%2...Fs/IRF540N.pdf According to the specs it's rated for 33 amps.

scooter

iTrader: (11)

33 amps should be way overkill. I didn't look at the specs for either, but higher ampere rating is almost always a positive

vorteciroc

Generally a 2.8mm Terminal will have a 30A continuous maximum Ampacity.

So the Transistors (or MOSFETS) should be rated for 60A depending on frequency and duty cycle (if the design is half way decent).

BlackLightning

Thanks everybody. After reading this article https://www.instructables.com/C4-Cor...roller-Repair/ I pulled the clear plastic cover off the center relay and checked the continuity on the wires and it seems one of them is bad. Not sure whether I should attempt to replace the wire or just try and find a replacement relay. I still have to try and test to see if the transistor is actually bad or if the smoke I saw was just the solder melting since it all seems to be gone from under the heat sink.

TOM305T/A

Blacklightning, "i unplugged it, put the lights up manually and then plugged it back in and both lights went down automatically" 'is that a sign of a bad headlight module?

BlackLightning

According to my IRL Firebird buddy, that's actually normal. The issue that made me think I had a bad module was that the passenger side light wouldn't go up or down at all but the motor worked when jumped from the battery. When I replaced a melted fuse on the module board the lights would go down but then the passenger side transistor (Q1 on the board) started overheating and I had to abort testing.

I ordered FAIRCHILD FQP50N06L MOSFET, N transistors
And Omron MY4-DC12 Relay, General Purpose, Double Throw, 12 VDC, 4 Pole, 75mA relays going off what they said on the Lotus and Corvette pages about a similar issue.

The gold circle on the metal part of the transistor that I thought was a small heat sink is apparently just a rivet, I'm having a hard time finding the same one, at least on Amazon. The worst part is going to be getting the old one out without making a mess of it...

vorteciroc

Gently apply a light amount of pressure to the Rivet with an Electric-Drill, using a Drill-Bit that is slightly smaller in diameter than the Rivet.
Do not rush, and do not apply much force or the PCB and/ or near-by Components can be damaged.

As a side note: Fairchild FETs, and Omron Switching-Components, are both excellent products!

vorteciroc

If anyone is new to Soldering... Flux will be your Best-Friend!
Flux can be applied from a syringe, to make a small Pool of Flux on the PCB... if having trouble with assembly.

De-soldering with a large/ powerful Iron makes thing easy...
Do Not get the PCB too hot.

A small Tip or Micro-Iron will probably make most of the assembly easier.

Apply Flux-Core Solder to the Iron first...
Then apply some to the PCB Contacts...
Then the Iron again...
Then the Component...
Then the Iron again...
Then Solder together.

You guys are very lucky that this stuff is OLD Technology!
Be very happy that you do not have to work with Micro Suface-Mount-Components, that are so small that a Micro-Scope is needed for Repairs/ Assembly.

Good luck, and have fun!

TOM305T/A

yea, im trying to figure whats going on with my lights. my original module is toast. no power getting to lights. i got a new used, "tested" module. i put it on and it closes my headlights. but wont open them

OrangeBird

iTrader: (1)

Hi Tom, one thing you could check is this; The module is supposed to have +12V on the white wire with the headlight switch off, and +12V on the yellow wire with the headlight switch on. Since your lights close but don't open, it'd be a great troubleshooting aid to know whether the yellow wire actually does get power when the switch is in the on position.

BlackLightning

Thanks for the info and tips, you guys!

PSA for anybody else undertaking this: the 2-pack of Omron relays that's $9 on Amazon has the wrong kind of pins for this board, d'oh. The module with the PCB pins sure isn't as cheap or easy to find as it apparently was a few years ago.

Ironically I found a C5 Vette board on eBay for less than I'm spending on all the stuff to fix this one but I feel obligated to at least attempt it. If it works guess I'll have a spare board at least...