Headlight problems (Late C4)

[GiDvEtTe84]

Hey guys! Well, my right headlight door isnt flipping. The motor and actuator are working fine. The problem is the control module, as i have the late model C4 2 wire upgrade. I have changed one of the transitors inside before, but now it seems some resistors are bad too. Due to the burn marks, i cant read the colors. Anyone happen to have a schematic for the part? I need to rebuild the circuitry so i can get it working again. I will try to get a pic of it to you guys if i can. Thanks.

 

[GiDvEtTe84]

Ok guys heres a pic. Seems like that burnt resistor is a 120KOhm? I also need to find out how to test the mosfet transistor (which i have changed before) Any help from you electronic gurus would be appreciated.

 

[Nitronick]

There are in-circuit transistor testers, but you are looking at $50 to $100 or more compared to a couple of bucks for the replacements components. It would be cost prohibitive. Just replace both Q4, Q6 and the big one. Being that close to the fried one, They got pretty hot themselves, and I can almost guarantee they are bad or on their way to failing. Semiconductors don't like too much heat. It would be advised when soldering in the new ones, to put an alligator clip on the leads to act as a heatsink.
As for the resistors. They can take quite a bit of abuse and still do their job. But, I would change them just to be safe.

Good luck!

Mitch

 

[GiDvEtTe84]

Thanks I will be doing this. Can you tell if these replacement transistors will work?

Big one:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F002%5F017%5F000&product%5Fid=276%2D2072

Which Little one?:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F002%5F017%5F000&product%5Fid=276%2D1617

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F002%5F017%5F000&product%5Fid=276%2D1604

I cant tell if its an NPN or PNP.


Thanks!

 

[vetteboy86]

I would just replace it. However if you want to check it you will need a DMM or other cheap meter. You can check for continuity between the Drain and the Source of the MOSFET. I believe that would be the second an third pin. If there is continuity between those pins, with no voltage applied to the Gate (power off) then the MOSFET is bad. However with the part so cheap, you could just replace it.


Craig

 

[vetteboy86]

What are the part numbers on the transistor for Q4 and Q6?


Craig

 

[GiDvEtTe84]

Looks like this:

_______
| 227 |
| 78 |
\ ____ /


Q6 is blank. I guess its the same one.

 

[Nitronick]

The numbers you are looking for will be on the face of the component, not the top. You may have to clean it off a bit. If you can't get any numbers, you may have to look them up in the service manual.

 

[WhalePirot]

Seems like that burnt resistor is a 120KOhm?

I'd want to know why that resistor toasted, if possible, but am not an E-guru. I built and fixed a TV or two, but know enuf to be dangerous! Something pulled all that current through the resistor. Perhaps throwing all those other parts at it as NitroNick suggests will get to the root.

 

[Nitronick]

You're talking about that wire to the right of the transistor marked 227 78, right?
It looks to be labeled F2. That wouldn't be a resistor, but a fuse or maybe just a jumper wire.
Something caused this to see a whole lot more current than it was supposed to. It could have been just the large power transistor going out.

 

[Nitronick]

Gid,
After you get those old parts off of the pc board, you will want to check all of the traces on the other side of the board to make sure no solder has bridged between traces. This got hot enough to melt whatever F2 was, and solder melts at a pretty low temp.

 

[Nitronick]

I have changed one of the transitors inside before,

Let me ask you something here Gid. It this the same MOSFET you have changed before?
The reason I ask is, I have cross-referenced the RS number you posted (IRF510), and the BUZ10 in the pic, and these are not the same MOSFET. There are some differences in the specs of these two devices. One of the major ones is the power dissipation. One of them is 20 watts and the other is 150 watts.
BIG DIFFERENCE!
You cannot just go putting any old transistor in there. The specs have to match within a certain degree.

 

[GiDvEtTe84]

Thanks for the help. I have changed the that mosfet before, the one that say BUZ10. I dont think they are made anymore so im trying to find a suitable replacement. Can anyone recommend? I have already ordered from www.mouser.com. I will check the traces as soon as i can.

 

[vetteboy86]

It is a toss up with the mosfet. I suggested in your case that the mosfet failed closed, meaning a dead short. Or other times they will fail open, which I dont think you have a problem with. Looks to me that the heat was located around the mosfet. Perhaps the part did short, causing the increase in current, hence the heat. How much power is this board moving? You can buy a meter for around 20 bucks that has the capability of testing either an NPN or a PNP transistor. As for the mosfet, just replace it.

craig

 

[GiDvEtTe84]

I want to replace it. I just need a part number to replace the BUZ10 and figure out the type of transistor those other one are. Fun fun fun!

 

[vetteboy86]

I would imagine that a late model corvette might have a part that is still produced. You said it was an upgrade, so does the 96 have the same setup as you have? If so you might have a better oppurtunity cross referencing the part they have, versus what you need. Make sense? I guess you could contact a 96 owner with a service manual so they can give you a part number, and possibly some specs.

Craig

 

[GiDvEtTe84]

Well, The smaller transistors dont have any more writing on them.

Heres more pics.

http://kaplantel.net/~ktcisg/vette/board2.jpg
http://kaplantel.net/~ktcisg/vette/board3.jpg
http://kaplantel.net/~ktcisg/vette/board4.jpg
http://kaplantel.net/~ktcisg/vette/board5.jpg

I will try to re-do it as soon as i can.