Technical Tips > Post 84

Courtesy lights dimmer module - parts info/tech tip here

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Stingraynut:
The courtesy lights dimmer module is no longer available as a replacement part - with some help from an electronics guru, my 88 coupe has a working module again.

The part that had failed was in a T220 case, it gets hot when the lights are on and I would guess this is the major cause of the module failure.

It is 047 GE 8708 which is no longer available - after analysis of the circuit, the electronics guru found the current replacement for it - MJE 3055.

Mine has been working perfectly now for 5 weeks.

I've detailed a list of parts and as much info as I could find, in case it helps anyone else.

I think this tech tip need pics to show the parts and the module. The Corvettes Down Under Club website, here in Australia, has hosted this tech tip for me.

http://www.corvettesdownunder.com.au/pages/Dimmer.htm

Hope this helps someone

S'nut

Cameron 77C3:
My friend that would have to be the most brillant technical post I have seen.  Well done.

No wonder the transistor failed.  I checked the specs in my transistor manual.  It was under rated, by my standards, for that amp draw.  The heat sink was no way big enough in that closed environment.

Hats off to both you and your electronics mate.:}

Stingraynut:
Thanks Cameron 77C3

Several people told me not to bother trying to fix the dimmer, there's a Dick smith kit for under $20 - but it doesn't perform all the functions of the dimmer, but once again I had my 'stubborn' head on!! (although I prefer the word 'determined' -lol)

I'm amazed you found the 047 GR 8708 part listed anywhere - how do you mean it was under rated, it lasted 15+ years - I'd be very interested, just to tie up loose ends.

S'nut

Cameron 77C3:
It's the way I spec up systems when I'm designing my circuits.  Basically I over engineer my circuits.  If a heat sink is hot to touch then it ain’t big enough in my book.  But that’s just me.  I have always found that automotive industry run it to the wire when it comes to electronics.

Me, when a unit goes out my factory door I don't want to see it again just  because a $1.00 component failed

On the specs, I have some real OLD spec books.  I keep them for occasions like this.  You just never know when you want specs on something that’s not made any more.  And in the world of electronics that can happen over night.

Stingraynut:
I wish I'd know that you had old spec books when we were trying to identify a replacement!!

How do you think the replacement part - MJE 3055 will hold up?

How does it compare with the original ?

Is there a heavier duty part that would be better ? I would include it in the tech tip.

Quote "Me, when a unit goes out my factory door I don't want to see it again just because a $1.00 component failed"

- that's very good to hear, that kind of thinking seems to have almost disappeared - our microwave lost it's display after only 8 months, was repaired under warrantl but lost the display again after about 16 months! now out of warranty - everything's use it and chuck it now.

S'nut

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