Instrument voltage regulator?

[MaximRecoil]

I agree.  I did the "build it yourself" conversion before going to Carlisle last year and it got way too hot for me.  Hot enough that you would burn your finger if you touched it.  Seeing (and feeling) that, I ordered up the one from RTE and it is nice and cool and does not get hot.  There is even a red LED light that blinks to let you know it is functioning properly.

The RTE one looks great, but for a few dollars vs. $50, I'd rather try the few dollar method first. Instead of cramming it all into the shell of the original regulator, I think I'm just going to do it out in the open, and maybe screw it down where the soon-to-be unneeded condenser is currently screwed down. That way I'll be able to use a real finned aluminum heat sink ...



... along with thermal compound, rather than making the old regulator housing act as a heat sink (which has no fins, is very thin, and is made of who-knows-what kind of metal; i.e., not a very effective heat sink). I think that should keep it cool enough.  

[A383Wing]

I just mounted the 7805 chip to the outside of one of the OE regulator housings...that acts as the heat sink...been working fine on all my cars since 1996

[MaximRecoil]

I just mounted the 7805 chip to the outside of one of the OE regulator housings...that acts as the heat sink...been working fine on all my cars since 1996

Mounting to the outside of the housing would probably work a little better in terms of cooling than mounting it to the inside, and it no doubt provides sufficient cooling either way, given that many people have done it both ways without problems.

I like the idea of a real heat sink though (by "real" I mean something designed specifically as a heat sink for the 7805 chip, made out of a good, [and relatively thick] thermal conductor [aluminum] with fins for increased surface area) for a few reasons, e.g., peace of mind, not having to destroy the original (still working) regulator, and only being $3. 

[A383Wing]

I could not put the chip on the inside..that's where I put the capacitor

[MaximRecoil]

I could not put the chip on the inside..that's where I put the capacitor

Both the capacitor and the chip can fit inside, as long as you use a small enough capacitor. You can see pictures of it done that way here and here. Though it is neat and tidy looking doing it that way, I think better cooling results from mounting the 7805 chip on the outside of the case. Even better cooling results from a purpose-built heat sink (in which case you don't need to use the original regulator for anything). That's how Mopar Action did it in their August 2000 "Gage [sic] Rage" article:



(The heatsink I linked to previously is the exact one they used, by the way)

[MaximRecoil]

Does this look right?



Also, how is the instrument cluster's entire aluminum frame grounded? Is it just through the 5 little screws that secure it to the dash? If so, I think I'll add a ground strap to it just to be certain that the entire thing is well-grounded.

[A383Wing]

the center terminal of the 7805 chip is 12v into it....and where is yer capacitor?

and yes, dash is grounded through mounting screws

[MaximRecoil]

the center terminal of the 7805 chip is 12v into it....

According to all the instructions I've read, the center pin of the 7805 chip is negative and is supposed to be grounded. For example, from the Mopar Action "Gage Rage" article:

"The center pin is also connected to the mounting tab, and is ground."

And a diagram of the 7805 chip:

and where is yer capacitor?

It is just to the right of the "+" and "-" symbols that I added to the picture, which I added to show the polarity of the capacitor (10 μF, 35 volts):

and yes, dash is grounded through mounting screws

Thanks.

[A383Wing]

ok...yup..yer right about the center pin on the chip...it is ground....sorry..old age here...and I stopped making these regulators a while ago....

Bryan

[MaximRecoil]

ok...yup..yer right about the center pin on the chip...it is ground....sorry..old age here...and I stopped making these regulators a while ago....

Bryan

Okay, so the way I did it looks okay then?

[A383Wing]

yea...as long as the capacitor is going from "+" to "-" and it's large enough....also, the capacitor is polarity sensitive....meaning it has to be connected correctly so it works right..I can't tell from the picture....

from what I remember, (don't say it)....one end of the capacitor has either a "0" or a "-" on one end....I think that goes to ground

[y3chargerrt]

The side with the stripe on it is ground on a electrolytic capacitor is always ground.

[MaximRecoil]

yea...as long as the capacitor is going from "+" to "-" and it's large enough....also, the capacitor is polarity sensitive....meaning it has to be connected correctly so it works right..I can't tell from the picture....

from what I remember, (don't say it)....one end of the capacitor has either a "0" or a "-" on one end....I think that goes to ground

Yes, in my first picture I indicated the polarity of the capacitor with a "+" and "-" symbol, i.e., the positive leg is soldered to the middle pad (+12 VDC input) and the negative leg is soldered to the bottom pad (ground). In the second picture you can see the stripe on the capacitor more clearly, which indicates the negative leg. It is 10 μF, 35 volts, which is a suitable value according to all the instructions I have read.

I've dealt with capacitors a lot before; I've installed a lot of "cap kits" on old arcade monitors and power supplies; and I soldered components to boards in a PCB factory for about two and a half years when I was younger.

The side with the stripe on it is ground on a electrolytic capacitor is always ground.

Yes, and the negative leg is also the shorter of the two legs on a radial capacitor.