[sdiy] White Lithium Grease for Heat Sink?

[mike ruberto]

Thank you Tim! It's good to know I can get away with it.
Unfortunately, it's moot now as I just discovered that the pass
transistor in this power supply isn't to blame at all.

I think I could use some assistance with it. Here is the schematic.
http://i108.photobucket.com/albums/n13/somnium7/gear/RX7PSU.jpg

Problem is the +22V is very low. Initially it measured 6.5V on the
output. I just swapped the big pass transistors - Q1 and Q2 with each
other.

Now I have -22V and +10V. Grrrrrrr.
This is such a crap circuit design - biasing those fixed regulators
like they did. Just kill the ripple rejection!

I need to go take some voltage measurements around M301 and D302. If
the problem is blatantly obvious to somebody please tell me. It would
be hugely appreciated!

Mike

On Feb 16, 2008 9:15 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
>
> On Feb 16, 2008 5:52 PM, mike ruberto <somnium7 at gmail.com> wrote:
>
> >
> >
> >
> > I was wondering if I could get away with temporarily using white
> > lithium grease for the thermal bonding between a power transistor and
> > a heatsink. Any reason this would be bad?
> >
> >
> > Mike
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at dropmix.xs4all.nl
> > http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >
> >
>
> The main function of heat sink compound is to eliminate any air gaps between
> the mating surfaces of the device and the heat sink. This is why you only
> need a thin film of compound. In that respect, lithium grease should work
> okay. It may not work as well as actual heat sink compound, but I think it
> will be better than air(which is a surprisingly good insulator). You should
> eventually replace the grease with proper HS compound, but it should be okay
> as a stopgap measure.
>
>
> Tim (meant to send the reply to the list) Servo
> --
>
>
> "Imagination is more important than knowledge." - Albert Einstein