Re: Ampliphone HV FAQ is done!!!

On Mon, 7 Jun 1999 15:11:12 -0700 , you wrote:

>If the FAQ is for hot-rodding the Amplifone it might be worth a mention to
>replace those rubbery-fabric insulators that Atari was fond of for a while
>with something with a better coefficient of heat transfer. Even good-old
>mica+heatsink grease is pretty good. Most of those "dry" heatsink materials
>that claim all sorts of super-high heat transfer efficiencies never seem to
>work very well in the "real world", IMHO. Low-tech silicone grease is
>pretty good, although messy.

That's a good point, and something I do when ever I have to replace a
heatsinked part. There's a local surplus store that sells the mica
insulators for a few cents each, I just bought a "whole bunch" and
replace any of the "rubber" insulators I run into.

>> I don't believe Michael's original intent was to "make things simple",
>> but was to "make things a best as they can be", which is the only
>> reason I brought up the insulator in an, email to him, in the first
>> place.
>>
>I understand. I'm still a bit of the opinion that it might no be a bad idea
>to insulate them both and use liberal amounts of silicone grease. Not that
>it *does* anything on the 7824, but people tend to buy and sell machines and
>when the next owner decides the "fix it up" and sees one with insulator and
>one without they might be tempted to remove (or simply forgot to put back
>on) the "important" insulator... Plus, people like symmetry. :-)

Sure, but you don't really go through all your working games just
looking for un-insulated parts to slap insulators on do you? ;^)

>(I'm guilty of such a screw-up from working on a car amp a couple years ago.
>It had a couple MOSFETs or something where one was insulated and the other
>wasn't. The insulator was looking pretty cooked so I removed the heatsink
>and cleaned both MOSFETs and heatsink with alcohol really well. I got
>interrupted by something and came back to the job a few days later. I
>couldn't really see where the old insulator went anymore, but I *knew* is
>was the one of the right... Of course I was wrong and let the magic smoke
>out when I powered it up. *grrrrr*. Sure, it's a "don't do that" error, but
>if they both had heatsinks I wouldn't have had enough rope to hang myself...
>;-)
>
>On the other hand, no-matter how much idiot-proofing there is, there'll
>always be a better idiot somewhere...

Pretty scary, I did almost exactly the same thing with an old
Harmon-Kardon car power amp. (It had a really weird double heatsink
thingy that required a separate insulating strip I failed to notice,
that slid a bit when I reinstalled the transistors.) And it used
those damned Japanese transistor that are a pain to find (mail order!
Yuck!)

Man I was pissed! I hate it when I look at something that's working
great, and just can't resist that urge to break it!

-Zonn
Received on Mon Jun 7 17:46:10 1999