As for the thermal compound, it depends on the compound. I use Arctic
Silver which cures after an hour or two of use, giving the appearance of
being dried out. It's supposed to look (and feel) that way. I never
had the white Silicone heat transfer compound dry out. As I worked for
the company that makes it, I had one large tube ( several lifetime
supply if you repair computers. ) You put a small gob in the middle of
a quantity just large enough to eventually cover the contact area.
Your line voltage may be high as I'm assuming you are running
conventional power supplies. I've had several Astron switchers fail.
They promised a new fan which failed on day 2, but it never arrived.
So, with Astrons, I stick with conventional configurations. On that
note, be careful, the configuration or parts may not match. Also, on
the BIG, 50 and 60 ? amp supplies (forgot which mine is). I had a screw
fall down the side. It was only a little flash, but it took out two of
the pass transistors. For only a little more I was able to get pass
transistors rated for quite a bit more current. I replaced them all,
and it's been running over 5 years (I think)
73
Roger (K8RI)
On 1/28/2015 11:13 AM, Charles Compton wrote:
On both of my Astrons, I noticed that the output transistors ran extremely
hot. Check to make sure that the thermal compound on the transistors and
associated insulators is not dried up. Properly apply fresh compound to
ensure adequate heat transfer to the chassis. More is not better and thermal
runaway is not your friend. This could be your root failure cause.
73
Charlie
K4BQP
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