>
>Feel the face of the power supply, if it is about 130-140 degrees, you
>may have a problem. I thought it was normal, but on repair the face is
>running fairly cold.
Electrolytic caps have more going on than most people realize.
They have finite design lifetimes, and an interesting equation to
predict the impact of ripple current and temperature on that lifetime.
Jim Williams at Linear has, IMHO, the best equation, it's in his design books.
The temperature term is basically +10C = -50% lifetime.
It pays to just change the things out every few years.
When I worked for Muzak, we of course had a lot of amplifiers in the
field, and lots of them coming in for repair.
After a while I noticed that some would come back again, with
different transistors blown than the previous failure.
This led me to look at why the transistors were failing, and in most
cases, a bad cap was at the end of the chain.
So, I started replacing electrolytics wholesale on any amps that had
failed transistors.
Repair rates dropped rather sharply. That, and Cramolin (now DeOxIt)
were my two major discoveries at the time.
When I joined, the repair shop was five guys busy most of the day,
when I left, it was just me, bored most of the day.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Repeater-Builder/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
