[Kenwood] PS-430 troubleshooting

Sat, 12 Jul 2003 11:04:22 -0700

Jerry,

Many years ago I too had a PS 430. When it failed, I realized
that it
has a design concept flaw. If for any reason, the output voltage
drops
due to overload (despite the current limit), the cooling fan is
not very
effective. As  result heat builds up.
At the time I modified the supply by installing an auxiliary
voltage regulator.
The input to the regulator was right at the output of the
rectifiers. The entire
fan circuit was connected the auxiliary 12 volt source. While the
board was
out I also replaced the cheap pots with Cermet type.
The 'bad' part for this modification is that it required some
'minor surgery'
on the printed circuit board.
Overall, it was worth the effort.

73,

Mort,  KB6BSN

----- Original Message -----
From: "Dr. Gerald N. Johnson, electrical engineer"
<[email protected]>
To: "Tom Bowman" <[email protected]>
Cc: <[email protected]>
Sent: Saturday, July 12, 2003 7:48 AM
Subject: Re: [Kenwood] PS-430 troubleshooting

> Most likely the electrolytic capacitors have reached the ends
of their
> lives. The big filters especially. Or it could be that their
connections
> (if screwed) have come loose. Electrolytics do have a finite
lifetime
> which is shortened by more than a couple years of no use.
>
> Its also possible that there's an open diode in the rectifier
section.
> That would make the hum frequency 60 Hz instead of 120 Hz, so
checking
> the frequency of the hum is a handy diagnostic technique.
>
> These parts are easily identified by their size, and a
schematic may not
> be necessary.
>
> The schematic of the PS-430 is probably in the service manuals
for the
> TS-430 and TS-440, maybe the TS-130.
>
> 73, Jerry, K0CQ
> --
> Entire content copyright Dr. Gerald N. Johnson, electrical
engineer.
> Reproduction by permission only.
> - - -
>
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> Larry Wilson KE1HZ [email protected]
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