It sounds like you may have an open cap in the string.
Carl
KM1H
----- Original Message -----
From: "Pete Soper" <pete@soper.us>
To: <amps@contesting.com>
Sent: Monday, June 06, 2011 3:04 PM
Subject: [Amps] Titan 425 power transformer question
> Folks,
> A bug deposited a big glop of mud (+ larvae) into the gap between one
> of the PS caps of my Titan and also glued the top of the cap to the side
> of the power supply metal cover. The cover and the rest of the case was
> very well grounded and the PS fuses never blew, the amp just stopped
> working. I have no idea how long a mud/dirt short was in place, but the
> larvae obviously didn't make it out alive.
> The cap in question tested obviously bad and I made an exact
> replacement. All eight caps now behave the same now, except the voltage
> across each varies by 1-5%.
> I spent a few days reforming the caps while fretting that the
> transformer/rectifier by itself is only putting out about 1300 volts in
> the "high" setting.
> With the caps in place there is only 1650 volts present (i.e. about
> 550 volts short of spec). If a 14 watt signal is put into the amp
> briefly the plate voltage dives to about 1kv and comes back to 1650 over
> the course of 3-4 seconds. All of the rectifiers are open one way and
> dropping 1/2 volt the other way (with a meter having a diode test
> position).
> Am I correct to think the transformer is toast?
>
> Regards,
> Pete AD4L
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