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Re: [Amps] GS35b FWB issue

Subject: Re: [Amps] GS35b FWB issue
From: Ian White GM3SEK <>
Reply-to: Ian White GM3SEK <>
Date: Mon, 11 Jul 2011 20:00:43 +0100
List-post: <">>
Carl wrote:
>I was considering mentioning the 6A10 (aka 6A100 by a few mfg) but that wont
>solve the problem. It could be caps arcing (an open equalizer resistor can
>create havoc). An arcing transformer is before the diodes. I assume the
>wiring and connectors has all been checked for arc paths.

I agree with Carl. If all the diodes came from Mouser in the same 
purchase and some of them have been OK in the amp for 2-3 years until 
now, then it isn't the diodes. Something else in the power supply has 
changed recently and is *causing* the diodes to blow.

Arcing would be a definite candidate because it could cause very high 
flyback voltages in the transformer windings.

A possible way to check for arcing would be to drive the various 
individual components (transformer, capacitor stack etc) with a current 
limited DC hi-pot tester.


73 from Ian GM3SEK
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