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[Amps] RE: burnt-looking adhesive/sealant ... ?

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Subject: [Amps] RE: burnt-looking adhesive/sealant ... ?
From: Will Matney <>
Date: Mon, 19 Jul 2004 13:11:15 -0400
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The plate choke looks to have a bunch of corona dope or black silicone adhesive around its base. I would say there has been an arcing problem here. More than likely, the windings on the choke were loose and they added the adhesive to keep them in place. Whey they put it on the top of the blocking capacitors is beyond me. The parasitic suppressors have been replaced also. By the looks from everything, parasitics have been what's caused all the problems of the arcing. That amp has been "retired" and the HV power supply used for something else. Your looking at a lot of cleaning to get it back to where it once was. Besides, without looking underneath the chassis, I'm afraid what might be there too! The tank coils should be cleaned with a tarnish remover, then sprayed with a polyurethane varnish to prevent corrosion. The tune and load caps should be cleaned well also. Especially where the wiper meets the plates. It looks like it was once blower cooled with chimneys. The chimney clips are still there by the looks of it. If not, a big fan is needed to blow directly on the tube envelopes. Fan cooling is necessary underneath to keep the tube pins cool too. Last, make up a new set of parasitic suppressors for the tube anodes. Finally, there's no way of telling how good those tubes are. In the end, I wouldn't spend very much on this item, maybe $100 at the most.

Will Matney
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