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Old March 5th 19, 07:38 AM posted to sci.electronics.repair
Phil Allison[_3_] Phil Allison[_3_] is offline
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First recorded activity by DIYBanter: Aug 2014
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Default Engl valve amp disaster

Gareth Magennis wrote:




I still don't have the schematics for this amp, maybe putting the protection
diodes on the heater circuit instead of ground was a big design mistake.
I have moved them to ground.



** That the HV diodes connect to the heater line ( instead of chassis ground ) likely did not cause the failure, but it sure caused all the damage.

FYI:

A tech working for the maker / importer is NO use to you when it comes to bad design problems. I see a lot of them these days in tube amps and have to modify circuits to effect a reliable repair.

I don't give a hoot what the amp maker or even the customer thinks of this cos *** I *** am the one liable for a repeat failure both financially and in terms of reputation.



..... Phil