Please help troubleshoot Ecoplate II amp hum

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Well-known member
Oct 8, 2014
Hi all,

I have 2 ecoplate amplifiers and one is notably humming and the other is silent. You can hear mild mechanical noise from one amp and not the other and it is being amplified at the output. I replaced in the transformer in the humming amp with a new old stock transformer matching the other amp and it didn't help. When I came back to this issue this week I noted that the fixed negative voltage regulator was shorted. I was getting no capacitance readings on all the filter caps on that side of the circuit. Today I just replaced that regulator and is still hear hum. I'm getting symmetric postive and negative 18v on both sides of the power supply currently. I'm not sure what other parts to start replacing. I ordered a few positive fixed voltage regulators just in case that is contributing to noise despite the fact that its not shorted. I'm not sure how the amp was working with negative side shorted prior. I'm wondering what other components if any could have been damaged in the process. I have included schematics. Any wisdom would be appreciated. I'd like to use this plates in stereo and this is preventing it.


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