Pultec MEQ-5 clone SRPP transformer hookup and hum
« on: August 25, 2008, 04:58:31 PM »
Hi,
 I have been searching and reading as much as I can find on this subject, I am trying to put together a dual MEQ-5, I have the two SRPP Boards stuffed and wired up to the transformers but I am getting an incredible amount of hum.  I am using two Amveco 62062 Toroid transformers, here is a rough diagram I made to make sure I have it hooked up right.

I followed the instructions on the "Transformer heat" Thread.

thanks

Howard



I also want to add, when I have just one SRPP board connected it's very quiet.


inputoutput

Pultec MEQ-5 clone SRPP transformer hookup and hum
« Reply #1 on: August 26, 2008, 06:42:56 AM »
you might find this info handy  http://www.groupdiy.com/index.php?topic=5429&postdays=0&postorder=asc&highlight=amveco+pultec&start=45&sid=98fc52e005a4e4022cdb9b72bc2dd554
 bout the voltages (250V) and the 3K3 resistor.

Remember it mentioned in an earlier PEQ1 post,  that a builder here got rid of his hum by experimenting with the rectifiers.  Think he went for 6A 600V rectifiers.

If you ve already have looked at the ground through a scope, and checked the voltages on the 317 regulator, I would swap the rectifiers and see what happens.  And keep a lookput on where the ground goes to chassis. If it is on both the input and from the PSU, you might have a groundloop humming.

The regulators needs fairly large heatsinks to work right


 

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