Relayed Help on Aleph4

[mefinnis]

Hi All,

For some strange reason I get a lot of help requests on Aleph amps, most of which I can answer easily ....... however, this one's got me stumped !!

Could one of the EE theory types offer any help?
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Dear Mark,

I'm building your Aleph4 version and experiencing some problem. All seem to be right but when turn on without load (I try first on speaker and burn it), voltage at output goes about 84V (power supply is +- 42V) and burnsR22 and on FET boards the Mosfets and resistors asociated (.68 e 220 ohms), that relate to the s terminal (not S).

Thanks for advice

Matheus
matheuscosta@yahoo.com
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PS: I have already told him to check that the pin configuration of his FETs matches and that they are installed correctly, can't see how this would occur unless FETs are installed incorrectly ;-)

[Edited by mefinnis on 10-12-2001 at 05:56 PM]

 

[promitheus]

I think that there could be a mistake with the pin layout. Some fets have different layouts. You should check again your connections, unless you have oscilations going on. I can´t really say anything else from the info you gave. Good luck solving your problem.

 

[Ligado]

Hi,

Thanks to promitheus and mefinnis, I really commit a mistake in wiring fet pcb to main pcb (changing "s" by "S"). Then the baby work for about 2 hours (great sound) and stop. I checked and find that same fets are burned, that are wired on "s" terminal on the fet boards.Before this,when I turn on the amp I touched all fets and find that these two fets are working hotters than others. Can be this a problem with pcb layout? I notice that only these fets has your source wired directly to R22. I'm looking in the schematics and I think that all fets must have yours sources (before source resistor)conected together. Am'I wrong? (P.S. fets are IRFP250N,matched at .02V, isn't the best choice but are what I can take in my city in the South of Brazil)