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Sovtek MIG-30 schematics
Old 27th August 2007
  #1
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hangman's Avatar
 

Sovtek MIG-30 schematics

hello,

I just got a Mig 30 very cheap. its one of the earlier Sovteks, actually serial number #000038.

The amp has this ugly Buzz to it, but I can't seem to figure out what exactly is causing it.

I've replaced the filter caps with good quality F&T capacitors, and the diode rectifier was being weird, so I replaced both. the AC ripple is much better... but I'm still getting what I would consider to be unacceptable hum.
the power transformer has a audible buzz when the power is turned on.

could that be a part of the problem? the power transformer puts out the correct voltages, but the sound that the transformer makes, is practcally the same sound as the one I hear through the speakers.

does anyone have schematics for these? I have the Mig-50 schematics, but I don't want to assume that everything is the same in this amp.
Old 30th August 2007
  #2
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hangman's Avatar
 

ok, scratch that. the voltages are high. due to the power transformer being designed to have 110volts on the primary.

I was measuring 7 volts on the filaments! 525volts B+.

reading about these things online alot of people talk about them blowing through tubes and transformers... I'm willing to bet they would be better amps if run at 110volts.

looks like I'll be replacing the power transformer.
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