So the high channel on my Mig60 lost volume, tone knobs don't really do anything, and there is little to no distortion. "Low" channel remains fine.
I replaced both input jacks, tubes, replaced C22, R3, R2, and reflowed any suspect areas in the high input signal path. (I know I shotgun-ed it)
I chopsticked it with no luck.
The MIG schematic provides no voltages for me to check, and I f-ed up and didn't check them myself when I first got the amp.
I do not own an oscilloscope.
So, what is next?
Sovtek Mig60 gain loss/high channel
Moderators: pompeiisneaks, Colossal
Re: Sovtek Mig60 gain loss/high channel
did you try replacing whatever preamp tube is used by just that input?
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Re: Sovtek Mig60 gain loss/high channel
Is this your amp? If so, the way the hi/lo is setup, it could only be a handful of components that have failed. This is assuming your lo channel is indeed 100% OK.
My first guess would be plate load resistor, then coupling cap, but only because you said you replaced the tube and the input jack. The input 470K is still intact, eh?
I would assume the first triode's plate should be somewhere reasonable in the 170-230V range.
Also, ignore the black markup, that was pre-existing when I snagged the scheme
My first guess would be plate load resistor, then coupling cap, but only because you said you replaced the tube and the input jack. The input 470K is still intact, eh?
I would assume the first triode's plate should be somewhere reasonable in the 170-230V range.
Also, ignore the black markup, that was pre-existing when I snagged the scheme
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Re: Sovtek Mig60 gain loss/high channel
Smokebreak wrote:Is this your amp? If so, the way the hi/lo is setup, it could only be a handful of components that have failed. This is assuming your lo channel is indeed 100% OK.
My first guess would be plate load resistor, then coupling cap, but only because you said you replaced the tube and the input jack. The input 470K is still intact, eh?
I would assume the first triode's plate should be somewhere reasonable in the 170-230V range.
Also, ignore the black markup, that was pre-existing when I snagged the scheme
All the resistors are fine when checked with a DMM.
As far as the lo channel, if it isn't fine, then it is barely effected by whatever failure I'm getting.
I'm gonna start replacing shit, from V1.1 back to the jack (not that there is much left that is original).
I have a new tube socket in my shop, I'm thinking that maybe the socket went to shit, but only somewhere on the V1.1 side.
More updates tomorrow.
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M
If it's not a open plate load resistor on V1-1 then I would have thought that replacing the low Jack would have done it!
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Not screaming like the passengers in his car!
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Sovtek Mig60 gain loss/high channel
ok, new update. The EQ is indeed not doing anything on the low channal as well. I'm going to start working my way to the tone stack..
Re: M
OK, so after testing everything up to the PI, re flowing anything that looked suspect.. and replacing everything around V1.1, this response made me want to double check the jacks. I put a piece of metal in between the switch and + on the low jack and let her rip. Turns out I replaced a faulty jack with a faulty jack. Story of amp troubleshooting it seems.Stevem wrote:If it's not a open plate load resistor on V1-1 then I would have thought that replacing the low Jack would have done it!
Thanks for the help!
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Re: Sovtek Mig60 gain loss/high channel
I had the exact same problem when I had a Mig 60.....the stock jacks are junk...the Mig 60 was a respectable amp for the price, TONS of bang for the buck.