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First off, I'm new to tube amp repair, so please be patient with me.
I just received a Sovtek Mig-60 from my friend and it doesn't make any sound when I use either the high or low inputs other than a hum after the "standby" switch is pressed. The "presence" knob is scratchy and I can hear some crackling as I turn the knob, but nothing from the guitar. I've checked the speaker cab and guitar with another amp and everything sounds fine.
I opened up the amp and the first thing I noticed was that one of the smaller tubes was missing (the middle one). My friend said that he never had a tube in the middle spot, so he thinks that isn't the issue (should I still be getting sound?). The missing tube looks like it is wired to the "pre amp" knob on the front panel.
Next I checked the 1/4" inputs and both were bent, which wasn't allowing the "tip" of the 1/4" cable to connect to the circuit, but after temporarily fixing this with alligator clips I still wasn't able to hear my guitar.
I've inspected all of the components visually and I don't see anything that looks like it was fried, but there are signs of heat on the metal. My friend said that those visual signs were from an electrical surge about 10 years ago. The amp was serviced and was working after.
I just don't know where I should start testing in the circuit to try and diagnose the issue and hopefully repair this amp. Thanks in advance!
Here's a schematic: https://irationaudio.files.wordpress...-schematic.jpg
Joshua
Also, I keep getting an error when trying to update my location... I'm from the US.
I just received a Sovtek Mig-60 from my friend and it doesn't make any sound when I use either the high or low inputs other than a hum after the "standby" switch is pressed. The "presence" knob is scratchy and I can hear some crackling as I turn the knob, but nothing from the guitar. I've checked the speaker cab and guitar with another amp and everything sounds fine.
I opened up the amp and the first thing I noticed was that one of the smaller tubes was missing (the middle one). My friend said that he never had a tube in the middle spot, so he thinks that isn't the issue (should I still be getting sound?). The missing tube looks like it is wired to the "pre amp" knob on the front panel.
Next I checked the 1/4" inputs and both were bent, which wasn't allowing the "tip" of the 1/4" cable to connect to the circuit, but after temporarily fixing this with alligator clips I still wasn't able to hear my guitar.
I've inspected all of the components visually and I don't see anything that looks like it was fried, but there are signs of heat on the metal. My friend said that those visual signs were from an electrical surge about 10 years ago. The amp was serviced and was working after.
I just don't know where I should start testing in the circuit to try and diagnose the issue and hopefully repair this amp. Thanks in advance!
Here's a schematic: https://irationaudio.files.wordpress...-schematic.jpg
Joshua
Also, I keep getting an error when trying to update my location... I'm from the US.
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