Fellas,
Does anyone have a service manual for the little mark tube? Have any of the more technically inclined folks here resolved any issues with it?
Here is what I have:
Powers on.. no sound. Opened it up and found that the phantom power toggle wiggles the preamp board for the balanced input. Broken legs on the gain knob. Bypassed the balanced gain knob (don't need that input anyway) Now I have signal and think it is good.. yay!!
I get a loud click through the speakers from output relay and it works fine. It seems to be fine always on first power up.. BUT!!!! If I turn it off after being in for a while regardless of whether it was in use or just idle, the relay will not kick on and the internal led labeled ProtI is on (RED). Turn off wait a few and it works fine again. Played it a little at decent volumes and saw the other Red ProtT LED come on and go off, or go on and stay on until owered down and back on.. also saw relay clicking off and back on while signal was still passing.. arced pretty good inside relay.. forced shut off, dimmed lights in garage. This is the problem described to me by the owner (father in law) All of this with gain low and no preamp clipping into a 4ohm cab with no crossover.
Questions.. are thes LEDs current protect or thermal protect? Has anyone else seen these kind of protection circuit issues in these amps? This amp has been gigged heavily for a few years so it is not a dud from factory.
Does anyone have a service manual for the little mark tube? Have any of the more technically inclined folks here resolved any issues with it?
Here is what I have:
Powers on.. no sound. Opened it up and found that the phantom power toggle wiggles the preamp board for the balanced input. Broken legs on the gain knob. Bypassed the balanced gain knob (don't need that input anyway) Now I have signal and think it is good.. yay!!
I get a loud click through the speakers from output relay and it works fine. It seems to be fine always on first power up.. BUT!!!! If I turn it off after being in for a while regardless of whether it was in use or just idle, the relay will not kick on and the internal led labeled ProtI is on (RED). Turn off wait a few and it works fine again. Played it a little at decent volumes and saw the other Red ProtT LED come on and go off, or go on and stay on until owered down and back on.. also saw relay clicking off and back on while signal was still passing.. arced pretty good inside relay.. forced shut off, dimmed lights in garage. This is the problem described to me by the owner (father in law) All of this with gain low and no preamp clipping into a 4ohm cab with no crossover.
Questions.. are thes LEDs current protect or thermal protect? Has anyone else seen these kind of protection circuit issues in these amps? This amp has been gigged heavily for a few years so it is not a dud from factory.
