So I'm not holding out too much hope repairing this Bugera T50 as it's mostly surface mount and I haven't had any luck finding a schematic but I'm going to give it a go.
It will occasionally pass sound to the speaker cab, but mostly not. I have not been able to figure out what conditions get sound. It just randomly outputs sound for a few seconds and goes silent again. Sometimes this happens when it's first turned on and other times and a couple of minutes. It always goes silent very quickly, like 3 seconds. It has a fresh complete set of JJs that did not affect the problem. If I take a line from the FX send to the return on another amp I get good sound. All of the channel switching and channel knobs work. So I believe it to likely be an intermittent connection somewhere in the PI or power amp section. Usually in this case I would just reflow all of the solder joints in those areas, but with surface mount...not so much.
My plan now is to start measuring voltage on the PI 12AX7 and the two EL34s and compare the results to other EL34 based amps just to see if there is a pin that is not getting or sending what it should. Does this seem like a reasonable approach to an amp without a schematic? The PCB is black and tracing the circuit is going to be difficult to impossible.
Thanks for any suggestions!
It will occasionally pass sound to the speaker cab, but mostly not. I have not been able to figure out what conditions get sound. It just randomly outputs sound for a few seconds and goes silent again. Sometimes this happens when it's first turned on and other times and a couple of minutes. It always goes silent very quickly, like 3 seconds. It has a fresh complete set of JJs that did not affect the problem. If I take a line from the FX send to the return on another amp I get good sound. All of the channel switching and channel knobs work. So I believe it to likely be an intermittent connection somewhere in the PI or power amp section. Usually in this case I would just reflow all of the solder joints in those areas, but with surface mount...not so much.
My plan now is to start measuring voltage on the PI 12AX7 and the two EL34s and compare the results to other EL34 based amps just to see if there is a pin that is not getting or sending what it should. Does this seem like a reasonable approach to an amp without a schematic? The PCB is black and tracing the circuit is going to be difficult to impossible.
Thanks for any suggestions!
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