So, I had to clean some scratchy volume/gain pots on all the independent channels of my TSL100 and now have a problem. The problem is with the clean channel in that when I have both the volume and gain knobs off there is still a good signal present. I have read a few instances of this happening and in one case the guy sent it back to have it worked on. In that case is was a faulty tube and setting bias to get it fixed. Another couple of people think this supposed to be this way, and I know that is just not the case. So I have changed the 200k Gain pot and later the A1M pot just to make sure those were not the culprits.
The symptoms are simple: when you have the the volume & gain all the way off = some signal. When you turn up the volume pot going up to 10 there is a part around 6-7 that gets quieter then signal comes back to normal. When you have Volume all the way down and raise the gain pot to 10 there is no signal and a bit of a hum is then present. (There is a guy that described the exact behavior on the Marshall forums website but no solutions or any follow ups at all there...) When you switch to the crunch channel and turn up the volume (with out gain) it's loud. If you turn up just the gain on the crunch channel there is some signal that will come through and there is no hum. Same thing on the Lead channel too. Before I did all this it was fine.
I may have confused the order of my power tubes but I always mark 1-4 on some masking tape and keep them in the right order. If I moved the tubes around in the original order>>> could that cause the bias to not be set right now? I have not ever biased an amp and need to learn how. I have all the instructions on how to do this but just gonna take it slow as I go there.
I have inspected the clean channel circuit board and there is nothing wrong that makes any sense for it to behave this way. None of the wiring is hooked up incorrectly and nothing clear in the regards to a damaged trace or something on those lines. I will next take the whole thing apart again to inspect the lead board to make sure there is no solder problems on any CON type ribbon connection going to that board. Will make sure that no traces or anything was damaged on the lead board as well. Will do that tomorrow night so I will have to keep ya'll posted as to anything I find there...
But does anyone know or has anyone come across these symptoms on this amp before? Any help or thoughts are appreciated, thanks.
The symptoms are simple: when you have the the volume & gain all the way off = some signal. When you turn up the volume pot going up to 10 there is a part around 6-7 that gets quieter then signal comes back to normal. When you have Volume all the way down and raise the gain pot to 10 there is no signal and a bit of a hum is then present. (There is a guy that described the exact behavior on the Marshall forums website but no solutions or any follow ups at all there...) When you switch to the crunch channel and turn up the volume (with out gain) it's loud. If you turn up just the gain on the crunch channel there is some signal that will come through and there is no hum. Same thing on the Lead channel too. Before I did all this it was fine.
I may have confused the order of my power tubes but I always mark 1-4 on some masking tape and keep them in the right order. If I moved the tubes around in the original order>>> could that cause the bias to not be set right now? I have not ever biased an amp and need to learn how. I have all the instructions on how to do this but just gonna take it slow as I go there.
I have inspected the clean channel circuit board and there is nothing wrong that makes any sense for it to behave this way. None of the wiring is hooked up incorrectly and nothing clear in the regards to a damaged trace or something on those lines. I will next take the whole thing apart again to inspect the lead board to make sure there is no solder problems on any CON type ribbon connection going to that board. Will make sure that no traces or anything was damaged on the lead board as well. Will do that tomorrow night so I will have to keep ya'll posted as to anything I find there...
But does anyone know or has anyone come across these symptoms on this amp before? Any help or thoughts are appreciated, thanks.
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