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Hello,
I just did a cap job on both an Acoustic 134 and its brother, an Acoustic 135. Tremolo on the 135 is great, not working at all on the 134. There is only one version of the schematic for these amps I have been able to find (https://www.manualslib.com/manual/89...ml#product-134) and it presents a problem.The amps have 3 circuit boards, one for "normal" channel, one for the other channel including reverb and tremolo, and one for the power supply. The problem is that the PCB with the tremolo on is a much different revision than is shown in the schematic. It is revision F (17-11 F). The PCB in the 135, the one that is working, is revision E, looks pretty close to the other one but I don't know what difference there might be between E and F as far as the tremolo goes, they could be identical in that regard. But without a useful schematic I'm kind of stuck, despite being able to use the working unit for reference. The version in the schematic shows an LDR, the symbol looks similar to a Fender "roach", but as you can see from the attached pic of the version 17-11 F board, there does not appear to be anything resembling an LDR, as least that I can tell. The PCBs have a trimpot (bottom left in the attached pic) that seems to be for tweaking the tremolo in some fashion. On the unit that works, when turned one way the volume increases but at some point the tremolo effect goes away, same for turning it the other way, except that the volume decreases until again the tremolo effect is gone. On the unit that does not have working tremolo the pot is not doing anything at all. In the pic, the tremolo intensity pot is far left and the speed pot is next to it. I could really use some advice on how to move forward troubleshooting. Thanks in advance,
- Bob
I just did a cap job on both an Acoustic 134 and its brother, an Acoustic 135. Tremolo on the 135 is great, not working at all on the 134. There is only one version of the schematic for these amps I have been able to find (https://www.manualslib.com/manual/89...ml#product-134) and it presents a problem.The amps have 3 circuit boards, one for "normal" channel, one for the other channel including reverb and tremolo, and one for the power supply. The problem is that the PCB with the tremolo on is a much different revision than is shown in the schematic. It is revision F (17-11 F). The PCB in the 135, the one that is working, is revision E, looks pretty close to the other one but I don't know what difference there might be between E and F as far as the tremolo goes, they could be identical in that regard. But without a useful schematic I'm kind of stuck, despite being able to use the working unit for reference. The version in the schematic shows an LDR, the symbol looks similar to a Fender "roach", but as you can see from the attached pic of the version 17-11 F board, there does not appear to be anything resembling an LDR, as least that I can tell. The PCBs have a trimpot (bottom left in the attached pic) that seems to be for tweaking the tremolo in some fashion. On the unit that works, when turned one way the volume increases but at some point the tremolo effect goes away, same for turning it the other way, except that the volume decreases until again the tremolo effect is gone. On the unit that does not have working tremolo the pot is not doing anything at all. In the pic, the tremolo intensity pot is far left and the speed pot is next to it. I could really use some advice on how to move forward troubleshooting. Thanks in advance,
- Bob
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