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Fender acoustasonic sfx2

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  • Fender acoustasonic sfx2

    Amp was making a cracking noise, I looked over board and only found C155 appeared loose. Seemed like legs were broken in cap. I changed cap and now I have no power..no power led comes on. U27 (7915) is getting hot. Which if I'm correct is a voltage regulator? I changed it and U26, and U28. U27 still gets hot and not power. Amp looks like it has had power transistors(amps)changed before. I did pull all 3 fuses and test them and they are good. I can hear the transformer faintly buzz.

    Download Error - Schematics Unlimited

  • #2
    Power supply voltages are plainly labeled on the schematic. Which ones are there? Which ones are not? I wouldn't have changed all of those parts unless voltages were missing and they were proven bad. Troubleshoot the supply rather than shotgunning it.
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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    • #3
      Yea they were cheap had them here so I swapped them out..I suck at solid state stuff!!

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      • #4
        Of course there are some differences between tube and solid state, but your troubleshooting approach should be much the same. Check voltages, find something off, narrow it down to a connection, bad part, burnt trace, etc. You can often install new problems when you just randomly replace parts. Check those power supply voltages and see which of them are off.
        "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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        • #5
          I'll get some voltages and post them. What I did check was off.

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          • #6
            After some quick simple voltage tests(that I was being lazy on &#128580 I found D63 open, which explains why U27 was getting hot..thanks for the butt kicking I deserved to just go do it right and test instead of looking for an easy answer..lesson learned 😎, thanks again!!

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            • #7
              The side speaker is not working, I have tested the speaker and it's good, hooked front speaker to the side outputs and it won't work there either..pulled Q33 & Q29 and tested they are good. Pulled Q31 & Q35 and they tested good as well.

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              • #8
                You will get more help if you post the actual schematic and not just a schematic site like your above link.

                fender-acoustasonic-sfx-ii-guitar-amplifier-schematic.pdf
                It's weird, because it WAS working fine.....

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                • #9
                  Sorry that's the way it comes up every time..I found it though, bad trace.

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