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HELP my ampeg!!!!

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  • #31
    A good place to start before replacing the flyback diodes would be to check them for leakage or shorts. Lift one end of each string and measure each diode for forward and reverse voltage drop (on the diode range of DMM).
    As far as the internal fuse, it is not really necessary, most amps don't have them. In the case of this amp it was a 10amp fuse. It is just a back-up in case someone replaces the regular fuse with larger than a 10amp. In such a case, if there is a fault in the amp, the internal fuse will blow. If you wanted to put one in, you could use a pigtail fuse like the original, in series with the fuseholder, or add an inline fuseholder in series with the main fuseholder.
    For the master volume, you are correct, the earlier models did not have a master, but they were often added aftermarket and usually in the rear panel.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #32
      Looking at your pics. The pic sany0251 shows (as near as I can tell) that one of the flyback diodes is half missing. It's a pretty safe bet it's bad. They should all be checked. You can replace them with 1N4007 and use 3 in series instead of just 2 (total of 6 diodes). That said, it's obvious from your pics that there were/are other problems. Start by cleaning up all of the residue from the flame outs. The residue can be conductive and cause problems if you don't get it out of there.

      This was likely a simple repair at one time that someone has exacerbated by installing an overrated fuse. If it were in my shop, knowing the fuse was basically hardwired, I'd give the entire amp a thorough once over.
      "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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      • #33
        Good eye Dude!
        The flyback diodes are a safety feature, some amps don't even have them. So you can remove them and leave them off till you get everything else working, I would suggest putting them back in at some point before re-assembling the amp.
        Have you built the bulb limiter yet?
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


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