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Recent content by grindfix

  1. grindfix

    Beginning my foray into tube gear. Looking for some advice

    You can Ohm-test each winding of all 3 transformers for opens and shorts. If all checks out good, replace the blown resistor and power up on DBT to monitor all vitals. You will need to install a 10-ohm resistor between each EL80 cathode and ground to monitor current flowing through the tube...
  2. grindfix

    Beginning my foray into tube gear. Looking for some advice

    Forgot to mention, and you most likely know this, all circuits that are powered downstream of that burned resistor will not get power either.
  3. grindfix

    Beginning my foray into tube gear. Looking for some advice

    I missed it when viewing on the phone. The blown resistor indeed appears to be R85, which is the dropping resistor for the output tubes' screen supply. Without screen (control grid) voltage, output tubes will not conduct, so no sound. Why it's blown and what else smoked in the excitement is...
  4. grindfix

    Beginning my foray into tube gear. Looking for some advice

    If you plan to work on this, before spending money on anything, I'd suggest testing all transformers for opens and shorts.
  5. grindfix

    Beginning my foray into tube gear. Looking for some advice

    Any chance that you posted the wrong photo? The thing you circled seems to be a fuse holder. Fisher used Red plastic fuse holders in the console amps.
  6. grindfix

    Need Help Identifying a Make/Model of a tube amp

    Give it some time, put it on the back burner. Someone who's seen those before may chime in someday.
  7. grindfix

    Need Help Identifying a Make/Model of a tube amp

    Maybe try working with ChatGPT or Gemini? I rarely use a simple Google search anymore. Those AI options pull much more relevant search results to filter through than pages and pages of Google search results
  8. grindfix

    Need Help Identifying a Make/Model of a tube amp

    It looks very resembling the amp that came out of Cordovox accordion amplifier enclosure. The one I had was only one channel, PP7591 with 6SN7 driver and 5U4 rectifier and a choke. This one has the same looking transformers but has additional, perhaps treble channel. I always thought those amps...
  9. grindfix

    The Underside

    Two of the best-looking undersides of my scratch builds.
  10. grindfix

    Transform covers help.

    If you heat the brass with a plumbing flame torch, it turns copper red. Probably should be coated after that to maintain the color
  11. grindfix

    Does anyone have a nice clean The Fisher "bird" image file?

    Yes, covers over the open bobbin transformers. EL95
  12. grindfix

    Does anyone have a nice clean The Fisher "bird" image file?

    It went on to the faceplate of this little amp I built using Filharmonic transformers and most of the circuit
  13. grindfix

    Fisher 400 loud noise from right channel as soon as its turned on

    Completely agree with all the above recommendations, all need to be done, but not before the output transformer is verified. Push-Pull output that was making a loud noise and then stopped making that noise makes me suspect that the OT primary winding is potentially toast. Hopefully not
  14. grindfix

    Fisher 400 loud noise from right channel as soon as its turned on

    No credible person would say this. New production good 7868 tubes require more negative bias voltage at the grid, otherwise they run off the rails. This may not be the reason for your situation but it’s just a proven fact that you cannot run those tubes without bias circuit modifications.
  15. grindfix

    Fisher 400 loud noise from right channel as soon as its turned on

    I just noticed that your impedance selector jumpers are connected incorrectly. The jumper should be connected to the impedance tap that best matches your speaker, and then the speakers connect to the most left terminals of the strip. To discharge the power supply, you should connect a 10Kohm or...
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