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  1. Are you sure that the sovent of the nickel paint...

    Are you sure that the sovent of the nickel paint did not melt the wire insulation and caused a partial winding short? This would explain the dulled tone. An L(CR) meter that displays Q or D=1/Q could...
  2. Schematic? I don't think your OT is bad. But...

    Schematic?

    I don't think your OT is bad. But measure DCR on both sides of the primary wrt CT.

    Do all 4 6L6s show an idle current of 49mA?
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    Because of the non-uniform spatial distribution...

    Because of the non-uniform spatial distribution of the magnetic flux, there is no simple relation between output level and coil area/turns.

    PU output is the sum of the induced signal voltages in...
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    The DCR solely depends on wire length and actual...

    The DCR solely depends on wire length and actual gauge. For a given PU assembly and wire gauge the DCR is a crude makeshift indicator of turns number and thus of inductance (frequency response) and...
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    The nice thing about the coil estimator is that...

    The nice thing about the coil estimator is that it allows to estimate the achievable turns number which is way more important than DCR.
  6. Not sure if I understand. You used conductive...

    Not sure if I understand. You used conductive paint under (metal?) covers?
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    DCR is a parasitic property of conductors. All it...

    DCR is a parasitic property of conductors. All it does is produce losses and damp a PU's resonance. It completely loses its informative value if different wire gauges or different coil dimensions are...
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    While I doubt that you can exactly replicate the...

    While I doubt that you can exactly replicate the P-90 tone with alnico poles (as opposed to steel poles) I think the most important factor would be to use a similar turns number (around 10,000) to...
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    Is the footswitch cable (as well as the switch...

    Is the footswitch cable (as well as the switch itself) well shielded? Also the amp internal wiring to the footswitch is critical.
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    More turns will result in higher output and lower...

    More turns will result in higher output and lower resonant frequency. There is no relation between output and resistance.
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    As Enzo would say (and I heartily agree): Why...

    As Enzo would say (and I heartily agree): Why repair something that isn't broken? (I also own a couple of rather old Tek scopes types 547 and 453, no repairs done yet).

    Bad PS caps would make your...
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    I think Naphta (or mineral spirits) is preferable...

    I think Naphta (or mineral spirits) is preferable over any alcohol because it's water repellent, is better at dissolving greasy and waxy deposits and doesn't attack nitro lacquer. (Dan Erlewine uses...
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    Well, the mod suggested by Chuck results in 10k...

    Well, the mod suggested by Chuck results in 10k grid stoppers - and the original circuit effectively has 220k grid stoppers.
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    I would use naphta (lighter fluid) or...

    I would use naphta (lighter fluid) or white/mineral spirit, but be aware of high combustibility.
  15. I was involved in the design and safety...

    I was involved in the design and safety approval/certifiction of many a power supply and am not in favor of modifying a power supply that doesn't conform to safety standards.



    What do you mean...
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    There seems to be a misconception. While a grid...

    There seems to be a misconception. While a grid (series) stopper resistor (1k to 10k is sufficient) can avoid oscillation, a large grid (shunt) resistor does not.
  17. Sorry, doesn't open here.

    Sorry, doesn't open here.
  18. From the paper: "Sealing out corrosive ...

    From the paper:

    "Sealing out corrosive gases can help to protect metal surfaces against atmosphericcorrosion. Corrosion inhibitors/lubricants applied at any sliding contact ...
  19. In fact almost all plated (nickel, chrome, gold)...

    In fact almost all plated (nickel, chrome, gold) covers I tested got slightly attracted to a neo magnet, but typically not enough to lift the cover. Most unplated covers showed essentially no...
  20. So the culprit should be the macbook's power...

    So the culprit should be the macbook's power supply.




    From what you describe above this looks like a potential safety issue.
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    Thanks. There seems to be sufficient distance...

    Thanks.
    There seems to be sufficient distance between the PT and the tank. I would use shielded wiring inside the chassis connecting to the reverb jack.
  22. That seems to confirm that the problem is...

    That seems to confirm that the problem is restricted to the V2/V1 section. As pulling V1 makes it worse, it seems to be somehow involved as well. What happens if you ground the V1 grid?

    Did you...
  23. Where does the "grounding of V2A" happen? Can't...

    Where does the "grounding of V2A" happen? Can't see it from the preamp schematic. The grids of V2A and V1A seem to be connected?

    Does the oscillation at the plate of V2B stop when you pull any of...
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    But that's typical for the non-inverting triode...

    But that's typical for the non-inverting triode in a LTPI. However the tube has 2 inputs, cathode (non-inverting) and grid (inverting).
  25. Lanolin is wool wax and I don't think you want it...

    Lanolin is wool wax and I don't think you want it on high current contacts.
  26. Looking at the picture, I don't think there is a...

    Looking at the picture, I don't think there is a problem with the switch at all. The contact area looks shiny and like others said, all it might need is a little Kontakt 60 (followed by Kontakt 61)...
  27. Means that it probably contains silicone grease,...

    Means that it probably contains silicone grease, which doesn't easily wash off with soap.

    Often Vaseline (petroleum jelly) is used on contacts. But there are more specialized products sold e.g. by...
  28. There is certainly something like contact grease....

    There is certainly something like contact grease. E.g.: https://www.amazon.com/LubriMatic-11755-Dielectric-Electrical-Contact/dp/B001446LP4

    The grease found inside pots is typically for...
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