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  1. Also, notice how the standby switch works by...

    Also, notice how the standby switch works by connecting the two out of phase signals from the PI, effectively cancelling each other out. I like it. but I wonder if it's noisy.
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    That would not warrant a board replacement, it's...

    That would not warrant a board replacement, it's a common failure corrected by soldering in bits of solid wire or snipped component leads to replace what has burned. What concerns me most here is why...
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    F&T tend to be larger in size than IC of the...

    F&T tend to be larger in size than IC of the value. Given the reliability of F&T and the known failure rate of IC caps, maybe there is a corelation there. It's enough for me to stick with F&T and...
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    Plate voltage is 464.5, screen voltage is 464.3v.

    Plate voltage is 464.5, screen voltage is 464.3v.
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    This is not the question. At first I quoted the...

    This is not the question. At first I quoted the Cathode resistor, Enzo called me on it. It should have been screen resistor, an error I corrected.
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    I measured with no signal, as I thought was...

    I measured with no signal, as I thought was proper.
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    Sorry, 470 ohm screen resistor that measures 466...

    Sorry, 470 ohm screen resistor that measures 466 ohms. Fixed it.
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    Screen current, straighten me out

    In revisiting screen current relative to plate current and biasing, I did some reading and measuring. I had gotten into the habit with fixed bias of only measuring cathode current, and thinking plate...
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    yes, this one breaks the connection at pin 8 and...

    yes, this one breaks the connection at pin 8 and routes it thru your ammeter.
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    So, when measuring with a socket type bias probe...

    So, when measuring with a socket type bias probe or across a 1 ohm cathode resistor, I am measuring total dissipation, right? Plate and screen?
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    Customer opted for JJ KT77s, and rated at 800v,...

    Customer opted for JJ KT77s, and rated at 800v, works for me. JJ datasheets sometimes get lost on me. Looking at this one, is this a max diss. 25w or 28w?
    ...
  12. You are experiencing the future now. I predict...

    You are experiencing the future now. I predict once us dinos who remember when products didn't suck as bad, and could be repaired reasonably are extinct, the acceptable norm will be disposable...
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    I'm not an engineer, and don't have mastery over...

    I'm not an engineer, and don't have mastery over the math. This is a dead stock piece that was recently paid top dollar for because of that, so I am not inclined to attempt to re-design the power...
  14. Thread: PT spludge

    by Randall
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    PT spludge

    I have a pawn shop find 66 Fender Pro Reverb in for an overhaul. The dog house was in pretty rough shape with bad caps, a discolored node resistor, and a cloth coverered wire that had sparked to a...
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    I'm going to say that engaging the footswitch...

    I'm going to say that engaging the footswitch grounds the base of Q1 and therefore turns it off, shutting off the oscillator.
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    "but if you keep a 1M permanently across the...

    "but if you keep a 1M permanently across the switch (as discussed in the previous posts), then the screen is not disconnected from HT at any time"

    tubeswell can you elaborate on this? This has...
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    So, per my orignal post, the 3A 125vac switches I...

    So, per my orignal post, the 3A 125vac switches I have on hand aren't going to be reliable, sounds like. I have one in my Bassman build, and I have not experienced any pops or sparks with it.
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    Talk to me about switch rating.

    Talk to me about switch rating.
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    "Electrical tape's been know to come unwrapped."...

    "Electrical tape's been know to come unwrapped."

    It's not going to unwrap if it is only under the clamp band, which is what I think Chuck and Leo are talking about.
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    With regards to can cap shells being tied to...

    With regards to can cap shells being tied to ground, HOLY SHITE!. I just checked this Hiwatt, and indeed the LCRs are exposed at the bottoms, and show they are tied to neg. On two of them there is...
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    pentode/triode switch

    Is there anything wrong with this method of pentode/triode switch? I have read where some say a resistor should be included for current limiting, is this true?

    Also, would a 3A 125vac switch be...
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    "Cans often have the shell connected to the...

    "Cans often have the shell connected to the negative terminal. This can make fireworks used in a totem pole arrangement.
    Are they negative shell, or more like the Marshall LCR type where the shell...
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    Schematic? Whoops! Fixed above. The...

    Schematic?

    Whoops! Fixed above.

    The schematic shows 506V B+, which is just about what I am getting. And I proposed 385V replacements, so even better?

    edit: I just realized the 385v cans are...
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    Capacitance questions

    In this following power supply circuit, I am not sure why the filter caps are stacked as they are. I am replacing all the filter caps, and have questions about what ratings I can use. The schematic...
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    Why is the diode changed in the bias mod? Would a...

    Why is the diode changed in the bias mod? Would a 1N4007 do the job?
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    "I dīont know if I understood correctly but the...

    "I dīont know if I understood correctly but the DR504 does not need a voltage doubler. Itīs enough to extend the voltage divider to the good side with an adjustable resistor."

    Could this be...
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    OK, no KT66s for you.

    OK, no KT66s for you.
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    So, is what I am hearing here, stick with KT77s...

    So, is what I am hearing here, stick with KT77s because of the higher plate voltages?
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