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  1. Replies
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    Let's get it working in manual mode first. With...

    Let's get it working in manual mode first. With the pull switch out you should have +14V on U7 pin 7 and -14V on U5 pin 8

    At the junction of R91 and R100 you should have a voltage from 0V to about...
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    109

    It should still oscillate with a polarized cap...

    It should still oscillate with a polarized cap when the pull switch is in. You could lift one end of R87 to eliminate the switch as a suspect. Can you sweep the phasing effect with the pull switch...
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    109

    U5 pin 8-14 side is part of the modulation LFO....

    U5 pin 8-14 side is part of the modulation LFO. there should be a slowly changing DC voltage on pins 8 and 14. I would guess if it's not oscillating the problem would be the pull switch, Range pot or...
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    77

    Plug your signal generator into the reverb return...

    Plug your signal generator into the reverb return jack. Signal level at the jack and at pin 5 should be the same. Level at pin 7 should be much greater, if it's the same as pin 5, C44 or R59 is open...
  5. I would use 100uF 35V. This appears to be the...

    I would use 100uF 35V. This appears to be the schematic.

    https://music-electronics-forum.com/attachment.php?attachmentid=57145&stc=1&d=1582723678
  6. They look yellowish to me, maybe they're white. ...

    They look yellowish to me, maybe they're white.

    https://music-electronics-forum.com/attachment.php?attachmentid=57141&stc=1&d=1582672181
  7. My best guess is that one or more of the small...

    My best guess is that one or more of the small yellow electrolytic caps is bad.
  8. Replies
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    664

    Here's another one. A tape measure with memo...

    Here's another one. A tape measure with memo recorder. I bought this many years ago thinking it would be great for those times when
    I get down from a 30ft ladder and suddenly forget the measurement...
  9. Replies
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    664

    The magnet pick-up tool gets a lot of use when...

    The magnet pick-up tool gets a lot of use when I'm working on the car, though there are still a couple of sockets lost down there somewhere.
  10. Replies
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    664

    This is a set of 1/4" deep sockets I put...

    This is a set of 1/4" deep sockets I put together, inch and metric. Very handy.

    https://music-electronics-forum.com/attachment.php?attachmentid=57099&stc=1&d=1582509477
  11. Replies
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    664

    Got this a few years ago. When I need extra...

    Got this a few years ago. When I need extra pressure.

    https://music-electronics-forum.com/attachment.php?attachmentid=57077&stc=1&d=1582324960
  12. Replies
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    381

    I haven't seen one like that but would the...

    I haven't seen one like that but would the plastic part unscrew like the all-metal ones?

    https://music-electronics-forum.com/attachment.php?attachmentid=57053&stc=1&d=1582249522
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    212

    You could parallel a resistor across R2 which...

    You could parallel a resistor across R2 which will boost the gain when S1 is closed (out). Try 1K, and parallel a 100uF cap across C2 to maintain low end response.
    ...
  14. Replies
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    I have 2 Yorkville YSM1p monitors with the exact...

    I have 2 Yorkville YSM1p monitors with the exact same problem described above. I also noticed a slowly rising DC voltage on U2 pin 8 up to about 6v when the hiss would start.

    ...
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    106

    This is all I have for ITAM ...

    This is all I have for ITAM

    https://music-electronics-forum.com/attachment.php?attachmentid=56960&stc=1&d=1581783473
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    I go for the Rustic/Homemade effect. In other...

    I go for the Rustic/Homemade effect. In other words I'm too cheap to buy one.

    https://music-electronics-forum.com/attachment.php?attachmentid=56922&stc=1&d=1581296026
  17. Replies
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    443

    Yes, that's a more accurate way to put it. My...

    Yes, that's a more accurate way to put it. My equation only applies when both capacitors are the same value as they are in this case.
  18. Replies
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    443

    Maybe Bipolars were more expensive. The thing to...

    Maybe Bipolars were more expensive. The thing to remember is that two caps in series of equal value will become half the value of one. The voltage rating will be unchanged.
    Somehow there must be a...
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    Here it is in schematic form. I'm not sure we...

    Here it is in schematic form. I'm not sure we know the value of the caps yet. Whatever they are, the bipolar cap should be half the value marked on one of the originals Or just use 2 caps...
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    When you get the boards out look closely at all...

    When you get the boards out look closely at all jumper wire connections between boards, the solder often cracks there. Also re-solder all the tube sockets. I've also had trouble with filament...
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    685

    As I remember it the problem with aluminum wire...

    As I remember it the problem with aluminum wire is that it is too soft, will squash under a screw and loosen easily, then arc over and burn your house down, whereas copper has a bit of springyness...
  22. Replies
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    786

    If I ever see a brown spot on a molex socket used...

    If I ever see a brown spot on a molex socket used for a heater connection I hardwire the two wires. End of story. No need to measure anything.
  23. Replies
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    201

    The leads on these are flat. I'd like to see the...

    The leads on these are flat. I'd like to see the datasheet but that seems highly unlikely


    https://music-electronics-forum.com/attachment.php?attachmentid=56847&stc=1&d=1580590400
  24. R144 is 220 ohms/ 2 Watt ...

    R144 is 220 ohms/ 2 Watt

    https://music-electronics-forum.com/attachment.php?attachmentid=56846&stc=1&d=1580573443
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    201

    On the newer version schematic they use 2SC373 in...

    On the newer version schematic they use 2SC373 in place of the 25H. I ended up using 2SC1000. The 25H was making a lot of noise. Now on to fixing the tremolo and reverb
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    Thanks g1, I have those and other old Yamaha...

    Thanks g1, I have those and other old Yamaha schematics. No luck. Looking in some of my old books it looks like the C401 is indeed 2SC401 made by Sony. There is also a
    2SC293 on the board, a TO5...
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    201

    Yamaha TA-30 Transistors

    I'm working on an old TA-30, seems to be an earlier version than the schematics that are available, ser #20049 pcb #LC-0400-2.
    I'm curious about the transistors, I can't find data anywhere. they are...
  28. Replies
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    A friend brought me a non-working U87 a while...

    A friend brought me a non-working U87 a while back. Like Mick I didn't want to touch the capsule. It's always been the point where I would give up on a mike. This one was visibly grimey and I figured...
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