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Laney TT50H No Outout

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  • #31
    It's hard to understand what those readings mean. Do you mean on the 2000K resistance range C37 reads 013 ?
    Then I would say it is bad. Remove it and check it again out of circuit. It should measure into high Meg ohms or OL. A low resistance means it is shorted.
    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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    • #32
      That's correct, on 2000k resistance range. I'll pull C37 and test it, do any of the other readings need parts pulled and tested?

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      • #33
        C37 was the only one that really stood out. And like Jon Snell said, it was already the prime suspect. So hopefully it is the culprit here.
        "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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        • #34
          C37 out of circuit charges to OL on 2000k resistance range, discharges from about 190 to 0 on 200mv range. Checking for continuity after pulling C37, 1st photo shows C37 trace to the right near V6 has 0.00 in continuity range. Next two(2) photos show C37 trace going to pin#9 and empty location, both reading OL on continuity range. V5 pin#9 and the empty location on trace read 0.00 on continuity range? All other preamp tubes pin#9 read continuity to any connected trace except V5.

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          • #35
            No pictures are showing.
            With C37 removed, what do you measure on the board at the C37 pads, use 200 ohm range on meter.
            "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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            • #36
              Jumped positive side of C37 trace to V5 pin#9 and have 0.00 on continuity range in all directions of trace.

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              • #37
                Photos

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                • #38
                  Starts at 40 goes down to 0.4 then climbs to OL, did it several times, does the same every time C37 pads on 200k resistance range.

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                  • #39
                    Correction: pin#1 on V5

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                    • #40
                      Sorry, I have no idea what is going on here. Is that cap (removed) C37? And there is a trace connecting it's positive pad to V5 ?
                      The schematic shows no such thing. If we don't have the correct schematic for the amp, there is not much we can do.
                      "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                      • #41
                        Not sure about schematic but photo I posted clearly shows trace from C37 going to V5. I have a light under the board making traces easy to see.

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                        • #42
                          Regardless of schematic errors, there is only one path to excess current draw to ground is either C37 leaking, the valve (very unlikely), valve holder or a solder bridge/damaged track.
                          With C37 out, V5 out and a replacement R43, what happens.
                          Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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                          • #43
                            Any suggestions at this point? If I replace R43, reinstall C37 and jump it to V5 am I likely to have same issue? Do you think R43 burning damaged the trace to V5 and there is still another issue? Thanks for the help on this.

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                            • #44
                              Jon's post above was a suggestion.
                              Originally posted by Jon Snell View Post
                              With C37 out, V5 out and a replacement R43, what happens.
                              "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                              • #45
                                I have to order R43, are you saying replace V5 socket also? I jumped C37 to V5 and have continuity? Not sure what's being said here.

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