Kustom Coupe stopped working

Discussion in 'Glowing Bottle Tube Amp Forum' started by jwp333, Apr 28, 2018.

  1. jwp333

    jwp333 Tele-Holic Ad Free Member

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    My Kustom Coupe 36 stopped working this week. Pilot light isn't on, power tubes aren't lighting up. There is another light that shows the channel in use that is working. I've haven't removed the covers to see if the preamps tubes are lighting up. No advance warning.

    I'm going to take it to Sam Ash most likely because I don't really see an independent shop close by. When they look at it, what kind of repair can I reasonably expect? I assume a fuse has blown for some reason. What other kind of explanation is likely?
     
  2. Lonn

    Lonn Friend of Leo's

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    Why not just pull the chassis and look for the fuse yourself?
     
  3. JayFreddy

    JayFreddy Poster Extraordinaire

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    Most likely a power tube went bad, which tripped the fuse.

    That's what tube amps do.

    If I were you, I'd start by replacing the power tubes and then put in a fresh fuse.

    If that doesn't work, it's possible that the tube failure may have taken other components out.

    That would be my cue to visit the amp doctor.

    But start with the power tubes and the fuse. Chances are good that's all it is.
     
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  4. slider313

    slider313 Tele-Afflicted

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    Call, before you take it to Sam Ash. They probably don't have an amp tech on site and will likely offer send it out. That will be costly. See if they will give you the name of a tech in the area.
     
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  5. jwp333

    jwp333 Tele-Holic Ad Free Member

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    Tried the extra fuse in the power plug receptacle. No luck. Pilot light didn't start up at all. The power tubes don't look burnt or anything but I know that probably doesn't matter . I'm going to take it in this week.
     
  6. kbraker

    kbraker Tele-Meister

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    Always use caution when it comes to tinkering with amps. Caps and other electronic bits can be dangerous if not given proper attention.
     
  7. Dacious

    Dacious Poster Extraordinaire

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    Channel switching light coming on but heaters and power light not suggests either there's a heater fuse on the board blown. Or the connection from the transformer to the board has a bad join or broken trace. The heaters are the only thing that carries significant current and the pilot light is often off the same circuit.

    Google tube radio repairmen in your area, doesn't have to be a guitar guy.
     
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  8. jwp333

    jwp333 Tele-Holic Ad Free Member

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    The local electronics repair shop/ kustom warranty shop ended up replacing 3 capacitors and resistors. No fuse or tube failure found. Final tally of $159. I’ve only played with it for about 30 minutes so far but it hasn’t failed yet.
     
  9. wanderin kind

    wanderin kind Tele-Meister

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    Nice circuit! i built one of those with EL34's and it sounds fantastic!

    which channel do you use most, clean or overdrive?
     
  10. jwp333

    jwp333 Tele-Holic Ad Free Member

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    Clean mostly although I've gotten some good sounds out of the overdrive at practice levels with the volume knob on the guitar turned down. I got it because James Brown designed it. Seems like he got to make all the decisions about it. The self biasing feature is unusual, but I'm not sure if it contributes anything in particular to the sound.

    The oddest thing about it is the reverb. Got a lot of boing to it.
     
  11. Les H

    Les H Tele-Holic

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    I have one of these and they are really decent amps. I remember when I got mine I already had a twin reverb and Koupe is everything I wanted the twin to be plus an overdrive channel that was actually useable.

    One day a couple years ago it blew a cement resistor that was close to the power tube sockets and when it went it literally blew one of my tubes in half. It was scary as he'll when it happened. I had it repaired but I have only felt comfortable using it sparingly which kinda sucks. Plus with Kustom just being a shell of the company it once was parts are very hard to come by.

    I did read that because of how the electronics are designed there is no escape from the heat they produce as the lay out is all straight up from the tubes. I bought a small fan that I lay in the back aimed straight up to blow the tube heat away.

    I just wish I felt like I could trust the amp enough to gig with again. That line out was spot on with how the amp really sounds. Best line out I've ever used.
     
  12. zombiwoof

    zombiwoof Tele-Afflicted

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    I played through one of those amps belonging to my brother at an out-of-town jam and was really impressed with it. And it has tremelo AND vibrato!.
    Al
     
  13. jwp333

    jwp333 Tele-Holic Ad Free Member

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    To update since the repair, all is good and actually better than before. The overdrive channel is more controllable and the reverb doesn’t have as much boing as before. I don’t think that it’s all in my head. Really is a good amp.
     
  14. jrblue

    jrblue Tele-Afflicted

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    That's a pretty versatile amp. I hope the repair makes it more reliable, as those are apparently somewhat self-destructive designs. Hopefully, yours is squared away now. Glad to hear about the reverb! I hate those "boingy" ones!
     
  15. jonnferrell

    jonnferrell TDPRI Member

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    Heat is the enemy of the Coupe series, worse on the 72 than the 36, but both run hot. I recommend one 12 volt fan screwed on the tube cage of the 36 pointing out and wired to the pilot light, and two on the 72. I also recommend cutting a hole on the back panel and putting a grate on there to let the trapped heat out. It works! My 72 has no more heat problems and my power tubes last a lot longer.

    If you have a 72 Coupe with problems (or even if you don't) right now on ebay you can get brand new chassis with boards and new tuck and roll, speaker baffle, tube cages, cords, etc all in a package for 59 bucks. If you want the same with transformers 118 bucks. Really, everyone that has a 72 coupe should buy one just for the insurance. Your 72 stops working? Well pull out the chassis, hook up the stuff, brand new amp!

    http://rover.ebay.com/rover/1/711-5...0001&campid=5338148343&icep_item=192634504852
     
  16. jonnferrell

    jonnferrell TDPRI Member

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    I love the line out! If you add a fan to the back of the tube cage and point it out, it pretty much cures the problem. I have gigged mine for years and never had a problem with the fans working.
     
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