Traynor Ygm-3 Broken - Need Help!

[msoftich]

I got a broken YGM-3 for free from a guy I work with. I don't really have experience in electronics or guitar amp building although I have done quite a bit of reading and know how to do simple tasks like bias my ENGL (newer) amps, but as for troubleshooting old amps I am kinda in the dark. I hope to find some answers here...

So the problem with the TRAYNOR is:

I turn on the power, flip the standby switch, no sound... No hum No pop with the throw of the switch, nothing. Next I looked at the tubes and all are not lighting except the last EL84. I assume it is either a faulty PT or possibly the 6.3V heater wires are bad or the connection is bad...

What do you guys think I should do?

[drlowlow]

the schematic is posted here
http://www.schematicheaven.com/barga...rmate_ygm3.pdf

according to the schematic the EL84s in the middle of the filement wiring which is odd that is the only one being lit, but I have seen situations that somethings aren't wired in the exact manner that is described on the schematic. If one of the tubes on that 6.3v line is getting voltage than we know that at least that winding on the power xformer is good so we can gather that either most of the tubes are bad, most the sockets need to be cleaned (probably worth doing anyways), there is an open in the wiring, or a combination of these. you can troubleshoot all these with the amp in standby mode. be advised though that even though HV isn't applied there still can be charges big enough to kill in the amplifier from the power capacitors. it is possible that this is the only problem with the amplifier. good luck and keep us informed on what you find.

[msoftich]

I fired it back up after cleaning the sockets with contact cleaner and all the tubes lit up this time but still no hiss or pop from the speaker when throwing the standby switch. The tubes eventually all stopped glowing except for the last EL84. I am clueless...

[drlowlow]

I imagine when you were cleaning you managed to shake the contacts that were loose on the filament line and then in time they loosened again. take a chopstick or other similiar insulated device and prod the the filament wires while you have the amp in stanby mode, it is obviously between the lit and the unlit el84.

the no sound from speaker issue could be a good number of different things. the first thing I would do is unplug the speaker plug and check if it has the correct impedence with a dmm.

[Garydean]

Test the speaker with another amp or use a 9V battery to test it. See if it pops then. As far as the amp, you'll need to remove the chassis and check the pin readings. Visually inspect the wires and connections. Be sure you understand the danger involved with probing around high voltages. Be careful!!

[msoftich]

well, i had it open yesterday and looked around a bit only to notice that the filament wiring is pretty loose on the 2 EL84 tube sockets. I shook them around a bit and got all tubes up, and started with a plate voltage reading. I was getting pops through the speaker while checking these and then threw the standby switch and I could hear some noise and the tremolo working. I threw it back on standby, went upstairs to get my guitar, plugged it in, threw the standby switch and nothing. No sound! All the tubes were lit up. I went to check my plate voltages again and now I don't get any pops. Back to square one. Anyone have any clues what I should do next?

[Amp Kat]

It's pretty evident you need to get those sockets changed and it will most likely undue your connection problems as it seems that's what's going on. The tubes will work their way out again dropping out the heater voltage from vibration probably when you need it the most. Don't rule out a cold solder joint on a component also but it really does sound like a connection problem.

[52 Bill]

the filament wiring is pretty loose on the 2 EL84 tube sockets. I shook them around a bit and got all tubes up

You should start by fixing the filament wiring, so that it works correctly. As long as there is a possiblity that it is not working right it will throw off all your other testing. Follow the wires from the transformer to all of the tube sockets. Look for bad solder joints or broken wires.

I was getting pops through the speaker while checking these and then threw the standby switch and I could hear some noise and the tremolo working.

I don't know if it's possible to check any voltages or hear pops with the standby off, as it will shut down all of the voltages to the amp. In some amps, the standby shuts off the signal path, but on yours it shuts off the power supply to the signal circuits.

I went to check my plate voltages again and now I don't get any pops. Back to square one. Anyone have any clues what I should do next?

Take plate voltage readings starting at the output tubes, and work your way to the first pre-amp tube. Compare them to the schematic and tell us what your results are.

[msoftich]

well guys, I put in a new 3 prong AC cable and soldered all connections for the filaments wiring on all sockets and sure enough that was it. She is sing now! I'd like to say thanks for helping me out on this one guys and I am sure I will have a lot more questions in the near future as I try some mods on this amp. Thanks again.

Mark

[GonzaloCobo]

I msoftich, how do you open the YGM-3? I have one, I need to clean the pots, i retire the screws but is imposible to open the case

Gonzalo

[Gtr_tech]

The top pops off. Take out the 4 screws then pry the "lid" off. I have one of those, thats how it works.