5E3 woes....

[tylerrussell]

Here's hoping someone might be able to help a newbie. I built a 5E3 two years ago and have used it exclusively for gigs, practice, etc. No problems, which is remarkable considering it is my first build. Lately, in the middle of playing it will hiss a bit~then no sound at all. Hit the stand-by on then off and viola~everything is fine again. Chopsticked, cleaned tube sockets, replaced tubes with known good ones; sometimes it will just make some noise then cut out until the stand-by switch is toggled. One wire connecting the two 6V6's made noise when chopsticked~I re-flowed the joints and that didn't help. I replaced that wire and the noise stopped. Can anyone give me any idea of where to look? I have a multimeter and can keep one hand in my pocket. It is a rather ugly build internally, but it has worked fine from the get-go. Any input is appreciated.

[shooter]

I have a multimeter and can keep one hand in my pocket.

have it opened up, play til it fritzes out, then measure VDC on all your PS taps, including bias volts.

If they are good, do the same at each plate n cathode pin.

[tylerrussell]

Thanks, Shooter. I assume you mean VDC on the filter caps? I'm sorry, but I don't know exactly where to measure!

[shooter]

Yes, VDC.  look at your schematic, there are "taps" on the PS rail, one for PA tubes, probably 1 for your PI, and 1 or more for preamp tubes.  My guess is a loose socket connection, or bad/leaky filter cap, by measuring the rail volts compared to the plate & cathode you get a pretty good sense of where to start your search.

EDIT:  you can do this when it's working as a "baseline" then when it's quits.

The problem could also be signal loss, but that's harder to find with a meter

[drew]

Could the standby switch itself be the culprit?

[John]

Could the standby switch itself be the culprit?

That was the first thing I thought of too. He can try bypassing that see what happens at the next practice.

[tylerrussell]

Hopefully the .gif shows up. I'm afraid that I don't know exactly where to check these voltages. Would it be possible for one of you guru's to high-light the appropriate areas? I realize it's a lot to ask~ but I would like to get this amp back to its previous state. Thank you all.

[tylerrussell]

Just realized that is not the layout I used~ mine has a stand- by switch. The rest is the same except for .022 coupling caps instead of .1's.

[Tony Bones]

Just start with the voltage across each of the three ps caps. Those are the big 16uF , 450V caps. Also measure the voltage across the cathode bias resistor for the output tubes. That's the big 250 ohm, 5 watt resistor with a 25uF cap across it.

[John]

What Tony said. Highlighted areas just in case. :) These voltage are VERY approximate since I don't know what you're starting with.

[shooter]

the standby switch

+1
I've never built an amp with one so I forget they exist

[tylerrussell]

Thank you all for the input. The voltages read from left to right:
                                         18.24
                                          330
                                          292
                                          226
Patiently waiting for it to get cranky.

[John]

If it starts acting up, and your high voltage at the first node (330vdc) drops way down, I'd suspect that standby, for sure (if it's not the rectifier tube). Where do you have it installed in the circuit?

[tylerrussell]

This is the actual layout. Will try measuring thar first node when she acts up. I have tried another 5y3 recently. Seemed good for a few hours, then..... same thing. Don't know why the pic is so blurry....    Thank you all again for the assistance.

[tylerrussell]

seems that the pic didn't post

[tylerrussell]

Maybe this time....

[sluckey]

Just imagine you had to use that tiny pic to build this amp. 

Surely there's a bigger one somewhere.

[John]

http://site.triodestore.com/5E3DeluxeLayout40-18017120V.pdf


Young'uns. ;)

[tylerrussell]

Young'uns. ;)   "????????


Ha, I'm 65. Can barely use a computer let alone build an amp!!!!!!

[John]

Then I salute you! I'm 53, started this hobby in my forties, wish I'd been 20's. The older the brain, the less spongy it is. Or that's my excuse, anyway.

[shooter]

I'm 65. Can barely use a computer

I'm 60, played with computers since I was 14, made good money at but now I've forgot on purpose everything I knew
hang out here and we can get you building amps, just give up computers, the Gkids will help you with that

[tylerrussell]

The grandkids talk so far over my head with this stuff I get dizzy sometimes. Off to rehearsal (with a meter). Bet it doesn't act up......

[EKDENTON]

Another thought......maybe take a look at the filaments when it stops running to see if they are still lit up. Might be a bad solder joint on the filaments?

[Ed_Chambley]

Check your cathode resistor on your power tubes.  I had an amp come in that the Power Tube cathode was grounded and the tubes got too hot and would stop working.  Amazingly enough, once it cooled down they would work again.