5E3 tweed deluxe home build just died

[thebigkevdogg]

Hi, I have had a 5e3 kit for a few years and it has been great...until last night. I turned it on and nothing is coming out. It worked perfectly at our a gig on Monday. Does anyone have any idea what the problem could be?

Some measurements, all fully on, no standby (some seem way off):

5Y3:
I'm getting almost nothing from 2 to 8 and 4 to 6.

12AY7 slot (with a 12AX7 in it):
Pin 1 to GND: 435V (!!)
Pin 6 to GND: 435V (!!)

12AX7:
Pin 1 to GND: 435V (!!)
Pin 6 to GND: 453V (!!)
Pin 8 to GND: 0V

6V6's:
Pin 4 to GND: 490V
Pin 3 to GND: 490V

Standby to GND: 493V

Do I need a new rectifier? PT? something else?

Thanks a lot!
Kevin

[tubeswell]

Try plugging in a new 5Y3GT.

[thebigkevdogg]

Thanks for the reply. Unfortunately I don't have an extra on hand, but I already ordered one. I'm heading to Hawaii tomorrow and will have to try it out in a week when it (hopefully) is here and I am back.

[Enzo]

Looks to me that none of your heaters are working.

Those readings on the rectifier tube are AC volts by the way.

[Amp Kat]

Also when you return measure across the cathode resistor and see if you measure any voltage. If you get nothing that is a good sign Enzo's assumption is spot on.

[thebigkevdogg]

OK I see why I wasn't getting anything over the rectifier...I was checking DC, and the DC setting was too low for the DC side.

The actual values are as follows:
Pin 8 to 2: 5v AC
Pin 6 to 4: 725 V DC

What would cause the heaters to not work (what would I need to replace/fix)? I think this might be right, as I did notice that the tubes aren't heating up.

As for the cathode resister (excuse my extreme ignorance, but that's the big one across the 25 uF Cap from pin 8 on the 6V6's to GND, right?

Anyways, if that is indeed the cathode resister, then there is no voltage across it, and in fact there is continuity between them.

I'll be able to check things once more this afternoon before I hop on a plane.

Thanks a lot!

[Enzo]

If the tubes don't light up, that is your problem. Possible transformer failure but very unlikely. More likely a wiring problem. Does you r pilot light come on?

Follow the heater wires from the transformer to the pilot light and tube sockets. Look for a place where a wire has come loose or the solder cracked.

[thebigkevdogg]

If the tubes don't light up, that is your problem. Possible transformer failure but very unlikely. More likely a wiring problem. Does you r pilot light come on?

Follow the heater wires from the transformer to the pilot light and tube sockets. Look for a place where a wire has come loose or the solder cracked.

The pilot light turns on...I'll check the wiring for the heater wires when I get back from Hawaii in a week. I seem to remember the heater wires maybe having continuity with ground, but I'll have to check.

Thanks!

[Bruce / Mission Amps]

The pilot light turns on...I'll check the wiring for the heater wires when I get back from Hawaii in a week. I seem to remember the heater wires maybe having continuity with ground, but I'll have to check.

Thanks!

It is not unusual at all to see a homebuilt amp have a loose solder connection from the PT to the pilot lamp holder or to one of the lugs on the 6V6s... which is supposed to feed filament voltage to the other tubes... etc.
I'd just double check all that filament wiring stuff with a hot soldering iron before going to far.

[thebigkevdogg]

Well everyone's suspicions were correct! It was a broken solder joint on one of the terminals of a 6V6...the heater wires. It's back up and running and sounding great!

I have noticed something though, but it's possible that it's all in my head since I'm looking for something to be wrong. Anyways the volume control seems to be even more jumpy, and most of the volume gain happens between 0 and 1, whereas before it would happen between 0 and 3 (no tone mod). The chassis also seemed to be pretty hot, which I don't necessarily remember.

Is it possible that this a result of running it with unheated tubes when trying to figure it out? Did that mess something else up? If so where should I check?

Thanks a lot for all of your help!

Kevin

[MWJB]

The chassis will get reasonably hot, via the heaters & because the 6V6s are running high idle currents (probably 35-40ma) producing heat. The PT will get warm, now there's a load on it, and transfer heat to the chassis.