B+ question

[newguitarsmell]

I'm working on a 5e3 and a resistor keeps burning up and my B+ is way to high...

[newguitarsmell]

Sorry for the duplication of the pic....

I tried two different rectifier tubes. I'm thinking I'm not getting any signal?

[labb]

Probably a short to ground to fry the resistor. Check around V1 and  V2. One or both of those tubes may be bad. and check C12.

[sluckey]

Is C12 installed backwards? If not, use your ohm meter to check for a short from positive side of C12 to chassis. The short may be C12 or it may be in the wiring connected to C12.

[newguitarsmell]

Hi Guys
I managed to rewire whatever it was that was shorting my Cap and frying my resistor - win.
I redid my bus bar - seems OK. The amp fires up - the voltages are in normal range. I assume this means I didn't fry my PT.
Nice hum (low) to the speaker but no signal. I checked the tubes, I checked the cord..
Gut shots here - I don't know how you guys make your amps look so wonderful and my gut shots look like a war zone - getting better, but still. apologies for dog hair.

[newguitarsmell]

guts

[newguitarsmell]

guts

[newguitarsmell]

more

[newguitarsmell]

I can hear the volume pots effecting the hum of the speaker - and I can also clearly hear the tone pot is effecting the quality.
I think it's something simple - it's like the guitar just isn't plugged in - I will go back to it after lunch break. Maybe I will see it then..
 

[newguitarsmell]

I realized I had a short in one shielded wires... and my numbers are no good
PLEASE HELP. My voltages are in Green
I am using Classic Tone 40-18090 OT and Classictone 18021 PT

[vampwizzard]

theyre close. Are you sure the filter caps and power resistors are still ok? what rectifier tube are you using?

[66Strat]

IMO, the problem lies with the power transformer. It is rated to deliver 710 volts under a 100 mA load. Vintage 5E3 power transformers were rated at about 700 volts (350-0-350) in a no load condition.

Edited to add verbiage.

You need a power transform that delivers about 650 volts under load (325-0-325).

http://www.classictone.net/40-18021.pdf

[sluckey]

I expect to see voltages like that when you use that Classictone 18021 PT. However, I see you are using a 560Ω cathode resistor. Why??? Should be 250Ω. Using that 560Ω resistor causes the output tubes to run cooler Running the output tubes cooler means the B+ is not being loaded much. Change for 250Ω/10W and voltages should drop a bit.

[newguitarsmell]

Hi e - I replaced it after I took the pictures. It is now 250 Ohms/10W I thought about that, too. but the voltages are still so high! Is it because there is basically no signal
load?

[sluckey]

no

[newguitarsmell]

When I was sorting out the BBQ resistor , Sluckey said my Cap was shorted to ground. That was exactly right. At that point I pulled all the Capacitors and made sure they were all still good. I have checked each of my connections for conductivity - I redid the input section and found 1 shorted wire which I fixed... It seems SO close to working.
I feel like it's something so stupid I'm just not seeing it.
M

[newguitarsmell]

I will shoot another picture of the input area.

[newguitarsmell]

more

[newguitarsmell]

another

[66Strat]

Hi e - I replaced it after I took the pictures. It is now 250 Ohms/10W I thought about that, too. but the voltages are still so high! Is it because there is basically no signal
load?

No.

Tubes draw current. At idle, a 5E3 should draw about 80 mA of current, 100 mA at clipping. This is the load seen by the power transformer. The resistance in a power transformer's primary and secondary windings will cause the "no load" voltage of the power transformer to "sag" down to the voltage under load rating.

[newguitarsmell]

The 5y3 tube is a new Sovtek one. I tested all the tubes on my tester and every one works perfectly. I have wired something wonky and I can’t find it. Poo

[sluckey]

The 5y3 tube is a new Sovtek one.

Get a real NOS 5Y3. B+ voltage will decrease.

[newguitarsmell]

I have one so I will try that. I doubt that will solve my no signal problem.. will report back...thanks for all the help guys. I’m almost ready to take it out back and shoot it.

[sluckey]

I doubt that will solve my no signal problem

I agree. No signal is a separate problem. Probably a wiring error.

I don't consider your voltage reading to be a problem.

[shooter]

Someone want to double check, I'm coming up with 19W a tube using green numbers and 250ohm 

[66Strat]

Hi e - I replaced it after I took the pictures. It is now 250 Ohms/10W I thought about that, too. but the voltages are still so high! Is it because there is basically no signal
load?

No.

Tubes draw current. At idle, a 5E3 should draw about 80 mA of current, 100 mA at clipping. This is the load seen by the power transformer. The resistance in a power transformer's primary and secondary windings will cause the "no load" voltage of the power transformer to "sag" down to the voltage under load rating.

IMO, the problem lies with the power transformer. It is rated to deliver 710 volts under a 100 mA load. Vintage 5E3 power transformers were rated at about 700 volts (350-0-350) in a no load condition.

Edited to add verbiage.

You need a power transform that delivers about 650 volts under load (325-0-325).

http://www.classictone.net/40-18021.pdf

Pffft , pffft, Testing...Testing....doing my best spit on mike impersonation

[shooter]

 

the amp can operate at 437vdc, but not at 19W

[newguitarsmell]

Thanks everyone for the encouragement. It WORKS and sounds Wonderful.
I have almost no idea what the deal was but I suspect something under the board - something shorting to the chassis? Who knows. Maybe I just had to pay my dues. All the info you all helped me with today really helped me figure out what it WAS NOT - I wish it. hadn't taken me four or five hours of head scratching to get here - but done is done and it sounds great. I replaced the rectifier with a NOS one and that helped - and I added a choke which helped more.
Someday, I hope, it won't be such a royal pain in the booty.