5e3 junk box build

[nosaj]

I have a 5e3 junk box build I am working on. Following the layout. It appears the transformer they used is not 6.3 centertapped as mine is. My thinking was tape off the centertap and it would be ok Is that correct? I wired the heaters on the tubes as per the layout, should i detect voltage on pin9 of the 12ax7's? I am not.

Thanks,

Nosaj

[g1]

Is one side of the heater winding grounded?

[nosaj]

One went to the pilot light and the other went to ground. Centertap just taped up. Which is the way I understood the layout.

Thanks,
nosaj

[Dave H]

If you've wired it to the original layout you'll have to tape off the CT because the originl layout has one side of the 6.3V winding grounded. It's the side connected to pin 9 of the 12AX7, 12AY7 so you won't see a voltage there.

[nosaj]

If you've wired it to the original layout you'll have to tape off the CT because the originl layout has one side of the 6.3V winding grounded. It's the side connected to pin 9 of the 12AX7, 12AY7 so you won't see a voltage there.

Yes that was my question no voltage on pin9.

Thanks

nosaj

[g1]

As far as hum level goes, you may find it is quieter with that side of the heater winding lifted from ground, and the heater CT run to ground or power tube cathode instead.

[nosaj]

As far as hum level goes, you may find it is quieter with that side of the heater winding lifted from ground, and the heater CT run to ground or power tube cathode instead.

I think I'm being dense here, Lifting it from ground and tying CT to ground halves the available voltage. I'm missing where to put the lifted 6.3 leg.

Thanks,
nosaj

[g1]

All heater connections at the sockets that are currently grounded would be disconnected from ground and connected to the lifted 6.3 leg.

[nosaj]

Ok for the moment I want to leave the heaters as is. then move them over once things are working.

Started checking some voltages and pin1 V1 got 460v that shouldn't be right should it?

Thanks,
Jason

[g1]

No, the 460V there means the tube is not conducting. Try another tube there, check that the heater is lit, check the cathode resistor and it's connections.

[nosaj]

It was the heaters so i went and rewired them pin 1 I think was 260, but will follow up with all voltages. Got a lot of hum which I believe is going to be lead dress.

Also noticed that the hum will get louder and quieter depending one of the 6v6s redplating. Thinking solder connection as it happens after it's warmed up.\


Here's voltages

V5 5y3 pin2 271 pin8 272
V4 6v6 pin3 272 pin4 219 pin6 33 pin8 34
V3 6v6 pin3 259 pin4 219 pin6 33 pin8 34 When red plating pin3 282 pin4 260 pin6 28 pin 8 28
V2 12ax7 PI pin1 247 pin3 79 pin6 233 pin7 68 pin 8 113
V1 12ax7 pin1 245 pin3 83 pin6 245 pin7 0 pin8 83

Hum happens with V1 and V2 pulled. not passing signal yet. Will check on that after dealing with the red plating issue

Thanks,
nosaj

[Dave H]

Also noticed that the hum will get louder and quieter depending one of the 6v6s redplating. Thinking solder connection as it happens after it's warmed up

It could be a faulty tube. When it's red plating measure the grid voltage (pin 5). If it's zero swap the 6V6s over to see if the red plating follows the tube. It will hum if the 6V6s are mismatched.

[nosaj]

Faulty tube. another question since I used a center tapped filament. on the 6v6s on the fender layout pin 2 is tied to pin1 then to ground. Should this change?

Thanks,
Jason