#183 voltages

[CHIP]

As stated in previous posts, there is something wrong with your screen voltages. pin 4 on the power tubes.

[lionaird]

As stated in previous posts, there is something wrong with your screen voltages. pin 4 on the power tubes.

I actually have another choke floating around somewhere. Might be worth to give it a go. Thanks

[erwin_ve]

As stated in previous posts, there is something wrong with your screen voltages. pin 4 on the power tubes.

I actually have another choke floating around somewhere. Might be worth to give it a go. Thanks

Having plate voltages at v1, v2 and v3, suggests you choke is working. Imo you should double check the wiring from the filtering board to your screen(pin4) voltages at the power tubes as other mentioned before.
See the schematic with outlined red markings.

[ToneMerc]

As stated in previous posts, there is something wrong with your screen voltages. pin 4 on the power tubes.

I actually have another choke floating around somewhere. Might be worth to give it a go. Thanks

Having plate voltages at v1, v2 and v3, suggests you choke is working. Imo you should double check the wiring from the filtering board to your screen(pin4) voltages at the power tubes as other mentioned before.

Ditto, hard to tell from my handheld screen, but it appears the screen termination on pwr board is wired to the wrong location.

TM

[CHIP]

I actually have another choke floating around somewhere. Might be worth to give it a go. Thanks

Having plate voltages at v1, v2 and v3, suggests you choke is working. Imo you should double check the wiring from the filtering board to your screen(pin4) voltages at the power tubes as other mentioned before.

Ditto, hard to tell from my handheld screen, but it appears the screen termination on pwr board is wired to the wrong location.

TM

From what I can see he has it wired correctly. A red wire is coming from the power board to pin 6,
which then he used green wires to connect the others.

[lionaird]

Ok. Checked all the connections from/to the power PCB and all seems to be wired correctly. Including B+2 out to pin 6. Very weird

[erwin_ve]

Ok. Checked all the connections from/to the power PCB and all seems to be wired correctly. Including B+2 out to pin 6. Very weird

What voltage reading do you have at B2?
I ask this specific because in all the voltage readings you didn't mention B+2. If you have the right voltage there; the wire to the screens might be broken. If you don't have a voltage there something is not wired correctly at the filter board.

[lionaird]

Ok. Checked all the connections from/to the power PCB and all seems to be wired correctly. Including B+2 out to pin 6. Very weird

What voltage reading do you have at B2?
I ask this specific because in all the voltage readings you didn't mention B+2. If you have the right voltage there; the wire to the screens might be broken. If you don't have a voltage there something is not wired correctly at the filter board.

My B+2 voltage reading is 508 Volts. I get the same reading on pin 6

[erwin_ve]

Ok. Checked all the connections from/to the power PCB and all seems to be wired correctly. Including B+2 out to pin 6. Very weird

What voltage reading do you have at B2?
I ask this specific because in all the voltage readings you didn't mention B+2. If you have the right voltage there; the wire to the screens might be broken. If you don't have a voltage there something is not wired correctly at the filter board.

My B+2 voltage reading is 508 Volts. I get the same reading on pin 6

And what are the screen resitors readings, between pin 4 and 6, in Ohms with the amp off?

[67plexi]

What power transformer are you using looks to have dual B+ secondary’s.
If so use the red/red not the red with the white stripe.
You want 465 volts B+.

[lionaird]

And what are the screen resitors readings, between pin 4 and 6, in Ohms with the amp off?

Hmm, can't get any ohm reading when measuring the screen resistors at any of the power tubes

What power transformer are you using looks to have dual B+ secondary’s.
If so use the red/red not the red with the white stripe.
You want 465 volts B+.[/code]

Yes, that's correct. I'm using the 345-345 secondaries. Same as in the schematics of the Ceriatone clone. So I should use the 320-320 secondaries to tame the voltage a bit?

[lionaird]

How very bizarre. All 4 screen resistors didn't work. I replaced them with new ones and suddenly the beast comes to life

Voltages again.

B+: 491V
B+2: 488V
B+3: 462V
B+4: 336V
B+5: 328V

V1

1: 197.5V
3: 1.890V
6: 198.6V
8: 1.9V

V2

1: 196.5V
3: 1.695V
6: 203V
8: 1.963V

V3

1: 321V
2: 39V
3: 62V
6: 326V
7: 38V

V4

3: 489V
4: 479V
5: -45.5V
6: 488V

V5

3: 488V
4: 480V
5: -45.5V
6: 487V

V6

3: 489V
4: 480V
5: -44.8V
6: 487V

V7

3: 488V
4: 479V
5: -44.9V
6: 487V

[martin manning]

I'm using the 345-345 secondaries. Same as in the schematics of the Ceriatone clone. So I should use the 320-320 secondaries to tame the voltage a bit?

I think that would be a good idea. If you haven't done so already, I would also put the 1R current sensing resistors back in so you can easily check the idle current.

[lionaird]

I'm using the 345-345 secondaries. Same as in the schematics of the Ceriatone clone. So I should use the 320-320 secondaries to tame the voltage a bit?

I think that would be a good idea. If you haven't done so already, I would also put the 1R current sensing resistors back in so you can easily check the idle current.

Ok, using the 640V secondaries now which brings B+ down to 450V. Don't really need the 1R resistors because my bias meter shows idle current and dissipation wattages. I adjusted the idle current to around 40mA which gives me a dissipation wattage of 18 Watts...

Everything is working now. Apart from the LED of the 50/100 switch. The switch doesn't really seem to do anything either. I measured it and it take pin 1/8 of V4 and V7 off ground. Doesn't really seem to reduce the output wattage though...

[erwin_ve]

How very bizarre. All 4 screen resistors didn't work. I replaced them with new ones and suddenly the beast comes to life

Voltages again.

B+: 491V
B+2: 488V
B+3: 462V
B+4: 336V
B+5: 328V

V1

1: 197.5V
3: 1.890V
6: 198.6V
8: 1.9V

V2

1: 196.5V
3: 1.695V
6: 203V
8: 1.963V

V3

1: 321V
2: 39V
3: 62V
6: 326V
7: 38V

V4

3: 489V
4: 479V
5: -45.5V
6: 488V

V5

3: 488V
4: 480V
5: -45.5V
6:

V6

3: 489V
4: 480V
5: -44.8V
6: 487V

V7

3: 488V
4: 479V
5: -44.9V
6: 487V

When wirewound resistors have a big current to swallow they sometimes act like a fuse. Seems that has happened. Question is why was there a big current?