290BX PT - d'lite 22 6V6 powering up issue

[pompeiisneaks]

For the curious, here's the PT Datasheet:

https://www.hammfg.com/files/parts/pdf/290BX.pdf

~Phil

[mehfuzhoss]

i took out the relay board power supply and the relay board. not considering the footswitch for now. I am following this layout attached. the green arrow marked 3pdt switch. what is it's function?

i want to use the OD channel only without the need of the switch. how should I wire it ?

[mehfuzhoss]

relay psu and relay board removed pics.

[pompeiisneaks]

first did you do any of the troubleshooting steps suggested to trace the signal? That switch looks to me like either a rock/jazz switch or a mid boost switch or something similar, but I'm not as familiar with the differences to know at a glance.

the relay power supply removal doesn't necessarily help/hurt, now you've changed a few more things so some more variables are different, which means potentially other tests need to be done.

Have you gotten the voltages documented for the different B+ nodes and the pins of the different tubes as mentioned?

~Phil

[mehfuzhoss]

I have installed 2 100 ohms on the 6.3v heater wires and grounded. now it is not noisy anymore!!!

here are my voltage findings -

v1
Pin 1 : 393
2: mv
3: 5.7
4 & 5: 3.23 ac
6: 395
7: mv
8: 395
9: 3.20 ac
50
v2:
Pin 1: 398
2: 5.45
3: 11.6
4 &5: 3.21
6: 400
7: mv
8: 11.58
9: 3.20 ac

v3
Pin 1: 330
2: 51
3: 79.5
4&5 : 3.22
6: 325
7: 52.2
8: 79.5
9: 3.20 ac


6v6
Pin 1: 13.7
2: 3.21 ac
3: 462
4: 461
5: -48 dc
6: -48 dc
7: 3.23 ac
8: 13.1 mv
9: 3.21 ac

6v6
Pin 1: 13.5
2: 3.21 ac
3: 461
4: 460
5: -48 dc
6: - 48 dc
7: 3.23 ac
8: 13.5
9: 3.21 ac

main nodes: 462, 457,407 and 400 DC
rectifier red wires has 343.8 and 343.6 AC
bias tap has 52.3 v


amp power up okay. but no sound when plugged in with a guitar.

[mehfuzhoss]

I spotted few errors in the layout. Please confirm.
5uf coupling caps with the resistors are not grounded.
Am i correct?
I know for sure the left coupling needs grounding. What about the right one, (coupled with 10m resistor ) that connects to the relay. Should i ground this one as well. Please confirm. My amp is coming out great. Its very complicated one so far...lol

The right relay's top lug 3 is connected to bottom lug 4?

I appreciate the forums kind help!

[mehfuzhoss]

bump...
i connected the left 5uf/resistor to ground. amp is making very low output at full volume. almost no tone change when eqing.
should I ground the right 5uf/resistor to ground as well? I reconnected the relay board back in. any suggestion other than audio probing ?

thanks

[rootz]

Close to 400V on the plates of V1 and V2. Definitely not right! Confirm the cathode resistors are grounded and the tube sockets make proper contact. You might have cathode resistors that are 22k and 33k? Anything over around 1.5 to 2 VDC on the cathodes of V1 and V2 is absolutely wrong.

[rootz]

bump...
i connected the left 5uf/resistor to ground. amp is making very low output at full volume. almost no tone change when eqing.
should I ground the right 5uf/resistor to ground as well? I reconnected the relay board back in. any suggestion other than audio probing ?

thanks

Yes, your cathode resistors and caps should all connect to ground on one side, the other to the cathode of the corresponding triode. Without ground connection current cannot flow, hence the triode can not amplify the signal at its grid.

[mehfuzhoss]

thank you for confirming. one more question about the volume pot wiper and right side lug being connected in the layout.
is this correct? please look at the screenshot. I don't have them connected at this time.

[drew]

thank you for confirming. one more question about the volume pot wiper and right side lug being connected in the layout.
is this correct? please look at the screenshot. I don't have them connected at this time.

I think the way it’s drawn in the layout in the third post in this thread is correct.

[fred.violleau]

What you think is a connection is actually the leg of the bright cap that extends too much on the drawing. There is no connection between the wiper and right leg of the pot.

Fred.

[rootz]

What Fred said! Volume pot middle lug (wiper) to bright cap and shielded cable (V1b grid connection). Left lug to ground (correct in layout). Right lug to bright switch and tone stack output (middle lug treble pot.

Please post you voltages for the preamp again. I'm interested in the plates. Is there still close to 400V in the plates of V1 and V2. If so, there is still something amiss there.