[Ebromyr]

Hi all, Im from Sweden so sorry for not writing in German.

I just finished my 50w clone and I get some strange results. All voltages regarding pre- and power tubes, plate, screen B2 are in the correct range.

I Cant get any sound on the clean channel, only on OD. The OD gain pot is responsive but not TMB or the master volume.

So this made me check the LDRs voltage and I cant really understand my readings.
The voltage after the bridge rectifier when im on the clean channel is 5,02 V DC. When I’m on the OD channel it drops to 4,83 V DC.

The voltage on LDR 1 + 4 is 2,323 V DC and LDR 2 + 3 has 0,583V DC when im on the clean channel. (Not correct from what I can understand?).

On OD channel i get 3,9mV DC on LDR 1 and 1,9mV DC on LDR 4. I get 0V DC on both LDRs 2 + 3.

Im using both the Power- and output transformers from tube town.

Would really appreciate any helpfull hints or tips

Cheers
/Eric

[Rene2097]

Hello Eric,

are you using the schematics from SLOclone Forums?

You are right, the voltages are odd. Is your footswitch wired up correctly?

René

[Ebromyr]

Hi René

No im using the schematic from this forum. I’ve only posted on the SloClone forum aswell for some help.

Will se if the images of the input and switching can be posted. Didn’t work the first time.

[Ebromyr]

Here are the rest of the pictures.

[Ebromyr]

Just to clarify, im using the Tesla Optocoupler 3WK 163 40 which should be equivalent to the VTL5C1.

[Rene2097]

Good morning,

did you check all the resistor values? Is C25 wired up correctly?

The voltage after the bridge rectifier when im on the clean channel is 5,02 V DC. When I’m on the OD channel it drops to 4,83 V DC.

The voltage on LDR 1 + 4 is 2,323 V DC and LDR 2 + 3 has 0,583V DC when im on the clean channel. (Not correct from what I can understand?).

When on the clean channel, there should be plain 0 Volts since it's a shortcut. Check all the connections beginning from V15 for cold solder joints.

Good luck and keep us updated,

René

[Ebromyr]

Morning

Well yesterday i found two things i’ve made wrong. First is that I’ve switched the OP transformer leads going to the anode connection. Second is that R83 in the switching circuit should be 47ohm but the one i got from the Vendor is 4,7 ohm. Quite irritated since it says on the reciept 47 Ohm. There fault for sending me the wrong one, my fault for not checking it in the first place.

Will be checking all resistors again and order new. Will check for cold solder joints aswell. Will be back with the results when I get it.

/Eric

[Ebromyr]

It’s working now!

Changed R83 and found I had connected the switch on the frontpanel wrong.
Just have to check of I have my OT wired wrong. What’s the consequenses if they are wired the opposite way? Oscilliation? Change of overdrive sound? I guess I can disconnect the NFB right? I’m quite new at this.

Cheers

/Eric

[smid]

If you have NFB then the OT has to be wired in the correct way. If you reverse the OT connection you have no longer negative FB but positive FB: Your Amp will scream at you, you can't miss it....
If you don't have a NFB, you can connect the OT either way.