Hi all need help please.
I built the vox AC30 clone almost identical to an Austrian guy's amp on the net...
http://homepage.univie.ac.at/markus.breier/php/amp_ac/the-plans/layout_e/
Checked everything 20 times it seems. Still no sound from my guitar on any channel. Only difference I did from his amp was I took a Hammond power transformer, output transformer and choke (vintage specs all). The output T has the exact same color wires as his. My choke is a 30H. The power T has one extra 'shield' wire which I have grounded to the mains earth. I left the extra primaries of the transformer unconnected and covered with tape and tucked away (230 vac here in Sweden).
Many volt readings are good but I don't really know what to be looking for as this is my first build. The incoming AC from the transformer is as expected for the high voltage 580 V, 6.3 V for the heater and 5V for the rectifier. the 6.3 has a central tap. (the 5v is listed 5 - 0 in the PT spects)
There is DC at the primaries of the Output T (some 390 measures against ground) but no sound is produced to my speakers except a small Hum. All tubes heat up fine so AC 6.3 is working its rounds.
I have tried swapping tubes around and changing rectifier tube. I have run out of ideas. There was initial hum and this was traced to loose ground. Checked under the board and all the wiring time and time again. heating wire works, lamp on, Tubes are heating up, not overheating. There is some interference nose as I measure the connections with my multi meter to the Ecc83 tubes (at the grid I think) the blue wire connection.
I can rin my sterio reciver radio through it an there is some radio coming out out the Celestian Vintage speakers but its quite distorted. Amp Volume and Master volume actually do function on this horrible radio signal.
This is my first Amp build so I am not too familiar with what to expect where in measurements for this VOX AC30 AMP version. I did have to relocate the Choke and first caps on the OT side (not as the Austrian drawing had them). I have rewired most things looking for bad solders. I have checked measured resisters etc.
Does anyone have a page of info to compare readings?
Would a ground loop have such non-working effect on the whole thing? (I ran a ground wire to take the 'shield' of the input signal at the input jacks and isolated the solder station near the input jacks with plastic. I don't really understand star grounding; but I understand the principles. I just made one chassis connection and ran all grounds to that (except the shield from the transformer, it goes to the AC ground/mains).
Any suggestions about what readings I should look for and where?
Best regards,
Hugh
I built the vox AC30 clone almost identical to an Austrian guy's amp on the net...
http://homepage.univie.ac.at/markus.breier/php/amp_ac/the-plans/layout_e/
Checked everything 20 times it seems. Still no sound from my guitar on any channel. Only difference I did from his amp was I took a Hammond power transformer, output transformer and choke (vintage specs all). The output T has the exact same color wires as his. My choke is a 30H. The power T has one extra 'shield' wire which I have grounded to the mains earth. I left the extra primaries of the transformer unconnected and covered with tape and tucked away (230 vac here in Sweden).
Many volt readings are good but I don't really know what to be looking for as this is my first build. The incoming AC from the transformer is as expected for the high voltage 580 V, 6.3 V for the heater and 5V for the rectifier. the 6.3 has a central tap. (the 5v is listed 5 - 0 in the PT spects)
There is DC at the primaries of the Output T (some 390 measures against ground) but no sound is produced to my speakers except a small Hum. All tubes heat up fine so AC 6.3 is working its rounds.
I have tried swapping tubes around and changing rectifier tube. I have run out of ideas. There was initial hum and this was traced to loose ground. Checked under the board and all the wiring time and time again. heating wire works, lamp on, Tubes are heating up, not overheating. There is some interference nose as I measure the connections with my multi meter to the Ecc83 tubes (at the grid I think) the blue wire connection.
I can rin my sterio reciver radio through it an there is some radio coming out out the Celestian Vintage speakers but its quite distorted. Amp Volume and Master volume actually do function on this horrible radio signal.
This is my first Amp build so I am not too familiar with what to expect where in measurements for this VOX AC30 AMP version. I did have to relocate the Choke and first caps on the OT side (not as the Austrian drawing had them). I have rewired most things looking for bad solders. I have checked measured resisters etc.
Does anyone have a page of info to compare readings?
Would a ground loop have such non-working effect on the whole thing? (I ran a ground wire to take the 'shield' of the input signal at the input jacks and isolated the solder station near the input jacks with plastic. I don't really understand star grounding; but I understand the principles. I just made one chassis connection and ran all grounds to that (except the shield from the transformer, it goes to the AC ground/mains).
Any suggestions about what readings I should look for and where?
Best regards,
Hugh
