Early and bad PbF but is it the problem here, most of the ECC83 socket solderings were very iffy . Volume dropped and owner changed the valves. Volume came up but a distortion on the overdrive channels emerged soon after. Redoing those socket solderings and usual suspects on front controls board has not cured the distortion problem. schematic on elektrotanya Harsh cut-off more like clipping and no sign of any smooth saturation, rounding of the peak/s, just launches into cut off on the peaks (not troughs). With all pots at mid posistion the signals ,clean and OD, are sinusoidal and amplitude ratio of about 2:1 OD:Clean in the gain and tone block. That preceeds the valve V7 which with mid pots and order 10mV amp input 400 Hz has on pin2 , grid, about 100mV pk-pk for clean but 7 volt on OD thence clipping. All valves test fine, all R in relevant area are fine. A cap problem ? but coinciding with valve changing? I've not inspected underside of that wired-in board but I'm assuming a cap PbF solder problem. Vol drop could even be the bad PbF at the input socket but problems appearing / disappearing at "intimate" handling suggest PbF problems. There is loads of relays in this design also .
- posted
12 years ago