25-01-2021, 07:28 PM
Hello again,
The support is much appreciated. I injected a fixed sine wave into the tape head preamps on both sides and the signals were the same on the oscilloscope at various points. So V1 circuitry was actually fine. Next stop is V7 and I realised that stupidly I'd replaced a 1.5k resistor with a 1.2M on one cathode of the ECC85. Now the playback output is fine! I think there may be an issue with one of the bias oscillators but I'll get to that in a few days.
The support is much appreciated. I injected a fixed sine wave into the tape head preamps on both sides and the signals were the same on the oscilloscope at various points. So V1 circuitry was actually fine. Next stop is V7 and I realised that stupidly I'd replaced a 1.5k resistor with a 1.2M on one cathode of the ECC85. Now the playback output is fine! I think there may be an issue with one of the bias oscillators but I'll get to that in a few days.
