Fourth Vivat PWM

Paul writes:

This weekend I’ve been working on the ‘final’ Vivat PWM – this is the ‘US spec’ one that we changed the mains transformer on. The electrolytic capacitors are stamped ‘1953’, so it’s a good early one from MkII days.

I’ve now married it to the recently restored ‘spare’ power pack and begun restoration/testing.

So far, so good. All the suspect capacitors have been changed (every single one leaked like a sieve) and testing has started.

So far, I have working:

  • PSU
  • Video amplifier
  • Sync separator
  • X timebase & O/P stage
  • Y amplifier
  • Line scan
  • Field scan
  • Magnetic focus supply

All that’s left is the CRT heater supply – I’m going to fix that with another, extra transformer (as the main transformer is the wrong voltage for the CRT fitted) and the EHT unit.

Here are two pics showing the caps changed and the PWM and PSU with its EHT unit to the left.

Not sure when ‘first light’ will be (I have real work to do), but possibly back end of this week. Fingers crossed that the tube is good!