Ok HM605 is dealt with. New bridge rectifier installed at lunch and it’s burning in for a bit. Trace is a lot sharper and if you turn the brightness up now it doesn’t drop out any more.
Edit: quite surprised at this. Now the amplitude is gone because, quite frankly it's being hammered here but it's still triggering fine!
Signal source:
Not bad for a 60MHz crate!
Got my "yellow/red" HM605 seen to about the same time BD139 was working on his:
X-Pos. nylon coupling thingy cracked, 68V & 140V slightly off, amplitude slightly off, timebase badly off.
Moved on to one of the two HM205-3's that need sorting:
Var. timebase nylon coupling thingy cracked (they always are), component tester fuse.
Here also a little frontend and timebase readjustment were needed, supply voltages were OK.
On these the digital memory has few adjustments (overall vertical position and an individual vertical position for each channel, which IMHO doesn't make much sense) so once the sweep length is set the analogue timebase must be set to match the digital timing.
After adjusting all the frontends and timebase I went on to try and get the switching between analog/digital seamless but that wouldn't fit, digital was slightly low in amplitude despite +12V being spot-on and here being a VR2401 "Y-Gain (DIG) / YF-Gain mit Eprom" that one would expect to be there for that purpose but isn't as it affects both analog and digital gains. (As per schematic... Must have been during Oktoberfest.)
Probing at the ADC's with trace just out of the graticule the MC10319 wasn't showing any Over-Range so I decided the digital amplitude adjustment would go on the ADC's Vref, which in turn makes the overall digital vertical position more useful as getting decent overlap requires a few iterations.