"David C. Partridge" wrote in message
.. .
Inherited this antique as a DOA, so thought I'd try to fix it for some
fun.

Immediate obvious problem was that the electrolytics in the PSU had
failed,
so on general principle I replaced every electrolytic in the machine, and
now it powers on and I've got the vertical amp calibrated against local
references (no they aren't certified, but have been checked against kit
that
*is* in calibration), and the sweep timings appear to be pretty darn close
anyway, so I've not dinked with the sweep unit. +24V, -24V and +105V
are
rock stable within seconds of power up.

One remaining problem though, when I power on the scope, the scan line is
excessively bright even with intensity turned right down and this takes
about 20 minutes to settle down to a reasonable level (at which point I
need
to turn intensity up to about 50%).

Where should I be looking for the culprit - my initial thoughts are
pointing
me to the HT/EHT section or possibly the "bright-up" circuit. Any
suggestions on the likely causes of the problem would be helpful. Could
it
be the ceramic caps in the HT supply, or possibly the switch on Thermistor
(TH301)? How best to check?

Thanks
--
Dave Partridge (remove xwy from replyto email address)



Is the CAL waveform or a standard external 1V/1KHz square wave reduced
in size on the screen?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/