Archon wrote in message
...
On 5/5/2013 3:21 AM, N_Cook wrote:
With about half mains voltage , for a bit of personal safety. About 20V
over
C-E of one driver Q and 120V over C-E of the other, whenever powered up.
Plan of campaign will be to try biasing on the off one and see what
happens.
Could a leaky driver transistor be the most likely cause of
non-oscillation?
one sliver-mica cap could have metal migration , others are polyester
and
ceramic. Otherwise loads of diodes and coils.


Just scanning the info on Yahoo Tek scopes, the batteries need to be in
situ as part of the regulation on these, bad things may happen
otherwise? (so they say, no experience with them myself) JC

yes, by the "power supply board in isolation " I meant with also the 2
battery packs, but minus the other 2 boards and CRT. I've decided to
desolder the pair of TO220 2SC2333 500V/2A and try a pair of TO220 BUV46
850V/8A switching Qs, will try later today