7844


Brian
 

I would like to thank Chuck , Dave and Jerry who all offered words of
help over my power supply problem . I have fixed it . It was one of
the capacitors in the power supply . The only place in the whole
mainframe where tantalum caps are used (in the one I have anyway) and
it wasn't one . After removing the covers I was looking over the
pcb's to see if there were any signs of a problem . Nothing
immediately came to mind but then I realised the capacitor without
the plastic sleeve looked odd . Using a multimeter it did not appear
to be faulty but on close examination ?? it had been so hot at some
time the plastic sleeve had split along the length of the capacitor
and was now shrivelled up and trapped between the capacitor and the
pcb . I checked the associated diodes and all was ok so I fitted a
new capacitor . I couldn't re-assemble the power supply quickly
enough so that I could try it out . When I switched on it ticked at
me about a dozen times , I thought it was not going to work but then
it started and has been fine ever since . Another fault showed very
quickly , no beam 2 horizontal deflection . I found this one very
quickly , one end of L5999 had NEVER been soldered ??? . It has now
and everything is great .
Any ideas as to what option HD was , I cant tell the difference
between this scope and another one I have access to -- there appears
to be no difference except blue crt phosphor , but that was option 78
wasn't it .

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