Hi....recently I picked up an old Tek 475 200Mhz scope not working I managed to get a full service manual for it but have had no luck getting it running.
The +50 Volt rail (which I belive all other rails are derived from) is perfect, as is the 110V, +15, +5 rails.
The negative rails are out, the -8Volt rail reads -6 volts but the -15 Volt rail is way out at -23 volts.
Im not an expert with this stuff but like to have a go, it would be a shame to chuck it out.
Its really annoying me because the schematic for the -15 volt supply "looks" so simple, Ive checked caps, all resistors, transistors and even replaced the IC (MC1458) with no change at all.
The CRT works fine, lots of brightness, the vertical amps both appear fine but the timebase is werid, some (lower) ranges wont display a trace at all and the higher ranges show multiple horizontal line (with no input) and the trace "curves" to the left hand side of the screen.
If I apply the cal signal input I can see the square wave but triggering is erratic, reminds me of my first "KnightKit" scope I got when I was a kid that used a thyratron in the timebase.
Info/parts are a little scarce in this part of the world (Australia)
Does anyone have any hints/suggestions???? Thanks