|
Ground stakes on all boards
power resistors on chroma board with crystalized solder pads, reflow
jumper wires on top of chroma board,green corrosion, breaks off. The CRT will turn a solid color like screen control turned up too high.
Grid coupling cap, .01 between the power resistor and a 6GU7 will be weak, the other .01 grid coupling caps for the difference amps will prob be ok.
a trace on the side of the PCB near the horz out tube may fracture, back this up with a buss wire. It connects to a 390k resistor at the horz blanker tube. this shows as a loss of HV due to the blanker tube supplying too much neg bias to the horz out.
Caps in the vert feed back .0082 1kv mainly. the vert out cathode bypass cap, 50uf I think, its on the sweep board. Often ok, but if you doing for someone else then prob should be replaced.
1k power resistor on term strip near vert out trans, ofter the term strip solder has crystalized due to heat.
focus stick, sometimes goes bad mounted to side of fly.
horz output tube coupling cap. I replace this just to be safe.
Filter caps, of course these can be bad, if someone else set then I would restuff the cans just to be safe.
thermistor is fragile often broken.
on off switch is gets a lot of abuse. I use a remote power switch (the kind that are often sold during Christmas time for remote turn on of light) to save wear and tear on all my old vintage stuff.
Check line voltage. PT may have a high line voltage jumper that can be used. Better to use if line voltage is high, which is often the case.
check and adj horz eff coil, often a minor tweak can save 10-15ma or more good for fly life.
Check shunt tube and HV setting per sams. there is a 1k 5% resistor that is used to check voltage drop across for checking current in shunt. Generally you want to see about .5 to 1.5v drop across this while watching normal programing. think you will see this with the HV set to about 23kv and the fly current around 200ma
|