oscilloscope display problem

[naimead]

Hello,

I have an oscilloscope which seems to be well preserved but I don't see any output on the screen even when I push beam finder.

I opened it an gave a look inside where there seems to be nothing wrong.I used a multimeter to check that the internal voltage on board is the one that is supposed to be(+30V,-30V,200V,+5V,-5V) and everything is fine.I checked the wires from the circuits to the screen and everything seems to be fine too.While I was playing with the various screen options I found that the graticules are responsive and they become positive(their intensity augments) when I turn the proper option clockwise.

What do you think the problem could be?

thank you all,

naimead

 

[(*steve*)]

2 very basic checks.

1) Is the heater drawing current?

2) Is the EHT supply working.

Please be *very* careful checking the latter.

 

[poor mystic]

When checking the EHT supply, just look at the low voltage side. If the oscillator is working (you'll need another 'scope) and there is continuity in the EHT transformer, and there are no fizzes, sparks or ozone smells, I would say the EHT is probably good.

As Steve says, there are several kV involved - do not attempt to measure this directly.

 

[Rustynutz]

Probably a good idea is state make modal etc
get hold of the circuit diagrams and include with your post
and you might get a better response from folk, you might even find someone who has had this problem before? (common faults) with dead screen's any of the above plus amp's down cap's, transformers, signal loss etc etc etc
when you power up or switch off is there any sign of life ,ignore the graticule that generally just a back-light lamp, turn that off and try?

 

[Phillip Brown]

Sir, I have a BWD oscilloscope 845 (Storage) with an open circuit transformer T552 which provides the EHT -1390 volts, plus other windings. I need a replacement for it, or else the whole board for the Power Supply. If it helps, I have a handbook I can copy in return, as part of deal.
Yours,
Phillip Brown
(ZL2IM)