need help fixing a Leader scope

[stefanv]

The screen on my 25 year old Leader LBO-508A went blank yesterday. I’
regularly fix electronics, so I opened up the case to check it out. No
being used to work on scopes (or HV TV equipment) it looks like I’ll nee
at least the schematics to measure it out. And now I don’t have a scope t
do this anymore!

- Does anyone happen to have the schematics of the Leader LBO-508A or kno
where to get them? A google search got me 1 good link but the email cam
back

- Any suggestions on where I should start to find the problem? All th
heatsinks in the High voltage and final amp are getting still warm. But n
picture on the tube. Anyway to make sure the tube is still good and gettin
power?

- Could I bring the video signal outside and hook it to some othe
display?

I appreciate all the help I can get.

Thanks!

Stefan

 

[Pooh Bear]

The screen on my 25 year old Leader LBO-508A went blank yesterday. I’m
regularly fix electronics, so I opened up the case to check it out. Not
being used to work on scopes (or HV TV equipment) it looks like I’ll need
at least the schematics to measure it out. And now I don’t have a scope to
do this anymore!

- Does anyone happen to have the schematics of the Leader LBO-508A or know
where to get them? A google search got me 1 good link but the email came
back

- Any suggestions on where I should start to find the problem? All the
heatsinks in the High voltage and final amp are getting still warm. But no
picture on the tube. Anyway to make sure the tube is still good and getting
power?

- Could I bring the video signal outside and hook it to some other
display?

I appreciate all the help I can get.

You might save yourself a lot of time by checking the heater first. If that's
gone the tube is scrap.

Graham

 

[stefanv]

You might save yourself a lot of time by checking the heater first. I that's
gone the tube is scrap.

Graham

Thanks, Turned out I was lucky and I found very small numbers on the trac
side of the PCBs. This way I eliminated some areas to have problems an
ended up in the HV power supply. Everything was there except for th
-2000V. From the parts and traces I understood it was a regular voltag
doubler. Found the 1st cap (1600V .5uf) to be "open", replaced it and m
scope is up and running again. Took about an hr or 2, well worth it.

Thanks for the suggestions

Stefan V