Brody Radford wrote:
> 
> Well as far as I know it is an Australian clone (of perhaps a Tektronix but
> I'm not sure). I'm up for the challenge of fixing it, and need it any way
> since I'm a student.
> I'll test the transformer outputs, and my use a step down transformer
> connected to the high v outputs to test them. I'm pretty sure that�s the
> problem, I don't want to put my head and ear too close to the circuit when
> its on but I'm sure the sound comes from the transformer (EHF or inverter
> transformer? Not named in diagram) There is no smoke and as far as I can
> tell it doesn't get overly hot. You're exactly right though Declan, I have
> never fixed a scope or power supply. All I'm going by is my superficial
> knowledge of electronic circuits to locate and solve the prob by looking at
> the schematic. Like I said it would help if I had a scope to fix it ;)
> Thanks for inputs and I'll try your suggestions.
> 
> Brody


Hi Brody,

since you have the diagram, you should be able to locate the problem.
Hoever, I don't think that testing the HV with a step-down transformer
is a good idea. This transformer would need a kV rating on the primary
in order to test your HV. It would be better to build a resistive
voltage divider. Normal metal film resistors and most carbon film
ressitors are rated for 500-1000V, if you take ten of those in series
and glue them into a plastic tube with one of those cheap thermal glue
guns, it will make a nice 10:1 high voltage divider.

One other point from own experience: did you have a look at the solder
joints underneath the HV transformer? I have seen more than one
monitor with one of the joints burnt off or loose, giving rise to a
buzzing noise....
You say there is no smoke. Is there a smell of ozone when running it
and the transformer is buzzing? If not, you might not have arcing
either....

Uwe.
-- 
Author: Uwe Zimmermann
  INET: [EMAIL PROTECTED]

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