IBM Monitor ShortCircuit HSP

[Jan]

Hi,
I've an IBM 6556 17" monitor. The HSP circuit has a short circuit.

The HSP transistor Q507 was short circuit, so I replaced it.


Under power up I noticed that the transistor Q507 short-circuit again.

I've got information that a capacitor are the reason for this short circuit
of Q507.


I've tried to locate this capacitor but with no luck so far. I don't have a
schematic of HSP circuit

Anyone that can help.


Regards

Jan

 

[John Gill]

Jan:
I assume by HSP, you mean the high-voltage. I would check the high-voltage
transformer (flyback). My flyback test is as follows:
1. Measure the resistance from the HV anode to ground. It should
read open circuit. Any resistance ususally means it is bad.
2. Check the capactance from anode to ground. It should read about 2.5
to 3 nano-farads. I usually assume 1.5 to 5 is OK.
3. Check the primary winding with a flyback ring tester.
Also
4. Check any electrolytic capactors near the horizontal driver transformer.
5. Check for any shorted FET's or bad electrolytic capacitors in the
circuit that supplies the B+ voltage to the flyback (and HOT).
Note: these tests will not always find a bad flyback.

Hope this helps...
John