Sony GDM-2038 Line Deflection Help Please!

[Dave Bullock]

Dear Fixers

I have a lovely Sony Trinitron monitor that has suddenly died, and need
some experienced insight please.

A few weeks ago the monitor died and I found that the LOT driver 2SD1887
had gone short circuit.
Not realising that the line output stage and the EHT circuit had
different driver transistors, I searched my junk and found a 2SC3897
which looked very similar when comparing datasheets.

I fitted the new transistor and the set burst into life and has worked
happily for about a month.
However it died again and the PSU was 'wailing' like crazy.
This time both the EHT transistor (2SC3897) and the 2CS3997 (line
deflection transistor) are short circuit.
I wonder if there is a stock fault that anyone can give me a hint about?
Alternatively ..is it possible to get hold of/buy this part of the
schematic somewhere?
It seems a shame to have to 'bin' such a lovely (and up till now) trusty
monitor.

Can someone help please?

Thanks in anticipation....Dave

 

[[email protected]]

Dave:
I would the small electrolytic capacitors that are part of the
driver circuit for these transistors. They are usually located
nect to the driver transformer. Use an ESR meter, or just replace
them if in doubt.
Many better monitors use an FET to regulate the supply voltage
going to the flyback and sweep transformer. Sometimes the FET
will short or the electrolytic capacitor will weaken causing the
FET to fail to regulate properly.
Of course, the flyback (LOP transformer) might be going bad,
which means it is time to look for another monitor.
Hope this helps...
John