Sony 21" Trinitron Monitor Fault [CPD-E530]

[steve30]

I was just wondering if anyone could assist me with this 21" monitor.

When I turn it on, the power light flashes orange. The service manual says this is indicative of a B+ issue.

A few years ago I replaced a capacitor on the regulator circuit that powers the heater. That seems OK now. A while back it started having a lot of flickering in the picture. Its difficult to describe but it "looked" like there might be a bad connection in the video signal somewhere. Then it eventually just conked out completely with the flashing orange power light, and I haven't bothered looking at it again till now.

I don't use this monitor much, but its a good quality monitor so I'd like to get it going again. Does anyone have any ideas? The problem is that its quite difficult to test any voltages when the monitor is turned on as it is very difficult to access the boards when everything is plugged in.

I made a teardown video in case it is of any interest to anyone:



Any suggestions are welcome.

Thanks
steve30.

[inse]

Just some general tips:
Probably the horizontal transistor has died shorting the B+ voltage rail.
The flickering indicates that there has been an issue with broken solder joints at the flyback transformer or the transistor.
Also check for cracked capacitors in that area.
The most unpleasant fault would be a broken flyback transformer that had been arcing inside.

[shakalnokturn]

To add to inse's advice if it is a shorted horizontal output or flyback transistor it is important to understand why it failed. The cause can be broken solders, defective flyback transformer, bad B+ supply or poor base drive.
It is worth checking the decoupling and series electrolytics in the base drive(s).

[inse]

Nothing to be heard or seen anymore?

[shakalnokturn]

It seems to happen to a lot of topics in the repair section

[steve30]

Thanks for the suggestions. I'll try and have another look at it when I get chance.

I must admit the solder joints do all look OK but my eyes may well be deceiving me. I have in the past had a CRT monitor with a flyback transformer which had shorted. Fortunately I was able to get a schematic of the transformer so I was able to test it, but I was also able to purchase a replacement (albeit a non-OEM part, and it wasn't cheap).