I received a PVM-14M4U last week that unfortunately had been quite damaged in shipping. The tube mounting bosses had sheared off and the entire tube was loose inside of the monitor. The external metal chassis was dented and plastic cracked in several places. After some inspection (the tube and neck seemed intact) I turned on the monitor and it was still operational, but with a number of issues:
- The menu had shifted down vertically significantly clipping the last menu line (and “NO SYNC” text was completely outside of the frame)
- The monitor refused to sync to 50 Hz input signals resulting in a black screen
- 16:9 button resulted in black screen
- 60 Hz 240p input worked, but with issues:
- Horizontal waving, slowly moving over time – getting a bit better after 30 minutes of warm up. Very bad in overscan mode.
- Clipping of the top part of the image
- Red/green/blue retrace lines visible on top of the image
- Lightly smacking the side of the monitor resulted in a flash increased brightness on the display
- Audio didn’t work
- A wide band of image noise was slowly sweeping vertically across the image.
Before: https://i.imgur.com/kBHH2f1.jpg
After: https://imgur.com/Y5ka1xH.jpg
From reading some reports on excessive V BLANK adjustment indicating having a ticking time bomb, potentially burning out the flyback transformer, I decided to replace the C584 and C572 capacitors. (C584 to 1µF per Sony’s service bulletin)
C572 had traces of electrolyte leakage on top, and C584 had an ESR of 84Ω, so both seemed in need of replacing. When testing ESR (in-circuit) on a few other random capacitors I found several more that had unusually high ESR values, so I decided to simply recap the entire A board (>150 caps). I also noted that the ground lead on the flyback transformer had a cracked solder joint (likely a result of the rough handling during shipping), so I reflowed that.
Turning the monitor back on after this, I was a surprised to find that the V BLANK issue was not resolved – it basically had no effect at all. I still need V BLANK set to max (255), and the same 11 first lines are missing from the test pattern. Some other things did improve though:
- The horizontal wavy geometry is now mostly gone. In overscan, there is still a hint of it, but nothing in normal scan mode.
- The large horizontal band of image noise has disappeared.
- Lightly smacking the monitor no longer causes momentarily changes in display brightness (this was probably the cracked flyback solder joint)
- Audio is now working.
- There is very little warm-up effect. The geometry is basically unchanged from cold to warm.
What are other potential reasons (beyond A-board Capacitors) for clipping the first 11 lines of 240p signal and showing RGB retrace lines despite maxing out the V BLANK setting? Should I be concerned about breaking other components that the note on (https://crtdatabase.com/crts/sony/sony-pvm-14m4u) warns about?