Sony PVM 20M4E - Contrast Bloom

[fourmthree]

Hi - First time poster here. Already had a good look around the site for similar threads but not a lot of joy. I'm looking for some help, please?

I have a Sony PVM 20M4E (European model) which I've had for about 9 months. I initially dialled in some decent settings from the Service Menu for SNES, MD, Neo Geo, Arcade etc - but nothing drastic. I referenced the official service manual to do this and was mostly happy with the results barring a few little convergence issues (bottom left corner, particularly).

It's been exclusively used with a MiSTer using VGA to BNC. The power cable and in-line switch were purchased from https://misterfpga.co.uk/

Yesterday I finally got round to plugging in some retro consoles:

Sega Saturn - connected via SCART

Xbox - connected via SCART

Nintendo Wii - connected via Composite to a SCART connector

These consoles were connected to a bi-directional SCART to BNC cable into the PVM. I had mixed success. The Saturn wasn't connected properly (I had the wrong cable attached to Ext Sync) but it was easily resolved. The Xbox was perfect.

The Wii wouldn't produce an image, although there was definitely a signal and it disappeared on power on/off so something was getting through. The connection chain for the Wii was:

Wii official AV cable (red/white/yellow RCA plugs) >cheapo Composite to SCART connector > female to male SCART connector > SCART to BNC cable > PVM

After that I went back to the MiSTer and the image now looks blurry compared to before. Using the 240p test suite shows the grid lines and monoscope lines are now off. The menu text for the MiSTer makes me think I need glasses now!

Any ideas what's happened? My instinct tells me the cheap composite to SCART connector is the culprit or me toggling the IN/OUT switch on the SCART to BNC connector.

I went back into the service menu and restored all the values to their standard ones, just to get back to a base value.

Late Edit: Tally light has just come on Red. Power cycling seems to have resolved the tally light but the picture is still blurry.

Later Edit: I've always kept the Brightness and Contrast knob at the middle setting but if I turn the Contrast knob down to near the lowest value, the clarity of the image is what it was like before. So it's mayabe not 'blurry' more like there's added 'bloom' to the picture. Does that make sense?

Any advice is greatly appreciated!

TLDR: My Sony 20M4E looks blurry after plugging in some retro consoles. How do I fix it?

[Josh128]

Its very hard to attempt a guess at whats going on with no photos of the issue. Post some so we can see. Without them, from what you describe it sounds like your contrast and brightness is turned up too high. Your PVM may have some drifting controls or something.

[fourmthree]

Hi

Sorry, I've done that now. For what it's worth, I had a look inside the (non-service) Menu and played about with the Sub Control and User Preset options but the general consensus is that 'contrast' is too high and this needs to be compensated by lowering it to near maximum and increasing 'brightness' to bring out any dark areas of the image. It's also really washed out doing this! Reminds me of Xbox360 via VGA...

So I've set everything to their base levels, including the front turn controls. The blurry ones are with everything set to how the PVM was before and the ones where they are less blurry are with the Contrast set to lowest and brightness set higher to compensate.







Hope this shows the issue I'm having.

Thanks for your help.

[jd213]

Might be something that could be fixed with a recap, but not sure.

Have you tried other inputs such as composite and S-Video?

[Josh128]

Have you tried adjusting the "screen" pot on the flyback? This will lighten or darken the screen by adjusting the screen voltage.

Try the guide shown at the page below-- its not PVM specific, but the general concepts will work.
https://crtdatabase.com/faq/crt-color-adjustment

[fourmthree]

Might be something that could be fixed with a recap, but not sure.

Have you tried other inputs such as composite and S-Video?

No, not yet. I don't have the necessary connectors for Composite or S-Video.

[Ryeno]

Wii official AV cable (red/white/yellow RCA plugs) >cheapo Composite to SCART connector > female to male SCART connector > SCART to BNC cable > PVM

Buy good quality 50 ohm (not 75 ohm) RCA to BNC adapters like the AIM CAMBRIDGE - CINCH CONNECTIVITY 25-7510.
You can also use the Wii component cables.