Hacking RGB into a SONY PVM 20N1U

[soviet9922]

Hi guys, finally find in a flea market a 20 inch er PVM i couldn't believe my luck cost me 5USD.
Well the monitor was perfectly clean inside seem little used, externally in very good shape.
The only bad thing is that this model don't have RGB just composite and svideo, anyway using svideo the picture is very sharp, but most of my stuff is RGB so it's useless for me.

So i decided to gut the thing and see if is possible to hack RGB input into it, the insides seems like good news this model seem to be a few components away from the RGB equipped models.
A small board inserted in the PCB (not sure why sony keep it installed) (pictures below) that have the RGB input for the ribbon that go to the missing jacks in the back of the case.
Even the jack is labeled for RGB etc, theres no sync there but sync seems to go from the ribbon that is currently attached to the svideo and composite line.

I have two questions anybody have the service manual for this model ?.
If someone see this and have experience doing a hack like this on this model or a similar one maybe can illuminate me

[soviet9922]

Ok some advances first got a service manual for a similar model uploaded it here : https://www.filehosting.org/file/detail ... 10-00e.pdf

Next soldered a push button to the empty pads in the front where the original button for the rgb model should have been:


Ok pressing the button show up RGB on the screen yeeeay .

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Then rigged up a quick cable to scart plug and soldered the leads to the small board that is present in the monitor they are no wires going to it in this model.
The connector is self explaining have RED GREEN BLUE GND on the pcb.


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The colors and picture from the test system (a psx) shows fine.
Of course the screen shows NO SYNC, connecting the composite input will not help because is in RGB mode and this input is disconnected.
I have to check how to get sync to work not sure how.

[opt2not]

Hmm, wondering if it's expecting Sync-on-Green? rather than a separate sync input.

[buttersoft]

Hmm, wondering if it's expecting Sync-on-Green? rather than a separate sync input.

The N2 sets have an option in the ordinary menus, not the service menu, to set ext sync. I wonder if it's there for the N1, or if the menu is different. If it is there, that pic third from the end in the first post, with the red and white connectors on the edge of the board shows CN402, and the ext sync input to the A board. Looks to be the same connector from the N5 service manual. You shouldn't need to amp the sync, but it's a case of suck it and see.

If there's no option in the menus it might be possible to make yourself a SoG signal by combining sync and green in some way, i guess. You could try a PS2 first to make sure it's going to work as those will output SoG. Or maybe someone could dump the IC002 eeprom from an N2 variant, that might work. Sadly i no longer have the N2 set i was working on awhile back.

[MKL]

Same mod on a similar monitor:

https://www.facebook.com/groups/4438761 ... 090359825/

[soviet9922]

Hmm, wondering if it's expecting Sync-on-Green? rather than a separate sync input.

The N2 sets have an option in the ordinary menus, not the service menu, to set ext sync. I wonder if it's there for the N1, or if the menu is different. If it is there, that pic third from the end in the first post, with the red and white connectors on the edge of the board shows CN402, and the ext sync input to the A board. Looks to be the same connector from the N5 service manual. You shouldn't need to amp the sync, but it's a case of suck it and see.

If there's no option in the menus it might be possible to make yourself a SoG signal by combining sync and green in some way, i guess. You could try a PS2 first to make sure it's going to work as those will output SoG. Or maybe someone could dump the IC002 eeprom from an N2 variant, that might work. Sadly i no longer have the N2 set i was working on awhile back.

Thanks for the info have found this thread on assembler games now, that talk about this (the sync option in the menus you mentioned) https://assemblergames.com/threads/modd ... uts.52392/
The thread have little information on how the OP performed the mod but he mention this:

"Installing R30 (10 ohm) has definitely unlocked the relevant RGB stuff (sync and aspect ratio) in the menus. This was not accessible before."

Now on my monitor is not the N5 is NU1 the resistor mentioned R30 seem to be present is a tiny smd resistor on the bottom close to the jungla ic i'm not sure if is a resistor or i should swap it to get this menu.

[soviet9922]

Same mod on a similar monitor:

https://www.facebook.com/groups/4438761 ... 090359825/

Thanks for the link i have applied to enter the group (is private), so i can see it.

[soviet9922]

Hmm, wondering if it's expecting Sync-on-Green? rather than a separate sync input.

I have tried using the sog option but the monitor ignores does nothing.

[buttersoft]

I found the service manual - from a reddit thread. Doesn't look like there are resistors to set the model on the PVM-N1/N2 SII chassis.

https://imgur.com/a/Y5ZMzGu - scroll all the way to the bottom, click the ellipsis and download the post.

from here, where the RGB mod for the N1 is described in more detail by ziggythehamster. V.nice of him to share, of course
https://www.reddit.com/r/crtgaming/comm ... ge_issues/

[soviet9922]

Thanks for the links this proves very useful for mi .

Now i have see that the VDP is different on the U1 is not even a sony part, have little to do other monitor models.
Tried to feed sync using the VDP 3 different luma and video inputs to no avail the monitor will not pick up any signals, according to the manual are all 1v peak to peak. I believe that the sync input must be selected using i2c internally on the vdp and this is not happening.

Then i tried the brute force method forced the VDP to do blanking even when the composite input is selected by feeding 5v to the BLK pin, and connected rgb to the ic directly. This proved to work i have sync and a display looks much sharper than composite.
But even terminating the rgb color signals correctly the colors luck fucked up like they bleed on the screen. To the right.

I surrender there's not much else to try.

[soviet9922]

Hi sorry to reanimate my old thread, i was wondering if somebody have resolved the RGB mod for the 20N1U ?

[ElBartoME]

I modded a 20N1 a while back successfully. If I remember correctly you set the model in the service menu. I'm in bed right now so I'll check tomorrow if I can find something in the service manual.

EDIT: Yes, you need to set MODEL to 1.

[soviet9922]

I modded a 20N1 a while back successfully. If I remember correctly you set the model in the service menu. I'm in bed right now so I'll check tomorrow if I can find something in the service manual.

EDIT: Yes, you need to set MODEL to 1.

That is great to hear! if you can elaborate later about how you performed the mod?
Also, how did you get into the service mode, and what option was changed exactly?
Thanks!.

[ElBartoME]

How to get into the service menu is written on page 13 in the service manual buttersoft posted: https://imgur.com/a/Y5ZMzGu

And the model entry can be seen on page 14.

What I did is I looked at the schematics in the service manual. There is a table next to the schematics that tells you the different values depending on if it is a N1 or N2. You can see some of the components are missing on the N1 (C413, C414, C510, R401, S006, but JR451 needs to be removed). I also added BNC jacks as well as the resistors, capacitors and transistors on the input board Q.

Input board: https://i.imgur.com/bxyeE94.png

For the A board you need to check what you serial number is, as there are some differences:

A board: https://i.imgur.com/fvI9R20.png
A board: https://i.imgur.com/nG7Mp3l.png

[soviet9922]

Hi thanks, now populated the missing components on the A board
Enabled in the service mode the RGB option is set to 1.
Wired the RGB button etc.
In place of populating the BNC plugs on the Q, the board wired a SCART plug to the S board directly.

Now turn on all seems well, hook up my genesis via SCART and start testing perfect picture sharp image.
But then after selecting RGB mode the brightness will start turning itself down slowly until the screen is almost 100% black.

So checked the service manual and noticed that in the service menu options RGB settings 61 62 63 (red cutoff) were all 0 so set to the default values on the service manual.
Now after selecting RGB input the screen will slowly increase brightness until the screen gets white and the monitor will shutdown and go into protection after maxing out.

So this very bizarre brightness thing happens only in RGB input if I stay on Line A or B this doesn't happen.
Also if I get into the service menu on RGB mode this issue doesn't show up the brightness stays constant for hours problems.

Any idea what this could happen ?.

[ElBartoME]

Do you have capacitors in series with your Scart plug to the s-board?

In the original schematic there are 10uF capacitors in series to r, g, b and sync.

[soviet9922]

Installing caps there makes the image look bad.
Found the issue it was an option the service menu it was at value 0 and should be 1.
Change that and it fixed the issue.