Problem with Phillips 21GR2550 (G90AE chassis)

[Hamselv]

Hi there,

I apologize for writing in English on this German forum. I understand German fairly well, but I can express myself more clearly in English

I am about to use a Phillips 21GR2550 TV as an arcade machine monitor, and I am sending RGB signal and H/V hold to the TV via a SCART plug. This works really well and I get a nice picture, but I do have one problem:

As I don't want to rely on a remote control, I need the TV to switch to the AV channel automatically. I am doing this by putting 12V onto pin 8 in the SCART plug. But unfortunately the TV keeps switching between AV channels 1 and 2! The picture is rock-stable, but I get the annoying, bright green on-screen display in the top left corner, switching between "EXT1" and "EXT2"! Obviously, this gets really annoying, fast!

Any ideas what is going wrong here?
I am getting the 12 V from a PC power supply, and I have measured the voltage at 12.05V, fairly constant.


Another problem is that the picture is slightly too large for the screen, and I don't know how to adjust it. How do I get to the service mode for this TV? Or are there any pots or trimmers inside the TV that I can use?
I guess a service manual would be helpful, but I haven't been able to find one anywhere.

Hope you guys can help me out here!

Thanks

 

[Rudi 1956]

Hello Hamselv,

My English is not very good but I try my best.

I think you also need 12V on pin 16 of Scart input.

In this chassis there is no service mode (i think so but i am not quite shure)

First you must ajust one voltage in power supply via potentiometer,
an then you can ajust the picture (also via potentiometer)

LG from Austria Rudi

 

[Hamselv]

Thanks

Hi Rudi,

Thanks for the answer! I will look into SCART pin 16...

I just got the service manual from Thomas in the other section of this forum. As far as I can tell there is a service mode available by shorting two internal pins in the chassis while powering up, but I haven't had the time to try it just yet (still at work ).

Anyway, I am pretty hopeful about the whole situation now!

Thanks.

 

[Hamselv]

Doh!

It seems I was looking at the wrong service manual (Phillips xGR21xx instead of xGR25xx). For the xGR25xx I only have the 'generic' manual for the chassis that Phillips used (G90AE), and in there, I can't seem to find any reference to a service mode. Too bad, because the GR21 manual stated that it was possible to switch off channel numbers (OSD) from within the service mode.

In you guys' experience, will I be able to find 'extra' features in the correct Phillips manual instead of the G90AE manual?

I have found the pots to adjust height and width (yippee!), but the problem with constant switching between EXT1 and EXT2 is still unsolved.

I read a bit about SCART pin 16. Apparently, on some TVs, applying 1-3V on pin 16 will force the TV to use the RGB signal instead of Composite (still from the SCART plug).
But in my current SCART plug I have left pin 16 blank, although I still get a nice RGB signal on screen!?! Perhaps applying 1-3V on pin 16 would help the TV to settle down and stay on one AV channel? I get the feeling I have a lot of trial and error testing ahead of me...