LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complete...

[TKez]

I don't think it is. Continuity suggests it's going to ground which I'm sure it shouldn't be. No difference when connected but unlike your experience there's no missing resistor in the path.

I don't think it is. Continuity suggests it's going to ground which I'm sure it shouldn't be. No difference when connected but unlike your experience there's no missing resistor in the path.

Check for a jumper to ground somewhere on the blanking line.

R203 is a jumper to ground, needs to be replaced with a 75 ohm resistor.

@Dramaking9 Love to know if you ever got this sorted.

I'm trying to RGB mod a very similar board because the component in has a weird flicker.
I also accidentally turned off the component input in the service menu.

It seems to be getting sync, but I can't seem to get blanking to work.

SCART is enabled in the service menu.

What I've tried:

"Making it look like the schematic"
I removed the composite connector, but because the SCART sockets I have don't fit, I've soldering VGA cable directly into the board.
I populated the 4 filters by removing a couple jumpers that LG had in some of the inductor and resistor positions, then adding the inductors (L201, L204, L206, L207) and 75 ohm resistors (R203, R204, R205, R213)
Installed jumpers to R217, R218, R219. I'm not sure why these are marked as resistors and a star, but no value is shown and they're not mentioned anywhere else.

I'm getting the blanking voltage from pin 14 on the VGA which is has 3.3V on it via this Mister board. I've tried various series resistor values to bring it into the 1-3V range but I only ever get black.

In desperation I've also tried jumping 3.3V from the chip itself to EXT-FB on the chip, and even the 5V off the chip. No dice.

The display appear to sync correctly when I change resolutions and modes on the mister. I can see via the 'AV1' overlay that the scanlines are changing with mode changes, and it goes into 480i correctly.

What I don't understand.....

L204 & L206 are marked J/W, L207 is marked TIN instead of having values in henrys. I just put 10uH like L201 next too them.
There are capacitors marked with stars also that aren't explained anywhere.

The FB pin on the scart (16) is labelled on the schematic EXT-FB after R19. This pin though is located directly next to the Ycpcr 'dvd' inputs on the chip, and it was grounded via a jumper at the chip also shown grounded on the schematic. I tried ungrounding it by cutting the trace as the jumper is under the chip and I can't get to it. No help.

There is another FB input on the chip right next to the Rin, Gin, Bin inputs, but its shown connected to the PIP circuit.
So im not sure which blanking pin is right. I tried both. No dice.

The other annoying thing is, getting into the service menu was via holding menu on the TV and pressing menu on the remote.
Stupidly when I was in there I managed to change a setting 'Key" which changed the button format on the TV so in no longer has a 'Menu' button. This means I can't get into the service menu anymore. Can these chips be factory reset?

Docs https://drive.google.com/file/d/1sOm1Wb ... share_link

[TKez]

[Dramaking9]

Hi,

Unfortunately I simply wasn't able to get a picture at all. From reading your posts you have made more advancements than me but have a different set of issues. I never had problems with the service menu but I moved on from the project with it unresolved. The CRT sits in a lonely corner waiting for me.

[TKez]

Hi,

Unfortunately I simply wasn't able to get a picture at all. From reading your posts you have made more advancements than me but have a different set of issues. I never had problems with the service menu but I moved on from the project with it unresolved. The CRT sits in a lonely corner waiting for me.

Seems in our case things are complicated by this PIP module. Because both the Scart connector, and the PIP module are optional configurations to these boards, (neither are installed in my TV model), the jumper configuration is complicated and is undocumented in the service manual other than cryptic markings on the schematic.

I would have thought the gotcha was this jumper configuration for the pip module, but alas, I already get continuity from the cart RGB pins to the RIN, GIN, BIN lines on the chip.

I still can't figure out what's supposed to be installed near the scart connector with these cryptically marked components, stars, and missing values as they are going to affect the blanking voltage and I don't know what the chip expects.

Out of curiosity, why didn't you just use the component inputs?