Philips CRT 21GX1765 RGB mux mod

A client asked whether his Philips TV is RGB moddable, and provided some insights.

So I went on doing some research and found out that the actual model: Philips 21GX1765, of Anubis S-dd chassis, is actually moddable.

The TV arrived in a good working state.

Research

Jungle IC: TDA8362EN3, RGB = 0.7Vpp, blanking voltage has 2 detection levels, tested with 3V and displays fine. Download datasheet

Micom: PCA84C844 Download datasheet

Both are covered under metal shields, to access the chip, you needs to twist the door open.

The modding

Discharged the tube, safety first.

The stock mainboard has 4 diodes for RGB and blanking line towards Jungle IC, easy.

Traced the OSD input to Jungle IC, get distracted to the TELETEXT module(daughterboards on the left, viewing from rear). These parts also connect to the RGB input, but here we don’t want to touch them.

Find 4 jumper wire on the side of the mainboard that’s for Blanking, Red, Green and Blue. This is the place to inject blanking and RGB signals. On its right, remove R3257, R3256, R3255, those are the stock grounding resistor for the OSD RGB line. After removing, a nice GND hole appears.

Workout the resistors and diodes on Sunthar’s mod board.

Calibration

After installing the RGB mod, I noticed there’s a horizontal shift to the right. Common issue in RGB mod, and expected. This can only be adjusted by an onboard potentiometer 3420. Since it’s located beneath the tube coils, do this when the TV is off and discharged, for obvious safety reasons. Turning clockwise will move the picture towards right.