JVC AV-36850
JVC AV-36850 CRT RGB mod
I did not mod this CRT. However, important lesson was learned from modding this CRT.
This crt originally had composite and s-video only, its from 97 right before the D series .... The TA1242N jungle chip used on these CRTs were kind of a mystery. The chips data sheet is in Japanese and it was assumed from it that the jungle needed 0.5Vp-p rgb signals. Mark on shmups held my hand again through this one. We attenuated the signal to 0.5Vp-p and it was super dim. No amount of RGB levels or cutoff adjustment helped.
I was bummed out and thought I fried something when I turned the G2 (flyback brightness/screen) up too high to try and brighten the image.
Mark said he heard these chips needed 1Vp-p but it was basically unknown
Due to how dim 0.5Vp-p was I skipped 0.7Vp-p which is the SCART standard and went for 1Vp-p by removing attenuation resistors, using 180 ohm termination, and swapped mux resistors to 510 ohm. It came out perfect!
A tiny tweak to the G2 was all that was needed.
I own a dozen or so pvm/pro/ broadcast monitors and this tube here is now one of my favorite tubes! It was a pain to pick up, haul upstairs, recap, clean, and mod twice but glad I stuck with it! It was definitely worth the troubles!!!
CRT Safety
Caution
You can die doing this! So read carefully! CRT TV is not a toy. Do not open a CRT TV. If you don't have any prior knowledge about handling high voltage devices, this guide is not for you. CRT TV contains high enough voltage (20,000+ V) and current to be deadly, even when it is turned off.
Plan of attack
Theory
Sometimes it is nice to know the theory behind the mod. I have put this on a separate page. This shows how the various resistor values are calculated.
Service Manuals
Note: the service manual for this TV doesn't seem to have the schematics.
RGB Mux Schematics
Thanks to MarkOZLAD/deezdrama
RGB 
Blanking 
Mod details
Thanks to MarkOZLAD/deezdrama
- Remove SMD resistors R717, R719, R721 (factory OSD "grounding" resistors)
- For blanking we want to go from a 5V source into a switch then into a 1.8K resistor and then onto jumper W019
- For each of the RGB lines we want to bring in the external RGB, we want 180 ohm to ground. Then for each run a line from between these two resistors onto the RGB jumpers into a 510 ohm resistor then onto their respective jumpers.
- Replace caps C801, 802 and 803 with 0.1uF (104) ceramic caps
- Sync into factory AV port (composite or svideo luma, even component Y)
This is the way.
Pictures
