Hantarex MTC 9000 small points maybe missing ground - Solved

[mjnman]

I have a chassis with a first version of MTC 9000 with small white points in the screen, brilliant effect. (below a youtube video)

I tried to:
- replaced all electrolytic capacitors, total recap;
- replaced ceramic capacitor in the neck board C206;
- replaced flyback;
- tested with another tube;
- replaced transistor on the neckboard, TR201-202-203;
- checked all variable resistors on the neckboard;
- replaced RV7 on main board, brightness preset;
- removed fuse 2 then disabled degauss circuit and removed degauss cable;

I checked the main points and seems to be ok:
TP10 - 133.4
TP12 - 11.9
TP13 - 26.9
TP 1 - 24.8
SP11 - 202.9
G2 - 352.2 (ground on the NECK)

I tried to connect a direct ground cable between big heatsink and power socket and there is a little decreases of defect.
Maybe a bad component connected with ground side?
Please, what i can check? i don't know i can do.
In attachment the scheme of chassis and the video issue.

View: https://www.youtube.com/watch?v=cjd488gXUGw

 

[nem]

You sure it's not related to whatever is generating the test image? Have you tried different video sources?

 

[mjnman]

I used same cable with another chassis, MTC 900e, and there isn't the issue

 

[mjnman]

I replaced all transistors BC558B, BC548B and vertical deflector TDA1670. Nothing to do, same issue.​

 

[nem]

Thing is, MTC900e is a different chassis than MTC9000. It's perfectly possible the latter is more sensitive to whatever outside interference is causing those dotted lines.

 

[mjnman]

It's strange because the same connection with CA&G VI2100, Tatung VT2040, 2 MTC900e and MTC9000 clone (similar component distributions) work correctly. No earth issue and clear image.

 

[mjnman]

These are Jesus days...I found the problem.
From beginning I replaced:

- entire recap (solve flickering);
- replaced flyback (nothing);
- replaced ceramic capacitor in the neck board C206 (nothing);
- replaced transistor on the neckboard, TR201-202-203 (nothing);
- replaced ALL variable resistors (nothing);
- removed fuse 2 then disabled degauss circuit and removed degauss cable (nothing);
- replaced TDA1670A (nothing);
- replaced TDA2595 (nothing);
- replaced all transistors BC558B and BC548B (nothing);
- replaced transisitor BDX53A (TR17) (nothing);
- Checked all ground points (nothing);
- Checked all components near ground (nothing);

....at the end the problem was in the PSU!!!!...absurd.
fuck fuck fuck.

 

[nem]

Which PSU was that? You mean the 128VAC transformer for the monitor or the PSU for the game board?

 

[mjnman]

The chassis was attached at a PC mainboard with 15Khz linux kernel. The problem was on the PC mainboard PSU....i don't understand why only with Hantarex MTC-9000 and not with MTC-900e and others model.