Monitor Nanao ms8-26 repair help

[Bernardon]

Hello.
I need help, please.
I take for free gift, two outrunners cabinets.
And on the two machines the monitor on the right side,have several problems.
I check the chassis, and have lots of sodler joints in bad chape, I have resoldered, and changed all the capacitors to one monitor.
previousli , I have very dark image and interfernce grafics on top screen, with the new capacitors this problems solved.
now I have very good quality image stable and nice, but horizontal size is small, the vertical image i can adjust well.
I look the cabinets and the right side monitors are on top of transfermer and psu of game, I think the extra heat cause the problemes of over heat to the two
monitors on righ .
On this chassis is a narrow and other position horizontal size, but no solution to the fault.
The imge tube is good, because i put the good working chassis and i have full image.

Is posible the big red capacitors near the horizontal and vertical conector, stll causing this fault????????
I think this fault coul be a comun fault to this chassis, because, I have two with the exact fault small horizontal size image.

https://subir-imagen.com/i/e9rYx
Thanks

[grantspain]

what is the b+ reading?

[Bernardon]

Thank you very much, for your help.

The +b voltage is reading 62.6v dc
Here looks like is a problem, i read form internet, and must be about 92v
what you recomend to check?

[grantspain]

yes 92v is correct
you have to use a capacitor ground for the meter as the metal heat shield is not ground

[Bernardon]

I test like thi positive on tp1
And negative on tp2 on the board, whit the game disconected.

I test like this info i find on other forum, related to +b test on nanao ms8-26
Checking B+: Monitor powered off, disconnect your video signal from the game PCB. Power on the monitor with no video signal, put your red meter lead on TP1, and black meter lead on TP2(ground), you should be getting +92DC volts

I check the tp2 and is gnd to the capacitors gnd, and like you say the metalic shield is not gnd.

[grantspain]

if b+ is low then check the b+ pot itself, all the transistors and resistors in the regulation circuit - likely there is a corroded part

[Bernardon]

I tray to adjust de b+ pot and is doing absolutely nothing.
The votage is not changing at all.
I go to desolder the pot and check if is operating or is broken
The pot is working, i have tested.

[grantspain]

you have a lot of work to do, you will need to desolder one side of every resistor and diode in the regulation circuit and test with a meter, also need to check every transistor

[Bernardon]

Do you have a minimun readable schematic? , the ones i find are ilegible.

[grantspain]

ms8schematic.jpg

best i have

[PrincessPrinPrin]

My edit:

https://i.postimg.cc/cZjqnN5V/MS8-26-sc ... l.jpg?dl=1

This may be useful too:

MS826IC103.jpg

[Bernardon]

Hi, thanks for the help.
I tray to start checking, promtly, I tray to repair, the monitor.
I have the oder chassis to compare, values the info on this chassis is very poor.
Thanks.