Repair 5 same chassis TOEI TC-RM251S

[leopold]

Hello,

I have troubles with 5 chassis TOEI TC-RM251S from grey JALECO PONY MKIII 25"
(same model used into NEO GEO MVS-U4 also.)
I use to have 8 chassis of them. The problem on all of them was a flyback problem.
Dead flyback, sometimes flyback arcing sometimes not but dead flyback always.
The HOT was always good on all of them.
I decided to buy 8 brand new flyback (lucky me the reference was available) and do a partial cap kit ( everything unless all the video board / C30 bi polar 50V 4,7UF / C38 200V 470UF / C53 180V 680 UF in the power section)
After this new flyback and partial capkit, lots of chassis were running good.

I sold 3 machines runing good and i still have 5.

I use to have the 5 chassis runing good but now i have only 1 on 5 runing good.

1 = OK
4 = BAD

On the 4 bad chassis, they were runing and one day black screen during game.
i did few tests:
Check all solderings, everything is ok.
Light bulb test is ok with between 90V and 95V depending on chassis. (i can hear a noise maybe from power section or close to vertical during this test but i remember that noise from the others chassis i repaired during lightbulb test)
So i suppose the power section is working good. (maybe not?)
Neck tube didn't blow orange. Nothing here.
HOT is good, i decided to try a brand new one, same result.
(please note the HOT were good on all the 8 chassis i got)
This is were i am stuck, normally the neck tube should glow orange, everything looks good to work but nothing.

during the test chassis linked to the tube, I hear the same noise during the light bulb test.
I realise when i disconnect the RGB signal connector from the game pcb the sound i can hear is different, the chassis is closer to run but don't. ( i can ear a different tiny noise from the yoke)

My suppositions are:
- The flyback is dead again. But why after just couple of hours? What can cause a dead flyback? (i still have 2 brand new flyback if necessary)
- I have a problem into the power section going to the second part of the chassis, the VIDEO RGB side?
- I have a problem into the VIDEO RGB section, maybe a short circuit somewhere or maybe a problem with RGB AMP?
- Maybe something is causing a chassis protection and the neck tube don't glow orange?
- Maybe i am far from the reality and the problem is easy to solve?

Advices asked:
- What should i check?
- From where i should start from now?
- Any recommandations are welcome

I have one chassis runing so i can switch parts from one to another one to make tests. But i hope i will not fry the last one runing


Description of the chassis:

The chassis have few differents boards:
- 1: is from the power section when you plug the 110V wire.
- 2: is the for the VIDEO, where you connect the RGB signal from the PCB, including RGB Amplifier.
- 3: main chassis, with the rest of the power section, the flyback etc....
- 4: Neck Board
- 5, Adjusting pots board with Red, Green, Blue, Vertical size etc....

Tube is TOSHIBA A59JMZ90X

Lucky me, on 1 chassis i have a print on the solder side of the PCB and this help a lot to repair and understand more the chassis diagram.
Unlucky, these chassis are not that common, impossible to fing any Schematic.

Any help are more than welcome.
Thank you a lot!

Please find pictures of this chassis with the white print:

[radiantsvgun]

This is the same model I had in my NEO 25. I constantly changed caps, flybacks, ect on it. With its fragility and difficulty in picture adjustments with its remote board, I swapped a Nanao ms9 on. I had to change the yoke connectors but it works decently. Theres some H limit problems but it does work. I wonder if you could use a ms8-25 with better compatibility?

viewtopic.php?f=4&t=41015

[leopold]

Hi Radiantsvgun,

Thanks for your answer.
Could you please confirm me your toshiba tube reference? A59JMZ90X?
Do you confirm that you use the original YOKE on the tube?
You only change the yoke connector? or you change the yoke completely for a MS9 yoke?

I have one MS8-25 normally working but never test it. I will try this today and let you know.
EDIT: I tried but my MS8-25 is dead. So no results.

Thanks for your help, i will keep this in mind if i can't repair the chassis.
The fact is i have 5 chassis for 5 Pony cabinets, it will really help if i can save them.

[radiantsvgun]

Hi Radiantsvgun,

Thanks for your answer.
Could you please confirm me your toshiba tube reference? A59JMZ90X?
Do you confirm that you use the original YOKE on the tube?
You only change the yoke connector? or you change the yoke completely for a MS9 yoke?

I have one MS8-25 normally working but never test it. I will try this today and let you know.
EDIT: I tried but my MS8-25 is dead. So no results.

Thanks for your help, i will keep this in mind if i can't repair the chassis.
The fact is i have 5 chassis for 5 Pony cabinets, it will really help if i can save them.

Yes, I used the same yoke, just had to change the connectors. I am using the original A59 tube, which is lovely. You may have to set the jumper to wide. In my opinion, the Toei has the best colours of any chassis I've owned, but it is very difficult to normal operation. The nanao ms9 is a much better built chassis.

@grantspain - can you use a nanao ms9 yoke on a A59 tube for better compatibility or will that have problems with purity?

[matt5cott]

Might be my eyes and the small pic, but the flyback soldering doesn't look right on the horse shoe.

[leopold]

Yes, do not take care of this, i was doing a light bulb test this is why.

[leopold]

Grant's help me to repair 2 chassis on 4 by just one word.
On this sort of chassis there a "big IC managing all the deflection".
So i ordered 10 piece of this IC STK79915 SANYO because this is not easy to find online and minimum was 10pcs.
Well this repaired 2 chassis on 4.
The problem on this two repaired was a continuous noise like "unnnnnnnnnnhhh!!!!" no orange light at the neck.
This STK go always very hot this is why there is a big heat sink to cooler it.
Make sure you use non electricaly conductive heat sink paste between the IC and the heat sink (ceramic white paste).

Well now i have two chassis dead:

1: turn on, orange at the back of the neck, the monitor is on but black screen, no picture. probably a problem with the VIDEO amp but i swapped the video board from a working and same result.
Need helpplease

2: No power on, the power supply section is tested good but nothing happen. flyback is new, big IC is new.
after replaced by a brand new big IC when i first turned on, i heard one "tik" sound, maybe the IC is dead again.
Maybe something kill the IC? over power? Is it common?
There is no available datasheet for this IC...
Maybe my flyback is dead?