Nanao MS8-25FTB shutdown issue? vertical? + red bleed [fixed] + cap list

[MagicianLord77]

Hi guys, I really want to get my JP Terminator 2 cabinet working, it has a Taito badge on its side, and its monitor is a Nanao MS8-25FTB, that was having vertical collapse, then shutdown after 30 seconds or so, tube is Toshiba A59JMZ193X.

So, I first took these steps to try fix the collapse, in this order:

• Replaced IC401 LA7832 with LA7833 (haven't got LA7832)
• Installed socket and replaced IC103 HA11423 just in case (not sure if it could be related)
• Measured a bunch of components around the vertical area (ZD401, ZD501, both 6.2v zener are good), and after desoldering and closely measuring 2 transistors that seem related to vertical, multimeter displays some voltage (diode test) between C-E, got replacements, they don't have that weird reading, put them into the chassis but nothing changed (still same collapse):
  - Q402 PNP 2SA1408 Y - only found an O one to replace it with but hFE looks quite similar, maybe it doesn't even matter.
  - Q401 NPN 2SC3621 Y

Then I brought the monitor again to the workbench, and this time it doesn't even power on, I hear a slight "psu on" noise, but it is clearly not on, no hi pitched noise, no heater glow.
B+ is quite adjustable, goes from 80-something to 104v, left it at 94 which is around where the silicone blob kept the pot.

I was doing a bit more of research since it seems the MS8-29 is quite the same (unlike the MS8-26), found this one https://www.aussiearcade.com/topic/9842 ... ting-down/ , mentions the same odd transistors readings that I had, and then his issue was a bad fusible resistor R438, so went and checked mine, it is bad too!, measures megaohms.
His is 2.2 Ω, I guess because it's a MS8-29, mine is red/violet/green/green, so 2.7 Ω?

• Replaced it with a Vishay PR02FS0202708KR500 (Fusible 2W 2.7ohm), turned it on and still nothing, I guess because there's the shutdown issue
• Also got all capacitors and did a full recap (minus the filter one).
• Turned it on again and nothing.
• Took out and measured the HOT D1887, Vreg C3306, Diode thing C021M-15, C2688 Q532, all fine with TC-01 tester.

Now, by looking at this great thread viewtopic.php?t=46367, I think I should do some lightbulb testing. I got a 60W 220V one, that at 110V turns on dim and I measured uses 20W.

• Took the HOT out and hooked up the bulb between TP2 (gnd) and TP1 (b+), it turned on
• Then connected it between gnd and HOT collector, turned on too
• Then desoldered the FBT B+ pin (2nd one) connected it between the pad of that pin and gnd, turned on too, voltage is same as B+

What does this mean, what could be the next step?

I found on this thread viewtopic.php?t=45856 :

• to check for R562, took it out, depending on which lead I put in the multimeter it reads between 391.5k or 392.5k so I guess that's right?
• Also from the thread I took out and checked ZD903, ZD904, tested the zener voltage with a 10v psu, both work fine at 6.2v

Also something else, measured with a ring tester the primary of FBT, it measured around 40, or with B+ disconnected it is 46, isn't this a bit on the low side?

Any assistance appreciated!

[MagicianLord77]

Found the issue, monitor is working now!. After I installed a socket for the HA chip, I had put the chip upside down , I blame myself and the fact that it has an identifying dot in both its corners when the usual afaik is just one.
The amount of measurements I've taken to arrive to this conclusion is something but I think I learnt a good amount with so much digging. I've also found a couple odd measurements in the horizontal oscillator transistors, more on that soon

[MagicianLord77]

Trying to get a good picture, found red was bleeding a lot to the side all the time, with no way to adjust it. Pots did change the red color somehow between bad and worse but bleed was always there.
Went to check neck board transistors just with a multimeter, the MS8-26 schematic is quite similar, red related components are named 30X, green 31X and blue 32X.
One of the small red related transistors gave an odd voltage reading between its legs, sometimes can happen due to a diode being around, etc. so went to check for the same in the blue related transistor, that reading wasn't there
Upon closer inspection, a D301 1SS133 connected to the transistor looked suspicious, had a 1.8v forward voltage reading, while other diodes have 0.6v. Took it out, checked that still was the same off-circuit, and also it had a frosted glass look.
Replaced it with a 1N4148, turned the monitor back on, issue solved

I only have uncertainty about the B+ voltage of this chassis, does anybody know what's the right voltage? I only know MS8-26 is 92v and MS8-29 is 94v, what about MS8-25? Just kept it at 92v anyways, seems fine.

Also, here's my compiled capacitor list of it, chassis had all original capacitors. MS8-25FTB

Code Capacitance Voltage Note
C560 0,47uf 160v Flyback area
C909 100uf 160v
C906 100uf 160v
C448 100uf 35v
C442 100uf 10v
C432 100uf 35v
C440 10uf 35v
C332 10uf 250v Neck Board
C580 1uf 50v Flyback area
C577 1uf 100v Flyback area
C561 1uf 200v Flyback area
C552 1uf 50v IC102
C501 1uf 50v
C445 1uf 50v
C443 1uf 50v
C420 1uf 50v IC102
C401 1uf 50v
C913 220uf 16v
C911 220uf 25v
C910 220uf 50v
C570 22uf 250v Flyback area
C521 330uf 16v
C574 33uf 35v
C449 33uf 16v
C446 33uf 16v BP
R566 4,7uf 100v over resistor
C565 4,7uf 100v
C562 4,7uf 25v
C576 470uf 16v
C573 470uf 16v
C431 470uf 35v
C422 470uf 16v
C908 47uf 16v
C572 47uf 16v fb
C447 47uf 16v
C438 680uf 25v

Cheers!