This is one I fixed some time ago but still worth posting here.

Problem 1: The display would exhibit streaks of grey lines mostly around sprites as the pcb warmed up & progressively get worse over the period. Symptoms would sometimes completely disappear after 10-15 minutes.

Note the grey lines around the sprites.

After inspecting the board there didn’t appear to be any bad connections. I suspected an intermittent component fault.

I didn’t have any freeze spray so I cooled off suspect chips ( I used some ice wrapped up in a sealed plastic bag to avoid any leak )  and found cooling the transistor @ Q4 on the video board would reproduce the above problems. I replaced the faulty 2sc1815 transistor at Q4 on the video board which cleaned up the video sync signal.

Problem 2: Game boots sometimes, other times it does not start and boots to junk. 

Probed 6502 address pins, found that all were stuck high whenever the game failed to boot. All other signals looked OK. I tried substituting the main CPU for the sound CPU ( a  6502 as well ) but the symptoms were the same.

I traced the RST signal from the CPU to a 555 timer. There appeared to be a problem with pin 8 from the inverter at 9C to the trigger of the 555. Whenever the game booted to junk pin 8 of the inverter was floating & my logic probe was not registering the normal RST behaviour you would expect. I suspected a bad LS04 at 9C and planned to replace it.

Removed the LS04 at 9C. Pin 7 which is the ground pin was crushed under the IC. In other words it completely missed the plate thru hole ( it was blocked with solder ) during manufacturing and wasn’t making good contact with the ground pad. This game would have been faulty since the day it left the factory & explains the chip’s intermittent behavior.

Re-installed the inverter & re-tested with good results, no more booting to junk!

I got this Major Title 2 PCB for cheap from ‘Smitdogg’ of MAME team:

X i

He said me board had some GFX issues.Actually when I powered it up I got no sprites at all:

For first I checked the sprites EPROMs with my logic probe and found no activity on all pins.These four sprites MASK ROMs on video board are addressed by the ASIC “GA22” on CPU board :

I probed it and all its pins were silent too.I tried to reflow it without luck, sprites were still absent.Then, looking at the board, I noticed an open jumper ‘J3’ right hear the GA22 ASIC:

Looking at other M92 CPU boards I could see that this jumper was always closed to position ‘B’ (so with central and right pins shorted together).So I did it on my board too:

and sprites were magically restored!

Now the technical explanation.The jumper is actually for selecting which clock signal must be delivered to the sprites generator ASIC “GA22”.If closed in ‘B’ position, ASIC will receive a clock signal of 26.6666 Mhz (which is the correct value for most of M92 games) :

If closed in ‘W’ postition, the ASIC will get a 18.000MHz signal (no sprites with this configuration) :

Last issue to fix was some audio background noise:

I quickly traced it to a missing 47uF 16V electrolytic capacitor @C213 in analog sound section:

End of job.