Bally MPU-35 corrosion repair tip (NGS)

[vinito]

Woohoo! I got my brother's Nitro Groundshaker up & running today. Only a matter of time now before I shop it and get it out of here so I can drywall the room it's sitting in. It's got a Space Invaders sound rom in it so I need to get the right one in there, but other than that it seems OK.

The tip:
If you get a corrosion repair kit to refurbish the MPU, be sure to notice that the C5 capacitor is polarized and install it correctly!!!
I even noticed it was polarized from the schematic early on and still overlooked that I installed it backwards, which caused it to keep locking up. FINALLY discovered the problem today and quickly remedied it in about 30 seconds after wrestling with it for a couple weeks or so.
 

Won't be long now.

[Strangeways]

I used to collect and repair MPU -17 and -35 to repair for "fun".. Just "pass time" for 30 hours replacing the sockets, installing new chips, installing the corrosion kit from GPE and then fixing all the broken tracks ...

 

All I can say is if you can fix these boards, you can fix anything.. I still have a pile of them in a corner.. "one day" !!


Great to see you have fixed the board Vinto. After spending all the effort repairing the board, I know the feeling when it does not boot..

I remember a Stern -200 board that I spend hours on - It would not boot in my test rig, but it worked perfectly in the machine !!

[pinnies4me]

FINALLY discovered the problem today and quickly remedied it in about 30 seconds after wrestling with it for a couple weeks or so.

Probably quicker than Tony is going to find that shorted lamp socket though!  

[vinito]

Since I have a guru and a little more experience, and since Strangeways says I can fix anything now I ought to dig out the damned TZ sound board that I never could figure out. I ended up replacing it, but of course I don't have the heart to toss it. Maybe if I can get it working I'll sell it for exorbitant profit and split it 50/50 with Joe (the guru). Nah. I guess it really ain't easy bein' green.

I left it on for several hours and played a game now & then yesterday, then went ahead and hooked up a remote battery pack for memory too, so I guess I can say with reasonable certainty that the MPU rebuild is a success. What a relief.

[pinnies4me]

Well done!