1977 Bobby Orr Power Play Corroded MPU Repair (Bally -17)

I picked up a 1977 Bobby Orr Power Play about a month ago. It hadn’t booted properly in years and had been “dead” at one owner’s house, sold and then “dead” at the other owner’s place for a long time. The gentleman I bought it from was planning to get it up to speed, but just never got around to it. So, the game was need of a decent amount of attention.

The MPU on these games and the later Bally -35 (Stern boards from this era too) all had Ni-Cad rechargeable batteries directly on the MPU board. If these weren’t snipped off many years ago (and most haven’t been) then the board is usually covered in a nice layer of corrosion from the leaking battery. I’d say 50-75% of these games I run into have some level of corrosion on the board, whether they are working or not.

This game had what I would consider moderate corrosion; I usually won’t invest the time into severe corrosion clean-up as it is a timely process and there are replacement boards for these games available, albeit at a nearly $200 cost.

The usual areas affected, the reset section, LED and Q2 transistor area, and bottom ground plain all had corrosion damage. When booted, the LED light was “locked on” which is fairly common on a corroded board, and signifies that board is not getting through the boot-up process at all. When working properly, the LED on the board should flash seven times, six if you are on a test bench with just +5vdc, +12vdc and ground power.

Surprisingly, there wasn’t corrosion up under the sockets of the 5101 and U11 6821 PIA, but I did have to remove the complete reset section and everything below those chips. I sanded the board down to bare copper on the front and back, neutralized with a 50/50 vinegar/water solution (the corrosion is actually a base, so it takes an acid to neutralize) and re-populated the removed components.

Upon power on the bench, I got the needed six flashes. Took it out to the game to test the displays and see where that stood, and got all seven and a proper boot-up. I will still need to add a remote battery pack and re-tin the bare copper traces on this board.

This game still needs work as it has been sitting for a long time. Upon boot up, I could hear that the chime unit will need some attention, and I’m sure some other mechanisms will need work done as well.

In addition to fixing everything, I’m going to shop it out with new white rubbers, balls, clean plastics and playfield, wax playfield, new star posts, new pop bumper caps, new drop targets, LEDs in the GI and super bands. So, stay tuned as I continue work on this game. Once completed, it should be a pretty decent game for someone. This one will be for sale when complete.

1977 Bobby Orr Power Play, test boot in game to check displays.

1977 Bobby Orr Power Play, test boot in game to check displays.

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About Matthew Mandarano

Matthew is a cinematographer and video specialist by day and pinball fanatic at night. Somewhere in between he also finds time to play the guitar, collect vinyl records and watch a good deal of movies and TV shows.
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