Trying to help a friend get his Bally Playboy up and running again. The game presented in a non working state, 5 LED flashes. Tested all voltage test points on the MPU and all were well within range. Removed the MPU and installed an Alltek, powered on and game booted and played. Left my friend to enjoy playing his game and took the MPU home to investigate.

The history I received was that it had been working for quite a while and then the pf switches didn't register and the sound went funny, not playing all tunes. Eventually it wouldn't boot and that was how I found it. The battery had been removed long ago and replaced with a lithium coin cell. The board had some sockets replaced previous on the memory IC's and the CPU. The CPU itself has no markings whatsoever, wiped clean or sanded off. I replaced the sockets for the EPROMs and the CPU as these were still the originals. Also removed U12 (555), installed a socket and put in new ICs at U10, 11 and 12. Both PIA's and the 555. Installed back into the game and the board boots, start a game, beauty. Well not so fast, not one switch matrix switch on the playfield registers. Connectors J2 and J4 are both clean and pins soldered in place.

I've checked over the board thoroughly and checked continuity from each pin of J2 to U10 and from J10 to the CPU at U9, along with component values, all test ok.

I could replace the PIA at U10 and test, but my gut feel is something else is wrong. The sounds isn't right either and that is controlled by the other PIA at U11. However, the pop bumpers, flippers, slingshots and ball trough kickout work fine at power on/ball on the playfield. With the voltages and resistance to ground connections checking out, I'm at a loss to workout whatelse is common?

Is it possible that the CPU chip is the wrong type? But the board now boots ok and so I'm told the game was working. Any ideas? Hoping someone can help or seen this problem before.

Forgot to mention...when in switch test it reports a flashing zero indicating no switches are closed, which isn't surprising considering none of them register during game play.

Thanks for the reply. Absolutely none of the playfield switch matrix switches register a score with the original board installed. With Alltek board installed the game functions as it should.

Thanks for the tips. Just switched all the DIPs off and check each diode with a meter, unfortunately they all test ok. I guess I'll have to replace the PIA. It just doesn't make sense that the board exhibits all the same faults as before with 2 new PIA's installed. Should I go ahead and replace them again, or is there something else I should check first?

Thanks Cheddar. I spent some more time working on this today and can offer some further information. Just to recap, with an Alltek board installed the game functions perfectly.

With the original MPU re-installed (see above for the work done to it) I noticed today when methodically working my way through each playfield switch, some switches do register with the original board installed. However a large number of switches don't work and a few solenoids don't fire.

The working switches and solenoids are listed as follows:-

Switches 6, 8, 22, 23, 24, 31, 32, 39 & 40 all register.

Solenoids 1, 4 & 5 work, along with the flippers.

All the other switches and solenoids don't work. With all the DIP switches in the off position on the MPU board, then tested for continuity from the header pins of J2 through to the U10 PIA. Swapped U10 and U11 with the same issues. Installed new PIA's, same issues still exist. I'm lost as what to try next. Any ideas would be greatly appreciated.

Whilst I agree, the shotgun approach isn't always a good solution, I just can't understand whatelse could cause this issue as there is so few components involved. Especially components common to the inputs. Hopefully someone will see something I've missed.

Until it's daylight here, these are the best pictures I can manage. Will update with better pics in the morning.

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No, as wayout440 stated, I followed the shotgun repair method approach.

Haven't had an oscilloscope handy to test this. Is there any other way?

I will try this next chance I get. All pins on J2 test ok for continuity back to U10.

No, however it appears someone else has previously. All pins at J2 test ok for continuity back to U10.

What a difference some daylight brings, much better photos.

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