So I'm going to look at a flash gordon for someone, and I know some of the basics for a pin this old but wanted to arm myself with as much knowledge as possible.

I plan to pull all the fuses and check those, and verify all the power supply voltages on the rectifier board. I had the guy check to see if it gets the "7 flashes" but he claims the LED doesn't flash at all. Notta. So from my research, that means the system reset isn't even working as that's the first thing in the power on. He showed me some pictures, and it's a bit hard to tell but it doesn't look like there is any battery acid damage, not much if any, but possibly a tiny bit located within an inch or two of the battery.

I also know to inspect all the wiring harness plugs on the soleniod driver board, to ensure none of the plugs are burnt, or none of the header pins are burnt.

Beyond that, what would be the next common / easy things to check on this? I was hoping it would have more "flashes" on the MPU power on self test... but no flashes. I know the power supplies commonly need rebuilt, and sometimes the solenoid driver boards need rebuilt... the MPU often needs work ranging from battery acid repair (hope not) to I read something about certain type of chip sockets are not known to hold good connections on some of the chips, wiring harness needing rebuilt.....

Any advice on testing an early Bally game like this would be much appreciated!

So I got a chance to go take a look at the flash gordon pinball today.

I pulled all the fuses on the -54 recitifier and buzzed them all, they test fine. The 1 amp slo blo fuse under the playfield was popped, the guy only had a 3amp slo blo to temporarily put in. I wasn't super comfortable with it, but for a super temporary fix I figured it was fine. The coils weren't energizing anyways.

The -54 power voltages were all in range on TP1-TP5, both with J1 / J3 attached and disconnected.

All fuses on the -54 recitifier were good, one fuse clip seemed to be a bit dodgy, but I cleaned it up. TP voltages from TP1-TP5 were all in range on the MPU.

The solenoid driver board was a stern board, and DOES NOT appear to be the common stern SDU-100

It's this board, which I haven't identified yet so I don't know what the TP voltages should be:

ebay.com link: itm

The MPU board:

It seemed like it wasn't flashing at all (it may have been, more later). I removed all the connectors on the MPU, all the connectors on the SDB, and all the connectors on the Recitifer. None of the plugs seemed dodgy. At one point, it looks like some of the connectors may have been redone with IDC connectors. Some are a clearish pink instead of the solid white. No burning, signs of heat damage, or discoloration on any of the plugs. On the MPU, one or two of the header pin rows have what looks like slight tarnishing on them.

There is some battery acid damage. It looks pretty minor compared to what I've seen, but I do see corrosion in about a six inch by six inch area. What's weird is it's not "solid". Some vias appear corroded, some resistor legs... it doesn't look "horrible" but seems like it could cause trouble for sure.

Now, the pinball wasn't doing any flashes at all on the MPU. After checking everything I described above, I gently pushed on all the socketed chips... gave them a little wiggle pushing in on either side, then pushing in directly on the center. I still had my work light shining on the backbox, and after verifying my TP voltages, I shorted the adjacent legs of Q2 (LED did not appear to come on, but then again, my worklight was on and the LED is very dim when I did get it to come on). After powering up the pinball now, with the work light I was using turned off... I could see the LED flashing. Didn't appear to "flicker"... it just flashes steady as long as power is on, it will keep flashing. I tried several times, and each time the same thing, just a steady flashing of the MPU LED the entire time power is switched on.

Since I have verified all voltages are good, I think the problem is down to the MPU. Having said that, I didn't verify the test points on the solenoid driver board, but the test points on the MPU are all spot on.

Given all that, I'd love some feedback from you guys who are much more experienced than I am!

And a big thank you to those who have commented already

I'm actually fairly advanced at soldering, but if I can narrow this down to high confidence that the MPU is the problem, I think I'm going to recommend they either get an alltek MPU or send the board out for repair.

It'll probably take me 1-2 hours (at least) to pull everything off the board, replace the sockets, clean up the corrosion, probe around with a scope / check traces with a meter.... for what I make at my real job (software dev) the guy would better off I think to go another route than me repairing his MPU.

TNT amusements in PA is a rather big amusement dealer, and I'm sure they've done tons of them. For what the guy would pay me, he'd be better off having them do it (if they will... I don't know that they do it or not) or to just buy the alltek MPU and I'll install it for him.

The only reason I'm not quite there yet (though 99% sure) is that I haven't fully verified his solenoid driver is fine. Though, the voltages are all fine on the MPU, and from my understanding they go through the soleonid driver board so.... I'd say by implication the driver board must be health "enough" to not cause these booting problems? I just don't know enough about that solenoid driver board to say that.

BigAl56 All test points on the MPU are well within spec (no more than +10%). I fully tested all fuses, the fuse clips, all test points on the rectifier board and all test points on the MPU.

sbmania

That's the conclusion we've come too. I called TnT Amusements in Southampton PA and the owner picked up, he quickly told me that they won't work on it unless it's a game they sold. This one didn't come from them. He recommended Clive off of the Coin Op Caldron. I looked that website up, and as of 2007 they no longer repair bally MPU's with corrosion on them. Just the same... it would have cost $125 + shipping both ways.

I told the owner just to buy an altek MPU.