Backstory:

I see a post on Facebook for a Frontier pop up, with what appears to be a very random price attached. I send a message asking how much and he responds "1000 but very negotiable". Unique bargaining psychology aside, I decide to see how negotiable and throw out 500 bucks. He accepts and we're in the car!

I was told the game wasn't starting and took a quick look to make sure it was all there. I didn't ask very many questions because I wanted to be in and out before he started getting more messages. The pf has some wear but nothing I can't live with or touch up maybe and the backglass is nice.

First problem to solve:

Upon getting home the mpu looks pretty far gone with acid damage, but luckily there are pretty cheap replacements out there I can just drop in. I pulled the connectors from the rectifier board and checked the voltages as follows against the schematics:

TP1: 6v (should be 5.4)
TP2: 149v (should be 230)
TP3: 10.45v (should be 11.9)
TP4: 6.4v AC (should be 7.3)
TP5: 44.3 (should be 43)

The high voltage at TP2 is the only one causing me concern...do the rest seem reasonable? Based on what I've read on the pinwiki it seems like they are in an ok range. It looks like there are 4 diodes related to that HV I can replace and a resistor...should I start there? I want to get my power right before I start hooking things back up and then we can get a good mpu in there and see what other surprises await! Should be a fun project!

Any help is appreciated on the journey!20180714_133919 (resized).png

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Awesome, that makes sense. Onto step 2, ordering a mpu.

I thought So! Seemed to good to be true, and it's nice to have a project to chip away on so it not working was almost a "bonus" ha. I've never worked on an old Bally either so it will be fun to learn about.

Here's a random/dumb question: nothing is plugged into J5 on the mpu...the manual says "test connector". I don't have any stray connectors in the cab...I assume this is normally not hooked up?

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Appreciate the confirmation!

I actually took the screws out to get a picture so I do have those. I did catch the hacks but since the voltages seem good I was just going to live with it for now. Thoughts?

I'd hate to buy it if I don't need it. I'll see if I can figure out why it's hacked and what the hacks are doing...bypassing a burnt connector pin or something and maybe the original one can just be repinned. Just haven't had time to sit down with it this week yet but I'll take a look.

I picked up the NVRAM mpu and dropped it in and the game is up and running! Some minor adjustments needed but only a few tricky issues that need sorted out:

1. When I activate the A lane switch, the left sling fires. The center pop fires with the B lane switch and the right pop with the C lane roll over switch. I assume I have a short somewhere? The switch matrix in the manual makes it look like there isn't anything common between these though...

2. The credit display is totally out. I do have high voltage at the display board. The display doesn't look original (stern branding) and I'm assuming the glass is toast. I need to find one to test and see if it's the display or something else. The dip switch settings are set to display credits.

Any help is appreciated!

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I'm going to reflow the display headers and see what happens. I have access to a silverball mania so I want to see if those displays are compatable and try and swap it in if so to isolate the problem.

I'm having an issue with the game randomly resetting too. I think I probably need to repin the solenoid driver board and the rectifier board entirely. There are some suspect looking pins and it probably makes sense to eliminate the easy stuff first. I'll order a few connectors I don't have on hand and see if that clears anything up.

It looks like that's what it was, they clipped the wires from the connector and soldered them directly to the test points. All the voltages are good still...could that board be causing issues upstream?

I need to spend a bit more time trying to recreate the reset issue. I have a steady 5.25 on the mpu and the driver board but I need to measure while activating stuff. I'm starting to wonder if I have a switch issue...once in a while the game will reset all the drops during an active ball or double fire the drop reset when you start a game, but not consistently. I'll give the start button and trough switch a better look.

I assume you mean the flipper coil diodes and not the switch diodes (or both)? Do you replace all the coil diodes and switch diodes? I don't have my hardcopy manual in front of me, but the one on IPDB isn't very helpful spec/part number wise on these.

I assume I can just check them with my meter like any other diode and see if they are dead?

More just for my own education here - how does (or can) a bad diode cause the reset? Does the game think the coil is locked on or something like that?

I'll double check this, but I think its ok. This problem is odd, I think I have a short somewhere? If I press the switch manually, I can get it to happen after the game has been on for a few minutes. If the ball rolls over the lanes during play, it doesn't happen. In all cases, the rollover still triggers (so I'll collect the lane AND the pop will fire). I reseated all the connectors so I need to check this again - but it doesn't happen during normal play.

Ha! Well I owe you a beer on that one since you probably just saved me 8 hours of poking around under the playfield, yeesh. Appreciate that one - onto the reset problems! One step closer .

Found some pretty fried diodes on the left flipper coil. I get the right pop bumper randomly firing now here and there. I still have a reset but it's usually after you've been playing a game for a bit. Pointing to more bad coil diodes somewhere? The pop isn't firing all the time or in rapid succession, so I think the switch gap is fine...

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Some good news. I replaced all flipper diodes, did the ground mods, and reflowed all headers on the driver board and the reset issue seems to have cleared up and the game looks to be playing solid now! I’ll repin the connectors anyway but I’m guessing (very much guessing) the diodes were the problem, all four were pretty toasted and cracked. I think I just have cosmetic stuff left at this point (bulbs, cleaning, etc.) and it’ll be in the lineup. Thanks everyone who provided input to help me out through my first classic Bally. Looking forward to the next one (I hope my wife doesn’t read that part)...

Well in going through and replacing all the bulbs I encountered another issue. I had assumed that alot of the lights that weren't working were just burned out...that would have been too easy right?!

I noticed some acid damage on the lamp board components when I pulled it to replace the header pins. It looks like it's mainly hit the transistors and a few resistors. I have maybe 8 or 10 lights on the playfield not working. After replacing the pins on the right side of the board, I can move the connectors and some but not all of those lights will come on, leading me to believe I need to replace those female connectors as well (just didn't have the parts on hand tonight). All of the lights don't come on, so I'm assuming some of those components were killed by the acid and it's more than just connectors at this point.

It doesn't look like it hit the chips, so I'm assuming I can swap the components and be fine, but wasn't sure about some of the blackness on the traces. I was just planning to shotgun the damaged components since they should be cheap and replace the two female connectors and see where that leaves me. I was interested in some opinions on

1. If this is a fruitless effort and im just going to end up buying a new board anyway; and

2. Is there any point to repin the connectors on the left side of the board?

Thanks!

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Thanks, I appreciate that! I think my issue was (well, still sort of is) twofold. I repined the connectors at J1 and J3 and that seemed to clear some issues up, as when I would wiggle the connectors I got some lights coming in and out. As I was doing the connectors, some of the pins were crumbling as I pulled them out of the housing - so that was part of the issue.

The parts weren't very expensive, so I started swapping the corroded ones out for new ones. I didn't order enough (doh!) but I'm down to about 6 or so lights out, which I assume is connected to the rest of the damaged parts. I'm going to finishing rebuilding it and then see if any issues remain, but based on the results so far I'm feeling hopeful that the board itself is good and just the components need swapped out. I'll keep you posted for sure though and may take you up on the offer if I hit a dead end.

Probably true. I'm already almost through this one, so I'm just going to see it through for how cheap the parts are. If I'm still hitting the wall that will be the plan.

Thanks. If I still have some dead lamps I'll give this a try. I might need to hit you up for a pic...can't quite picture what you mean with the molex.

I'm down to one lamp out (hurray/ugh). I have voltage at the socket where the wire is soldered on...I'm thinking this means the socket is just corroded or bad inside? I'll try swapping with one from the coin door. I assume since I have voltage that everything board and connector wise is good now...is that a fair statement?

Check that. I jumped the socket to the one next to it and it lit, so I think my socket is fine and I have a lingering issue at the board or connector. I'll investigate today.

Well I found the problem, Q27 was bad on the board. I actually thought I replaced all the SCRs associated with the bad lights, but when I made my list I was in a hurry and wrote down Q28 instead of Q27 to replace. Figured that out today and were back in business.