I believe there is a fuse on the bottom side of the PF that protects the solenoids. If that's blown check for coil problems. If you turn the game on and a coil locks on turn it off right away and fix.

Check your ball trough switches in test mode. Are those working fine?

I believe the fuse Superchicken mentioned is on the bottom of the playfield. If that is blown then no coils would fire on the playfield.

Yes, there is a 1 amp slow blow fuse on the bottom of the playfield. If it's blown, there probably is a reason.

Your switch issues could be related to the header pins / connectors on the right side of the MPU. You may have cold solder joints on the MPU or bad connections between the header pins and the molex pins inside the connectors. You can isolate this some by wiggling the connectors back and forth slightly, then trying the credit/coin buttons again. Bottom right connector on the mpu is cabinet switches, the top right connector is playfield switches.

For the lamp's flashing on/off randomly.. you'll probably want to remove the lamp driver board (under the mpu) from the game. That board almost ALWAYS has cold solder joints at some of the header pins (ie. cracked solder joints around the pins on the back of the board where the solder joints are). This will cause flickering or lamps that work sometimes but not other times.. as the board expands and contracts from the heat. You'll want to check that board and fix any cracked/cold solder joints by reflowing the solder (at the very least). The best thing to do is first clean the joint with rubbing alcohol, then use a solder sucker or desoldering gun and remove the existing solder, then add new solder. If you can't do board work.. you would need to find someone that can help you with that.

Not 100% sure what might be happening with your credit display. There's a DIP switch setting for showing credits (check your game manual or IPDB.org link to manual if you don't have a manual). Odd that it's showing ball in play as zero and the ball in play light always on. This is in attract mode? I'm not sure if that kind of behavior could be bad 5101 RAM or not... weird things can happen when the 5101 is partially bad so it's a good idea to have an extra known-good memory to swap in there. It could be some of your issues are related to that too. If the board had corrosion and it wasn't all cleaned up that could also cause odd problems.

Does the credit display still show a "0" for ball-in-play or is that now fixed? Maybe it's just some bad solder joints on the boards.

You can't really test a 5101 RAM with a DMM unfortunately. There's a very handy tester that David Hoffman built available on his website at http://www.neoloch.com for about $30 that can test 5101, 6264 and 6116 RAM (this covers the 3 common types of RAM used in pinball machines). If you're handy with a soldering iron you can buy a kit too, so you have something to build and get better at soldering & a useful tool in the end. The RAM tester writes and reads data to each memory location to fully test the memory. That's why trying to check it like a logic chip with the DMM won't work.. you aren't really testing much on it. Anyway, if you have other 5101 RAM and can try that usually that works well enough, but if you're fixing up a few machines these testers start paying for themselves in time savings rather quick.

It could also just be garbage data in the 5101 as well. Reset each audit field via the 3rd coin switch on the door or by the momentary switch on the mpu.

Manual reset per each audit/setting. The downside of these older games, but once they're set then they're good until the battery dies. Check the manual for audit/adjust settings and their corresponding number.. some games need specific settings for sound (or you might lose background sound, speech, etc) and it's a good time to set high scores, while you're clearing them too. Any time you're replacing a dead battery or setting up a board that didn't have a battery on it, the 5101 *WILL* put junk values in these settings as early Bally/Stern boards don't try and detect valid data on the 5101 and clear it if it's corrupt. I don't think there's any type of verification of good data on the 5101.. just some test routines when the board boots up that read current data off the 5101, write test data, read test data, then replace with the original data that was on the 5101.

In Bally's you have to manually zero (and optionally set your desired highscore thresholds) each audit setting.

I think the fuse on the playfield is for the flippers only. The rest of the coils get their power through the fuse on the power supply board. Follow the wire and you should see the brown wire from where the fuse holder should be to the right flipper coil.

I am at work so, that is all from memory, so I may be wrong......

I think the fuse holder gets +43 vdc power from the flippers (up stream, brown wire) and the other side of the holder connects a yellow wire feeding the solenoids.

Bit rot in the ROMs?

There are both dip switch adjustments (read when board is powered up) and adjustments via the self test button. Manual should explain each in detail, they don't overlap.

Make sure the game is off before changing the dip switches.

on the coin door. you have to go through all the adjustments until you get to 33. Make sure your battery is up to date or you'll have to do it again next time you shut it off.

Switch 33 is the reset button on the MPU. When setting '04' shows up on the credit display, push S33.

I still think you need to actually set the high score levels for '01' through '03'.

What were the random audit values? A partially bad 5101 RAM can be a real headache to deal with. Unless you have a RAM tester or known-good memory to swap-out, you'll be chasing your tail until you've ruled out the 5101 if there's possible memory corruption occurring. If it was me, I'd invest in some type of RAM replacement and rule that out. I've learned my lesson time and time again with classic Bally/Stern boards to not trust the 5101 RAM and have extra memory around to immediately swap in when the machine is acting funky.

At this point, IMO your options are to spend $30 on a RAM tester from http://www.neoloch.com if you want to be able to test your own RAM (incredible deal for troubleshooting) ~OR~ spend anywhere between $5 and $40 on a RAM replacement that you can swap into your board. The RAM tester will come in handy in the future if you will be staying in the hobby for a while and will quickly pay for itself in time savings. You will VERY likely be buying a new RAM chip as well if once you test your RAM it checks out bad.

So that leads to the 2nd option.. trying a new RAM IC. I'd encourage you to buy a compatible RAM adapter INSTEAD of buying another genuine 5101 RAM. The 5101 itself is very static sensitive and they're $5-8 usually + shipping for one chip.. so if you need to buy new memory you really can't justify the cost if you can't luck into a deal where you can buy 10x or so 5101 RAM at a time for a few bucks a piece. It's just not worth buying a single 5101 RAM IC and spending $10 total, to then zap it while you're using it for testing and be in the same boat again. There are many replacement adapters available that adapt much less static-sensitive RAM to a 5101 pinout, including RAM adapters that use a lithium coin cell or memory capacitor and adapt 6264 low-power RAM to 5101 pinout and NVRAM that won't require any batteries on the MPU.

Here are just a few options for 5101 RAM adapters:
http://www.pinitech.com/products/5101_budget_ram.php (6264 RAM adapter)
http://www.pinforge.com/ (NVRAM)
http://lockwhenlit.com/anyPin.htm (NVRAM)

I'm sure there are others too, Tom Callahan (Pin-Logic) used to produce a few adapters but he is recently out of the pinball parts business after 50 yrs. Just so you're aware, the Pinitech adapters are mine & are available in kit form if you want to save a few dollars and don't mind soldering. The other links are for NVRAM adapters that will rid you of batteries completely made by various pinball enthusiasts. All are excellent options and would provide a much more rugged RAM for use when troubleshooting machines since they have machine pin strips instead of the frail IC legs.

Hope that helps, not trying to steer you clear from continuing to try and troubleshoot without putting out any money, but if you'll be messing around with similar machines in the future.. a RAM tester and/or one of those 5101 RAM adapters will help immensely. I've learned over the years that test equipment or something I know is good that I can swap in/out easily is well worth the price over hours and hours of wondering what that little black box is doing.

Check temp of your chips too while it's running.. if any of the cpu, eproms, etc get hot enough you can't keep your finger on them for very long then suspect that chip. You said you replaced the eproms, so likely not those. I had some boards crash because the cpu was bad and it was very apparent when checking the temperature of the cpu.. it would heat up within a minute or two and become too hot to the touch. You can't find every bad chip like this, but it's something to check. Anyway your audits getting corrupted seem to point to a RAM issue, but depends on what is happening exactly.

Unfortunately all you can do is isolate until the problem is found. Could it be memory causing all your issues? Possibly.. could it be 3 or 5 other things? Sure. Maybe the capacitors producing the +5vdc for logic power are going bad (verifiable by checking AC versus DC readings on the +5v test point on the mpu). Maybe you have a bad cpu chip. Spare boards and components help tremendously in isolating the issue. If you continue fixing up machines it's VERY wise to get a few spare working boards of whatever type of machines you're working on.. could be brand new replacements or something others have fixed up, or buy some AS-IS boards and fix them up yourself so you have a spare. Unfortunately that's just the nature of the beast.. the people that are able to quickly repair boards and machines as a hobby or business have the right equipment, technique and spare components/boards to make it easier to isolate and drill down to the problem quickly. Without spares, without tools.. anyone would have a difficult time wondering what is going on with the signals and where the problem is at since you can't often visually see the problem.

I like the Pinitech stuff. If there is any evidence of battery corrosion the socket should be replaced with a machine pin socket as this area is highly vulnerable.

https://www.greatplainselectronics.com/proddetail.asp?prod=IS-422-MP

Hey at least you ordered two of the Philips 5101's in case you zap one. Many people would just order one, pay $3 shipping on it.. go to insert it a few times and mangle the pins, then be left having to order more. Now you know what your options are next time

As Superchicken mentioned, definitely make sure you clean up the corrosion fully or it will come back to haunt you and if you haven't replaced the 5101 RAM socket you'll want to take a look at it and see if there's any corrosion before installing brand new RAM there. Many times it's so corroded that the socket pins completely break off.

They make ESD wrist straps with ground cords, anti-static gloves, work tables and mats (some of the mats have built-in grounding cables). Anyway, what I usually just do is touch something that I know is grounded that's in close proximity to what I'll be working on.. that way I discharge any static electricity just prior to picking up some static-sensitive component. Usually easier to find something that will work in the winter since it's dryer and build up of static electricity is more common, so you can't help finding things that release that charge

Seems like similar pinout from the TC5501 datasheet. Looks like a slower part which by itself can cause issues. Not sure if there's other differences between a 5501 and 5101.. interesting though.

It may also be the 6810 memory at U7. This is were the game settings are held after boot. Big Daddy carries these:
http://bigdaddy-enterprises.com/

If you do happen to need 6810 RAM I have a boat-load. Both F6810's (used pulls) and brand new Motorola MCM6810P's. I got a little paranoid at one point thinking I might have to replace that chip often enough and didn't have many at all. Between the pulls and new ones I must have 300x of them now, so I'm good for a while. Especially considering I've only had to replace one or two during the several years I've been fixing machines, so I'd think that means they don't go bad as often as 5101's. Hopefully the new 5101 solves things for you.

This kind of stuff is the reason I developed some Bally testing tools. It could be your plugs, could be cracked solder joints, switch capacitors on the mpu, break somewhere in the wiring, etc etc. You need a way to cut down the list of possibilities.. and work one issue at a time. If it was me and I just had a multimeter at my disposal I would check continuity from the coin door switch to the plug, then from the plug to the mpu. You will have to reference the schematics and follow the wiring. Also if you have a spare diode you can try faking switches at the switch headers on the mpu. I'll try and post something on that tomorrow.. not at the computer right now. You'd need to reference the switch matrix chart in the manual for how to hook that up.

Alltek is a good board replacement, but if your issue is with plugs, wiring or otherwise outside of the mpu you would be in the same boat. Helps to have an extra mpu board for things like this too. I think you just had more issues than the 5101 being bad, which is usually how it goes.