Put the game in Switch Test mode and make sure the Ball # display on the backglass is blank (i.e. no stuck switches). Bang around in different areas of the playfield with your fist and see if any switch numbers get displayed. If they do, look up the switch number in the manual to find out which one(s) they are and then adjust.

You could also hit the flipper button during that test....since you're getting scores with flipper action during the game, the offending switch(es) should get displayed in the test when you activate the flippers.

If you're getting 10-30 points, it's going to be a 10 point value switch. And like slochar said, it'll likely be one or both slings.

I did all that all that shows up is the open door switch. When. Manually testing all the switches they all work fine. And just once.
Hitting the flipper doesn’t activate any of the switches no matter how many times I hit it.

Also to the previous poster the slingshots are aligned fine, and I took the plastic off to see if the action of flipping causes movement on the switches. It does not.

I also flipped the board up while in a game to see if the action of the switches causes any vibration amount the switches I couldn’t see anything.

I guess the next thing I’ll do is disconnect all the molex and give them a shine.

It was a switch up by the rollovers, I adjusted it and it works fine!

Never mind... problem solved.

PSA for Flash owners: If you installed the NMP drop target magnet solution for the 3-bank assembly and are experiencing phantom scoring when the bottom pop bumper fires, you may need a mu-metal foil shield for the NMP PCB.

See here: https://pinside.com/pinball/forum/topic/1979-williams-flash-restoration-1/page/4#post-8066018

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Hey! My friend's Flash is acting really weird. When you play it for more than 5 minutes, it freezes completely. All the logic freezes, you can hear the background buzz so the machine doesn't boot, but you can't do anything. Turning it off and on again gets it to normal state, but it happens again when playing.

Any suggestions on what could be the issue?

Check your power supplies and voltage test points on the MPU board.

Looking for guidance on if this speaker hum I'm hearing is normal for a Williams Flash or is there something else I can chase down here. All sounds are working properly - it's just this hum that is most noticeable during Attract Mode. The hum does not get louder or softer when I dial up or dial down the volume. I know 1970's solid state pins aren't exactly high fidelity but the hum on this one is way louder than any of the others I've worked on before, including a 1980 Black Knight restoration I did a couple of years ago (same manufacturer and era). It's loud enough that when we're watching a movie in our home theater (which shares space in our rec room with my pins), we have to turn off Flash if it's not already off so the hum doesn't disrupt / distract the quieter portions of films.

I don't know how it behaved before the restoration as I got it in a heap of parts and never turned it on until I got to that point of the restore. You don't hear it during gameplay or over the constant droning sound effect playing in the background...this is only noticeable during Attract Mode.

What I've done so far:
- Sound Board was re-capped and a new pot installed
- Speaker is new, but I put the original back in as a test (same hum)
- All new ground braiding throughout the cabinet with dozens of checkpoints for continuity passing
- Ground braid contact points exactly match the way it was in this cabinet originally as well as comparison to other reference photos I've found online (including the lower cab ground strap to the wingnut in the backbox). I don't think I'm missing anything.

If ya'll tell me this is normal for a 1979 Williams Flash, I think I can live with it. But if I can reduce or eliminate this hum, I'm open to suggestion. Filter cap (where to put, what kind/size)? Replace other amp circuit components on the sound board (caps already replaced)?

Thanks...

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Do to my hearing loss I could not hear it. The only thing was the sharp pop
from turning the game off and on.

The Flash hum is fairly common and there are threads about folks who removed ground wires, made other mods to help eliminate/reduce it, but yes it is there. That said, your does sound a bit louder. I made a quick video of mine.

Thanks for going thru the trouble of making that video clip, @spinout. I dumpster-dove thru pinside and google last month looking for what others did to combat problems like this but none of what I tried so far has reduced it any. I'm going to do a deeper search now that this is one of the very last things on my restoration punch list to cross off - I'm anxious to call this project done!

I could never get mine quite enough, tried a bunch of rebuild kits and mods - nothing worked well.
Gave up and bought a new card and it is much better.

http://pinballpcb.com/products/sound-board-system-3-4/

Found this video and it worked for me. Removing ground pin 5 from J1 on the sound board reduced the hum by about 80% in my Flash. Question is why? I re-pinned J1 and J2 connectors to the power board and reflowed all connector pin solder on the power board during the board repair phase of the restore, so I don't think that played a part in the hum. Power board (all boards) got new caps as well.

That would suggest there is a ground loop issue. i.e. the sound board is getting ground from two separate sources with different levels of current.
In your pictures I see the cabinet ground braid behind the metal bracket mounts for the sound board. I would think that is the offending ground source rather than J1 pin 5. J1 pin 5 is the desired reference for zero volts from the centre-tap of the +/- 12V transformer output.
i.e. try isolating the cabinet braid from the sound board brackets instead.

I tried that this afternoon - no go (in fact worse). I isolated the cabinet braid from the sound board brackets and put Pin5 back on the J1 sound board connector. The loud 60 cycle hum is back but this time accompanied with loud crackling noises through the speaker as well.

It would surprise me (or maybe it wouldn't, given some of the questionable design choices in late 70's Williams pinball like BR's with no fuse protection) if the cabinet braid was in the wrong place as I've seen countless pictures of original Flash cabs on the internet and they've all been connected to the sound board mounting brackets.

My Flash is playing well (and quiet in attract mode) for the time being. I'll continue to tinker/research on this issue, but it sure seems like a lot of Flash owners have experienced the same thing.

It seems like an isolation transformer is needed to completely separate the sound effects
board from indiscriminate noises and frequencies from all the cpu/transistors effects influences
driven off from the OEM transformer.

Hmm, there are at least two problems here. The transformer taps to power the sound board amplifier are also used to power the digital logic (i.e. MPU) board. It is a dubious design to mix digital supply that is very noisy with analog supply and like vec-tor said they should be isolated. Secondly the sound board is located far from the transformer so the cables are likely picking up noise in the harness run.

If disconnecting J1 pin 5 from the sound board mostly eliminates the problem then I would just leave it at that. The cabinet ground braid is otherwise providing the transformer centre tap ground to the sound board because it's also wired to the power board ground from the transformer.

Thanks, Quench - that is what I'm going to do. So far it's playing great. I'll be posting some restoration wrap-up pix and game play videos in my restoration thread soon.

I am wrapping up a playfield swap on Flash, with all new bulb sockets, etc. The boards were professionally gone through prior to the swap and the game was playing fine. I have re-pinned all the connectors in the backbox (I didn't replace header pins) and I still have five switches that are not registering. The three right side star rollovers, the spinner, and the upper right standup target behind the rubber. I have continuity from the correct pins in the backbox connectors to each individual switch. All switches are in column 3, but the three jet bumpers work fine. What am I missing?

I just went into switch test. I removed 2J2 and 2J3 connectors and jumped the corresponding pins for the switches in question. They all register when jumping the pins. I then plugged the connectors back in and activated each switch. The five in question are not registering in switch test.

Not exactly the assistance I was hoping for.

Sorry I'm dyslexic... I read it that the 5 are now working.
Being dyslexic gets you in trouble sometimes.
Try:
1) continuity test from connector to switches on playfield.

Haha, gotcha. Didn't think you were actually trying to be snarky. I have continuity from connectors to the switches. I am pulling apart the harness in that area currently. Trying to see if something is not connected properly.

What I have found that helps at times is to go from the wire on the switch to the point on the circuit board, which help to tell if there's a connector problem.

An update to my dilemma.... There was one wire in the daisy chain that had broken loose, so that has been resoldered. But that didn't fix the issue. Found out that the 15 pin white/white connector from playfield to backbox was "bad". I repinned that connector (what a pain in the ass those are) and the five switches now all work. I have to check a couple of the pins since my ball kickout is now intermittent, but I think I am heading in the right direction. Thank you for the suggestions.

Next thing to troubleshoot. I've got several "phantom" inserts lit upon crediting a game. The 1, 2, 5, 2X, and right outane inserts are on without playing the first ball. Diodes are correct and new. I dont see any crossed wires. Thoughts?

Do they blink correctly during attract mode and in the lamp self test?

I believe so. I will confirm. All bulbs do work in test.

Are they LEDs?

Yes. LEDs.

They're probably ghosting try regular bulbs see if it's still doing it

I will try tomorrow. Still not home from a small tournament.

Yes

Replacing the problematic bulbs with incandescent fixed most of them. A couple are still lightly ghosting and one is still fairly bright.

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