This one actually took me months to find since it was an intermittent tilt that showed up about 2-3 times a month. With pictures.

https://pinside.com/pinball/forum/topic/i-was-losing-my-mind-trying-to-figure-out-this-intermittent-tilt-issue

My first Bally Corvette, having troubles with the LT-5 engine. Spent a ton of time checking all sorts of things: voltages, solder reflow, etc. The 6 foot ribbon cable was on wrong at the master board.... fixed it right up.

Finishing up my Mystic PF swap, think, hmm, that's odd, certain lamps locked on at on U1 on lamp driver board (didn't surprise me because the original game had many bad sockets, so thought was old problem). Put another Lamp driver in, problem goes away, figure, it's U1, right? Replace U1 on original board, same issue. Also seemingly unrelated, switch column 4 is not active but I figured that was something else.

Measured between GI and controlled lamp feed voltage showed that the switch column strobe was always high.... hmmm.... u1 enable and strobe= same signal on PIA.

Turns out 2 sharp wire ends on both a GI bulb AND a controlled lamp were piercing the column wire at 2 different places. Snipped and rerouted, all fine now. The clue that there was 2 cross connects was that the controlled lamp wiring stopped showing continuity to the switch column after I moved the harness, but the GI STILL showed. I thought the GI and the controlled were just cross connected somewhere else.

Real PITA though.

I blew up all the lamps in the backbox of an EM machine after converting it to freeplay by adding a jumper wire (as recommended on pinrepair.com). Turned out someone earlier had done a mechanical hack that made contact between two switch blades, so when I added the jumper wire 24 volt leaked into the 6 volt system. Had to replace all the lamps...

I took all the assemblies and plastics of the top of a game to replace the GI bulbs before I realized you could just unscrew them from the bottom to replace them.

Not really a fix, just a dumb move by me.

But it is easier to thoroughly clean playfield while the plastics and stuff are out.

About every third power up, my Elektra would have the same, one GI bulb out (lower left main playfield slingshot area). After numerous, adjustments, cleanings, wiggles, testing and bulb changes, nothing seemed to consistently fix this problem.

Finally, after removing the slingshot plastic and bulb in question to re gap and clean the socket contacts yet again, I barely noticed a small quarter inch sized sliver of thin, clear glass jammed into the light socket. It was practically invisible! Removed it and bingo, no more problem!

Since then I've kept a look out for evidence of smashed playfield glass or bulb shards in the cabinet bottom of any used or previously routed games. Two of my games showed evidence of this and on occasion small shards of glass have worked themselves free from wherever and suddenly showed up on the playfield! Yikes!

Adjusting pop bumper leaf switches on my afm.
Didn't turn the power off.
Made a short..
Fried the cpu.
This is about 3 years ago..
Took a year before I ordered a replacement cpu.
Took a few months before I installed it.
Then found out the security chip was fried too.
Took a few months to order one.
Cpu booted but didn't all work.
Last week finally started to work on that game again.
Scoop coil works intermittent.
Replaced the coil.
Replaced the connector near the coil.
Still works intermittent and usually better when the playfield is up.
So now we're 3 years later and my next step is to replace the wire from the backbox to the coil..

Anyone ever turn a JJP machine off and on too fast? For those of you that haven’t, the machine goes completely dead. After looking just about everything over on the machine I turned to the internet and found the solution.

You would think for the price of one of their machines they would have wired in a reset button on the computer rather than having their customers remove the backglass, open up the computer cage, and short out two wires with a paper clip to have the machine power on again

Or turn off before fully booted.

Some early WOZ's had it. Buried in the metal box with the boards, so people wouldn't hit it accidentally. They found it and pushed it anyway.

If you have a habit of running into this. Easy to install your own momentary contact push button switch on the connector on the motherboard. I don't remember which thread, someone was making a mod like this a few years back.

LTG : )

Here's one that just happened to me:

Originally, I wanted to upgrade my Diner to LA4 software from the LA3 that was currently in it. I downloaded LA4 from IPDB and burned it to the EPROMs that came with the game. Upon putting them back and firing the game up, the message U26 ROM FAILURE came up on the display. After trying to ensure the EPROMs were seated properly, re-burning the roms, switching the EPROMs around, and even switching back to LA3 software, I continued to get the same error.

From this, I concluded it was not the chip's fault, but the socket. I probably should have stopped here and confirmed with a logic probe, but this is where I got the idea to swap the socket out, as I know they wear out over time. After much desoldering & soldering, I put the roms back in, put the board back in the game, what do I get? U26 ROM FAILURE. Great...

Then I start thinking: the message is made to appear whenever that particular rom fails a checksum. What if I have a bad rom image with an invalid checksum? I got them from IPDB, they should be fine, but maybe I'll try something else. The only other place I knew to get them was Planetary Pinball's website, as they host all of WMS's roms. I compared the checksums using my rom burning software, and wouldn't you know: they were totally different! I burn these new roms, put them in, and she started right up!

I probably should have checked that way before pulling the board out, but all's well that ends well, I suppose. I also got some good experience with board work: nerve-wracking, but fun.

I was on a call. World cup soccer. Pop bumper a little dead. So like I usually do. Shut power off. Adjusted a switch and got a shock from the coil lug. Apparently game still had stored voltage one driver board. Got the dreaded check 12 volt message on power up. Blew cpu uln 2803. First time I blew a board with a powered down game.

Didn't know this was a thing. Is this only applicable for WPC-S games or any SS?

Restored my TZ in 2012. Would blow fliptronic or power driver board or CPU after two to ten games.

Went through my entire stash of boards, let it sit for 5 years and forgot about machine.

Wife wants it ‘finally’ fixed or no new pins. I went through entire machine, finally found a screw juuuust touching the diverter ramp coil windings. New diverter assembly I installed in 2012 someone thought it was a good idea to have that screw help hold the coil when they built it. Removed the screw.

Cost me $300-$900 every time it blew.

This one is bizarre.

ACDC premium, whenever the ball was on the lower PF the kicker would fire at all times not just when the ball was settled at the kicker.

We we replaced the opto sensors and you would think that did the trick but no.

I had an very good pinball technician come over he was stumped as well. He said everything physically is working correctly so maybe it’s software related. And he noticed I had pinball browser song modified but I had that for years and it was always fine. However I had been messing with the speech and music attenuation to get the sound levels better as well as other changes to default settings. The tech suggested I go back to default settings, still keeping the modified code. Anyway that did the trick.

Sadly I didn’t take note of what settings had been changed so I wasn’t able to re-check if there was a combination of settings that would make it recur or would be reproduced on a different machine.

Years back

Had a GTB Teed Off

Every flasher did not work and I couldn’t figure it out

Pulled the field out checked wiring and boards

Yeah …. Check the bulbs …. Every single 67 was blown :-/

LOL

On wpc the capacitors hold a charge for maybe a minute or less. You can see this when you shut down a game as the leds on the driver board stay lit . Opening the coin door may help if you work on the game after power up but sometimes that switch gets bypassed.

Had another in late 90,s. Indiana Jones was atop seller. Sold one and almost had to refund money. Would slam tilt occasionally. Went back 4 times and couldnt get the game to act up. Customers upset. I just joked and said I'm here so much I'll be getting mail here soon lol. Turns out a switch was installed incorrectly with diode reversed. This slam only occured when 2 balls locked in idol and a couple other switches were hit.
Thankfully now much better at finding these gremlins.
I hate the intermittent problems which I cannot duplicate.

Had another Pinbot. Easy fix right?Adjust Failure. Installed remote battery holder, rebuilt flippers,cleaned etc. Played great. Got hi score etc too.
In customers driveway leaving they come running out. Game quit working. So I go back in and can smell that dreaded electrical smell. Power game off on . Comes up u25 ram failure. Chip is hot too the touch. Not sure why replacing batteries caused this perhaps the chip was marginal to begin with.
Took board back replaced chip. Didnt charge customer as the game worked when I left.
I would like it to work for more than 15 minutes

The worst one by far here was a Wms Turf Champ, a game I looked for
for over a decade. Was so happy to find one didn't take a close enough
look so when I started in on the PF (clean/wax/rubber/lights) realized
the PF surface will need a lot more than waxing. Someone had slathered
on at least 2 layers of varnish without cleaning first. So dirt and crud was
embedded under and between the layers! Took 3 months to remove the
varnish one small area at a time being careful not to damage the original
artwork.

Easy fix turned into hell.

Years ago a customer came and told me Medieval Madness stopped working. Ball hit the right slingshot and it died.

Before I took the glass off I noticed the slingshot kicker was gone. Should be simple. Bracket holding it up broke.

Oh no. It had slid down and shorted a whole lot of neat stuff. Burned up the wiring to the draw bridge motor, blew stuff off of the driver board, on and on. 8 hours later back up and running. That to date is still the worst repair I ran into.

LTG : )

Would have been nice if wpc games had a bleeder resistor across the solenoid capacitor. The LED on power driver stays lit for a while after you turn the game off. I too have gotten a power off jolt from touching a coil lug and drawn a spark sliding a playfield back down. I think gottlieb used a 30k 1/4w resistor to drain the cap down faster after power off.

The WPC powerdriver does have a bleeder resistor and no LED for the solenoid power.

WPC95 on the other hand...nope

Had a Bally Kiss. This was in the 90,s CPU had acid damage. Repinned all the connectors on the CPU board. The connector on the lower left has 2 grayish wires. One is for 5vdc the other 45vdc. For some reason I reversed these wires by mistake.
Long story short blew almost every ic in the game. Displays, new cpu bd and sound board. Even the aux lamp driver bd wasnt spared. Very expensive and time consuming mishap.

I have another to add. Pinbot would not kick out a ball. All coils work in test and switches. Took a while of board swapping etc to figure visor motor switch was bad. If the software doesn't see a visor switch closure it won't kick a ball out.

Dracula. Had +2vdc coming out of the 12vdc bridge. IDC plug probably took longer than a minute to repin, but was easy to find already knowing the power path.

20211002_165559 (resized).jpg

Must be like a 1M resistor. This dracula just fixed I can draw a nice blue arc from a coil lug to the ground braid 60 seconds after the power goes off. I made a bad assumption one of the LEDs that stays lit for a long time was the sol bus V. I guess its probably +18v or whatever as the 12v would go flat quick.

Probably the resistor is blown. It should be close to zero Volt in a few seconds.

https://pinside.com/pinball/forum/topic/70v-on-coils-after-machine-is-shut-off#post-3275203

I had a Centaur 2 at a buddies shop. Dragged it over to the Texas Pinball festival to exhibit. When I set up the game I was getting all zeros at boot. Usually a ball trough error, which was helpfully pointed out to me at least two dozen times during the show. I spent maybe ten hours at the show trying to fix the game. Repin connectors, rebuilt boards, I ended up pulling stuff out of the machine and ran home to use my soldering station. Took it home without managing to fix it, put it into storage.

Something like a year later I set it up and figured out I could get the game to boot if I hip checked the machine at just the right time. Turns out a wire had broken off of the coin door when I moved it and was grounding out the switch matrix. Humbling moment.

Yep, it sure is. Probably will bump up the resistance to around 20k-30k so it does not burn up again as 10K at 70v is around a power of 1/2W. I hate taking out those power driver boards, so many plugs. On the list for later, not too big of a deal. I'd bet that resistor is smoked on a lot of boards and it just goes unnoticed. This game appears to have seen a lot of on time / play.