(Topic ID: 143516)

What did you learn from your last repair?


By swampfire

4 years ago



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  • 215 posts
  • 88 Pinsiders participating
  • Latest reply 3 years ago by MrWizzo
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#1 4 years ago

I've been collecting for 17 years, but I'm always learning. System 11 games seem to give me more learning opportunities than other pins. This month's installment is:

"Special Solenoids: special when lit (on fire)"

I was playing a nice game of Space Station a few weeks ago, and suddenly the knocker went off about 5 times. Shortly after that, a few other coils locked on. I quickly turned the game off and opened the backbox. There was a faint burning smell, but nothing obvious. I turned the game back on, and all seemed well until Q77 on the MPU board caught fire. I made some notes in my repair log, and tried not to think about it. I had new games that needed my attention.

Last night I decided to tackle this. First, I reverted to newb mode and tried swapping in a known good system 11B MPU board from my Whirlwind. Same result: Q77 caught fire on that board too! I grabbed a beer and my schematics. Q77 is one of 6 transistors that drive the "Special Solenoids". What makes these coils "special" is that they can be driven directly by a switch, not just by software. The pop bumpers and slingshots are examples. I checked, and sure enough one of my pop bumper switches was closed. I adjusted it and turned the game on with the coil fuses removed. This allowed me to go into test mode and confirm that everything else was working - displays, switches, feature lamps, etc. A quick check confirmed that several coils were now locked on - indicating that the PIA at U10 is probably toast. Tonight I'll get out my Hakko and try to fix all the damage.

What I learned: First, always try to understand the root cause first, before trying a shotgun approach (replace and pray). Second, the six Special Solenoids are a weak point in System 11 reliability. I'll get some fuse holders and put 1A fuses inline with the output of the transistor drives for each of these. I need to do this in Whirlwind too, when I get back to that.

#2 4 years ago

Please link your game to the thread, when you add your story.

#7 4 years ago
Quoted from Meatneck:

connectors, connectors, connectors. the answer to so many problems. especially on early solid state. spent 10 hours chasing feature lights..corroded trifurcons between mpu and light board.

Absolutely. I got so tired of connector issues on my Black Knight that I replaced them all - made it much more reliable. It was easier to do that when I only had 1 game.

#8 4 years ago
Quoted from DefaultGen:

Took me an hour plus 3 days waiting on a Bolt Depot order because I stripped the set screw

Today I learned about Bolt Depot - thanks!

#13 4 years ago

^^^ Same exact thing happened to me, on my JM. It sucks to think you're doing the right thing, and then render a pin nonfunctional.

#14 4 years ago

Tonight's lesson: Alltek boards are amazing, but not infallible. My Fathom had 2 problems:

1. Reset sequence not working (e.g. coils not firing when they should)
2. Settings were getting lost (e.g. sound reverts to chimes)

I swapped in a newer Alltek and Fathom is golden! Fortunately Alltek sockets all of their ICs, so it should be easy to figure out which component went bad. I'll start with the RAM and go from there. I think Alltek has a warranty, but I'm pretty sure this is a chip problem rather than a board problem.

EDIT: what a luxury - a lifetime warranty!! Makes me glad to be an early Bally/Stern fanatic:

http://www.allteksystems.com/warranty-information.html

#16 4 years ago
Quoted from NPO:

What I learned: document it, take pictures, write the symptoms down, write down what you did to fix it, and if possible take a video of the problem in action and a video of it fixed.
It helps A LOT more to see and hear the problem rather than writing a couple lines that could mean 1000 different things.

That's actually REALLY insightful. We're so used to writing up the problem and solution, but in 15 years 95% of the pinball community will use video. A pinball repair vlog would be very valuable. Challenge accepted!

#20 4 years ago

When get to the root cause of a difficult problem, I feel like the smartest guy in the world. But more often I discover that the problem was obvious all along, and I feel like a complete fool. Either way, I'm happy when I get to play again, without spending (much) money on the repair.

#28 4 years ago
Quoted from swampfire:

Tonight's lesson: Alltek boards are amazing, but not infallible. My Fathom had 2 problems: [...]

Dave at Alltek was very responsive and helpful. We figured out the problem after a few emails. It turns out that whoever installed a supercap in my board didn't make the required mod to allow charging it. D7 has to be jumpered out as shown below, otherwise the cap never charges to over 0.5V.

So, the problem wasn't the Alltek board, it was a faulty modification of the board.

IMG_7275.jpg

#31 4 years ago

Today I learned that I'm definitely not Targaryen - I burned a nice long section of my hand with my Hakko 808.

#38 4 years ago

The IC pad traces are very delicate; it's easy to remove them with bad soldering technique. Looks like I'm going back to solder school.

3 weeks later
#64 4 years ago

I learned that early Bally/Stern power supplies are much easier to work on if you remove them from the backbox, transformer and all. It's only 5-6 screws. And, you can connect it to 120/240VAC right there on your bench (but be careful, of course).

#69 4 years ago
Quoted from Arcade:

Nice knowing I can easily remove the whole thing for bench work. I was not looking forward to soldering in the tight little space in the head.

I actually did do that with Skateball, and I feel dumb now. I replaced the entire GI header while standing painfully to the right side of the game, ugh.

#81 4 years ago

I feel inspired to invent something better than a bungee cord for holding playfields up. Probably using 2x2, and adjustable so it can work with any pin. I still have a scar on my head from Centaur's under-playfield raceway slamming down on it.

#83 4 years ago

That's what I was thinking: start with something that slides onto the top of the backbox. I don't know how the pinball companies avoided personal injury lawsuits, with those flimsy metal cheater bars.

#104 4 years ago

I learned that I can calm down a too-powerful trough kick out coil by putting a 10W 3 ohm resistor in series with it. No more ball hitting the glass when it kicks out of the trough.

#112 4 years ago
Quoted from EvanDickson:

Replaced the GI input connector and reflowed pins for any relative connectors and I now have full GI on my Taxi instead of the lame handful of Gi I used to have.

If you can, replace the header side of those connectors too. The old ones likely have been damaged by the extreme heat. I hate pulling and replacing header rows, but it usually makes a difference.

#128 4 years ago

I struggled to adjust the roll-under switches on Medusa last night, and then finally had the idea to use a taller playfield post, so the switch leaves would pull closer together. Worked like a charm.

#141 3 years ago

Dirty Harry's magnet opto can only be repaired by removing both ramps. It's the Japanese car equivalent of changing the fuel filter.

#154 3 years ago

Before you replace that 9-year-old microwave oven that suddenly "died", make sure there's actually power at the outlet. I was really disappointed in myself when I plugged in the new one and it didn't work either...hello, it's a GFI outlet and it tripped.

1 week later
#171 3 years ago

Tonight I learned that B/W pins can have trough issues, even without magnetized balls. I just ordered a pack of PinBits trough sleeves to fix Dirty Harry, and prevent problems on my other B/W pins. I also learned that during a switch level test, most of the optos will register as closed. So they are "active low" from a logic standpoint. I pulled out some hair, but I'm really happy that I found the root cause of my Dirty Harry 1-ball multiball.

#184 3 years ago

I learned that, given the option, a Bally playfield will always come crashing down on your head. I outfitted all of mine with bungie cords screwed into the back after learning that painful lesson for the third time.

#186 3 years ago

I should just attach bungee cords to the wall, at the nearest stud, about 6" below the head so they're out of sight.

My right arm agrees with "NO EXCEPTIONS" today. Looks like I was attacked by a wolf.

#198 3 years ago

I got lazy when I repaired the GI connector for my Time Fantasy last year - replaced the female connector but not the header pins. My nice new connector burned again. This time I did the job right (replaced both).

#200 3 years ago

My "Time Fantasy" displays have been flaky for quite a while. I tried swapping out the display driver board, to no avail. I finally decided to try wiggling the "BCD Input" edge connector (4J7) during the display test - root cause found! To fix this, I cleaned both sides of the connector with Emery paper, painted the landing pads with solder flux, and added a small ridge of solder to each pad. Works like a champ now!

#203 3 years ago

If it's working, DON'T F--K WITH IT.

This morning I pulled the power driver board from my JM to replace a transistor. I thought, "Hey, as long as I have it out, I'll replace all the 15,000 uF capacitors". Big mistake - I ended up spending 2 hours repairing the damage I did to the delicate pads for C5 and C11. And since I had no reset problem, there was no good reason to replace them.

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