Hey folks,
This is my first post to the forum but have been a pinside member for a little while. The forum restoration content from all the experienced folks has been beyond invaluable and has gotten me to this point. I'm very appreciative!
I am a restoration newbie but fell in love with the process after doing minor fixes and upgrades to my first pins over the last couple years. Last winter I dove into the deep end with a Williams Flash system 4 I picked up that was really ready for the dumpster. It was probably ridiculous to try and save it, but in retrospect worth it due to what I have already learned. Anyhow, I was what I thought was in the final stretch with almost everything working after major work on all the boards, mechanics and cosmetics following the forum guidance (bulletproofing guides, vid's restorations, and expert fixes) until I hit a wall.

More background:
- Implemented power supply bulletproofing, re-capped, etc. and all checks out good.
- MPU checks out good, as well, the game worked all except for switches in matrix column #3 (see below). Replaced a suspect timer crystal and capacitor and minor bulletproofing. All checked out good.
- Unrelated, but bullet proofed and fixed everything with the soundboard.
- Replaced many coils, diodes oriented correctly (I believe) and all checked out when doing the coil test. (I did have one diode incorrect and had to replace the associated transistors on the driver board and all checked out fine).
- Redid many connectors.

The initial problems:
Pin went into attract mode fine and would start a game. Game would play and score fine with exceptions.
1. The two upper left star rollover lights are always stuck on both during attract and play mode.
2. All switches relating to column 3 in the switch matrix were not working, scoring, etc.
- Believe I verified all caps (replaced one on a pop bumper) and diodes are good under the playfield.
- Believe I verified all wiring is good through connectors (replaced due to heat damage) through to driver board.
- Believe part of the problem is tied to switch column (drive) section on the driver board. Voltage at #7 in the switch column drive connector was low. Found three bad resistors and one shorted capacitor (C51) in that section.
- Also found what appears to be a shorted Transistor at Q47 in the lamp row drive section.
- Did my best to test entire board with a DMM and did not discover any other problems. There may definitely be some, but I am a newbie!
- The board already had the resistor upgrades in place and some replaced transistors.

So, I replaced the problem resistors, transistor, and capacitors according to the parts list with the schematic. One problem is that it was very hard to determine the part specification for the replacement capacitor in position C51. Totally unreadable to me in the documentation online and printed. I thought I had it correct and now think I got it wrong.

Final problem:
Turned on the game and it went into attract mode briefly - then the driver board started smoking and I had to shut it off. I fear I put in the wrong capacitor or maybe something else.
- Verified with the DMM the new capacitor is shorted, new resistors are fried, and the transistor appears shorted again (Q47).
- Also highly suspect that IC17 is fried. Couldn't exactly tell where the smoke came from but a resistor (R206 I believe and one I had replaced) was super hot as well as IC17 was pretty darn hot.
My newbie attempt to fix things clearly did more damage so any guidance / insight is super appreciated.
- I have replacements for the IC (and will install a good socket) as well as the resistors and transistor.

Questions:
- Does anyone know the capacitor specs or have a link for the replacement I should use for C51? I now think it should be a 470uf 50v %20 but made the mistake of putting in a 100v initially.
- Is the Q47 transistor related to the two locked on rollover lights or something else? If something else, then where should I look for that problem and what does Q47 short relate to?

Clearly the work I did caused the problem so I am assuming it is related to the capacitor but I may be wrong. And was I even fixing the right stuff for the behavior I was seeing. Last note, some previous owner had replaced the same resistors that were reading bad in the same switch column drive area. Those were the ones with bad readings.

I'd like to give fixing the board one more shot, since so much time and effort has been invested to get to this point (and $$) vs. buying a replacement board but I am at my wits end and now over my head. I just want the final feeling of bringing this back to life and actually start enjoying it as well as devoting more time to enjoying the few pins we have.

Any guidance from experts is greatly appreciated. I've attached a clip of the driver board schematic.
Thanks for reading.
DesertPinGuy

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Thank you so much for the replies Inkochnito and Tallon and for jumping in to help. And sorry for the slow follow-up as I've been out of town. The schematics you posted were a great help!

I have a little bit of an update. I replaced IC17 and IC18, the bad resistors, and the bad capacitor (with the correct one this time) in the switch columns drive area. The pin now boots into attract mode, game will start and I am at least back to the problem I started with before I installed the wrong cap on the board and likely caused a short (I'm guessing) in IC17 somehow and got it smoking. All lights in the matrix and patterns in attract mode work great and the game progresses through the programming as it should. Thanks for the tips to get me this far!

So, where things are at now is that the lower jet bumper, upper right-center-and lower star rollovers, spinner, left and right kicker switches do not work.

Again, I only have basic soldering and meter skills and have a lot to learn. So any additional guidance is super appreciated.

"Make sure to disconect the 2J2 and 2J3 connectors before you turn the game on.
That way you can check the switches connector for strange voltages that do not belong there."
--> I want to make sure I do the testing correctly and don't zap the board. To test the voltages at the connectors do I just put one meter lead on ground and the other on each pin?
--> In terms of strange voltages, what would be a big red flag to look for?

"Also check if the switch connectors are connected to ground in some way. A short to ground can do strange things."
--> I could use some more hand holding on this one to make sure I do the test correctly. Inkochnito, can you describe the test process in some detail?

"I would suggest replacing both IC17 and IC18. Those are 7406 inverter chips. It might be hard to locate them, but a 74S06 is also fine."
--> Done!

"Which rollover light were locked on? Q47 is for lamp row 1 and does not have any rollover lights. Look in the lamp matrix and check all the lamps in row 1."
--> Solved! Chalk this up to another noob mistake on my part. I didn't realize that the top two left rollover lights are wired to GI until I saw there were no diodes with them. So there was no issue. I was paying most attention to the switches that weren't working. As well, all the lamps in the matrix seem to be working great.

At this point, I highly suspect there is a short somewhere or bad connection that I haven't been able to find. In looking at the switch matrix it looks like the problems are common to column 3 (GRN-ORN) and column 6 (GRN-BLU), but some of the switches in those columns are working fine.

Again, thank you very much for the help!

This gives me great direction. I'll carve out some time this weekend to cautiously and methodically go through the steps you outlined, Inkochnito and report back the results.

Again - many thanks!!

Ok a little progress was made - I think.

- Turned on the game with 2J2 and 2J3 disconnected. All voltages at the pins were 4.8 volts - great.
- Turned on the pin with 2J2 and 2J3 connected. All voltages at the pins were 4.8 except for 2J2 pin7 for switch column #3 green-orange wire. Voltage for this single pin was 40 volts. This is the troublesome column.
- Verified that almost all switches in switch column #3 do not work. The left and right jet bumper will fire but the lower jet bumper will not fire.
- Verified that all continuity through the connectors for all wires is good.
- verified that all continuity though the Green-Orange wire daisy chain is good all the way to the driver board.
- Verified that no column 3 switches have a short to ground.
- Verified all switch diodes are good.
- Also disconnected the three Green-Orange leads from the jet bumpers and still found 40 volts at the driver board on pin7 for Green-Orange. I did not check the 3 jet bumper diodes, since I figured with Green-Orange disconnected from the coils if it was a diode problem that would eliminate that possibility and the other switches would work. Maybe I'm wrong here. I still don't understand why two of the three pop bumpers work but the lower one will not fire. (see pic)
- Lastly, both the left and right kicker have not been working. I did find a broken lead on what looks like a capacitor on the left kicker. All the lettering is faded so it is very hard to read. (see pic)
- Can this be replaced with a 22uf 25v cap that I see is also on the lower jet bumper?
- If so, what should the positive side or lead connect to? I can't seem to tell from the cap which side is positive.
- I'm guessing this is a separate problem but may explain why both kickers are not working.

I didn't find any shorts visually anywhere on the playfield and would appreciate any additional thoughts are what would make sense to check for next.

I'm super stumped.

Thanks so much for getting me this far!

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Thanks for the super quick reply.
No I did not change out the PIA (IC11) yet. I wanted to make sure and eliminate anything on the playfield first in case I switched out the IC and cause a problem again. But will definitely keep that on the list.

Thanks for the education on the special coils and switch section - totally makes sense now. I'll check this out along with coils shorts to the switch matrix as suggested.

I'll save fixing the playfield caps now until the rest is figured out.

Thanks for getting me this far, folks! I guess in a way this can all be something positive, since I'm learning a lot.
More to come!

Well, here is my update for today. No solution yet and very baffled.

"The 40V at 2J2 pin7 is a big red flag! That's coil power and needs to be found. First (with the game off) remove the coil fuse F2 on the power supply board."
- Done

If the voltage is gone, check for at every coil for a short to the switch matrix.
- Voltage was gone.
- Checked every coil and every one appears shorted to the switch matrix (green-orange) from the power side and ground. Ugh - confused.
- Disconnected every diode from every coil and tested the diodes. All are good.

- Did find a partially broken coil wire on the center drop target. Nothing big but repaired the connection.
- All switches pass the switch test.
- All coils pass the coil test.
- Pin 7 on 2J2 constantly reads 40v from the second the pin is turned on, even in attract mode.

I can't seem to find any place where coil power can be shorted to green-orange. What the heck am I missing??

Thanks for the suggestion about the pop bumper and metal mount short, Cheddar. I'll start exploring that route too.

Any more ideas folks?! Again, I really appreciate this forum.

Finally some progress - a ray of hope! At least the source of the 40v short is now fixed.

- Started taking apart the green-orange daisy chain recommended by Inkochnito. Began at the rollover switch. No problem at the switch.
- Next moved to the top left pop bumper. Bingo! Couldn't find a short anywhere thought. Then measured the voltage of the housing bracket - 40 volts. Took forever to figure out what was going on. With the post from Cheddar in mind I closely examined where the leaf switch touches the plate in the pop bumper rest state. Bingo! The leaf switch was making contact with the triangular metal plate under the bakelite and causing the 40 volt short throughout. Checked all three pop bumpers and they were all assembled with the metal plate on the side that touches the leaf. I disassembled each one and moved the plate to the other side. (before and after pics attached) As well, replaced one of the coils that was reading a bit low on ohms and appeared stressed. Result, no more 40 volts in the green-orange chain and at the pin in the backbox.!! Interesting the source of the 40v on green-orange wasn't the one pop bumper that doesn't work. Thanks Inkochnito and Cheddar!!

So, that's the good news, and maybe it was a cause of some original problems on the driver board long ago? Someone had previously replaced the troublesome lamp resistors clearly after there was a fire or heat damage. As well there was the original bad cap and resistors in the switch driver section.

The bad news is everything in column #3 still doesn't work as well as the two kickers in another column.
- All coils still pass the diagnostic tests.
- No stuck switches.
- Manual switch testing for column #3 fail and both kickers fail.

So I'm guess the problems are probably back on the driver board now? The PIA as mentioned by Tallon?
Is there an easy way to test the IA with a multi-meter, since I don't have a logic probe?
Or, do you all think I should look somewhere else next?

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Whew, a lot to learn but I'm slowly getting there and it's starting to make sense.

"The Special solenoids are a seperate section.
So is the switch matrix, the solenoids, and the lamp section.
All seperate sections on the driver board.
Oke, all come together via their own PIA into the data stream to the main processor.
Did you connect at some point the switch matrix connector with the 40V still on the green-orange wire?
If yes, replace IC17 as it had 40V which would not be good."
- Yes, I definitely did connect it before knowing it had 40v through it. And, worse, I did it also AFTER replacing IC17 and IC18. Would it make sense to try switching IC18 and IC17 to determine if IC17 was bad, then replace it? Or should I just replace it?

Maybe some other lines had this 40V too.
- Pin #7 was the only one I found with 40v. All the rest were normal so am I likely ok?

"Please be more specific about the switches. Name them exactly by their number"
- Absolutely, The following switches don't work: (column #3) 17, 20, 21, 22, 23, 24; (column #6) 41, 42. The left and right jet bumpers (18, 19) in column #3 are the only ones that fire)

"The PIA is a last resort.
You are showing the wroug PIA by the way. PIA IC11 is next to the switch matrix section in the right side part of the board."
- Gotcha, it should have been PIA II ... and, appreciate the patience!

Argh... just found another issue. I've been focusing so much on the switches and coils I figured I should run the lamp matrix test again. Everything is great except for one dang lamp - the 3-Bank Right arrow is out. Switched out the socket and it is still out so adding one more issue to the list.

I imagine this is going to feel so good once everything is done, especially since this pin was in pretty bad shape - sitting for 15 years in a garage, exposed to a fair amount of elements, a home for mice - and all after what appears to be a lot of use and some repairs long ago.

Latest test results:

"You say the pop bumpers fire, but do they count points?
They have a seperate spoon switch which goes the the special solenoids section and activates the coil directly.
The other switch is the count switch which goes into the switch matrix and tells the cpu to count the points.
You can test this by moving the pop bumper ring down with your hand.
Does the right switch number show in the display during switch test?"
- So here is the behavior in switch test
- Manually trigger upper left pop bumper by pressing ring: no switch# displays, coil fires
- Manually trigger upper right pop bumper: no switch# displays, coil fires
- Manually trigger lower pop bumper: no switch# displays, NO coil fires
- Manually trigger lower left and lower right kickers: no switch#s display, NO coils fire
- Manually trigger upper right standup: no switch# displays
- Manually trigger the three star rollovers (right upper, middle, and lower): no switch #displays
- Manually trigger spinner: no switch# displays
- Same behavior in a game with the addition of no scoring on any of the switches

"Does the right switch number show in the display?"
- No, no switch #s are displayed for the above problem switches.

"The problem with the single lamp is most likely the diode on the lamp socket or the lamp socket itself."
- Diode checks out fine and will put on the list switching out another lamp socket.

"Exchanging the IC17 and IC18 can work, but would just move the problem to colomn 7 (which is not used in Flash).
If IC18 is good, everything should be working in the switch matrix (with the exception of colomn 7 which is not used)."
- Well, I hosed things up a bit trying to switch IC17 and IC18 after doing the above tests. In removing IC17 I broke one of the legs on the end. I went ahead and continued switching them around to see if there was any change in behavior knowing that it would cause problems in IC18. No change in behavior, the above switch problems remain.

I will have to buy a replacement for IC17.

Thoughts on next steps?

"IC17 and IC18 needs to be replaced by a know good 7406.
Otherwise we are still chasing our tail."
- I'll get them on order asap.

"I get the idea that you still don't get it how the special solenoids work.
You need to manualy move the metal ring down to activate the scoring switch.
If you push the plastic skirt you activate the special solenoid switch, which activates the coil directly.
In a sense you should also see the pop bumper switch number when the coil fires.
The same is true for the slingshot metal arm."
- Unfortunately I do understand how to manually trigger the special solenoids. I can push the skirt down on the pop bumper for the upper left and right bumpers and they do fire. When doing the same on the lower bumper it does not fire manually. And in no cases does the switch number indicate. Again, none of the problem switch #s display when manually running through the switch diagnostics.
- So, I went ahead and also switched out the problem coil to absolutely make sure it wasn't the coil or diode. No change. Weird.

Since column #6 is working, you should need to see the switch number in the display if you manualy move the metal arm of those slingshots.
- They don't.

"But first things first...
Get the IC17 and IC 18 working correctly.
We need to see some switches in column #3 first."

- When I first got the pin MANY months ago I am pretty sure I used a business card to clean switch contacts because there were several that were not registering (I remember problems with the top lane rollovers), but I honestly don't believe I did ALL the switch contacts. I'm wondering if I ignored the coil switches, since they all passed the coil diagnostics (I know the coil test doesn't mean associated switches are good. It may have been a brain fart.).
- Soooo...... I'm going to be doubly sure and clean the contacts and retest. It would be awesome if that simple thing was the cause of the remaining problems.

- And, yes I will order replacements for IC17 and IC18.

- Oh, I did change the problem light socket again. This time with a known good one from a different spot under the playfield. Bingo - bad socket as suggested.

Thanks again for the awesome remote diagnostic help and patience.

Ok, a little more progress last night and continued frustration.

- Made sure to clean the contacts of the problem switches just to make sure that wasn't a related cause. It wasn't - dang.
- However, I did find one problem with both slingshot scoring switches. It visually looked like they were making contact when the arm moved, but they weren't. The problem was pretty well hidden by the fish paper. I re-adjusted the sling switches and now they register during the manual switch test when moving the arms (display switch #41 and #42) and they now register points in the game when manually triggered. So a little progress. But, the slings still do not fire when the other switches are closed manually OR when the leads on the switches are directly bridged where the wires come in (wanted to make sure didn't have breaks in the switch stack or something).
- Now to the pop bumpers. Only the top left and top right bumpers fire when manually activated by moving the ring OR when the switch leads are directly bridged. The bottom pop bumper will not fire. Also, none of the bumpers register switch #s when manually tested.
- And still overall, none of the switches in column #3 register.
- Again, I checked the problem switch diodes as well as the voltages at all the switch lead points and didn't see anything strange like the previous 40v short. All looked normal, but I certainly can be missing something - rather, I know I am. For example with the coils, all of them will fire during the diagnostic system coil test but the slings and bottom pop bumper won't fire manually, even when bridging the switch leads. What the heck?

I'll be ordering replacements for IC17 and IC18 and wonder if I should just go ahead and pick up a replacement PIA II / socket and install them all.

Really trying not to go nuts or get too down about all this.

Hi Cheddar, thanks for the reply. I'm willing to do just about anything at this point, even buy a new driver board and be done with it. If you guys think it's worth going down this path I'm game. Would you have a recommendation for a reasonable probe to consider and link for the test rom mentioned?

Awesome. I haven't made any order yet in order to group as much as possible to save on shipping (and I will get some additional spare parts in case I hose things in the process again).

I'll do the special switch tests, prepare the order, and keep everything in mind.

Great help guys!

Yes - Yes - Yes!!! Major progress - finally! And all thanks to you folks on the forum!

So, I started with the 2J13 connector pin ground test. All the coils worked. What?
Then went back to the playfield and tested ground continuity from the good coils and the three special coils that wouldn't fire except in diagnostics. Ground continuity was perfect for the good coils and NOT for the lower pop bumper and two slings. I swear I had tested this fully a couple months ago. Then I saw it, literally right in front of my eyes. Now, I said from the start I was a noob but at least an ambitious one wanting to learn so this is for other newbies that are trying to do all the right things. Hopefully my folly will help.

A couple months ago, in the process of restoration, the led bulb order came in. I replaced the flashers under the "Flash" insert... and .... cut the two ground wires going to the warming resistors. I individually taped the ends until I would properly seal them. What I didn't realize was that it was clearly a daisy chain ground connected to the slings and lower pop bumper. So, all I had to do was solder them together and insulate. Now all coils work!! (for other noobs out there see the attached pics - it's hard to see but I'm holding the two separate ground wires by the warming resistor). I go so focused on the pop bumpers being in column #3 and couldn't wrap my head easily around multiple problems being at play.

So a big part of the remaining issues are resolved. What remains now is to fix the problem with the column #3 switches not registering. Hopefully the replacement IC17 and IC18 chips will do the trick. We will see and I will post an update once I get the order out and the chips in. In a way, in retrospect it is probably good I "caused" the ground problem. The 40 volts at 2J2 pin7 caused by the pop bumper switch shorts would not have been good to the driver board once fixed.

Hopefully the fix for remaining column #3 switch recognition problem will be resolved soon, but at least this was a huge hurtle. This was the first time the ball kicked around the entire table!!

Thanks again, everyone!! You all really rock! Sincere appreciation

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Well, I received some parts in the mail today and replaced the two 7406N chips for IC17 and IC18. No change. No switches in column three register during the switch test or during the game. Everything else is working absolutely great minus a little final tuning. Argh, I was so hopeful.

Any thoughts on the best next diagnostic steps or avenues to explore?

Much appreciated, folks.

Oh boy. Ok. I'll start carefully stepping through this and save the PIA testing for the last. I have a logic probe on order. When you mention the test with the diode. I assume that means desoldering one of the leads on each of the bad switches and testing the diode to verify it's good? This may take me a while but I'll keep posting progress. Hopefully this will also help the next guy .
Thanks for the guidance. I hope I get lucky before this gets way complicated.

Sorry, I got it now.
- Did the jumper test from PinWiki 6.19.3. The diode part threw me. Result was no switches registered for column #3.
- Checked continuity from 2J2-7 to pin 12 of IC17 and from pin 13 of IC17 to pin 12 of IC11. The path is good.
- Verified the two resistors and one capacitor in the switch column drive that I replaced test out good plus no shorts.
- All soldering is clean and good. Traces are good.
I could always be missing something, but all seems good according to the meter as well.

It looks like IC11 as suggested in the thread now needs to be replaced. This seems to make sense, since when I got the pin the resistors and cap off of 2J2-7 were visibly burnt and we know the cause was from the continual 40v short from the pop bumpers. I guess it hosed up IC11. Good thing the 40v got resolved to keep the board from getting damaged before these hopefully final steps.

So, have IC11 on order as well as a logic probe in case I have to dig in more.
Thanks for the continued help and letting me know if I've missed anything.
More to come.

Bingo!!!! Last weekend I put in a socket and replaced IC11 as a last step and last resort. Verified continuity in the column 3 chain. Turned on the pin totally expecting the switch problems to still be there, but I was wrong!! All the switches in column 3 now work!!!! You folks got me through all this and I can't thank you enough.

So, quick recap -
- Resolved 40v short from pop bumpers to the driver board that fried all the column three stuff.
- Resolved sligshots and bottom pop bumper not working due to intentionally cutting the ground wire attached to the warming resistors as part of the led upgrade I made for the flashers. Those special coils were in the ground chain. Re-attached the ground to itself (without the resistors). - Doh!
- Installed sockets and replaced IC17 and IC18.
- Replaced half a dozen bad / stressed resistors, one shorted cap, and 3 burnt transistors on driver board.
- Replaced special coil caps under playfield.
- Replaced one bad lamp socket - twice (learned to replace with a new socket vs. an extra old one that seems ok)

I can't thank folks on this forum enough. You all saved the day for me!!!! This pin would not be working if it wasn't for the forum. The restoration process started with acquiring this pin just about ready for the dumpster and it is turning out beautiful. I didn't fully realize what I was getting into and got in way over my head, but it was worth it with all that was learned. I have a ton more to learn but the experience was invaluable.

Thanks again!!!!