IGT S-Plus Bill Validator Not Working

[a69mopar]

So, I decided to look over the problem MPU a little closer to see if I could spot any signs that would indicate a potential issue (something burnt, or odd looking) that might be causing my problem.

Well, I did find a couple things disturbing that I’m a little confused about. There seems to be what looks to me like solder blobs, or solder spatter across portions of the board. One spot in particular is a blob of solder that looks to have fused two terminals together on what I think is some sort of logic chip. There is also various solder spatter, or blobs on resistors & the circuit board traces. The problem board as compared to the good working board is missing two diodes, but it also looks as if they were never there to begin with, so maybe that’s how this board was actually made?

I'm also concerned about what I am not seeing, could be more spatter in areas that I just can't see.

Anyway, I have uploaded pictures to an image hosting site for better clarity so you can see what I’m talking about. Please have a look at the pictures and see if any of this could be causing the problem with this board.

Pic No.1: Chipped Resistor  https://i.imgur.com/KiRSbmV.jpg

Pic No. 2: Missing Diodes  https://i.imgur.com/mE2QnE7.jpg

Pic No. 3: Good Board With Diodes https://i.imgur.com/OFMbnV7.jpg

Pic No. 4: Solder Blobs  https://i.imgur.com/VMLvZn2.jpg

Pic No. 5: The good board has no solder across the logic chip terminals  https://i.imgur.com/3UFGosM.jpg

Pic No. 6: More Solder Blobs  https://i.imgur.com/71oIWHM.jpg

Adding pictures in case the hosted pictures disappear . you may have to scroll to the right to see all

[a69mopar]

Pic 6 .   Thanks for the great quality pictures. They even look good when I shrunk them

[Jim]

I have sent you a pm,  please send the board to the person in the pm, your board will be tested, repaired and returned to you.

just send the board, with the chips, no battery please. no metal tray required.

Merry Christmas

Jim

[Jim]

your pm box is full, won't allow me to send you information.

Jim

[twinfire]

Hi Jim,

Thanks, for responding. I was hoping you would shed some light as to why there is this solder spatter, especially the logic chip in question. I can’t imagine this chip operating properly with those two pins shorted together like that. Even though the machine seemed to work initially, it could not have been operating correctly. It sure would be interesting to know what function that chip performs in the machine; would you happen to know this?

I have sent you a pm,  please send the board to the person in the pm, your board will be tested, repaired and returned to you.

just send the board, with the chips, no battery please. no metal tray required.

Merry Christmas

Jim

Jim, I appreciate you standing behind what you sell & wanting to get this repaired properly for me, thank you!

your pm box is full, won't allow me to send you information.

Jim

Sorry about the box, hadn’t checked it.

[twinfire]

We all like a happy ending right!

So, I decided to give this board one last ditch effort by making sure I was doing the clear chip process correctly. I reread the instructions carefully & followed them to a T, same thing happened; the machine gets stuck on 61 and will not advance.

I then read a PM from Jim…

Jim, at some point I know you will read this, but please don’t be upset with me sharing what is supposed to be private with the others here. The members that have been following this and helping me along the way with all their great suggestions, well, I’m sure would like to learn the outcome. 

So, here goes, the majority of this is cut & past from the PM I have sent to Jim.

Jim had sent me PMs graciously giving me options for getting the MPU repaired/replaced. One thing he mentioned was if I chose to do so, go ahead and pry on the solder bridge to see if it would break loose.

You can only imagine how many times I wanted to try that & member “Tilt” even suggested it as well, but I didn’t want to alter the board in any way from how I received it. I thought if I were to mess with the board there would be no way Jim would consider exchanging it for another. Well, since Jim the master slot machine guru suggested I try, I got my exacto knife, magnifying glass & went to work. I gingerly picked at the spec of solder & it popped right off! Virtually no effort whatsoever! Long story short, put the board back in and voilà it started working!

Granted, I’ve only put a hand full of quarters through it so far, but just couldn’t wait to let Jim & you all know the good news. 

Needless to say this was baffling, it consumed me, but once I saw that solder spatter I knew it had to somehow be the cause. It’s the intermittent part that was very confusing & Jim mentioned this possibility could happen with the solder that had created the bridge.

This board most definitely has had some sloppy soldering work done to it over the years, but I guess that’s to be expected given the age of the machines.

Anyway, just thought you all deserved an outcome to this madness & I will update should things change.

I am happy & thank Jim & all of you once again for your support and help.

Merry Christmas All!!

[knagl]

Great detective work, and congratulations on figuring out the issue and getting your machine up and running.