Error Code 21 on IGT Plus

[Stayouttadabunker]

... the other machine is still not clearing code 21. I will be trying the reel chip idea shortly, but I guess this means we can rule out optics as the issue?

No...you NEED the door optics to be working to clear the code 21 error.

You mentioned in the last video that "the main wire" may have a power problem.
That wire on the the back of the door panel next to the fluorescent starter is 115 volts household current for the belly door fluorescent lighting.

[Amg16]

Hi, I should have been more specific with the optics statement, I meant that the coin in optics under my CC seem to be fine since that same component works fine when plugged into the machine, I had thought the coin in optics were the issue for a couple of days

I'm not sure I'm understanding what you're trying to say in the second part of your reply, so since the belly door is lit up, we know power is properly flowing? Moreover, my machine does reset the code 21 light when I first close the door, so would that not mean that the door optics are at least somewhat functional?

[Stayouttadabunker]

Does pressing the Service Credit button add credits to the machine while the door is open?
Try that? Only works when the door is in an "open state".

oh..the power for the fluorescents is NOT the same power for the MPU and the rest of the machine.
The only other place the machine needs 115VAC besides the lighting is the hopper beau plug and hopper.

You may be right in that when closing the door it clears the error temporarily, but it comes right back right?
If so, then the problem could be with that coin-in optics board or a bad ground wire on the harness.

What I'm saying is, if you were to unplug the coin-in optics board harness at the white Molex connector, a [Code 21] would pop up.

That leads me to...>>>

1). Check the harness for continuity...easy thing to try is just unplug, re-plug, unplug, re-plug a few times.
What is going on is you're trying to somewhat clean the oxidized gunk off of the pins, and looking for better electrical contact inside the housings.

2). Swap out the coin-in optics board...maybe it's burned out?

3). Clean the three little holes that the emitter shines infrared light thru....the ABC optics inside need to "see" each other.
Try to shoot some compressed air in there to blow out any obstructions.

[Amg16]

I'll be able to check that button later today to be sure, if service credit is the same as test then I believe the repeated presses raise the credit by 1 each press, but I'll make sure.

As to your advice with the optics, the point I was trying to make in my other post and video yesterday is that the optics work in my other machine, and the other optics that work in my other machine didn't clear code 21 when I added them to this one as a test. Essentially, based on the other machine, both optics sets are working, and something in the machine isn't detecting or using the optics correctly (unless code 21 is stemming from something else entirely). I guess I just don't understand how the optics themselves could be the issue at this point if they work in stride in the other machine, and if the "working" optics from the other machine suddenly don't work in my code 21 machine?
The harness idea makes sense to me but I unplugged/replugged multiple times when I was moving the two CC/optics brackets around between the two machines yesterday, so I'm not sure how much more I'll clean the pins with continued plug attempts

[Stayouttadabunker]

I'll be able to check that button later today to be sure, if service credit is the same as test then I believe the repeated presses raise the credit by 1 each press, but I'll make sure....

You're misunderstanding the buttons...it's NOT the same as the Test button.
The Test button is the little white button that's next to the power switch or behind it....on older models, it's located on top of the door connector Molex coming out of the MPU enclosure. It's for switching between pages in the Accounting menus or Diagnostic test pages.
The Service Credit button is the small button located on the bottom of the coin-in optics circuit board uder the CC.
Each press adds a credit to the machine, up to max credits the SS chip allows.

The unplugging and re-plugging you've tried...but you haven't yet tested the harnesses themselves that relate to the Coin-In optics circuit board.
You need to test the harness going to that optics board for continuity.
Now's a good time to take it back out and pull out a multimeter on that harness.
The shortcut of course is to just swap the harness from the known good cabinet into this one to see if it works with this one.

Anyways, there's 10 pins coming off of that Coin-In circuit board....follow each wire from there along the harness, and make sure you have continuity at the other end.
You cannot "see" under the vinyl covering if a wire is broken.
That's why we use multimeters.

Below are the wires coming out of an IGT S+ Coin-In optics circuit board...>>>

Top wire is orange w/blue stripe...that goes to location 1 on the 3-pin Molex (pointy side) for the CC.
2nd wire is red w/black stripe...that goes to location 1 on the 12 pin Molex.
( You may need a magnifying glass to see the pin location numbers molded on the back of the housings.)
3rd wire is solid green...that goes to location 10 on the 12 pin Molex.
4th wire is orange w/green stripe...that goes to the flat side or pin 2 location on the 2-pin Molex for the Gate solenoid.
5th wire is orange w/red stripe...that goes to location 4 on the 12-pin Molex.
6th wire is orange w/yellow stripe...that goes to location 6 on the 12-pin Molex.
7th wire is orange w/brown stripe...that goes to location 3 on the 12-pin Molex.
8th wire is orange w/black stripe...that goes to location 2 on the 12-pin Molex.

You don't need to worry about the other wires coming FROM the 12-pin Molex to the Gate solenoid or the CC.
If any one or both of those two smaller connectors are taken apart, neither one will make the MPU shoot out the [Code 21].
You only get a [Code 21] if there's a problem with the Coin-In optics board, and/or the wiring going to it.
Good luck!

Below is a photo of an IGT S+ Coin harness and a Coin-In circuit board on the coin mech frame.
You can see on this particular board version, the little white Service Credit button on the bottom of the Coin-In board.
Click on it to enlarge if needed...>>>

[Amg16]

Hi everyone! Sorry for the delay in response, I've been on vacation and just now getting to work on the machine again.

Stayouttathebunker, I realize now reading back that I think I've created some confusion because I've referred to both the Test and Service Credit buttons as the Test button. To clarify, I've installed the code 21 machine's bracket with the comparitor and optics into my working machine, and when I did so the service credit button worked normally. However, both brackets and their respective service credit buttons do NOT work when plugged into the Code 21 machine. I believe it's shown in one of the videos I posted but neither button even makes a noise when the brackets are installed on the code 21 machine.

Being able to test the comparitor/optics on the working machine like this is what has made me confident that it's not an issue with those individual components, since the ones from the code 21 machine are working as intended on my other one. With that in mind, I agree with you that at this point the machine giving me code 21 must have an issue with either the wiring going to the circuit board or the MPU itself. I will definitely at the least be using a multimeter later today, and am considering trying the harness swap depending on how arduous I think it'll be to get the working machine's one reinstalled as it was. Thanks for the continued advice and I hope to have a more positive update soon!

[Stayouttadabunker]

I repeat...lol...>>>

"The shortcut of course is to just swap the harness from the known good cabinet into this one to see if it works with this one."

You can unplug it right behind the CC and Coin-In optics board.
Just remove the 2 screws holding the coin mech bracket and you'll see the huge Molex hanging there.
Try the known good harness from the good cabinet into the problem cabinet.

[Amg16]

Hi everyone, I'll type out the update here as well but posted a video explaining it:

https://youtu.be/997_30oKBl0

Essentially what I've found is that any combination of harness/comparitor/optics is working on my "good" machine, and no combination is working on the one that has code 21. No matter the combination, the machine still has code 21 and the Service credit button doesn't respond. Based on these tests, I feel comfortable saying that none of these can be the cause for the code:
-Harness
-coin comparitor
-coin in optics

With that in mind, I'm kind of just lost as it seems the vast majority of code 21 posts on here are resolved by replacing one or a combination of those three components. I would think the easiest place to look would be the main door harness and if it's properly powering the comparitor harness, but I'm not sure. I also know that some people in this forum have mentioned the MPU board, but the earlier pictures of the code 21 machine's board didn't seem to raise any red flags.

Overall, I'm all ears for next step suggestions. It turns out the multimeter I was going to use is broken, but I'm not against getting another one if testing the door harness or any other wires is the next best step. Thank you for any suggestions!

[sixcardmark]

Try the MPU on machine with the 21 code on the other machine and or vise versa. Do both have same SP chip?

[Amg16]

Hi everyone, sorry for the back to back posts but I found an interesting difference in the wiring of the door harness by the slots between the two machines. It might be absolutely nothing and/or irrelevant to my code 21 issue but I wanted to make note of it just in case.  I threw up a video as it's very difficult to explain over text

https://youtu.be/WzoAQK2hc4g

One thing I didn't notice when filming the video is my working machine seems ro have an extra screwed in wire compared to the not working one. Again, might be irrelevant, but wanted to hone in on any major door harness discrepancies

[sixcardmark]

Those black wires to that switch is NOT standard.  It may be door optics bypass switch someone has added.  The other two wires go to BV entry light I believe.