IGT slant top 1992 "sit down" spinning reel cherries slot machine - error 21

[mikeshodapp]

I have looked every where on forum and searched for info regarding slant top sit down igt machine and found nothing. I see lots of info on the video poker but nothing on slot version. If I am wrong, please let me know where to find.

So I bought two 1992 slant top slots recently for a great price. I had to drill the lock to get in and also bought a reset key. The 12 error was showing so i replaced the 3.6 volt battery on mother board. Ran the self test and the 21 error showed up. Does the coin comparator light up in any way to show that it has power or is working?

Both machines are now showing the same error? After installing the battery, it briefly worked and took a quarter and actually spinned one time. Then the error 21 showed.

Any suggestions or guidance would be greatly appreciated. Thank you in advance for any help.

[sixcardmark]

Codes are same as regular s+,  code 21 is coin in optics, located below the coin comparitor. The coin comparitor does not lite up when door is open.

[Tilt]

Error 21 is a coin in error.  It doesn't have anything to do with the comparitor, although a lot of people get hung up on that.  The comparitor's job is to compare the sample coin to the one dropping through.  It if matches it allows the coin to drop through the optics, if it doesn't it diverts it back to the coin tray.  The comparitor is enabled by the MPU board which only enables it when it is ready for play.  When the door is open the machine isn't ready for play, so the comparitor isn't enabled.  The LED on the comparitor only lights when it is enabled, so you won't see it lit with the door open.  Make sense?

The coin in optics sit right below the comparitor and there's three sets of them (A,B, & C).  The coin is expected to pass through them in order and at a certain speed.  If that doesn't happen a coin in error (21) will occur.  Dust, coin wrappers, and other foreign objects can block the path between the optic emitter and receiver.  That is a pretty common cause for the error.  Check those, and clean them well.  It's best to remove them, that way you can inspect and clean the assembly thoroughly.  Most of the time that will fix it, but sometimes an emitter or receiver may have failed.  In that case you'll need to replace the optics.   

[mikeshodapp]

Thank you both for the prompt reply. I had thought there might be an issue since the comparitor led did not light up. I will attempt a cleaning of the optics and see if that does the trick. Also, I had to drill the lock and am using a locking vise-grip to lock and unlock the top. If I don't hear a snap will that keep the error code alive? And lastly, is there a way to test the optics while the top is open?

I really appreciate your help guys. I sold one of the sit down slots and want to get it going for the buyer. So thank you again in advance. I will clean the optics tomorrow and let you know if that worked. What is best way to clean optics? Alchohol? Any recommendations on how to clean also much appreciated. Thanks again.

[Trisail]

DO not use     Alchohol?

Just water on a cloth/paper towel. The lenses are plastic - any clouding or scratches will most like damage them beyond repair.

[mrcrazy]

Take the coin unit out, Look at the green optics board. Unsolder Q2/Q4 on the green optics board. Depending on your model the small black surface mount diode will say Q2 or Q4 on the board. This disables some of the optics but repairs a lot of them. The down side is now anything that passes through it will register, but in a home thats not really an issue.
make sure your red digits are going out momentarily when you close the door or you have a door optics issue & the game will never clear the error.

Greg