Machine goes crazy when turned on

[gposing]

About 15 seconds after you turn the machine on the coin meters start to cycle, the handle starts clinking and the Coin Comparitor diverter starts clicking.  I have checked every connection for a bent pin and found nothing.  Checked to power coming from the power supply to the main board.  reading left to right I have 12V 12V 8V 8V com1 com2. 
 

[Amechanic]

Well it is Halloween..


Just kidding..    Do you have a different power supply to try or a different MPU board?  Those would be my first thing to swap out..

[gposing]

I just bought this new board and it worked for 3 days and my problem came back.  i do have another splus but afraid to swap.too many parts and mess up something else.

[Shaggy]

Swapping the boards shouldn't mess anything up. I had one act like that, the battery had leaked and made everything flash and do junk like that. Even if the other machine isn't close to this game, a swap will show whether the board is the problem.
So it was doing the same thing before Maybe Gary is right, power supply.

Dave

[Amechanic]

I agree with Dave. If you tried a second MPU and the same problem came back after 3 days, then I would try a different power supply. If that doesn't help then maybe your back plane / mother board has a problem.


Gary

[gposing]

I will pull the powersupply from my other one and keep my fingers crossed. 

[rokgpsman]

Did you or someone else maybe make and install game eproms on the mpu that might have been burned into eproms with the wrong speed rating, slower than they should be? Sometimes people will make a set of game software and use eproms that are too slow and things can act erratic.

[Amechanic]

I will pull the powersupply from my other one and keep my fingers crossed.

One thing you don't state in your original post is that is this machine a new purchase or something that you have owned for a while and it just went crazy? 

[knagl]

I just bought this new board and it worked for 3 days and my problem came back.

Are you saying that you had this same crazy behavior with a previous MPU board, and that putting a new board in fixed the issue for three days and now it's going crazy again?

The more you can tell us about your issue, what led up to it, and what you've done to try and fix it, the more we can help you. 

[Jim]

your power supply voltage looks to be normal.  do the reels remain locked in position when the machine goes haywire?  was the board you purchased "known good and tested" ?   have you inspected the mother board for any damage. ?  are you using the same chips for both boards? 

if you are afraid to swap boards, I would at least swap the software chips  from your good machine to the suspect machine, putting them back in the original machine wouldn't have any effect on its operation.  I find it hard to believe  that the power supply module is bad, have never had one go bad in twenty years of working on S+ machines, the only item ever to break on it was the fuse caps. 

two different boards with the same problem points to a problem elsewhere, an INTERMITTENT PROBLEM AT THAT, the fact that the one did work after you installed it. check all your connections, make sure all the connectors are clipped in place. remove the hopper and coin tray, close the door, now you can reach in there and move and wiggle things around to see if you can stop the craziness.

Jim

[rokgpsman]

One of the things to check is a flaky connection where the power supply cable connection is made to the motherboard (the horizontal board that the mpu plugs into). Look for something like shown in the picture below. Even if the white molex plastic connector housing doesn't have a burned/brown area you could have a bad contact inside the connector. Be sure to check the hidden back side of the connector too, along with the male pins on the motherboard that the connector connects to. They may be corroded or darkened and not allowing good electrical contact. This is one of the common things that can happen on an S+. The power supply voltages may be good where you measure them but they may not be getting thru a flaky connection like this.

[Amechanic]

   I agree. I forgot about that plug in the S+ machines..


Gary

[Shaggy]

  I agree. I forgot about that plug in the S+ machines..


Gary

Yeah they usually just won't let the machine come on at all. But if there is some way to make it whackier an S+ will find a way to do it.

Dave

[knagl]

Probably also worth unplugging the machine, then checking for any stray coins/tokens/screws/etc. in the power supply and also under the fixed motherboard in the bottom of the machine that could be shorting stuff out.

[rokgpsman]

Probably also worth unplugging the machine, then checking for any stray coins/tokens/screws/etc. in the power supply and also under the fixed motherboard in the bottom of the machine that could be shorting stuff out.

Good idea, especially if the machine was transported on its side since that lets any loose metal objects like coins, washers & screws move around all over the place.