550 NXT Touchscreen Com Error

[Billythekid]

I've had an intermittent problem that has gotten worse over time. I have a 17" LCD Happ touchscreen kit in my 550.
In normal game mode the machine reboots itself from time to time. When it does this I have pulled up the history log and noticed that there is a touchscreen comm error when the reboot happens. I've notice that if I get the machine up and into the menu system it does not reboot itself. Only if in game play mode. While in the menu I can go to touch calibration and calibrate it just fine. In other words, the screen is responded to touch and the machine is also receiving that touch command in the correct location. I opened the back of the LCD metal case which contains a video control board and the 3M micro touch module. Checked all those connections, checked the harness connection to the chassis. Also check the ribbon interface to the touchscreen screen. The machine being hot or cold doesn't seem to make it any better or worse.

Before I change out the 3m Microtouch I wanted to ask if anyone has had this error before?

[rickhunter]

You have a weak 12v rail on your power supply.  That has been my usual culprit when I get the reboots and touchscreen errors, especially if the touchscreen is powered by the main power supply and not the lcd assembly.

[Billythekid]

That would be the main 550 power supply, not the kit add on power supply that powers the NXT board. I assume that since the micro touch in inside the LCD chassis and powered through the cabinet monitor harness it's running off the main power supply. If I understand you correctly, that 3M micro touch module could be powered from
An independent power supply and possibly resolve the issue if it's related to 12v input voltage.

I've done a lot of power supply board replacement on my Williams 401 reel slots, are the 550 boards more readyly available? I recall them looking very similar only different mounting orientation from the 400's.

[rickhunter]

What kit add on power supply are you referring to?  In all the NXT conversions I have seen, the only difference is the inclusion of an auxiliary power cable that splits out of the main 24 pin power harness from the power supply to the backplane, if you are missing this aux power cable that plugs into the 8 pin molex on the NXT board, you will also get random reboots.  Since I am no familiar with the Happ version of the LCD kit, I didn't know if it was powered independently by it's own power supply, if that is the case, then most of the time the touchscreen controller board is powered by that power supply, but you will have to look at the wiring to see where the 3m controller is getting power from.  It has been my experience that the random reboots is almost always the 12 volt line on your main power supply no providing enough amperage during certain functions.

[Billythekid]

Thanks Rick,

I double checked and aux power box I was referring to is actually and inline 120v filter I believe. As it goes between the wall and the main power supply input. Yes, there is a set of wires coming off the main PS directly into the molex input on the NXT board. Since the 3M is powered off the main cabinet harness I'm going to try giving it it's own dedicated 12v as a test.

Thanks for the insight.

[rickhunter]

That alone may not stop your reboots.  I would check the power supply and re-cap or put in a new one.  The reboots are the first sign the power supply is borderline.

[Billythekid]

I guess the photo was too large of a file. Let's try this https://www.icloud.com/photostream/#A8GY8gBYGSyesP

If you can see that photo, you'll get an idea of what the Suzo happ 17" LCD kit for Williams 550 looks like inside.

Turns out the 3M Touch controller is powered by an internal power supply. (It's the black box, laptop looking PS) that powers a board that feeds the 3M. Wires are labeled 12v & 5v.

So if the reboots are because of the main PS 12v being low then the com error is just a symptom not a cause of the reboot.

[rickhunter]

I would agree with your assesment.

[Billythekid]

Just a follow up on this issue. Good  & Bad. The good is that after removing the power supply board, trying a spare that was bad and reinstalling the original powers supply the machine has been running 12 days continuously without any touch screen errors or reboots. The bad is that I can't say for sure what the fix was. I had checked all the connections on the touch screen many times without any positive result so I'll have to say there must have been some bad connection on the power supply connections??