Tom & Jerry LCD issue during spins and reachs

[Harleyguy]

Hey everyone

Just got a Tom & Jerry machine, and unfortunately it seems to have an issue with the LCD

During the idle animation and looping 'demo' video, everything runs just fine. However, whenever you get a spin, the LCD will flicker, and eventually go to a half pink/half dark screen. It also completely freezes during a Reach, and when it comes back it 'stutters' showing the numbers.

I've included a link to a minute long video below. Beginning shows what happens during a spin, second half shows what happens during a reach.

Tom Jerry Pachinko LCD issue - YouTube

Any thoughts? My first thought was a bad LCD, but letting it sit for a day and thinking, since it triggers new animations to play during reaches and spins, maybe its something else in the programming or a bad chip?

Any help or suggestions is greatly appreciated.

[Drunkenclam]

Worth checking the output from your transformer to make sure its pumping out 24vac, If the current draw is too nigh it can effect the voltage and make the screen go funny or blank. Also make sure its not getting too hot

But that does look like something screen or graphics related. Can't be much help, Sorry

[Harleyguy]

Tried on 3 separate transformers, including alone on a 6 port one designed for parlors and still does the same.

[heima]

I see two problems. Screen flicker and half screen.

Screen flicker - If you have an IR thermometer, check the temperature of the chips on the display board. I was thinking that it was a power problem, either too high of voltage, or too low. Are you for certain that good, clean 24 VAC is being fed to the pachinko? Are the power and video connectors all good and snug?

Half screen - Notice how the half screen occured during a reel spin? This means a "plane" of graphics was affected. This makes me think that either the GPU or the RAM or the graphics ROM is having a problem. Are any of the display chips socketed? Might be a problem there.

[Harleyguy]

Screen flicker - If you have an IR thermometer, check the temperature of the chips on the display board. I was thinking that it was a power problem, either too high of voltage, or too low. Are you for certain that good, clean 24 VAC is being fed to the pachinko? Are the power and video connectors all good and snug?

I don't have an IR thermometer, but I did try it on 6 separate transformers, all connecting to machines that are working great. Included by itself on a 6 machine transformer used in the parlors. Still an issue

Half screen - Notice how the half screen occured during a reel spin? This means a "plane" of graphics was affected. This makes me think that either the GPU or the RAM or the graphics ROM is having a problem. Are any of the display chips socketed? Might be a problem there.

Initially I thought it may have been an LCD issue, but since it only occurs during changes in the animation, I tend to think it may be a GPU or RAM issue as well and not necessarily the LCD screen itself.

I've reseated everything visible I can reach, including things not connected to the LCD. At this point I am positive it's nothing loose or disconnected. There are some chips I can't get to due to being sealed in, but I inspected them as best I could and nothing appears loose or blown out.

[heima]

..., but I did try it on 6 separate transformers, all connecting to machines that are working great...

I understand your methodology,but still it would be good to have a digital voltmeter to measure voltages. I was thinking that possibly the power being supplied to the graphics board is problematic. Power going into the power board might be fine, but what is coming out might not.

[Chumsize]

Hmm... saw something similar recently when hooking up a cheap Taiwan 8" LCD to its even-cheaper driver board. The flat ribbon cable from the LCD to the driver board had to be sat just right in its "slippy clamp down connector dealie" or all kinds of weird crap started to happen... So that could be it - but then wouldn't it happen all of the time? Why is it only happen only during a reach? Anything else that only happens during a reach? I mean - things that are supposed to happen that only accompany the flickering/etc? Do other parts of the playfield light up or "spin up" (to borrow from hard drive nomenclature)? Does Jerry smash Tom with a giant mallet?

I think if you can figure out what triggers it, you be closer to finding out the cause. The voltage problem seems possible, of course. Are all of the 6 transformers you tried 100-24 volt? You may need a 120-24v one. Only way to see for sure is with the voltmeter, as Heima has said.