I just finished a playfield swap on a High Speed, and now it's time to sweat the details.

I have a set of original good displays with no missing segments, but there is what I would call "noise" in the system.

When in display test, and the little dancing "asterisk" cruises from display 1 to display 2 character by character, individual cells light up a little bit in the corresponding column in the display below it. I'll include a picture.

When I boot up, and there have been no letters drawn yet -- there is no noise. It seems to be a symptom of drawing elsewhere.

I'm a novice with troubleshooting displays, so I hope to learn a lot. I have an extra set of 11A displays (player 1, 2 + "5" only) that I can swap in and out and try reseating cables, and as I learn more, I'll post more.

I'm starting with the standard sys11 reference: http://techniek.flipperwinkel.nl/wms11/index3.htm#display

thanks!
-mof

201501-HS-display3-4-5-noise.jpg

Step1: check power from power board.

"These voltages should be from 95 to 105 volts."

expect/actual (vdc):

3J5
pin1: ground,ground
pin3: -100, -106
pin4: 100,100
pin6: 5,5

-mof

Step2: Check the two 39k ohm resistors @ R1 and R4.

They check out with 39k ohm resistance each.

-mof

201501-HS-39k-ok.jpg

I have a Grand Lizard, I am going to try swapping components.
-mof

1. Swapped Main ribbon cable. No change.

Any ideas on what is likely causing this?

-mof

2. I tried swapping master display boards. No change.
-mof

I'm starting to wonder about the MPU, and what vulnerabilities could be there that could lead to this "noise"...

-mof

For kicks, I installed Pinscores on the High Speed, and they display perfectly.
-mof

Now I'm very confused. I put the High Speed display board AND the 5 displays and 5 ribbon cables over in the Grand Lizard, and the problem migrated into the Grand Lizard.

-mof

Wondering the most common causes of display noise as described in this thread. Also looking for resources where I can learn more about displays and how to troubleshoot them.

thanks,
mof

More data:

I swapped Display #5 (player #/ball #) and I get the same exact noise on both of them.

BUT

When I swap displays #1,2 with another set of Displays #1,2 from another set I have, the noise goes away.

So I have evidence that some noise goes away with a swap, and some noise does not.

Fascinating.

-mof