Here’s a nice vid that shows all the voltages being tested:

Quite common. Assuming you don't have a bunch of other mods hooked up to the 12v line, you should either have your power driver board rebuilt or hook up an external power supply for the Color DMD (and other 12v mods, like LED strips for example, if you have them). The latter is probably easier. The former may need to be done eventually anyway if your board is on the edge of being able to put out a stable 5v.

Can you measure the voltage at C31 on the MPU? Red on + and black on -

Unless you have a Kahr board installed (that creates a dedicated 5V input to the CPU from the unregulated 12V supply), overloading 12V will not drop the 5V line and cause a reset. You might blow a fuse but it won't have any impact on 5V. Installation of the ColorDMD won't cause this problem.

Resets are usually caused by 5V dipping due to coupling in the transformer and triggered when the high power coils are switching on and off and pulling a lot of current all at once. They're most common when hitting both flippers at the same time in rapid succession. If the output cap on the 5V supply isn't holding the voltage well, the voltage on the 5V line will fluctuate. When the 5V line dips below the watchdog voltage level, the CPU resets.

You're seeing it happen in multiball because that's when the coils are firing the most. If you can produce the problem when hitting both flippers, you'll see it happens with the display connected or disconnected.

I know Dmod knows the following information. I absolutely concur 100% with everything else written except the word "unregulated". The ColorDMD is *NOT* the cause of your problem.

This post is for others who may not know the difference between the "12V supplies" on the WPC power boards. There are two of them (+12VU and +12VR) and they are often confused. They are distinct and separate circuits (transformer secondary windings).

DMC (dot matrix controller) power header is shown here. The +12VU is passed to the DMD (dot matrix display).

01_dmc_power.jpg

The +12VU comes out of the power board at any of J116, J117 or J118 (they are electrically and keyed identical).

02_dmc_power.jpg

And the difference between the "12V supplies".

+12VU is UNREGULATED and generated by BR5 from J112. Shown in blue. Power is distributed to J117 to the DMC and subsequently to the DMD.

+12VR is REGULATED and generated by Q2 from +18VU from BR1 from J101. Shown in red. Power is distributed to J114 to the CPU. The Kahr board sits between J114 and J210 and (presumably) uses an on-board regulator that regulates the +12VR to +5VR substituting the original +5VR from the power board with its own supply.

03_dmc_power.jpg

That is borderline. Can you reseat J101, J102, J114 and J210 and retest the voltage at C31? Then see if you still get resets.

Not to be difficult here, but just trying to help.

I upgraded my MM with a ColorDMD. I had just fixed the cap problem with the high voltage, so I thought that everything was ok. It worked with the older DMD, so I thought no problem.

When I installed the ColorDMD, the game would reset like crazy. Turned out to be the ribbon cables were moved over one set of pins from the Power board.

Please take the time to check all the ribbons to help yourself out.

Thanks for the correction. I wasn't aware that the Kahr board runs off the regulated 12V supply.

Great catch from PinballManiac. If you have 5V at the power driver board and only 4.9V at the CPU, there's probably a voltage drop across one of the headers. If the voltage increased from 4.9 to 4.98, that may have helped.

If you're still having issues, monitor the voltage on C31 while flipping both flippers in rapid succession and see if it fluctuates. Start multiball on the game and do the same thing.

The GI hack is strange for sure, but I also don't see the ColorDMD wire harness in that photo. Where do you have it connected?

When I see stuff like that I would suggest you pull the board and inspect it. Who knows what else is lying behind the board hidden from view.

At least with that solution it is possible to disconnect the connector despite wires soldered directly to the board. It sucks when you have to cut the wires (or de-solder them) to remove the board.

It is not the source of the resets, but it just adds more problems into your GI than originally designed.

Any resets after reseating connectors?

Because of the voltage drop between these 2 boards, I would repin both J114 and J210.

It certainly would not hurt repinning J101, as that is a major source of most resets.

Likely, reseating them will be temporary. I had no resets on games for 2 or 3 months before it returned. I have my games on at least 8 hours per week, mostly during the weekend.

I have not ever really pinpointed J102 to cause resets, but the flipper power comes into the driver board at this connector. If they are dark and tarnished, I can see new pins making the flippers a bit stronger.

My statement means that it can affect the flipper power to all, not just to a single flipper.

Start with making sure the EOS is changing state close to the end of the flipper stroke. A sign of a misadjusted EOS switch would be that the flipper coil would be hotter than normal, which is when the flipper power would become weaker as it gets played more.

It is hard to remember which era are normally open and which are closed. Just match up with the other flipper side. 1/16" to 1/8" gap pretty much works on all EOS switches.

I have also seen flipper button optos (behind the cabinet flipper buttons) may be a problem as well. May clean the flipper button U shaped optos with glass cleaner or alcohol and Qtips. Also possible that the opto interrupter may not be breaking the beam correctly. You can swap the flipper opto board assembly from the left to right side and retest to see if it moves with it. Sometimes the transmitter opto in.the Ushaped opto is weak.

In the process of replacing the connectors, did you remove J116 to J119 or any ribbon cables? Maybe plugged in one pin off or whole row off (ribbon cables)?

Sometimes motors hit a bad spot and draw a bit more current than usual and blow out F116, which also will affect power to the ColorDMD and opto power. If you lose opto power, then you will have those coils with optos attached keep firing because the game thinks balls are stuck.

That is the correct fuse. I have seen a thin wire 3A slo blo fuse not hold up in the past. Bussman fuses are the best.