So here is the deal, I turn the machine on, everything works for a couple minutes, then the DMD goes out. I start diagnosing, here is what I found out. Looking at the main plug to the DMD, Pin 1 measures 119 V and Pin 2 measures 112 and rising, as soon as it hits 116 V the DMD goes out. I checked the fuses and BR1 on the DMD driver board and all good. I pull the plug off the DMD and Pin 2 measures 94 V.

What is causing this to happen. I looked at Piniwiki and it was starting to get a little confusing, had to stop and come to you guys for advise. Please advise

Thanks
Chris

#2 5 years ago

TOX

ChrisHibler

Chris' Pinball Repair

Chesterfield, MO

12y 120K 9,996 46

1st possibility...HV section of your DOT controller is going. Pretty common.
2nd possibility...The DMD has developed an oddball short that manifests after heating up. I've never seen this.

Divide and conquer is in order. Swap a known working Dot controller into the game to see if the behavior remains.

A HV rebuild isn't complicated if you want to take care of it yourself. I can take care of it for you too if you'd like. PM if that becomes the case.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#3 5 years ago

JKA

chrismoore701

Inactive member

Highland, IN

6y 19,650 49 3

What is the hv section of the dot controller?

#4 5 years ago

JKA

chrismoore701

Inactive member

Highland, IN

6y 19,650 49 3

And is there any way to test this?

#5 5 years ago

BTF

PinballManiac40

Pinside+ Frequent

14y 234K 17,627 104

With you measuring the -112, -100 and 62 volts at the DMD power plug would be the same as measuring it at the output connector of the DMD controller board.

These are all the parts you need to rebuild it, as what Chris is mentioning.
https://www.greatplainselectronics.com/proddetail.asp?prod=WPC-HVP-KIT

#6 5 years ago

BTF

PinballManiac40

Pinside+ Frequent

14y 234K 17,627 104

You can go with the LED or LCD ColorDMD and not worry about repairing the HV section since it will not be required with the colored display.
http://shop.colordmd.com/colordmd-replacement-display-for-corvette-pinball-machine/

#7 5 years ago

TOX

ChrisHibler

Chris' Pinball Repair

Chesterfield, MO

12y 120K 9,996 46

Testing power:
http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Testing_DMD_Controller_Power

Have at it.
If it tests bad, send the board out for repair.
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info

#8 5 years ago

JKA

chrismoore701

Inactive member

Highland, IN

6y 19,650 49 3

Kit on its way, will keep you posted

#9 5 years ago

AAA

pintechev

Inactive member

11y 91,300 4,437

Did you test it and determine the kit was needed?

#10 5 years ago

JKA

chrismoore701

Inactive member

Highland, IN

6y 19,650 49 3

I tested as much as I could and understand. The voltage at pin 2 of the DMD climbs to 116 V and the DMD shuts down. Pin 1 measures 119 V. When it is unplugged pin 2 measures 95 V. I checked BR1 and all the fuses and all is good. IS there anything else I am missing?

#11 5 years ago

TOX

ChrisHibler

Chris' Pinball Repair

Chesterfield, MO

12y 120K 9,996 46

Unloaded (unplugged DMD) voltages will be somewhat lower. I wouldn't put too much weight on that measurement. However, the climbing voltages are the concern.

Install the entire kit.
Clip the parts from the board rather than solder suck. Remove each leg carefully. This will limit additional damage to a probably heat damaged board/traces.

Let us know how it goes. Interested.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

1 week later

#12 5 years ago

JKA

chrismoore701

Inactive member

Highland, IN

6y 19,650 49 3

She works. I can’t believe i fixed it. I installed a high voltage rebuild kit. I have replaced an item here or there. But never 20+ items. It was tricky to get all they off and the solder cleared out. All good and working now. Now i have the upper gi lights out. That is next.

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