score display on tommy

Well, I thought my main mission at the moment was locating to purchase a RFM pin.
Turns out tonight will be spend on searching for a repair.
Daughter Decided to play a little on the tommy, as I watched her after about 5 min I noticed there was nor display, don't know if it was that way from the start of game play or not.
I shut the unit off a couple times but doesn't display on restart.This is the first issue I have had with this machine
Getting ready to open the back glass but was wondering if someone had any ideas for me while I start on my search.
Thanks

#2 11 years ago

AJD

the_pin_family

Inactive member

Herndon, VA

12y 31,900 2,363 8

You should start by reseating your connectors to the DMD and checking voltages. This should get you started. Just copied from the net.

Voltages Needed for the DMD Controller Board.
Since all the dot matrix displays essentially have their own computer on the controller board to control the score display, a supply of good +5 volts is needed for the controller. If a display is not working, first check the controller board for +5 volts. Often the connector carrying +5 volts can gain resistance, which will lower the +5 volts. This can be enough to make the DMD not work (this problem happens most with the super-sized 192x64 DMD).

On the super-size 192x64 DMD, the input voltages are low (+5 volts and +24 volts coming into the display). Sega did this because the 192x64 DMD has it's own power supply on the dot matrix controller board itself (the highLer voltages are not supplied by the main power supply). This is unlike the other two smaller dot matrix

Medium 128x32 DMD, connector P1:

P1 pin 1: -110 volts
P1 pin 2: -98 volts
P1 pin 3: KEY
P1 pin 4: Ground
P1 pin 5: Ground
P1 pin 6: +5 volts
P1 pin 7: +12 volts (only used on Babcock displays)
P1 pin 8: +68 volts

#3 11 years ago

LTG

Pinside member

Hopkins, MN

12y 191K 56,989 24 7

Be sure all connectors are on secure. Check the pins the big connector goes to for cracked or poor solder joints.

Then whip out the old meter and see if voltages to the big connector are right. That will let you know what next.

LTG : )

#4 11 years ago

MYN

rajung

Inactive member

Checked the pins on P1, have ground on pin 4 and 5, big whoop
Other pins drop from 0.5 down t0 0.0 volts , basically no voltage at any of them

#5 11 years ago

TOX

ChrisHibler

It doesn't sound like the power was measured correctly as complete absence of power would be odd unless a connector was removed.

Refer to this Williams section. Voltages will vary some, but the process is identical.
http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Testing_DMD_Controller_Power
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#6 11 years ago

MYN

rajung

Inactive member

Well after getting a new look at it this morning
here is what I came up with but I did have to check them on the back side where the wire pierces the molex, couldn't get to where the pins go into board unless removing the other boards.
pin 1 112.7 v
pin 2 100.7V
pin 3
pin 4 good ground
pin 5 good ground
pin 6 5.07v
pin 7 12.01 v
pin 8 10.77 purple wire w/yellow stripe, so I have to assume since this should be around 75v
the voltage doesn't stay at 10.77, it will drift down to 6.5 and then back to 10.77 but I suppose that could be due to getting a good contact in that molex pinch connector.Any advice on where this voltage originates from?
Thanks all

#7 11 years ago

TOX

ChrisHibler

Yup. You found the problem.
The DMD needs +68VDC (or so) at pin 8 to work.
That 68V is created on the power supply, upper left corner of backbox.

If you don't have the skills, experience, and tools to fix it, send it to a qualified repairman. The traces on DE power supply boards are fragile and are easily damaged.

I do not recommend the Rottendog replacement as the components he uses are prone to failure as implemented.

If you would like to send the board to me, I have a bunch of them in the queue right now that I plan to knock out soon. Send me a PM if I can help ([email protected]).
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#8 11 years ago

MYN

rajung

Inactive member

Thanks I will.
By chance, is it possible to check that voltage on the power supply board to eliminate the chance of it being a voltage drop from the power supply the DMD via harness
thanks

#9 11 years ago

TOX

ChrisHibler

Absolutely.
See image below. The HV connector is on the left side of the PS, near the bottom, CN5. It's kind of a booger to get to.

--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

DEHVPinOut.jpg

#10 11 years ago

MYN

rajung

Inactive member

At that point I am only getting 8 volts there with harness still connected and measuring at the wire pinch area.In the process of removing board and stare at it awhile I guess?

#11 11 years ago

TOX

ChrisHibler

You can remove CN5 and measure the voltages. That won't hurt anything.

Staring at the board sometimes helps me...the light bulb goes on, and bam!
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#12 11 years ago

MYN

rajung

Inactive member

Sent a pm Chris.
The capacitor on c7 location looks like it leaked a little at the bottom, small crust
also,using an ohm meter on resistor at r6, it doesn't have any resistance . Both are right below the heat sink.Don't know if this can cause my very low voltage when it should be 68v.
Maybe I have other issues with it but never noticed anything else acting up other than dead DMD

1 week later

#13 11 years ago

MYN

rajung

Inactive member