(Topic ID: 96246)

Tech: ST:TNG won't enter Service


By CUJO

5 years ago



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  • 33 posts
  • 10 Pinsiders participating
  • Latest reply 5 years ago by CUJO
  • Topic is favorited by 1 Pinsider

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#1 5 years ago

My ST:TNG won't go into the Diagnostics menu anymore when I open the coin door and press the
Service button on the 4 button panel. The only thing I have done just before this happened is pull the apron to fix a intermittent wire to the kickback coil. I used the solenoid test before and after to verify I fixed that broken coil lug wire.
The game will power on, start fine and play a game. I get the message on the DMD when I open the coin door but pressing the service button does nothing. I don't see any wires that have come loose on that switch but haven't pulled it out of the mounting plate yet to take a closer look.
Any thoughts?

#2 5 years ago

Button sounds like it is flakey, do the other three work?

#3 5 years ago

No..Volume Up/Down buttons do nothing either. It's like all 4 buttons are dead.

#4 5 years ago

Look for a broken wire at the bottom of those switches. The common wire that runs to all of them.

Reseat the connectors at the bottom of the WPC board. While you're there, check the battery holder for corrosion. It is very common for corrosion to kill the self test switches.

If all looks OK, pull the connector for the self-test switches (see manual) and use a clip lead connected to ground to tap the header pin for ENTER. Be careful not to let the lead touch anything unintentionally.

Let us know what you discover,

#5 5 years ago
Quoted from CUJO:

No..Volume Up/Down buttons do nothing either. It's like all 4 buttons are dead.

Do you happen to, on occasion, get the service/door bong and DMD text saying to open the door to press buttons while the door is closed?

#6 5 years ago

I do get the BOING BOING BOING and the DMD message "Coin Door Open..." only when I open the coin door.
Never any other time.
All 4 buttons are dead.. Will check batteries next.

#7 5 years ago

check the connections to and from the coin door interface board.

#8 5 years ago

Dropped the 4 switch assy and shorted the 2 black wires to the 1 orange wire on the 1st switch (emulating a switch press)..nothing. Opened backbox..batteries less than 6 months old. no leakage now or prior.

#9 5 years ago

Will lift the playfield and start tracing harnesses from coin door to backbox I guess

#10 5 years ago

Had the same problem once.Get yourself a new set of switches.And pay particular attention to grounding them all together.

#11 5 years ago

Make sure the direct switches are plugged in at the bottom of the CPU board, and that you don't have a case of battery leakage on the CPU.

#12 5 years ago

Should I reflow solder to all of the switches?

Quoted from cody_chunn:

Look for a broken wire at the bottom of those switches. The common wire that runs to all of them.
Reseat the connectors at the bottom of the WPC board. While you're there, check the battery holder for corrosion. It is very common for corrosion to kill the self test switches.
If all looks OK, pull the connector for the self-test switches (see manual) and use a clip lead connected to ground to tap the header pin for ENTER. Be careful not to let the lead touch anything unintentionally.
Let us know what you discover,

They only other thing I did was disconnect the two wire harness to the Klingon BOP ship. Trying to pull it out of the game to replace it with a modded one but the screw that holds the support wire is not loosening no matter what I try.

Pretty sure that won't affect anything either.

Going to have to dig some, read some before I do as you suggest. Unless someone has a link..

#13 5 years ago
Quoted from CUJO:

Will lift the playfield and start tracing harnesses from coin door to backbox I guess

The coin door harness (including switches) will plug into the board on the inside front left of the cabinet. You might check there is the whole door is dead (e.g., lights out as well).

#14 5 years ago
Quoted from wizzardz:

The coin door harness (including switches) will plug into the board on the inside front left of the cabinet. You might check there is the whole door is dead (e.g., lights out as well).

No, the coin door is lit. Both Quarter Insert bulbs are lit.
I lifted the playfield..all is connected. I do see a square 9 pin female molex there with no mate by the little circuit board.

#15 5 years ago

Bump..Any other ideas?

#16 5 years ago
Quoted from CUJO:

Bump..Any other ideas?

Check fuses
Hold the button down and wiggle the coin door harness.
Re seat all connectors.
Look really close at the board below the batteries, this could have been cleaned before but that stuff comes back.
If you removed the CPU make sure that connector isn't behind the board.

#17 5 years ago
Quoted from cody_chunn:

If all looks OK, pull the connector for the self-test switches (see manual) and use a clip lead connected to ground to tap the header pin for ENTER. Be careful not to let the lead touch anything unintentionally.

Remove J205 and briefly jumper pin 9 to ground. This will emulate pressing the enter button and tell you if the problem is on the CPU or playfield wiring.

#18 5 years ago
Quoted from terryb:

Remove J205 and briefly jumper pin 9 to ground. This will emulate pressing the enter button and tell you if the problem is on the CPU or playfield wiring.

Tried what you said and the DMD message was to open the coin door to access the buttons so I guess the problem is in the wiring., not the CPU board. (Whew!) I have tried wiggling the harness around between the coin door and the little pcb board on the left front cabinet wall. I have shorted out the switch with a screwdriver on the lugs and no go either. Very strange..It can't be the switch in the coin door if I short the lugs and nothing happens, right?

#19 5 years ago

The lights on the coin door get power thru that little PCB on the front left cabinet wall? Or thru a power harness?
The coin door lights are working as are the two white switches that detect when the door is open.

#20 5 years ago
Quoted from CUJO:

Tried what you said and the DMD message was to open the coin door to access the buttons so I guess the problem is in the wiring., not the CPU board.

Sounds like it since it responded to the jumper, but just to confirm try this with the coin door open.

Do the coin switches work?

Quoted from CUJO:

The lights on the coin door get power thru that little PCB on the front left cabinet wall? Or thru a power harness?

I'm not that familiar with Stern, but that's what wizzardz stated above.

#21 5 years ago
Quoted from terryb:

Sounds like it since it responded to the jumper, but just to confirm try this with the coin door open.
Do the coin switches work?

I'm not that familiar with Stern, but that's what wizzardz stated above.

No, the coin door switches will not work when Pin 9 on J205 is attached to gnd. In fact, it goes into audits and scrolls rapidly unless I unhook the gnd wire. Pressing the coin door switches does nothing when the jumper is on but i can keep tapping ground and the dmd will advance to the next setting in audits.
Does this tell us anything else I can use? Thank you.

#22 5 years ago

You only need to ground the wire momentarily. This simulates the press of the enter switch. Because you (in essence) held the switch down it scrolled through the audit menu. This is normal behavior and says the board is working.

Now short the org-gry wire at the coin door switch to ground (again momentarily). If that works then the ground wire that goes to the switches is open at some point.

#23 5 years ago

You need to run a continuity test (using your meter) from the wires in the J205 plug, down to the coin door switch assy on the coin door.

Presuming the wires check OK (check all 4 switch wires plus the ground wire, then try this : each switch is actually TWO switch circuits (they're double pole switches). WMS only wires one pole.

you can jump the 2nd pole in parallel, which will help guarantee good contact when you press the button.

#24 5 years ago
Quoted from litz:

You need to run a continuity test (using your meter) from the wires in the J205 plug, down to the coin door switch assy on the coin door.
Presuming the wires check OK (check all 4 switch wires plus the ground wire, then try this : each switch is actually TWO switch circuits (they're double pole switches). WMS only wires one pole.
you can jump the 2nd pole in parallel, which will help guarantee good contact when you press the button.

Got a little more hands on with the harness this AM and found this hack job from the prior owner.
Not sure how or why but one of the wires is broke in two (see pic) but they are not the same color code so maybe not. That mess was wrapped in electrical tape at the J5 Connector on the A-17051-1 PCB. The wire coming out of J5-Pin 4 (LT Coin 1) is cut/broke. If you look closely, you'll see the other wire that is coming off the solder cluster spot that is clear with a black line on it.
That "cluster" solder spot is labeled RT Coin 3 on the PCB (J5-Pin 6). Can anyone guide me how to straighten this out and how things are supposed to be here? Thanks! Have a Safe And Happy Forth!!!

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#25 5 years ago

Image4.jpg

#26 5 years ago

I wish I could take that diagram and hit a home run with it but I'm a little lost still on why all those wires were soldered together.

#27 5 years ago

My guess is someone was either trying to "trick" it for quarter play, by having one slot trigger two inputs, or was trying to rig up some sort of freeplay setup.

I'd simply undo everything they've done, and re-pin it correctly, then see what does and doesn't work.

#28 5 years ago

#29 5 years ago

Will finish "repair" and post results when I get it done.

#30 5 years ago

Done!

Sure looks good now but no difference. Still won't enter the Service Portal.
Is it possible that Interface PCB board could have gone bad?

The VOLUME UP/VOLUME DOWN switches do not respond either so it's all 4 switches in the coin door that are dead.
Does this point to a single ground wire for all 4?

#31 5 years ago
Quoted from terryb:

Now short the org-gry wire at the coin door switch to ground (again momentarily). If that works then the ground wire that goes to the switches is open at some point.

#32 5 years ago
Quoted from terryb:

terryb said:
Now short the org-gry wire at the coin door switch to ground (again momentarily). If that works then the ground wire that goes to the switches is open at some point.

Yep, it senses continutity when I short the org-gry wire to the ground spot on the coin door.
Time to trace that black wire backwards...
Thanks!

#33 5 years ago

SOLVED:
One of the two black wires had broken off the left coin door switch lug. Soldered it back on and all is now working
with the Coin Door buttons. Thanks to all who assisted w/ suggestions.

However new problem developed:
See New Thread: ST:TNG Kickback Coil Not Firing

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