Stern SAM World Poker Tour - Switch Matrix Problem

[DRD]

A row in the switch matrix died mid game.

I have checked continuity from the board connector to the switches, this is fine

I have checked continuity from the relevant board pin to the tranny, this is fine

Does anyone have any idea what the fault might be please?

Does anyone do board repairs for these games ?

Thanks

 

[stoptap]

Check the diodes on the switches of the relevant row.

 

[DRD]

There is some crazy @@@@ going on here. Someone has detonated a grenade in the switch matrix.

My game had been away on loan for a few months, but seemed to work fine at the ukcs christmas cracker event. It withstood a day of competition. Then home. Left in the van for a few days.

Might condensation have caused this from sitting in my van for a week ? I did give the game many hours to warm up before I fired it up

I tested the mpu board by using a wire with a diode to connect the relevant row to a column

This enabled me to determine that the dead switch row was caused by a failure of the q2 transistor

Put it back together. Now certain switches caused the entire relevant column to trigger !

This was caused by a faulty q4 transistor.

Seemingly fixed

Now an opto has died on the lock mech. It is the emmitter side that has failed.



Does anyone know where I can buy these from pls @myPinballs ?

Another opto has also died, this goes into a 4 way opto board

Getting beyond a joke now


Thanks

 

[myPinballs]

I have slotted optos that should work on these types of boards. Do you have a part number from the manual for the opto itself?

 

[Pick Holder]

I doubt it sitting in a van for a week would be an issue.

It could be an age failure! Voltage spike. So many things.

Same with the opto. Things do fail for no reason.

 

[DRD]

By buying some new opto boards and salvaging some surface mount components and soldering them myself I got all my optos going.

In test mode these worked fine. I appeared to have a properly working switch matrix.

One game later and all the faults came back. Loads of dead optos. Some dead microswitches. So i dealt with the symptom, not the fault itself

I think that the problem lies on the receiver side of the optos. The emitters are all ok. So something is putting big volts down the switch matrix somehow. Quite possibly during gameplay - like solenoids, flippers etc

The fault is blowing surface mounted transistors on the opto receiver boards, and trannies on the mpu

Is there a good, methodical, way to test for shorts like this pls, or is it looking for solder splats, a fallen bolt etc

Thanks

D

 

[Moonraker]

Yup, most likely caused by a particular solenoid firing and that firing spike getting on to the opto receiver circuit.

It could be a short with a soleniod but I suspect more likely is a failed component allowing the spike on to the receiver circuit but knowing which component will be very, very difficult to determine. I'd probably follow the wiring diagram from the opto receiver and see if there is a comon component or pathway with the soleniod driver section. A real PITA to find and sort. Good luck.

 

[Pick Holder]

Oh dear. You have got 'one of those' problems that could take you a while to sort. Or you'll find it quickly!!

Run the game with a multimeter on the test points. Make sure you have a good 5v & 12v. Then do the same with solenoid and other power.

Sometimes it's a question of checking the basics!

Also I had a weird fault years ago on a wpc95 game. Turned out the transformer main molex plug was going bad!

Did the game reset when you lost the switch row?

 

[DRD]

Can anyone test the main boards in the backbox to see whether there is a board fault ?

I need to order some new components to replace the fried transistors. At least they are cheap. I am going to do a check of the voltages, look around for loose things, see whether the multimeter can find a short n the looms .....

It is ugly, but i suppose I could fix everything up. Test the switches all work. Then systematically fire some solenoids to see what klls it ?

Trying to be lgical about it, the things that changed are

1 movement, bringing the game back home from a loan-out
2 being sat in the van

So I am hopeful that this is a physical short

After i fixed it up first time around, the one game i started kept playing, there was no reset or reboot. Just a load of dead switches

 

[Pick Holder]

Which transistors is it frying?

I'm collecting my family guy soon so would test your boards but I can't do it for a week to 10 days

My guess is a screw came out and shorted something. Or make sure an opto sensor is shorting on a ramp.

 

[Moonraker]

After i fixed it up first time around, the one game i started kept playing, there was no reset or reboot. Just a load of dead switches

You may not have fired the particular solenoid or it's intermitent or the dead switch prevented the solenoid from firing...

 

[DRD]

I will pull the various boards tomorrow to see whether the faults are the same as last time

I will also mark up the switch matrix diagram to record the dead switches

Thanks for your help here

 

[DRD]

I am not familiar with stern, sega or data east . Wpt is my first from this stable

Looking at voltages on the solenoid board, I have tested them all for DC whilst the game is in attract mode. the results ...
+5 ... 5.06
-12 ... -14.48
+12 ... +14.33
+18 ... Varies between +18.58 and +18.72
+20 ... +24.27
+50 ... +70.8

Then DC voltages on the mpu ...

+3 ... +3.33
+5 ... +5.05
+1.8 ... +1.83

Are these acceptable for a stern ?

Thanks

 

[Pick Holder]

They look fine
Start a game and retest.
The 50v will read 70v unless under load.

 

[DRD]

I will have to do some soldering tomorrow before it will start up, as all the ball trough switches are dead !

Like the first time it did this, it has fried the entire 2 and 3 rows. So no switches work at all in these 2 rows. I checked by running a wire between the rows and columns on the mpu.

Last time i had to replace q2 and q3, then the switches registered again

It is deja vu. All over again