Working on a Bally Star Trek.

I've just replaced the MPU with a Altek, and adjusted the dips as per factory spec. The machine is now working, but I'm getting garble on the displays.

Heres's what I'm getting:

With pinscore displays nothing at all.

With the original displays I get a ... mess. For example nothing showing in the game/ball counter. the player displays will indicate 55 at game start vice 00. Once the scoring starts the displys revert to Garble.

This is an untested machine, I've not seen it work properly. I can confim all the individuals displays are working properly (tested in another machine) and I have cleared the MPU memory as per altek installation instructions.

Is this an issue with the MPU , lamp driver board, or Voltage regulator solenoid driver board?

Any ideas, hints, or suggestions?

The first solid-state generation of Bally & Stern pinball machines often have:

- cold solder joints under the header pins of ALL displays. Reflow.

- often bad resistor(s) on the display boards. Esp. 100K resistors. Replace bad ones.

- bad connectors (J1 on the MPU for display issues)

- sometimes corroded traces inside the glass, or gassed-out/burned digits.

- check the high-voltage going to your displays. Make sure it is below 190V.
  Otherwise there are probably shorted transistors on the Solenoid Driver HV section.

Good luck !
- Sylvain.

So

I installed a new board solenoid driver board in Star Trek and the problem still exists. I'm going to start inspecting for the other indications.

New question for anyone who has played Star Trek. When the last ball drains does the Star Trek normally let out several quick loud bowel-releasing bangs from under the playfield.

It scared the life put of me the first time, I was ready for it the second, but should it be happening?

Quoted from Kingston Pete

When the last ball drains does the Star Trek normally let out several quick loud bowel-releasing bangs from under the playfield.
It scared the life put of me the first time, I was ready for it the second, but should it be happening?

Isn't that the usual knocker, one knock per free credit (and 3 for setting a new high-score-to-date at the end of a game) ?

Cheers,
- Sylvain.

Quoted from sylvain

Isn't that the usual knocker, one knock per free credit (and 3 for setting a new high-score-to-date at the end of a game) ?

Cheers,
- Sylvain.

Exactly.  Congrats...you just set a new high score !!!  Set the dips so that no games are awarded for high scores.

Makes sense. It is quite a shock if your not expecting it while trouble shooting an electrical fault.

Can one display affect the others?  

I know the MPU is brand new, so that shouldn't be the issue.
I've swapped out the voltage regulator with a confirmed working one it didn't clear the problem. On that issue I checked the voltage, it is 230VDC at the displays. I know that is high, but my Mata Hari is the same and it functions properly. I attempted to adjust the pots on both, and it didn't make a difference to either.  I also have the 5 VDC at the display TP1.

So in my mind the signal isn't getting to the displays or it is somehow getting corrupted.

One display will affect the rest. I pulled all the displays and tested one socket with a new display. I am now getting the proper scores. Cheers guys, thanks for your help.

Quoted from Kingston Pete

On that issue I checked the voltage, it is 230VDC at the displays. I know that is high, but my Mata Hari is the same and it functions properly. I attempted to adjust the pots on both, and it didn't make a difference to either

You most probably have shorted transistors and diodes in the HV section on the Solenoid Driver board(s).
This is confirmed by the fact that adjusting the potentiometer does not adjust the output HV voltage.

Operating the displays at full-blast will shorten their life...

Just an observation and a recommendation to fix your solenoid driver(s).
Fixing the board is much cheaper than having to replace multiple displays down the road.

I am just trying to help...

Cheers,
- Sylvain.

Thanks Sylvain

I think I will take yor advice. I was just looking 190VDC regulator and it doesn't look that complicated, so it should be a quick find and fix.

Where would you recommend I find these individual components?  In days gone by I would think radio shack, but I doubt they would have small items like that in stock these days.  somewhere Canadian would be prefered, I don't think I can stomach any more duty fees for a while.

On a bright note, I just spent the last hour playing Star Trek. Very cool game. I think I'm going to enjoy it.

If you haven't read it already, be sure to check out http://www.pinrepair.com. It WILL help you to diagnose your problem.

For electronic parts, http://www.greatplainselectronics.com is a good choice. There's also http://www.bigdaddy-enterprises.com/ which sells HV rebuild kits. You can get all the parts from GPE, but Big Daddy has them all in neat kits.

One thing I would like to reiterate... your displays will be affected by bad connectors on J1 of the MPU and J3 of the driver board. If the displays test good in another machine and the MPU and driver board are known to be good also, the only potential issue left is the connectors. Again, http://www.pinrepair.com is your friend.

And, as Sylvain already mentioned, you definitely should NOT be running your displays at 230volts. Rebuild your HV section immediately or you'll be putting your displays in serious jeopardy of outgassing and/or burning badly. You should have about 170vdc-190vdc at the displays. 230vdc is BAD. Of course, if you're using Pinscore displays, it doesn't matter what your HV is set at because they don't use HV at all. In fact, if you have a driver board with the HV fuse on it, you should just pull it.