(Topic ID: 83132)

TECH: Bally MPU AS-2518-35 Won't Boot (Xenon)


By jalpert

5 years ago



Topic Stats

  • 11 posts
  • 4 Pinsiders participating
  • Latest reply 8 months ago by BigAl56
  • Topic is favorited by 2 Pinsiders

You

Linked Games

#1 5 years ago

I've got a Xenon that I'm trying to get to boot. When I turn the game on, a few play field lights come on, there is speaker buzz, and the LED on the MPU goes solid dim.

I took the MPU out and fed it +5VDC, +12VDC and GND through a computer power supply and (after replacing the 5101) got the 6 flashes I'm looking for.

Per "the guide," I put the board back in the game, I disconnected all the connectors except J4, the power connector.

At this point I measured the +5VDC and + 12VDC test points and got an odd reading of +4.1VDC and +11.1VDC respectively.

Also per "the guide" as long as your power supply is good, with everything else disconnected, a known good MPU should boot.

Admittingly, I got a little lazy (the power supply boards are very servicable) and I found a good discount on a new Rottendog power supply.

Threw the new power supply in, same result. +4.1VDC on the +5VDC test point and +11.1VDC on the +12VDC test point.

Here is what I don't understand. Per "the guide," you only need the power supply hooked up and J4 on the MPU plugged in to test this board in the game. However, there is no +5VDC coming from the power supply, apparently +12VDC goes to "J3 pin 10 +5 regulator input" and J4 on the MPU is the power connector but it's expecting +5VDC.

Also, with all MPU connectors plugged in, same symptom, a few lights, speaker buzz and a solid dim MPU LED.

Just for good measure, I already have this coming:

https://www.greatplainselectronics.com/proddetail.asp?prod=BALLY-P22E-KIT

Any ideas? What's the simplest way to get +5VDC and +12VDC to the MPU so I can start working from there? Is just having J4 plugged in the MPU sufficient? Is my problem really on the solenoid driver board?

#2 5 years ago

Okay...

So 12v unregulated DC is created on the rectifier board. It is usually more like 15v, so your 11v is unusually low. For now, unplug lamp, mpu, sound board. Check the 12v line on the rectifier board then check it on the driver/voltage board. They should read the same, if there is a difference, repin the connectors. Next up the LM323K on the driver/regulator board turns the 12v into 5v for the logic. Check both 5v test points on the driver board, if they are 4.1v there, replace C23 12,000 uF filter cap. If voltage still low, replace LM323k.

My best guess is your C23 filter cap has failed.

#3 5 years ago

Thank you so much for your reply. The caps are in the mail anyway, and if that doesn't work I'll switch out the LM323k.

It sounds like the guide has some bad info in it. Here is what is says:

"The J4 MPU Board Connector.
If you don't want to make a work bench test fixture for repairing your Bally MPU board, there is an easy way around this. Assuming your Bally power supply is working correctly in your game, when testing a Bally MPU board, you only need to use connector J4 on the MPU board. The J4 connector is the power connector. With it only attached and a working power supply, you can quickly test your Bally MPU right in the game."

So, is this a bogus test? It sounds like the game needs the (solenoid) driver board to convert that 12v to 5v so I don't see how just having the power supply and the MPU plugged in could possibly get it to boot.

If that's wrong, it cost me about $70 but maybe I'm not understanding it correctly.

Quoted from barakandl:

Okay...

So 12v unregulated DC is created on the rectifier board. It is usually more like 15v, so your 11v is unusually low. For now, unplug lamp, mpu, sound board. Check the 12v line on the rectifier board then check it on the driver/voltage board. They should read the same, if there is a difference, repin the connectors. Next up the LM323K on the driver/regulator board turns the 12v into 5v for the logic. Check both 5v test points on the driver board, if they are 4.1v there, replace C23 12,000 uF filter cap. If voltage still low, replace LM323k.

My best guess is your C23 filter cap has failed.

#4 5 years ago

Well... Everyone calls it the solenoid driver board.... but it actually does a few other super important things. I like to refer to it as the voltage regulator / solenoid driver board

The one main other fucntion it does is taking the dirty unregulated 12v and turning it into clean 5vdc for the computer to run with. If this part of your driver / voltage regulator board is bad, the MPU/computer will not run.

When the guide says power supply is good, they talking about rectifier board and voltage regulator/solenoid driver board.

Andrew

#5 5 years ago

Got it. It's on me, but even if it wasn't the guide has helped me hundreds of times so I couldn't really bitch about it

Quoted from barakandl:

When the guide says power supply is good, they talking about rectifier board and voltage regulator/solenoid driver board.

#6 5 years ago

Changed out the three caps from the GPE kit above and the game boots right up. Thanks.

4 years later
#7 8 months ago
Quoted from barakandl:

Okay...
So 12v unregulated DC is created on the rectifier board. It is usually more like 15v, so your 11v is unusually low. For now, unplug lamp, mpu, sound board. Check the 12v line on the rectifier board then check it on the driver/voltage board. They should read the same, if there is a difference, repin the connectors. Next up the LM323K on the driver/regulator board turns the 12v into 5v for the logic. Check both 5v test points on the driver board, if they are 4.1v there, replace C23 12,000 uF filter cap. If voltage still low, replace LM323k.
My best guess is your C23 filter cap has failed.

Having the same issue all of a sudden everything went crazy, loud buzz, shut the machine off, disconnected all connectors at pwr/rec tested TP's and individual pins to back box and playfield, they are pretty close, TP3 on the is 15.11 pwr/rec. I added the reg/sol board back in, on the TP3, 6 and 7 are 3.87, TP1 is a little low 4.1. TP5 is good 11.68. I'm going to check the pins, wiring punch downs on reg/sol J3, then follow your recommendations, thanks.

#8 8 months ago
Quoted from Craigb:

Having the same issue all of a sudden everything went crazy, loud buzz, shut the machine off, disconnected all connectors at pwr/rec tested TP's and individual pins to back box and playfield, they are pretty close, TP3 on the is 15.11 pwr/rec. I added the reg/sol board back in, on the TP3, 6 and 7 are 3.87, TP1 is a little low 4.1. TP5 is good 11.68. I'm going to check the pins, wiring punch downs on reg/sol J3, then follow your recommendations, thanks.

TP5 (11.9vdc) on the SDB should read high. Like usually at least 15v because the big ass filter 12K uF capacitor keeps the voltage up at the top. Without it it you get "ripple" which can show up as average DC voltage reading showing low.

Based on your symptoms I'd expect the 12k uF capacitor has failed or you have a bad ground connection. The 12v return is isolated (orange wire) and often is found burnt. You can sure up the grounds on the driver board with no bad effect. Pinwiki has info about "ground mods".

The noise from the sound board could very well be from either the ground return of the 12v opening up between driver and rectifier or tons of ripple from a bad 12k uF filter capacitor across the 12vdc (c23 i think it is).

#9 8 months ago
Quoted from barakandl:

TP5 (11.9vdc) on the SDB should read high. Like usually at least 15v because the big ass filter 12K uF capacitor keeps the voltage up at the top. Without it it you get "ripple" which can show up as average DC voltage reading showing low.
Based on your symptoms I'd expect the 12k uF capacitor has failed or you have a bad ground connection. The 12v return is isolated (orange wire) and often is found burnt. You can sure up the grounds on the driver board with no bad effect. Pinwiki has info about "ground mods".
The noise from the sound board could very well be from either the ground return of the 12v opening up between driver and rectifier or tons of ripple from a bad 12k uF filter capacitor across the 12vdc (c23 i think it is).

Thanks, I'll check it out, either tune up the board or upgrade it.

#10 8 months ago

One other thing I meant to mention, but forgot on the sol/reg TP4 I have 258vdc 28 volts high, on the rec, A2J4-6 I have 193.2vdc.

#11 8 months ago

Follow Barak's advice. As a rule of thumb on these first gen Bally games it's best practice to replace the large caps on the power supply and, if it's still present, remove any battery on the MPU and replace with an NV Ram.

Promoted items from the Pinside Marketplace
2,200 (OBO)
Machine - For Sale
Hayden, ID
$ 149.00
From: $ 20.00
Cabinet - Other
Rock Custom Pinball
$ 50.00
$ 30.00
Electronics
Third Coast Pinball
Wanted
Machine - Wanted
Egg Harbor Township, NJ
$ 279.95
2,000 (OBO)
Machine - For Sale
Milford, OH
$ 7.00
Electronics
Third Coast Pinball
$ 16.00
Electronics
Yorktown Parts and Equip

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside