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(Topic ID: 273376)

Bally as-2518-17 mpu issue

By Theonlylilo

3 months ago

Topic Stats

  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 3 months ago by ChrisHibler
  • Topic is favorited by 1 Pinsider


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MPU_Sockets 004a.jpg
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#1 3 months ago

Hi everybody! I'm trying to repair a Bally -17 mpu from an old Mata Hari.
The board has some acid traces, but I've cleaned up well all the area.
So, I burned the Leon test rom ti be placed in U6 and the LED flickers as per manual.
I've installed U9 (6800), U10-U11 (6821), U7 (6810).
Once I put the U8 (5101) the LED is stucked solid on always with test rom.
Also the same story with both 2716 that I've burned with ipdb images.
The 5101 Is ok because working in another machine. The eeprom are verified with GQ programmer..
Any suggestion?
Thanks in Advance

IMG_20200719_132705 (resized).jpg
#2 3 months ago

I know the 5101 works in another machine, but, do you have another one to try? Also, can you post a pic of the 5101?

#3 3 months ago

Hi! Yes, I have another ones to try and I will follow your hint.
But the program should go on indipendently from other chips.
From Leon's Borre page:
"This program does not lock-up. This means if an output of a chip is bad, the program will continue to work. This way you're able to use a led in series with a 2Kohm resistor,a multimeter or a logic-probe to read all outputs of chips and know if everything works. To have some means of control that the program runs ok , we connect a control-led who will flash in rhythm with the test . The led on the cpu-board will also flash, because it is tied to the signal CB1 of U11, this of course if U11 is working normally.
This test checks only Cpu 6800 (U9) and both 6820 chips (U10 and U11) and is not dependent on memory chips (U7 and U8) and of no game-specific eproms (U1, U2, U5, U6)"
From the moment the program is stopped when the U8 (5101) is installed... Where I am wrong? Also for U2 & U6...

IMG_20200720_071626 (resized).jpg
#4 3 months ago

Did you tried with all chip except 5101 (u9/u10/u11/u2/u6/u7) ? How many flashes have you ? I've pretty same behaviour on my bally mpu 35 (2 flashes without 5101 ram , but solid green light with it).

#5 3 months ago

To be clear, using Leon's ROM, when you install the 5101, the program locks up. Right?

I would check for a solder bridge created when replacing the 22 pin 5101 socket.
The easiest way to check is...
1. Set meter to continuity.
2. Black on pin 1.
3. "rake" pins 2 - 22 with the red probe. There should be no "chirps" of continuity.
4. Move Black to pin 2.
5. "rake" pins 3 - 22 with the red probe. chirps.

Continue this process until you are only testing between pins 22 - 21.
Some pins might chirp, like pins 11 and 12 are tied together by the PCB traces.
Compare your results to the schematics.
Happy hunting.
Chris Hibler - CARGPB #31 ... for board repairs - The Place to go for Pinball Repair Info

#6 3 months ago
Quoted from ChrisHibler:

2. Black on pin 1.
3. "rake" pins 2 - 22 with the red probe. There should be no "chirps" of continuity.
4. Move Black to pin 2.
5. "rake" pins 3 - 22 with the red probe. chirps.

I do the same thing but with an analog multi-meter and watch how fast the needle moves.

To the OP, look at whether installing the 5101 is upsetting the reset signal.

Since you've used SIP sockets, put the board up to a bright light and look for solder shorts between pins/traces.

MPU_Sockets 004a.jpg

#7 3 months ago

So, checking again the board now has troubles in the reset section.. sometimes boots, sometimes not and jumpering pin 39-40 of the cpu, the led starts to blink.
But with 5101 the led is always on, despite the trick.
With multimeter the traces under the 5101 are ok, and the lamp confirm that..
The path is good from every pin of 5101 to the correspective pin..
I'm stucked. I have to change hobby

#8 3 months ago
Quoted from Theonlylilo:

I have to change hobby

Nahh. You'll get it. Keep pluggin'.
I see that you had to rebuild traces above/around U11. I'd review that work closely to ensure none of the traces that run between pins aren't shorted to those pins. Your meter on continuity check is the best tool. Somewhere, you will find a shorted or an open trace.

Also, Leon's ROM should be exercising all of the data/address lines at the 5101. A logic probe should show all of them pulsing consistently.

We look forward to your impending victory!
Chris Hibler - CARGPB #31 ... for board repairs - The Place to go for Pinball Repair Info

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