Disco Fever: Please Help, System 4 audit mode continually scrolls

I'm moving this topic to a new thread, so we don't hijack the other thread.

OP
Quoted from Brewchap:
A strange problem with the system 4 board. After it boots, it shows that it is on ball 4 and the credit number is rolling from 01 to 23 over and over non stop.
Also on the system 6 board, I can start a game, but the game never ends. It keep going and going, ball, after ball. Like that damn rabbit you see on TV.

Quoted from slochar:
System 4 is stuck in audit mode it's showing you the results of the audits.
System 6 probably needs its ram reset, the balls to play is supposed to be capped at 1-9, but if it's zero, you will get endless balls. There's no bounds checking when it reads the # of balls to play, just when you set it. Going in to the setting for balls in play and cycling it through a full cycle should fix that.
Williams really needed a way to re-load cmos defaults other than a battery pull, or putting a different set of roms in there (which "should" reset it, but doesn't always)

Quoted from slochar:
The advance button is not getting its signal to where it needs to be or its stuck.... double check it's on the correct header, IIRC it's one of the upper 2 4 pin ones on the mpu.

Yes it was in the correct location. Removing the connector and then booting the pin, the credit numbers show 1 and the ball number shows 4. But no more rolling, unless I add the connector back, then it starts rolling numbers non stop, Even if you pull the connector again, it's still rolling.

#2 4 years ago

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Brewchap

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A video of the rolling numbers.

Just a note that I have a system 6 MPU and driver board that I tested with also. It did the same thing until I wiped out the CMOS.
Wiping out the CMOS on the system 4 does nothing however.

#3 4 years ago

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Brewchap

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I pulled the NVRAM and installed a 5101 chip. On power up I got the same rolling numbers, but a quick hit of the power switch I got all zeros on the display. I could not add credit, but pushing the started button started the knocker firing and credits loading up fast till I shut it down. Could I still have a MPU board problem and it's not boot up correctly?

#4 4 years ago

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Brewchap

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I also noticed that the MPU will still boot up with the 5101 socket is empty. Should it do that?
I forgot to add that the credit number still roll.

#5 4 years ago

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Brewchap

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I used Leon's test ROM and the two LEDs on the CPU board started flashing together, passing Leons test.
But I am unable to get the Andre test ROM to run.

#6 4 years ago

AMS

barakandl

If audit mode continually scrolls on a system 6 MPU one of the battery terminals probably has a ripped out through hole. That disconnects ground from a chip that handles diag buttons and makes it constantly scroll audit mode.

#7 4 years ago

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Brewchap

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Thank you Barakandl, I have a system 4 board so IC5 is in a difference place on the MPU board but from what I understand is that a faulty IC5 chip will display the same symptom that I'm having. How can I check this?

Also how can I get Andre to boot? Is this my whole problem is that the MPU is not booting correctly?

#8 4 years ago

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Brewchap

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I re-burned Andre test ROM again and now it works.

#9 4 years ago

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barakandl

Check gates attached to the coin door diag buttons to change state when pushed. IC24 P8 and P6 would be normally low and go high when the buttons are pushed. When that chip has no ground connection it makes audits scroll in a system 6 MPU so it could be bad specially if the audits scroll when 1J4 is removed.

Untitled (resized).png

#10 4 years ago

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Brewchap

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IC24 Pin 6 starts out LOW and when the Diag button on the MPU is pushed, it goes HIGH
IC24 Pin 8 starts out HIGH and when the Diag button on the MPU is pushed, it goes LOW
The Diag buttons on the coin door do nothing when pushed and tested on IC24

EDIT: The above info is incorrect. I noticed that the chip number 1 leg is to the top of the board, not the bottom like the rest. Retesting now......
IC24 pin 6 starts out LOW and the HIGH light comes on with the LOW light still lit when the Advance switch is pressed.
IC24 pin 8 starts out with the HIGH and LOW light on and pulsing, when the Auto switch is switched to manual the light goes LOW with a steady tone.

#11 4 years ago

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Brewchap

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Quoted from barakandl:
so it could be bad specially if the audits scroll when 1J4 is removed.

Audits scroll when 1J4 is connected at boot up
Audits do not scroll when 1J4 is disconnected at boot up, sorry for the confusion. BUT when the 1J4 is connected with the game on, the audits scroll.

#12 4 years ago

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Brewchap

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Something that I noticed, the displays starts messing up when the audits scroll. Is it possible that IC18 is bad? The Diag from IC24 trace back to it.

#13 4 years ago

AMS

barakandl

OP
Quoted from Brewchap:
Audits scroll when 1J4 is connected at boot up
Audits do not scroll when 1J4 is disconnected at boot up, sorry for the confusion. BUT when the 1J4 is connected with the game on, the audits scroll.

What is going on here is the is there is resistors on the MPU that pull up 1J4P3 and 1J4P4 to HIGH 5v when it is open circuit / the button is not pushed. 1J4P2 is the /IRQ which is pulsing at I think around 1 millisecond frequency and is used as the common side to both buttons. When the button is pushed /IRQ is sent to the PIA which is monitoring the state of 1J4P3 and 1J4P4. When the CPU sees that pulse it knows a diagnostic input button happened.

If the audits only scroll when the connector is on and the display also mess up something could be happening to the /IRQ signal. Double check that 1J4 is wired right and the coin door buttons are wired right. You could jump 1J4P3 and 1J4P4 to 1J4P2 at the connector to go around the coin door buttons.

In system 6+ they stopped using /IRQ and used ground as the diag button common. They probably decided sending the CPU's /IRQ to the coin door was a bad idea that is asking for trouble.

#14 4 years ago

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Brewchap

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Hmm, displays are fine now....Might be that something else is going on.

Quoted from barakandl:
If the audits only scroll when the connector is on and the display also mess up something could be happening to the /IRQ signal. Double check that 1J4 is wired right and the coin door buttons are wired right. You could jump 1J4P3 and 1J4P4 to 1J4P2 at the connector to go around the coin door buttons.

Jumping 1J4P2 to 1J4P3 advanced the audit by one number
Jumping 1J4P2 to 1J4P4 starts the scrolling numbers

#15 4 years ago

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Brewchap

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Swapped out IC1 and IC18 with no change in behavior. I just had to try.

#16 4 years ago

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Brewchap

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~~OK I just changed out IC24 (7400,) and now at boot up, the Audit does NOT scroll, even with 1J4 hook up! Now, I'm still dead in the water as all that I see is 1 credit ball 4.~~

I had the chip backwards. Really need to clean my readers.

As far as the wiring goes, I put the system 6 board in and had no problem with the pin.

I don't see anything else in the schematic to mess with other than the resisters or caps.

#17 4 years ago

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Brewchap

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What trips the game to go into Audit mode anyways?

#18 4 years ago

AMS

barakandl

OP
Quoted from Brewchap:
What trips the game to go into Audit mode anyways?

If the valid RAM check fails it boots into audit mode other wise when the coin door button is pushed it goes into audit mode.

If it works properly when you manually jumper the male board pins with the connector off yet immediately goes to audit mode and always scrolls when the connector is on then I'd say the diag button is stuck closed or not wired right.

#19 4 years ago

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Brewchap

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No, It does not work properly when I manually jumper it.
I can manually jumper it and the scrolling starts up.

#20 4 years ago

AMS

barakandl

OP
Quoted from Brewchap:
No, It does not work properly when I manually jumper it.
I can manually jumper it and the scrolling starts up.

Because the irq is pulsing i'd expect it to scroll when diag advanced button is held down or the jumper stays connected.

Double check the coin door diag button wiring. Make sure the auto up latching button wire is not swapped with the diag advance and it's not stuck closed. Make sure the wires leaving mpu go to the right coin door button and not shorted or pinched anywhere.

The fact that the audits stop scrolling when the connector is off makes it dunds like the mpu is ok and it's a button or wiring problem.

#21 4 years ago

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Brewchap

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~~Is this yellow jumper suppose to be there?~~

Never mind, the yellow wire makes the white wire common to both switches.
It looks like the white wire has been moved from the lug that had solder on it and soldered to the yellow wire. What are your thoughts?

20191103_103600(0) (resized).jpg

#22 4 years ago

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Brewchap

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Ok, I checked the wiring as you suggested. The wires are in the correct location, they are not shorted and the switches work the way they should. I found that pin 2 and pin 4 are always connected to each other due to the Auto/Manual switch being in Auto mode. I also found that 1J4P2 is always pulsing as you stated that it should. The diag advanced button advances one at a time when pushed.
With that said, As long was 1J4P2 is pulsing with a direct link to the Auto/ Manual switch, it will always roll.
It also look as if the switch should always be in the Manual mode from the look of the schematic.
20191103_104729 (resized).jpg

#23 4 years ago

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Brewchap

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Quoted from barakandl:
The fact that the audits stop scrolling when the connector is off makes it dunds like the mpu is ok and it's a button or wiring problem.

Yes that's true, with the connector off at boot up, there is no scrolling. With 1J4 not connected, and I boot the pin, I jump pins 2 and 4 together and the scrolling starts again, would that not be a MPU problem and not a wiring problem since the connector is not even hooked up?

#24 4 years ago

AMS

barakandl

OP
Quoted from Brewchap:
Yes that's true, with the connector off at boot up, there is no scrolling. With 1J4 not connected, and I boot the pin, I jump pins 2 and 4 together and the scrolling starts again, would that not be a MPU problem and not a wiring problem since the connector is not even hooked up?

Jumping the two pins is doing the same thing as pushing the coin door diag button and holding it down. If it starts scrolling with the connector on then those two pins are probably electrically connected mimicing the diag button being held down.

If it scrolled with the connector off then I'd think it is a mpu issue.

#25 4 years ago

CCN

pincoder

Pincoder Diagnostics

5y 50,050 467

Just to add some info about the IRQ: The pulse is continually generated on the MPU board (by an independent circuit). It should always be pulsing and has nothing to do with switch signals to or from any of the switches. It is simply used by the CPU chip (via software on the ROMs) for internal housekeeping etc.

It also (and still) amazes me to hear of pinball machines being rewired incorrectly, and then being handed off that way to someone else. Like, did they think they actually fixed it when they did that?? grr.

Having said that, hopefully yours is just a matter of correcting the wiring on that switch

#26 4 years ago

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Brewchap

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What setting is the Auto/Manual switch should be setting in?

It looks as if the switch should always be in the Manual mode from the look of the schematic. I have been leaving it in Auto, which causes the scrolling.

#27 4 years ago

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slochar

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7y 86,550 6,915

Perhaps this is a dumb question and maybe you covered it earlier....

The game will always come up in audit mode without batteries in it, and if you happen to have the auto/manual set to auto, it will start scrolling.

#28 4 years ago

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Brewchap

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Quoted from slochar:
Perhaps this is a dumb question and maybe you covered it earlier....
The game will always come up in audit mode without batteries in it, and if you happen to have the auto/manual set to auto, it will start scrolling.

The boards had a NVRAM installed and it was still booting up in Audit. So I just added batteries and a 5101 chip, and now it boots with no problem. So, nope, not a dumb question. And yes the Auto/Manual was set to Auto

#29 4 years ago

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Brewchap

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Now I got a different problem since I am out of Audit mode. Two or three times after I power up the pin, I hit the start button and the MPU completely dies. Another time or two I can get the game started, play a ball or two and the game will just shut down. The MPU seemed to work just fine when I was using the test roms. Pincoders, Leon and Andre. Power supply was just capped. So I am quite surprised that it keeps dying.

Yea, it getting pretty consistence now. Start it up and it will just shut down.

#30 4 years ago

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Brewchap

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