(Topic ID: 329960)

System 80, Rotten Dog MPU & Driver Board

By tcw16505

2 days ago



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  • 12 posts
  • 4 Pinsiders participating
  • Latest reply 1 day ago by G-P-E
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MPU080.pdf (PDF preview)
r6532 (resized).jpg
cabinet power (resized).jpg

#1 2 days ago

I installed Rotten Dog MPU80 plug-and-play replacement board for most Gottlieb S80 and S80A and a Rotten Dog GDB080 direct plug-in replacement for the original Gottlieb System 80 Driver Board.

After the install everything checked out well but an annoying sound board issue that still needs addressed (Loud buzzing between game sounds). So I coined up and proceeded to play the first game. Ball one went well no issues but I wasn't sure if all three pop bumpers were working and quickly started ball two while reaching for the closest to the front popper. It was dead. As I looked up while reaching for the power button I saw that the displays were already out.

The +5V LED1 and Reset LED2 remain lit. No schematic available on Rotten Dog website.

I have not heard anything from Rotten Dog. "Technical Support after allowing well over the customary 24-72 hours for a response, they have a lot of boards out there, so busy I suppose.

Logic probe capable. Thanks for any direction. - Tom

#2 2 days ago

Does your game have the under-playfield pop-bumper driver boards? I am not familiar with the replacement board set by Rotten Dog. Are all your fuses good, and voltages measured OK?

#3 2 days ago

Pop bumpers are self-contained with their own control boards and solely triggered by physical ball contact. There is absolutely no link between your pop bumpers and your MPU aside from the scoring switches. However, I believe the pop bumper driver boards get their 5-volts from the MPU harness.

And if your displays are now out too, did you check your power supply board for all the proper voltages? Have you looked at your fuses?

IMO, this sounds like a flaked out power supply or power supply connector. Over the years they get hot and very loose.

Was the game properly working before you replaced the boards?

#4 1 day ago
Quoted from minnesota13:

Does your game have the under-playfield pop-bumper driver boards? I am not familiar with the replacement board set by Rotten Dog. Are all your fuses good, and voltages measured OK?

Yes, under-playfield pop-bumper driver boards. The one for the bottom popper was unplugged. The paper on this bottom popper coil has seen some heat. Fuses and voltages check out. I just powered up the game and the lights are not in attract mode but the sound is and still no displays.

Quoted from sparky672:

Was the game properly working before you replaced the boards?

Purchased this game was not working. I put these new boards in. It operated in attract mode with controlled lights operating. Now its not booting. Attract mode sounds work and back glass light controls work. GI works.

Quoted from sparky672:

And if your displays are now out too, did you check your power supply board for all the proper voltages? Have you looked at your fuses?

F7 is the display voltage in the cabinet and the schematic says 60VAC. I only have 39VAC (A2J1-7, A2J1-7). I lifted the fuse and checked the voltage and its pulled down due to a load. It measured 63VAC with the fuse lifted.
cabinet power (resized).jpg

#5 1 day ago
Quoted from tcw16505:

...I only have 39VAC (A2J1-7, A2J1-7). I lifted the fuse and checked the voltage and its pulled down due to a load. It measured 63VAC with the fuse lifted.

This part should be easy to resolve, since the 60 VAC is only used for displays and nothing else. However, the 60 VAC goes to the power supply A2 in the head and is then rectified to 60 and 42 VDC. Test all voltages at the power supply test points.

With power off, unplug all displays and the power supply. Turn on and check voltage again.

Plug in only the power supply and see if the 60 VAC comes back up.

Assuming it goes back up to 60 volts, plug in each display one at a time and check voltage. Just remember to turn off machine before plugging/unplugging each display. See if you will find a display that is causing the load.

#6 1 day ago

I believe my issue lies in the CPU that does not boot.

At present I have no displays and no controlled lighting, just GI. On Rotten Dog MPU080 LED #1 and #2 stay on continuedly when power up.

TP. 1, 4.98 VDC
TP. 3, 4.98 VDC
TP. 4, 83.3 mv DC, AKA LOW. I think the IRQ (Pin 25 on R6532) that is directly connected to TP. 4, is normally HI on this chip. The R6532 sets all the outputs on the "Z" chips, Z16A, Z16B and Z40 to give you the digits in the displays.

On TP. 4 I have cycled the power a couple of times now. I had it pulse for the first few seconds and then it went LOW. I cycled the power again and it went HI and stayed Hi. I observed that when TP. 4 is HI pins 21-25 on the R6532 all go HI and when LOW pins 21-25 on the R6532 all go LOW. Also when in LOW The credit display shows 0 credits.

I don't know if the issue is with the R6532, what drives it, or what it drives.

r6532 (resized).jpg MPU080.pdf

#7 1 day ago
Quoted from tcw16505:

...I only have 39VAC (A2J1-7, A2J1-7). I lifted the fuse and checked the voltage and its pulled down due to a load. It measured 63VAC with the fuse lifted.

60 VAC being pulled down twenty volts has nothing to do with your MPU.

Quoted from tcw16505:

Purchased this game was not working. I put these new boards in. It operated in attract mode with controlled lights operating. Now its not booting. Attract mode sounds work and back glass light controls work. GI works.

If it wasn't working before installing new boards, then it likely has a lot of the common Gottlieb issues; flaky power supply, bad grounds, bad capacitors, bad connections, etc.

#8 1 day ago
Quoted from sparky672:

60 VAC being pulled down twenty volts has nothing to do with your MPU.

I checked the voltage after removing all connections from displays and the voltage drop remained the same.

#9 1 day ago
Quoted from tcw16505:

I checked the voltage after removing all connections from displays and the voltage drop remained the same.

What about the A2 power supply? The 60 VAC goes directly into this. Completely disconnect A2 and check voltage drop again.

If you still have a voltage drop, then there is a wiring fault someplace between the transformer and A2 power supply.

#10 1 day ago
Quoted from sparky672:

What about the A2 power supply? The 60 VAC goes directly into this. Completely disconnect A2 and check voltage drop again.
If you still have a voltage drop, then there is a wiring fault someplace between the transformer and A2 power supply.

I removed all three plugs from A2. The Voltage went to 72VAC.

I'm guessing during this condition the driver board is somehow freed up to do as it pleases?

Here is what else happened:
The Gong (bell) fired briefly
The right Popper fired briefly
Q & T coils fired briefly
The center playfield controlled lighting came on and then dimmed and stayed on dim

About 5 seconds pass and Q & T coils come on and stay, and then the red and when I powered on a second time the black drop targets reset and stayed on.

#11 1 day ago
Quoted from tcw16505:

I removed all three plugs from A2. The Voltage went to 72VAC.

Sounds like you have a very serious problem within A2. It's critically important to get the A2 power supply working to spec before doing anything else.

Quoted from tcw16505:

I'm guessing during this condition the driver board is somehow freed up to do as it pleases?

Without A2, the Driver and MPU have no power. However, you still have power on the playfield components without any control of the driver board, which is why things are popping off when you power up.

When the machine is non-operational, you have to be methodical and start at the beginning... fix the A2 power supply first.

https://www.pinwiki.com/wiki/index.php/Gottlieb_System_80#System_80_.2F_80A_Power_Supply

#12 1 day ago

I agree with Mr Sparky about the A2 power supply being the first thing to look at. The big transistor in the middle is notorious for having a bad connection.

But to answer your question about what is driving the IRQ at TP4. Note - the "IRQ" signal name.
You will find the same "IRQ" signal names at: U1-Pin4, U4-Pin25, U5-Pin25, U6-Pin25, J10-Pin16 and resistor R1. All of these pins are tied together. IRQ is supplied by the three RIOTS (U4, U5, U6). Normally you cannot tie three outputs together but this signal is different ("Open Collector outputs"). None of the three RIOTs pull the signal high but any or all of the three RIOTs can pull the signal low. Resistor R1 is responsible for pulling the IRQ signal back high. U1-Pin4 is the interrupt input to the CPU. When IRQ is pulled low - the CPU is interrupted and it then checks the three RIOTs to see which one is pulling it low (requesting service) and performs an appropriate function at that time (e.g. update displays). If the IRQ gets inexplicably stuck low, this is often caused by a defective RIOT. In your case, it does not seem to be stuck low.

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