(Topic ID: 126045)

Gottlieb System 80A - No boot, displays show "0"

By ForceFlow

7 years ago


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  • 39 posts
  • 7 Pinsiders participating
  • Latest reply 5 years ago by mrdoarcademan
  • Topic is favorited by 6 Pinsiders

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#1 7 years ago

So, I've been working on a Gottlieb Touchdown. Up until this point, the electronics have been working fine.

I plunged he ball, hit a rollover, hit a pop bumper, hit a slingshot, and the slingshot started machine-gunning. I turned the game off, adjusted the slingshot switch.

When I turned it back on, it wouldn't go into attract mode.

The player 1 & 3 displays show the number "1" and sometimes alternate to the number "0". The credit display occasionally shows gibberish or flashes zero along with the other displays.

After attempting to troubleshoot by checking voltages, swapping in a power supply, and swapping the old one back, all of a sudden, the knocker started firing as soon as I turn the machine on. It alternates between 4 knocks, 3 knocks, and 2 knocks. But, sometimes when I turn the game on, it doesn't fire the knocker at all. It's very intermittent.

The manual and System 80 service manual don't seem to have anything that fits these symptoms.

Any ideas?

I thought I was all ready with this machine to bring to Allentown to have out for free play, but now that it's acting strangely, I'm not so sure I should go through the trouble of bringing it.

#3 7 years ago

Voltages on the transformer's fuse panel test good. Voltages on from the bridge rectifiers check out. The bridge rectifiers themselves appear to test good. Voltages on the power supply are good.

If this isn't a power issue, what else might it be?

#4 7 years ago

I swapped a known good rottendog MPU in, but all it did was show zeros on the player 1 & 3 display, and the credit display.

After swapping the rottendog MPU back into its original machine, that machine started displaying the zero on the credit display, nothing on the player displays, and did not go into attract mode. Looks like it somehow killed the rottendog MPU.

Something isn't right here...

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#5 7 years ago

Welp, guess I'm hitting the road soon for Allentown and leaving this pin behind since I can't get it up and running in time. Unless someone thinks I should bring it for on-site assistance/troubleshooting.

This makes me sad considering all the time I sunk into this the past week to get it ready.

#6 7 years ago

As it turns out, I had the dip switches on the rottendog board set I incorrectly--I swapped the zeros and ones positions.

So, the rottendog now works in both games, so I feel a bit better about that. The original board still has the same problem, though, so I think I'll still leave it behind and not bring it to Allentown this time.

#7 7 years ago

With the original MPU, the player 1 & 3 displays now just display a "1" in the tens digit. It stopped alternating between a 1 and 0, so I don't quite know what that means.

Leaving the reset board disconnected doesn't seem to make a difference in the MPU's behavior.

#8 7 years ago

Photos of the board:

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#9 7 years ago

Some new findings:

The 7404 chip at z11 gets hotter than the other chips.

The 6532 RIOT chip at u4 gets hot enough to burn fingers.

Should those chips be getting that hot?

[edit]: So, it appears that for U4, pin20 (+5v) and pin16 (PB7) are shorted on the board.

http://upload.wikimedia.org/wikipedia/commons/9/97/6532_RIOT_Pinout.svg

pin16 on the RIOT leads to z11, which makes sense since that chip was getting warm too.

Considering there is nothing shorting those two pins on the back of the board, I'm guessing there's an issue with or under the socket. So, the next step is removing that socket and seeing what's underneith it.

#10 7 years ago

Pull the connected leg out or cut it off the the 7404 and see if the short to 5v on the goes away. Hope that it does, because a 7404 is a lot easier to replace than a 6532.

If it turns out that 7404 is bad you probably shorted something under the PF when you made your adjustment. That 7404 is between the switch matrix and the 6532.

I would go over very carefully anything you adjusted under the PF before putting the repaired MPU back in. Would hate to blow out something again because there is a short to high voltage on the switch matrix.

#11 7 years ago

I am looking at the schematics more closely. It looks like Z11 is used in maybe 6 dedicated, non matrix switches. I would figure out where they are used and look for problems. Specially if PB7 is for something you adjusted.

#12 7 years ago

The 7404 was socketed as well, so that made testing easier.

It looks like multiple legs were shorting.

When I pulled the 7404 chip, the short on the board vanished.

When I removed the chip, a broken leaf appeared to fall out, so maybe that 7404 socket was causing a problem in addition to the issue with the chip.

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#13 7 years ago

That looks like a pretty crappy socket for the 7404. I would replace it, specially if you think a piece fell out of it.

Use a new 7404. It should not have shorts to vcc.

Dedicated switches are probably things like the slam switch, credits, start.

#14 7 years ago
Quoted from barakandl:

That looks like a pretty crappy socket for the 7404. I would replace it, specially if you think a piece fell out of it.
Use a new 7404. It should not have shorts to vcc.
Dedicated switches are probably things like the slam switch, credits, start.

One of the other chips has that same socket. I might as well replace both of those to avoid future issues.

Yep, according to the diagrams, it looks like this 7404 controls exactly those sort of switches.

I don't have any 7404's in my parts drawers, so it looks like I'll have to order a few.

Thanks for steering me in the right direction

#15 7 years ago

Crappy socket used at Z11.....i would replace it or them if more are used. Z11 is only buffering switchmatrix strobes and the board will boot without it. In Z12 also a few ports are used as addressline buffers, without that chip your board won't start. Switchmatrix RIOT U4 contains RAM which the program needs in order to run (U5 also and U6 provides memory for the stack). If you are familiar with test ROM's you are welcome to use mine. Z11 usualy fails when something wrong happened under the playfield and the solenoid voltage enters the switchmatrix. Check also the switchmatrix diodes under the playfield after something happened like this.

Edit: Andy was a bit faster about the crappy sockets

Marco

#16 7 years ago

I finished replacing the sockets, but when I was testing the other 7404 chips, I found a second bad one. I might as well order a small handful of them when I get a parts order together. Is it common for these chips to go bad?

#17 7 years ago
Quoted from ForceFlow:

I finished replacing the sockets, but when I was testing the other 7404 chips, I found a second bad one. I might as well order a small handful of them when I get a parts order together. Is it common for these chips to go bad?

Not really, but get a handful of them as 7404 is used often by all manufacturers. Inverter/buffers for switches/inputs usually fail when the input gets hit with over or negative voltage. Like in a WMS 3-6 driver, the 4049 and 7406 for the switch matrix drive/return get blown out when you accidentally short, feature, gi or coil voltage to a switch. What designation is the other 7404 that failed? Might be able to connect the dots as to why they failed. If the other one that failed is also in the switch area, that might be a clue.

#18 7 years ago

The other one was at Z14. Looks like it handles half of the switch matrix, but the switch numbers on the schematic go from 1 to 32, while the playfield diagram lists switch numbers 30 through 67.

[edit]: ah ha--switch numbers correspond to the strobe and return lines. Never realized that before. So, switch 30 would be strobe/row 3, column/return 0.

#19 7 years ago

Z14 is also a switch matrix IC so give a really good visual check around the things you adjusted. If just one circuit of Z14 is shorted, reference that to the switch matrix and go over every switch associated and look for problems.

#20 7 years ago

When coil power is shorted to the switch matrix, you can blow any/all of the ICs at Z11, Z12, Z13, Z14, Z15, and U4. Using the diode test outlined in the PinWiki has successfully identified a failed 7400/7404/7432 every time for me on System 80 boards. U4 being hotter than U5 and U6 is a clear indication of problems. Sometimes, the diode test can help identify a failed RIOT too. You are on the right track. Keep going.

Use quality sockets.
The solder pads on System 80 boards come free fairly easily with too much heat. Be careful.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#21 7 years ago
Quoted from ForceFlow:

Is it common for these chips to go bad?

In the System 80 switch matrix...yes.
They act as fuses when HV is shorted to the matrix.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#22 7 years ago

Well, it looks like switch #36 "on right flipper" might have been shorting with the EOS switch.

The rottendog MPU I stuck in the machine says there are no shorted switches now after going through a switch test.

Now I'm just waiting on the new chips for the original MPU to be shipped. I made sure to get extras so I'll have them on hand if I need them.

1 week later
#23 7 years ago

My order finally came in.

I replaced Z12 and Z14, but there was still no boot.

Then I replaced the u4 RIOT chip, but there was still no boot.

The displays simply show a single zero in the 1 & 3 player displays, and the credit display.

All the legs for z11-z14 and u4 make contact through the board.

#24 7 years ago

The clock signal is pulsing on the CPU at pin-37 and the CPU reset at pin-40 remains high.

The 5101 RAM at z5 pin-17 is pulsing. The R/W pin gives a steady signal.

There doesn't appear to be any shorts on U2, U3, or on the 5101 (aside from the pins on the 5101 that are linked by paths on the PCB).

The various U2 and U3 pins appear to give various steady high and low data, though I don't know how to interpret whether or not any of the probing results are actually the expected readings or not.

#25 7 years ago

I socketed and replaced the 5101 RAM, but it didn't appear to have an effect.

Any ideas?

1 week later
#26 6 years ago

Ok I had the same problem first disconnect the door slam tilt photo.JPG 12.JPG then you have to add a mod to your mpu board cut off a leg from a
diode and solder it on photo.JPG 11.JPG I haven't had a problem
with my system 80a after add this mod to it good luck

#27 6 years ago
Quoted from Raff:

Ok I had the same problem first disconnect the door slam tilt photo.JPG 12.JPG (Click image to enlarge) then you have to add a mod to your mpu board cut off a leg from a
diode and solder it on photo.JPG 11.JPG (Click image to enlarge) I haven't had a problem
with my system 80a after add this mod to it good luck

Thanks for posting, but this isn't a slam switch issue. The slam switch issue symptoms are different.

I ordered some EPROMs and the pinitech test board, and plan to try Leon's and Marco's test ROMs to see if they reveal a bad IC somewhere. I expect that they will be delivered sometime next week.

#28 6 years ago

sorry I should have said you don't have to disconnect the slam switch on the door , just add that mod across the capacitor that will bypass the slam switch

#30 6 years ago

I've been following your progress and see that Chris H is on this thread but I wanted to mention something I saw in case it may help. Just another "Shot in the Dark" for you, playing Inspector Clouseau (my favorite late actor). I noticed that the CPU board in the first pic of your boards is a D20869 and came out of a "The Games" and your game is a "Touchdown" which would mean your board has been swapped out for some reason. I assume because the battery puked alkaline all over the original board. Anyway, it may be possible that your newer CPU board might require a 3K pull up resistor at the TC1 pins 7 & 11. Ed at GPE mentions this from time to time, sometimes the CPU board won't boot to attract mode without it. Perhaps it's worth looking into.

Steve
System 80, not just a job, it's an adventure

#31 6 years ago
Quoted from blownfuse:

I've been following your progress and see that Chris H is on this thread but I wanted to mention something I saw in case it may help. Just another "Shot in the Dark" for you, playing Inspector Clouseau (my favorite late actor). I noticed that the CPU board in the first pic of your boards is a D20869 and came out of a "The Games" and your game is a "Touchdown" which would mean your board has been swapped out for some reason. I assume because the battery puked alkaline all over the original board. Anyway, it may be possible that your newer CPU board might require a 3K pull up resistor at the TC1 pins 7 & 11. Ed at GPE mentions this from time to time, sometimes the CPU board won't boot to attract mode without it. Perhaps it's worth looking into.
Steve
System 80, not just a job, it's an adventure

It's worth a try. However, the board was originally working without it before the short on the switch matrix.

#32 6 years ago

Okay, then that won't help. Switch matrix issues can sometimes be tricky (and though it rarely gets that far), it'll take out a gate in Z8 (7402), the input/output device selection. I'd give that gate a look over to be sure input/outputs are good, it may be what's locking it up.

Steve
System 80, not just a job, it's an adventure

Quoted from ForceFlow:

It's worth a try. However, the board was originally working without it before the short on the switch matrix.

#33 6 years ago

One more suggestion...
...set your DMM to continuity, and start buzzing U4, pin 1 to every other pin on U4.
...1 to 2 thru 40
...2 to 3 thru 40
...
...39 to 40
NONE of these connections should buzz.
If one does, there is a solder bridge between two traces or legs.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#34 6 years ago
Quoted from blownfuse:

Okay, then that won't help. Switch matrix issues can sometimes be tricky (and though it rarely gets that far), it'll take out a gate in Z8 (7402), the input/output device selection. I'd give that gate a look over to be sure input/outputs are good, it may be what's locking it up.

Some pins on Z8 are pulsing, and some are high or low, though I'm not sure what else to test for tell if the chip is actually operating properly.

Quoted from ChrisHibler:

One more suggestion...
...set your DMM to continuity, and start buzzing U4, pin 1 to every other pin on U4.
...1 to 2 thru 40
...2 to 3 thru 40
...
...39 to 40
NONE of these connections should buzz.
If one does, there is a solder bridge between two traces or legs.
--

I didn't detect any shorts on u4, u5, or u6.

#35 6 years ago
Quoted from ForceFlow:

I didn't detect any shorts on u4, u5, or u6.

So that's good.
If you've gotten to the point that someone else needs to look at it, LMK.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#36 6 years ago
Quoted from ChrisHibler:

So that's good.
If you've gotten to the point that someone else needs to look at it, LMK.

Well, once everything that I need for using the test ROMS arrive, I'll see what the results are.

I also really have my suspicions about the U2/U3 ROMs, but I haven't seen a good way to actually test those, other than using some sort of replacement daughter board.

2 weeks later
#37 6 years ago

Well, all the parts arrived for the pinitech PCB tester, but I didn't have much luck with it or the test ROMs.

I also got the NeoLoch RAM tester, which told me the original RAM I had in the board was dead, but the RAM I replaced it with is good.

Since the RAM went bad and since I'm not getting a flash out of the board tester, I'm wondering if the short on the board also took out the CPU. I have a couple CPUs on order, which should arrive on Monday.

#38 6 years ago

So, the CPU and a few 47xx chips that I ordered came in. I replaced the CPU, as well as z7 and z8 as a good measure. z7/z8 didn't have any shorts, but I figured they were cheap and I didn't want them harming the CPU if they were acting up for some reason.

Much to my pleasant surprise, the tester board sprung to life and went through all its blinks.

Then I unplugged the tester board, went ahead and popped in U3, connected the connectors one by one, finally ended with attract mode and a playable game. I ended up playing a few long games without any problems.

So yikes, this was an adventure in board repair. I guess the CPU can give off some signs of life with a logic probe, but still be malfunctioning. And now I know how the testers react to a malfunctioning CPU.

Thank you everyone for taking the time to read, and especially those of you who took the time to respond to help me figure out what was wrong with this board.

11 months later
#39 5 years ago

I need to use this to diagnose

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