(Topic ID: 309407)

Where to begin DE GnR

By Md2020

6 months ago


Topic Heartbeat

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  • 26 posts
  • 8 Pinsiders participating
  • Latest reply 6 months ago by Md2020
  • Topic is favorited by 2 Pinsiders

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#1 6 months ago

Where to begin...
This has been the biggest project I've taken on so far. Lot of pain, blood sweat and tears these past 4+ months.
The short story is I tore it completely down for cleaning and service. Now I've finally got her back together.
OF COURSE there are issues- specifically with sound and cpu lockup upon inserting credits.
I was able to "play" a game by using the diagnostic service credit option, found some bad switches but the audio is completely effed.
I'm going to try to attach a video of what I'm talking about here.
Where should I start looking? I have a few ideas but I wanted to consult the think tank..

#2 6 months ago

Was the game working correctly BEFORE you overhauled it?

Yes, check all your power rails first. It's the heart of the system. So you want to address any problems there before moving on.

One bit of good is the system boots and runs, some people overhaul and can't even boot after. What this means is you should be able to access the game diagnostics. Run everything, every diagnostic, every switch test, etc... write down any failures. Don't get overwhelmed or assume everything is related. Your going to need to go step by step to restore the game to 100% operation.

#3 6 months ago

Thanks for the reply! When I picked it up the seller told me not to plug it in lol. There were a couple failed drivers so a coils were locking up.
With that said, it was DOA.
The diagnostics I have run so far (lamps, coils) have been successful. the 12v + and 12 v - and 5v to the sound board have tested fine. The audio is completely distorted and I don’t think it’s the amp. The right left center speaker test is a failure. It does not sound like a sine wave

#4 6 months ago
Quoted from Md2020:

Thanks for the reply! When I picked it up the seller told me not to plug it in lol. There were a couple failed drivers so a coils were locking up.
With that said, it was DOA.
The diagnostics I have run so far (lamps, coils) have been successful. the 12v + and 12 v - and 5v to the sound board have tested fine. The audio is completely distorted and I don’t think it’s the amp. The right left center speaker test is a failure. It does not sound like a sine wave

No problem. So by measurement and test, you know what is good. "You don't think its the amp" sounds like a guess. What makes you say that? Have you tested it to make sure it is operating correctly? Have you checked the speaker that is distorted with a meter? Have you tested the amp by replacing the distorting speaker with a known good speaker and had the same results?

#5 6 months ago

Did you check and make sure the sound roms are fully seated, and pressed onto the boards?

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#6 6 months ago
Quoted from jk2171:Did you check and make sure the sound roms are fully seated, and pressed onto the boards?[quoted image]

Yes indeed. I double checked the roms and also the connectors. I went through those tests. The "sine" wave just sounded like garbage noise and no matter what, sound was coming from all 3 speakers. The "Center" test was more quiet than left and right.
I also did the switch test and it seemed to wig out on me, I need to make sense of how a successful run through it is supposed to look. I'm guessing that what I'm seeing here are problems with the matrix? I'm wondering if all this is tied together? Now I'm afraid to turn it on for fear of frying the CPU and am wondering if I already fried the soundboard

#7 6 months ago
Quoted from Md2020:

I also did the switch test and it seemed to wig out on me, I need to make sense of how a successful run through it is supposed to look.

Ok, the switch test has nothing to do with sound, it either works or it doesn't, and it seems to me you have bigger problems if you can't run a switch test and you have sound problems.

#8 6 months ago
Quoted from wayout440:

Ok, the switch test has nothing to do with sound, it either works or it doesn't, and it seems to me you have bigger problems if you can't run a switch test and you have sound problems.

I can run a switch test, but I don't understand what I'm supposed to be looking for during the test- I've never done one before.
I've got the manual out right now and am trying to grasp it.

Should I power up the machine in diagnostic mode and relay what I see when I run the switch test?

#9 6 months ago

So the switch test works- except the coin switches cause the cpu to lock up OUTSIDE of diagnostic mode. I've been staring at the schematics and wiring trying to figure out what could be the issue here

#10 6 months ago

The pia chips on the Cpu board are suspect. The sockets go bad, thus the chips don’t seat properly, causing all kinds of strange boot problems and beyond. It’s very common on this era of data east.

#11 6 months ago
Quoted from shacklersrevenge:

The pia chips on the Cpu board are suspect. The sockets go bad, thus the chips don’t seat properly, causing all kinds of strange boot problems and beyond. It’s very common on this era of data east.

I only see one PIA that appears to be socketed, but according to the schematics it doesn't appear to be one associated with coinage. The board boots fine and the game plays with the exception of sound and some lighting matrix issues. Are you saying I should pull out and reseat the chips on the CPU board?

#12 6 months ago

I am NOT an expert like many others here but from reading many troubleshooting threads it is often suggested to remove the chips that are socketed and reseat them carefully. Same goes for ribbon cables and alike. This can do no damage to your game and hopefully help you find some issues. Of course you do this with the game powered off!

Try and be as methodical as possible taking copious notes

#13 6 months ago

I purchased this game DOA and have torn it completely apart for cleaning. The CPU board was sent out for service and to have the transistors replaced as well as the barbecue capable resistors. I know that the coin mech's are not part of the switch matrix, so I suspect I could test directly at the board to determine if its at the CPU or not

#14 6 months ago

If any of you guys have any suggestions, I'd be extremely grateful. Spent all day staring at it and testing theories that did not turn out to be the magic bullet.

#15 6 months ago
Quoted from Md2020:

I purchased this game DOA and have torn it completely apart for cleaning. The CPU board was sent out for service and to have the transistors replaced as well as the barbecue capable resistors. I know that the coin mech's are not part of the switch matrix, so I suspect I could test directly at the board to determine if its at the CPU or not

Yes, coin mechs ARE a part of the switch matrix. Look at your switch matrix table again in the manual. All the coin mechanics switches are in column 1. Yes, you can test directly at the board, to rule out a problem there. Even though the board was sent out for service, and you would hope that it was tested and worked 100%, it could have also been damaged in transit or during reinstall. Plus this will help rule out any playfield wiring issues (If everything works direct tested, but then reconnecting pf fails, you would have suspect playfield wiring or switches)

No need to pull and reseat any chips until you find it necessary. For now just press them down securely in socket (to resolve any possible chip creep)

Where you mentioned not knowing what do look for in switch test, just get the switch matrix chart from the manual, put the game in the switch test. It helps to remove all the balls and use one to activate ball triggered switches, and just see that every switch reports back the correct number on the display.

#16 6 months ago
Quoted from wayout440:

Yes, coin mechs ARE a part of the switch matrix. Look at your switch matrix table again in the manual. All the coin mechanics switches are in column 1. Yes, you can test directly at the board, to rule out a problem there. Even though the board was sent out for service, and you would hope that it was tested and worked 100%, it could have also been damaged in transit or during reinstall. Plus this will help rule out any playfield wiring issues (If everything works direct tested, but then reconnecting pf fails, you would have suspect playfield wiring or switches)
No need to pull and reseat any chips until you find it necessary. For now just press them down securely in socket (to resolve any possible chip creep)
Where you mentioned not knowing what do look for in switch test, just get the switch matrix chart from the manual, put the game in the switch test. It helps to remove all the balls and use one to activate ball triggered switches, and just see that every switch reports back the correct number on the display.

Thank you for the response. It occurred to me that I would need to test the coin switch in diagnostic mode if I pulled the harness off, right? The problem is that both coin switches register in diagnostic. But in play mode, the CPU locks up.
I doing the best I can to avoid frying anything new since I only have one of these boards on hand right now.
Can I pull CN10 and CN8 off while the board is in play mode? (I believe these are the connectors that have the coin switch send/returns). I'll need to double check the schematics to be sure those are the right ones.

#17 6 months ago
Quoted from Md2020:

Thank you for the response. It occurred to me that I would need to test the coin switch in diagnostic mode if I pulled the harness off, right? The problem is that both coin switches register in diagnostic. But in play mode, the CPU locks up.
I doing the best I can to avoid frying anything new since I only have one of these boards on hand right now.
Can I pull CN10 and CN8 off while the board is in play mode? (I believe these are the connectors that have the coin switch send/returns). I'll need to double check the schematics to be sure those are the right ones.

You could pull them off but let me explain something first. If all the switches work properly in test mode, your playfield switches, wiring, and switch matrix are verified good. Yest mode verifies all the hardware and low level logic regardless of what game code is running. Game play is controlled by game code, the upper level program. Good responses in test mode verify the hardware and low level logic. If it passes in test mode, then all that is good. If you suspect the problem occurs only in game mode, ROM program is buggy, defective, or incorrect OR possibly RAM is defective (not storing/interacting properly) OR there is something you are not understanding in the games settings and/or operation.

#18 6 months ago
Quoted from wayout440:

You could pull them off but let me explain something first. If all the switches work properly in test mode, your playfield switches, wiring, and switch matrix are verified good. Yest mode verifies all the hardware and low level logic regardless of what game code is running. Game play is controlled by game code, the upper level program. Good responses in test mode verify the hardware and low level logic. If it passes in test mode, then all that is good. If you suspect the problem occurs only in game mode, ROM program is buggy, defective, or incorrect OR possibly RAM is defective (not storing/interacting properly) OR there is something you are not understanding in the games settings and/or operation.

There is one bad switch on the playfield- the Axl Hole. There is an issue with the lighting matrix- some of the playfield lights are dimly illuminated when they shouldn't be during attract mode. My question is: would those other issues possibly cause a cpu lockup when the coin switch is triggered? I am mentioning this as during diagnostics, the attract lights are not illuminated. My theory was that something miswired/shorted on the matrix could possibly cause this to happen when certain criteria are met. Is this a possibility?

#19 6 months ago

The lamp matrix and the switch matrix are independent circuits. In test mode, does every switch work correctly and does every controlled lamp work correctly? The MPU board is designed to work in many games. It is the ROM software and specific lamp or switch locations that are given personality defining the gameby the ROM software. Lamps and switches must work 100% in test mode first. Hope that helps.

#20 6 months ago

Since there are audio problems as well - could it be that when the game goes to play that audio file when a coin is inserted (in attract mode) which might be corrumpt (or whatever) and causes the game to lock up? Physically, and electrically the switch is fine, but the sequence of events during coin up in attract mode is what seems to be messing up.

I'd bet on a ribbon cable plugged incorrectly, or the Roms on the sound board needing reseating (check that all the roms have been inserted correctly and not bent/broken pins) if it was recently put back together?

#21 6 months ago
Quoted from thefoxxman:

Since there are audio problems as well - could it be that when the game goes to play that audio file when a coin is inserted (in attract mode) which might be corrumpt (or whatever) and causes the game to lock up? Physically, and electrically the switch is fine, but the sequence of events during coin up in attract mode is what seems to be messing up.
I'd bet on a ribbon cable plugged incorrectly, or the Roms on the sound board needing reseating (check that all the roms have been inserted correctly and not bent/broken pins) if it was recently put back together?

Just unplug the sound board, remove it from the equation. The machine will run just fine without it.

#22 6 months ago

Post some pictures of the boards with all the connectors plugged in.
Also, do the test buttons on the coin door work?

#23 6 months ago

Also, move the volume control all the way up and down a few times. That could be where the crackling is coming from

#24 6 months ago
Quoted from kba78:

Post some pictures of the boards with all the connectors plugged in.
Also, do the test buttons on the coin door work?

Test buttons work fine, I can see the coin door switches in diagnostic mode- the only switch I can't see is the Axl hole. Maybe I can start by fixing that to see if that helps with anything. Looks like all switches are on the same matrix, so maybe the diode is bad on one of the switches causing some weird condition?
The Axl hole switch will not register at all when I try to manipulate it.

BTW, PO reached out to let me know the 12v regulator on the sound board is bad. I had already cleaned the volume pot

#25 6 months ago

Well, been doing digging as time allows- Sound card is out of the equation, found a bad drop target switch that just turned out to be dirty contacts. I disconnected the switch drive/return connectors (CN8, CN10) and jumper'd coin switch directly across (with diode). Same outcome; lights stop, display drops out, straight up lock up.
I checked voltages coming off each drive section pretty much 4.5/4.6 average Vdc straight across.
I feel like I've exhausted my diagnostic testing. Where would I look now?
I know someone mentioned CPU. I do have an extra, but before I go removing ICs I want to make sure I'm headed the right direction

#26 6 months ago

Well, days have passed- problems have been solved. The coin up cpu lock issue has been resolved. What I did was change the pricing scheme and that fixed it. It's been said that switching over to Nvram can generate some bad values that need to be cleared. Sounds logical to me.
Also, the light matrix problem was narrowed down to the snake ramp bulb diode. I went through testing diodes at first, but I discovered this one by watching the behavior of the bulbs during game over mode.
Thanks for the support, fellas

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