Williams Defender restoration help

Arizato

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Hello,

I would really appreciate some help with restoring an old Defender Cabinet that has been in storage for 25+ years in a house without proper heating and isolation. I managed to grab this machine, Operation Wolf and a generic 1943 cabinet.

Picture included for those interested:

Defender.jpg


I am very new to this thing so bear with me. The old Linear PSU was toast, there was a small burn hole straight through it and components had been soldered together in such a way that I did not feel comfortable using it. It blew fuses left and right. So I changed it out for a PSU on Paradise Arcade Shop. Now the cabinet now powers on without issues. I also took out the CPU board and gave it a cleaning since it has clearly been a victim of battery acid at some point (Picture is from before doing the cleaning). After cleaning I did some probing using a multimeter on suspicious points to see if there was still contact between traces. I found nothing that really stuck out and the board seemed okay. The thing started and I could hear the iconic bootup sound, but the machine booted up to a blue screen with nothing seemingly happening except for a slight burst of "static" or "jumping" on the screen which to me indicated rebooting. It also seemed that the board could not complete initial ROM or RAM checks. The four LEDs lit up right as the cabinet started and turned off almost instantly, and then none of them ever lit up again.

So i started googling around which lead me to several threads here and I noticed how common it was for the 4116 RAM to fail. I tried turning the game on for a couple of minutes and noticed that all RAMs were cold with the exception of the rightmost RAM in the middle row which instead was really warm. I bought a full set of 24 RAM modules from this place: https://www.sintech-shop.de/en/4116...mtVvwz7C6aTXieFgrc0rEty8s2jn-FNRjEeO852w52m5A

Since I live in Europe it is really hard to come by certain parts here and this seemed to be the best option for me. I got the RAM home yesterday and started off by slotting them into the CPU board and I changed out the 40-PIN cabled between the ROM and CPU boards for good measure. Then I put the board back in a booted the game. The machine started (I wish I took pictures of the screen. The machine is not at my home at the moment. It's standing in a workshop about 15 minutes by car from my home) and I that the blue screen now only made up about a third of the screen with a slight diagonal offset, inside the blue parts I could see small artifacts moving a little along with small black dots. The other 2/3s of the screen was just dark. After about 30-45 seconds I noticed that the ROM board LEDs 1 and 4 were lit up. I looked it up online and first assumed it was complaining that ROM 9 was bad, but a few minutes later I also noticed that lights 1 and 4 being lit may also indicate RAM failure.

So I started taking out the new RAM one row at a time to see if there was any difference. The only thing I saw was the parts of the blue screen started having vertical black lines in it. I also checked the voltage to the RAM by measuring the corners. -5.10 volts, +4.99 and +11.99 which seems fine. So I put all the RAM back in but failed to noticed that I (like an idiot) put the rightmost top RAM in upside down. The RAM chips I bought were not really always clear which way they had to be put in since some has a really thin notch at the top and others had none at all. So I managed to fry one of my new RAM modules when I tried powering the game back on because I was not careful.

So, here I am turning to you. Do you have any pointers on where I should go from here? I am ordering more RAM today, going to have some more modules as spares. I am also aware of the 4164 RAM mod, but I want to try to get the machine in a working order before doing any potential modding.

Summary of things I have tried:

  • Changed the old Linear PSU with a Paradise Arcade Shop PSU
  • Changed the 40-PIN cable between the ROM and RAM board
  • Changed out all the RAM
  • Cleaned and sandpapered the legs on the ROM chips
  • Measured voltage to RAM
Is it possible that the CPU is bad? What about the chip directly under the 40-PIN cable. What is it for? I can't really seem to find any information on it except that it is a 7641 512x8 PROM from the schematics on https://www.robotron-2084.co.uk/hardware/boardset/williams-defender-early-series-boardset.

I have never used an oscilloscope or a ROM writer before and I am getting really lost here on what I should do next.
 
your battery holder is green, cut it off. I can't really tell from the picture but that might be in the traces there. :eek:

if the rom LEDs are all turning on just once that means the 6809 CPU is thinking, which is a good sign. it also means the rom board ribbon cable is mostly working.

the chip below the rom board ribbon cable header is Decoder PROM 1.

your problem is probably with the roms themselves. you can read about the different rom failure symptoms here: https://www.arcaderepair.net/williams-rom-board-information/ in accordance with the 4k files in the MAME rom set roms 2 and 3 are 2532s instead of 2716s, it's my experience these roms have gold contacts and they're very fragile and the legs can break off. if rom 3 isn't working the game's self test won't be able to run. so I would look there first. the old ribbon cables once you start taking the rom/input boards out I would venture the wires break internally and they'll need to be replaced for sure then.

I wish I could help more but I have other things to do now. we can talk later if you find anything.
 
your battery holder is green, cut it off. I can't really tell from the picture but that might be in the traces there. :eek:

if the rom LEDs are all turning on just once that means the 6809 CPU is thinking, which is a good sign. it also means the rom board ribbon cable is mostly working.

the chip below the rom board ribbon cable header is Decoder PROM 1.

your problem is probably with the roms themselves. you can read about the different rom failure symptoms here: https://www.arcaderepair.net/williams-rom-board-information/ in accordance with the 4k files in the MAME rom set roms 2 and 3 are 2532s instead of 2716s, it's my experience these roms have gold contacts and they're very fragile and the legs can break off. if rom 3 isn't working the game's self test won't be able to run. so I would look there first. the old ribbon cables once you start taking the rom/input boards out I would venture the wires break internally and they'll need to be replaced for sure then.

I wish I could help more but I have other things to do now. we can talk later if you find anything.

Thank you for your input. I will remove the battery holder ASAP. The board is cleaned up using IPA. I tried removing all ROMS except for ROM 3, also tried reseating ROM 3. No difference, sadly. Is there any ROM writer that has support for both 2532s and 2716s? I was thinking about checking for bit rot as a next step. What about the Decoder PROM 1? Is it possible to write a new decoder ROM to an empty chip using a ROM writer?
 
Is there any ROM writer that has support for both 2532s and 2716s? I was thinking about checking for bit rot as a next step. What about the Decoder PROM 1? Is it possible to write a new decoder ROM to an empty chip using a ROM writer?

Yes, older programmers will support 2716, 2532 and the prom for Decoder #1,
but those are getting hard to find and sometimes requires an old PC to work.

The "newer" programmers, which often have a USB connection will typically not support those older chips.

My favorite "relic" programmer is the Modular Circuit Technology (MCT) MOD-EMUP

If you can not find a programmer that does what you want, I can provide the chips you are looking for.

Steph
www.Hobbyroms.com
 
I just got a new set of ROMs delivered courtesy of @steph (Thank you!). Sadly I cannot see a difference when trying them out, though I got some new pictures to more accurately document the problem. The cabinet starts with the familiar sound effect and then goes to this blue screen with small black spots. I also noticed that when I start up the screen "scrolls" upwards. You can see the screen "move up" the size of one screen before remaining on this partially blue screen.

The machine also briefly lights up four lights on the ROM board and then almost instantly puts them out (which is normal to my understanding). Then the machine does exactly what I described above and stays that way until I turn it off. ROM board LEDs 1 and 4 light up about 20-25 seconds after turning the machine on.

I should also note that only the ROMs were replaced this time and I still have the old Decoder-1 PROM in machine. Trying to see if he can provide me a Decoder-1 PROM.

May this be entirely related to the Decoder-1 PROM?
 

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Lights 1 and 4 during initial boot indicate you have may still have one or more bad ram (or sockets)

1762520868157.png

Do you happen to have any other williams boards you can swap ram around with? I know its a new set, but you never know.

It could always be a false positive ram error. Meaning there's other bad IC's on the MPU board. The LS373's are culprits a lot of the times. There are others in the chain that I'd have to look up.
 
Last edited:
Which led is #1 versus #4? I've looked all over and couldn't find the answer. Doesn't matter when #1 and 4 are lit up, but it does when it's just one light. 😄
 
Lights 1 and 4 during initial boot indicate you have may still have one or more bad ram (or sockets)

View attachment 860154

Do you happen to have any other williams boards you can swap ram around with? I know its a new set, but you never know.

It could always be a false positive ram error. Meaning there's other bad IC's on the MPU board. The LS373's are culprits a lot of the times. There are others in the chain that I'd have to look up.
Defender used 74374s, but even if they were at fault the game would still boot but just not enter the game and actually say RAM ERROR 11/21/31 depending on which bank the bad 74374 is in. that would also be part of the data bus, this issue could have something to do with addressing. but I would think the pattern would be a little uglier and more broken. lol

the LED codes can be a little misleading too, because I think they'll represent either ram or rom faults. this problem could be a bad ribbon cable. there's a number of things that could be at fault that I can't tell because I'm not there to see it. :(

Which led is #1 versus #4? I've looked all over and couldn't find the answer. Doesn't matter when #1 and 4 are lit up, but it does when it's just one light. 😄
1/2/3/4

I just got a new set of ROMs delivered courtesy of @steph (Thank you!). Sadly I cannot see a difference when trying them out, though I got some new pictures to more accurately document the problem. The cabinet starts with the familiar sound effect and then goes to this blue screen with small black spots. I also noticed that when I start up the screen "scrolls" upwards. You can see the screen "move up" the size of one screen before remaining on this partially blue screen.

The machine also briefly lights up four lights on the ROM board and then almost instantly puts them out (which is normal to my understanding). Then the machine does exactly what I described above and stays that way until I turn it off. ROM board LEDs 1 and 4 light up about 20-25 seconds after turning the machine on.

I should also note that only the ROMs were replaced this time and I still have the old Decoder-1 PROM in machine. Trying to see if he can provide me a Decoder-1 PROM.

May this be entirely related to the Decoder-1 PROM?
you'll always hear the power on sound when you turn the game on because the sound board operates independent of the MPU.

and there's an outside possibility you could have a bad decoder 1.
 
Lights 1 and 4 during initial boot indicate you have may still have one or more bad ram (or sockets)

View attachment 860154

Do you happen to have any other williams boards you can swap ram around with? I know its a new set, but you never know.

It could always be a false positive ram error. Meaning there's other bad IC's on the MPU board. The LS373's are culprits a lot of the times. There are others in the chain that I'd have to look up.

Just got into this hobby and this is my first project (Might be a bad project for a newbie. But I got the machine for free). So I sadly don't have any spare boards to test the RAM in. Though I am considering getting a RAM tester just to rule out bad RAM modules. At least all the new ones are getting warm, while all the old ones except for one were cold as ice even after having the game on for several minutes.

Defender used 74374s, but even if they were at fault the game would still boot but just not enter the game and actually say RAM ERROR 11/21/31 depending on which bank the bad 74374 is in. that would also be part of the data bus, this issue could have something to do with addressing. but I would think the pattern would be a little uglier and more broken. lol

the LED codes can be a little misleading too, because I think they'll represent either ram or rom faults. this problem could be a bad ribbon cable. there's a number of things that could be at fault that I can't tell because I'm not there to see it. :(


1/2/3/4


you'll always hear the power on sound when you turn the game on because the sound board operates independent of the MPU.

and there's an outside possibility you could have a bad decoder 1.

I won't rule out that the ribbon cable might still be bad as I only swapped out the actual cable. Might be one or more cables that have a bad connection. I have a new entire set coming with the with new connectors as well. So I am swapping out the entire thing soon and soldering an entire new connector to the ROM board. I also have a new Decoder on the way.

What would you suspect if the new Decoder-1 and the new Ribbon cable don't do the trick? Am I right in assuming that the problem would most likely reside on the CPU board?
 
Just got into this hobby and this is my first project (Might be a bad project for a newbie. But I got the machine for free). So I sadly don't have any spare boards to test the RAM in. Though I am considering getting a RAM tester just to rule out bad RAM modules. At least all the new ones are getting warm, while all the old ones except for one were cold as ice even after having the game on for several minutes.



I won't rule out that the ribbon cable might still be bad as I only swapped out the actual cable. Might be one or more cables that have a bad connection. I have a new entire set coming with the with new connectors as well. So I am swapping out the entire thing soon and soldering an entire new connector to the ROM board. I also have a new Decoder on the way.

What would you suspect if the new Decoder-1 and the new Ribbon cable don't do the trick? Am I right in assuming that the problem would most likely reside on the CPU board?
yes I can't say definitively because I'm not there to see it but there's always a potentiality that you have an address bus issue where the rom data isn't getting to the DRAM section. it's not a very common failure I've seen but I have had boards where the 74367 address buffers around the MPU 6809 CPU (there's 3 of them) have gone bad. I don't know the science or logistics behind how the MPUs arrive at their default screen patterns, some are like a solid color screen, some are alternating color bars. (which I think represent the sections of the DRAM banks)

I would think though if it were an addressing issue you would just have solid color lights on the rom board. the CPU wouldn't be able to talk to it at all. so you could just have a bad Decoder 1 as that ties to the DRAM side. if it were a Stargate or Robotron you would see a 1-3-1 or sometimes 1-3-2 error in that instance.

was any previous solder work done to the MPU? like new sockets anywhere?

back when I'd get boards in to fix the first thing I would do is take all the 4116 rams out and set them to the side in the order I took them out of the banks. then you inspect each chip one by one to make sure the legs are straight. 45 degree bends suggest they were yoinked out from only one side and the opposite end comes out bent. another leg anomaly is the legs will have squiggles in them, which I think is from many years of just pressing them back into single wipe sockets. I use pointy fine pliers for straightening these out. I then flip flop the rams around, like bank 3-2-1 -> 1-3-2 so they're positioned in unique spots, then you test again to see if the game boots properly. with Defender I think you need at least rams 31-34 working to get any activity during the rug pattern POST sequence, otherwise it will be black or maybe solid color screen. Defender is tricky for identifying ram errors because it doesn't explicitly call it out with 7 segment display on rom board like Stargate and later games, it has that secret decoder ring LED code thing. and if you have a bootable game it will just say "INITIAL TESTS INDICATE RAM FAILURE" and it won't say the bad ram -- you have to press the Auto Up switch to the Manual Down position and press Advance to enter test mode and then it will say which ram is showing bad. and the ram failure messages go in order and stop on the first one found.

the test order is bank 3 ram 1 to 8 (1-3-1 is first) -> bank 1 ram 1 to 8 -> bank 2 ram 1 to 8 (1-2-8 is last)

so I suggest pulling rams 31-34 out and robbing from like 25-28 to put in their place to see if you at least get a rug pattern then. this is also mass speculation and spitballing because I don't have the game in front of me. I think it would be a lot of fun to figure out what's wrong. lol it's also time for me to rest for awhile 😴
 
yes I can't say definitively because I'm not there to see it but there's always a potentiality that you have an address bus issue where the rom data isn't getting to the DRAM section. it's not a very common failure I've seen but I have had boards where the 74367 address buffers around the MPU 6809 CPU (there's 3 of them) have gone bad. I don't know the science or logistics behind how the MPUs arrive at their default screen patterns, some are like a solid color screen, some are alternating color bars. (which I think represent the sections of the DRAM banks)

I would think though if it were an addressing issue you would just have solid color lights on the rom board. the CPU wouldn't be able to talk to it at all. so you could just have a bad Decoder 1 as that ties to the DRAM side. if it were a Stargate or Robotron you would see a 1-3-1 or sometimes 1-3-2 error in that instance.

was any previous solder work done to the MPU? like new sockets anywhere?

back when I'd get boards in to fix the first thing I would do is take all the 4116 rams out and set them to the side in the order I took them out of the banks. then you inspect each chip one by one to make sure the legs are straight. 45 degree bends suggest they were yoinked out from only one side and the opposite end comes out bent. another leg anomaly is the legs will have squiggles in them, which I think is from many years of just pressing them back into single wipe sockets. I use pointy fine pliers for straightening these out. I then flip flop the rams around, like bank 3-2-1 -> 1-3-2 so they're positioned in unique spots, then you test again to see if the game boots properly. with Defender I think you need at least rams 31-34 working to get any activity during the rug pattern POST sequence, otherwise it will be black or maybe solid color screen. Defender is tricky for identifying ram errors because it doesn't explicitly call it out with 7 segment display on rom board like Stargate and later games, it has that secret decoder ring LED code thing. and if you have a bootable game it will just say "INITIAL TESTS INDICATE RAM FAILURE" and it won't say the bad ram -- you have to press the Auto Up switch to the Manual Down position and press Advance to enter test mode and then it will say which ram is showing bad. and the ram failure messages go in order and stop on the first one found.

the test order is bank 3 ram 1 to 8 (1-3-1 is first) -> bank 1 ram 1 to 8 -> bank 2 ram 1 to 8 (1-2-8 is last)

so I suggest pulling rams 31-34 out and robbing from like 25-28 to put in their place to see if you at least get a rug pattern then. this is also mass speculation and spitballing because I don't have the game in front of me. I think it would be a lot of fun to figure out what's wrong. lol it's also time for me to rest for awhile 😴

Thank you for the detailed response!

No, I don't see any indications of any previous solder work on any components besides the old Linear PSU. There was a nasty burn through the board where the capacitor is sitting near the fuses. Someone had repaired this by creating their own traces and soldering the capacitor to those new traces.

I will replace the Decoder-1 and the entire ribbon cable setup when they arrive and report back. I will also try what you suggested about the RAM. Thank you once again for all the great input, mecha!
 
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