Robotron won't boot up

turkeybones

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So, I don't have a lot of technical knowlege with this stuff, so bear with me. I have an original dedicated Robotron upright that I've had since like 1996 and has never really worked right. It goes in and out of storage until I decide I want to try and tackle it again.

The current problem is that it won't even get past the rug test. I thought it might be a bad power supply, so I just installed an upgraded power supply and the 4164 RAM that was included with it, and it still does the same thing. Anybody have any ideas or maybe someone can point me in the right direction? It used to play fine, but would randomly reset and would give me an occasional RAM error. Any help would be greatly appreciated, I would love to get this thing working properly.

Thanks!
 
I don't know much about Robotron, but if it won't even boot into a self-test then maybe it's a PCB issue? Or perhaps the cables connecting the power supply to other parts of the machine are loose?

Have you tried using a multimeter to see where the power is being redirected? You can use a multimeter or a logic tester to see whether electricity is actually reaching any of the parts of the machine. That's what I'd advise trying.
 
If I remember correctly, those machines take 4116 RAM not 4164 RAM unless someone has done the socket swap. If you recall seeing it working before, are you sure you didn't pull out the original 4116's and replace them with the 4164 chips in error?

I'm also trying to remember if that machine gives you a series of lights on what's working versus what's not (LEDs in the cab). It's either that machine or Defender, I might be getting them confused.
 
There are a few ways to use 4164s...

1. Cut / jumper the power on the board... this involves physically altering the cpu board. (yuck)
2. Lift pins on the ram chips themselves, and apply jumpers (yuck)
3. Install a power adapter on the molex header which involves no changes to the board or RAMs (yes)

Hopefully your new power supply has been wired such that the equivalent of #3 is done.

Unlikely it is wrong if you are seeing a rug pattern anyway... it would look really bad if the RAMs were toasted.

Check the 40P ROM board ribbon cable going to the CPU board... re-seat it. For that matter re-seat all of the connections on the thing.
 
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As Retro said, if the power supply was not set up for 4164s, you would smell it a mile away.

Check on the ROM board, there is a 7 segment LED that should be flashing 3 digits. These are the diagnostic codes for what is wrong. Based on your description, it sounds like it will be flashing a 1-x-y number where x = row and y = chip number of a bad RAM chip. You can validate that it is the chip by carefully removing it and swapping it with one of it's neighbors. If the error moves to the new position, it is a bad chip. If it stays, then there may be a number of other uglier problems.

ken
 
HAHA!!! It works!!! Unplugging everything and plugging it back in actually worked!!! I love it when a solution is that simple, and cheap!!

The power supply and RAM I got from someone on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190401868839

The only tricky thing with it is that I can't use the game's on/off switch anymore, and I lack the know-how to rewire anything. The only thing that didn't work was the sound, but I had an extra Defender sound board that I put in and it seems to work ok, except some of the sounds are different. Anybody know if there is a way to fix that?

Thanks for all the responses, this forum is great for those of us who love to play the classics but don't have much technical experience.
 
HAHA!!! It works!!! Unplugging everything and plugging it back in actually worked!!! I love it when a solution is that simple, and cheap!!

The power supply and RAM I got from someone on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190401868839

The only tricky thing with it is that I can't use the game's on/off switch anymore, and I lack the know-how to rewire anything. The only thing that didn't work was the sound, but I had an extra Defender sound board that I put in and it seems to work ok, except some of the sounds are different. Anybody know if there is a way to fix that?

Thanks for all the responses, this forum is great for those of us who love to play the classics but don't have much technical experience.

You just bought and installed the biggest piece of shit possible for that poor Robotron. The sound errors are due to having the incorrect sound ROM on the sound board.
 
HAHA!!! It works!!! Unplugging everything and plugging it back in actually worked!!! I love it when a solution is that simple, and cheap!!

That probably means that the ribbon cable between the ROM card and the MPU board needs to be re-crimped.

The power supply and RAM I got from someone on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190401868839

The only tricky thing with it is that I can't use the game's on/off switch anymore, and I lack the know-how to rewire anything.

I was afraid you had done that. If you have the original power supply board and heat sink, there are several of us that rebuild them so that your game stays original. The RAM is not as big an issue, but there are several problems with switching power supplies that will cause problems with saving high scores and/or your game settings.

The only thing that didn't work was the sound, but I had an extra Defender sound board that I put in and it seems to work ok, except some of the sounds are different. Anybody know if there is a way to fix that?

Yes, but it would probaby stretch your technical capabilities. You would need to desolder some jumpers and then resolder them into different locations. You would also need to get the correct Robotron sound ROM and install it. Again, there are several of us that can do this if you don't feel up to it.

ken
 
I didn't realize that switching power supplies was frowned upon so much. It was just a shot in the dark on my part to try and fix my non-functioning game, but now that I know the boards seem to be working properly maybe I'll put the 4116 RAM back in and hook up the old power supply.

I used to get a lot of random resets with this game, which was what led me to believe it might be a power supply problem. I've had this game since 1996, in and out of storage, and I don't think it's ever worked 100%.
 
I didn't realize that switching power supplies was frowned upon so much. It was just a shot in the dark on my part to try and fix my non-functioning game, but now that I know the boards seem to be working properly maybe I'll put the 4116 RAM back in and hook up the old power supply.

I used to get a lot of random resets with this game, which was what led me to believe it might be a power supply problem. I've had this game since 1996, in and out of storage, and I don't think it's ever worked 100%.

Definitely pitch that switcher!!! Rebuild your power supply or have one of these gents do it.
Don't put 4116s back in keep the 4164s, they run cooler and therefore are more robust (no random resets)... however you will need to make one of these:
http://www.robotron-2084.co.uk/techwilliams4164.html
to use your original power supply with the 4164s.
 
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Is there anywhere that I can buy one of those adapters? Or perhaps I could enlist the services of someone on here to build me one?
 
There are a number of possibilites for why your system has been rebooting. An old power supply board is usually one of the first things to look at. Just because the 3 LEDs light up does not mean that it is working correctly. If you have not done anything with it since the 90's, there is a good chance that it will need a cap kit.

Also the original wiring harness has been known to cause issues of voltage drop from the power supply to the game boards due to oxidation on the header pins, connections to the wire in the connector coming loose and other problems.

The most common problems with switching power supplies and Williams games revolves around a quirk in the 6800 family of CPUs and the CMOS used to store high scores and game settings. When the supply voltage to a 6800 CPU (the Williams boards use a 6809 which is in the same family) drops below a threshold value (typically 4 volts or so), it begins to write random values through the memory space. If that write happens to hit a ROM, it is ignored, they are ReadOnlyMemory anyway. If it hits RAM, no problem, the RAM will be refreshed the next time it is powered on anyway. If it hit the CMOS, ooooohhh Mission Control, we have a problem! That random write could change the number of lives you get when you start, change it out of free play, wipe out your high score table, etc. The answer the Williams engineers came up with was to stick a large capacitor on the +5V power supply and to add a CMOS write protect circuit on the MPU boards that triggers when the 12V unregulated power drops. When the power is shut down, the big capacitor drives the CPU for a few miliseconds after the 12V unregulated goes down. This gives the CMOS memory protect circuit time to kick in and protects your game settings and high scores. Switchers do not have that time delay. When +5V goes down, the +12V goes down at the same time, which does not always give the memory protect circuit time to kick in. If the CPU spews into the CMOS area, bye bye saved stuff.

The other reason there is some hostility towards the vendor you bought from is just that he plays on the ignorance of non-technical users. He is right that new RAM and a new power supply will fix a significant number of the issues some of these older games are having. Much the same way lifting up the radiator cap and sliding a new car under it will fix most car issues. It is overkill. The original power supply lasted 25+ years. With a little rebuilding, and $10 or so in parts, it should last another 25 years. We won't get into the ethics of selling you $12 worth of RAM, $5 worth of wire and $15 worth of power supply for $90 plus shipping for something that will sooner or later trash your scores and/or settings ;).

ken

PS: Dockert and I both rebuild Williams power supplies if you don't feel up to the task. PM us fr details. Otherwise, Bob Roberts sells rebuild kits that cover the basics if you want to try it yourself.

You don't have your location in your header, so it is hard to see if there is anybody else near you that can help. Poke around in your profile and you can see where to set your location, believe it or not, that does help.
 
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