Robotron fails to properly startup

[otifrank]

Hello all.

I have a Robotron 2084 that I've owned for quite a while and only recently caught the bug to start trying to play again. Upon attempting to start the machine everything appears to go okay up until the initial loading screen(s). I get video and can observe the normal standard Williams first screen (rug) that is the scrambled looking screen. This screens stays for a few moments and the the monitor goes black as if it was about to actually load the game but, then the scrambled screen returns and this process just repeats.

Did a small amount of Googlin' and saw some articles that mentioned DRAM replacement as a possibility. I am a total "newb" on the electronics front and wouldn't really have a clue how to do this.

Can anyone provide advice on how I should proceed or what I might be able to learn to do to "fix" this and get the game to a playable state again?

Thanks.

[iankellogg]

There is a lot that goes on with these boards. I would start with the simplest thing and check/replace the NVRAM battery. If its the original AA batteries those need to be checked and changed every year to avoid damage to the board. If its a Lithium coin battery just need to check and replace when dead. sometimes the game can do weird things when the ram battery is dead, take a look at that first.

If you replace the battery and are still having issues I would peak at the LED screen on the PCB and look at what the error is, look at the manual in the self test section for instructions.

[otifrank]

So, I looked and there are batteries. Looks like 3 AA's. I was not able to remove them with just light to medium finger pressure and was scared to try to use a screwdriver to pry with. I figured that might not be a great idea. Can you recommend the best way to try to remove the batteries? Do I need to remove the mainboard from the back panel to do it?

Also, I can see the L.E.D. on the mainboard flashing 1 then 3 then 1. I looked in the manual but am a tad confused about what exactly the code means. I see one code that looks like maybe a bad RAM chip in Bank 3 Slot 1 but, then there's another code later in the table that to me looks like it could be the batteries, as you previously suggested. I'm unsure of how to proceed.

[iankellogg]

i usually just use a flat head screw driver . You won't hurt the batteries and at worse you will break the plastic which is replaceable

[otifrank]

ok. I got the batteries out and replaced them. No joy. 
The LED displays 1, then 3, then 1 and then repeats 1,3, and 1 and then it goes blank for a second followed by 1 and then 0 then the rug pattern on the crt goes black for a moment. The sequence then repeats.

From the manual, to me, this code seems to be suggesting a bad RAM chip. As I'm a total newb on the electronics front, this might be more than I know how to handle at the moment. Should I be looking at getting a local company to service the machine or is there some other way I should go?

Appreciate whatever advice you might offer.

[iankellogg]

So that means bank 3 ram chip 1 is bad (maybe). Williams are notorious for reporting ram errors incorrectly. The first thing I would do is reseat all of the ribbon cables on the CPU board, this probably won't fix it though and is just a good practice since this game is so picky. Next I would start considering some mild board debugging. One easy thing to test is to take out the ram chip under question and swap it with another ram chip on the board. If the ram error follows the swap then you need to buy a new ram chip. If it doesn't follow then there is something wrong with the PCB and board repair is required.

[otifrank]

Thank you so much for your guidance to this point. I truly appreciate it. I can certainly attempt to re-seat all of the ribbon cables with out much effort. As you point out, it couldn't hurt.

With respects to taking the RAM chip out and swapping it around, would I need to de-solder the RAM chip(s) to do this? I have never, ever, soldered before and therefore don't have the confidence to do so to the pcb. If I wouldn't need to solder/de-solder, would I need any sort of special chip pulling tool that you could recommend?

As far as if it comes down to board repair, would you or anyone else have any recommendations for someone trustworthy enough to send the board out to?

[iankellogg]

For the ram chip it depends if it is socketed or not. Sometimes they are, sometimes they are not. You would have to just take a peak and see if it is already socketed. You shouldn't be afraid of soldering, it's pretty much impossible to be in this hobby without owning a soldering iron and a multimeter. So better to start early, or I hope you have a lot of money to pay someone every time your game breaks down.

There aren't that many places left that offer repair services.

[otifrank]

You are right, I need to not be intimidated by soldering and I intend not to be in the not so distant future, it's just that I don't think it would be a great idea for me to try the soldering on the actual game board as a first effort.

Before I go poking about any deeper, does anyone with an actual Robotron machine know off the top of their head if the RAM chips are socketed or soldered? Certainly someone must have experience with this? If they are indeed socketed, do I need any specific tool to pull the RAM chip or will they come out by "hand"?

Thanks for any information that anyone is willing to share.

[iankellogg]

Just open the door and take a peak. I believe they are socketed, its been a while since i have looked at my boardset

[Kevsarcade]

Ive been working with a bunch of these williams parts lately as I am restoring a Robotron and I can tell you the first thing you need to do is check your power supply voltages. Especially the +5, if this get low it cause problems just like you have described and is a very common issue due to the age of the capacitors, connectors, the bridge rectifier and other parts. From what i've seen, once you get below about 4.9 volts, you start to get Dram errors because they are not seeing the proper voltage. If your voltage is slightly to low, like maybe 4.88 volts, you can pull one leg of resistor R10 on the power supply board and it will raise the voltage about 1/10th of a volt. If you are way low on voltage, try swapping in a switcher, this is a pretty rock solid fix and direct change over kits are available on the net. Do not start pulling rams with out at least checking your voltages, also you should see 3 LED's lit on the PS board, if not the PS is definatley your problem. The Robotron manual has a ton of valuable trouble shooting info as well.