robotron

blitz_8255

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Working on one of these that keeps coming up with "default settings open door and turn game off and on " All the switches work after I rebuilt the interface board. Found that the battery holder was bad so I replaced it, and now get proper voltage to the cmos ram H4334. I can get into setup and test but it won't let me change the cmos settings. When the screen is displying the" reset cmos" screen I can push the test switch and the game comes into attrack mode, pushing it again it goes into test. When trying to coin up iit makes the sound but doesn't add a credit everytime, then the number will jump by many. If I start a game it wil play just fine. Any ideas as to why I can't change the cmos settings??
Thanks for any help!
 
The CMOS could be simply holding corrupt data.
Remove the battery, reboot without the battery and see if you can alter settings that way.
Once you're good, re-insert the battery.

The other problem that you could be having is that you just have a bad CMOS and it might need to be replaced. I've seen the game do even more funky things than you're describing with a failing CMOS.
 
Thanks for the help! The remove battery trick didn't work so I have a cmos chip on the way from flea-bay. <$9 to my door! I'll let you know what happens.
 
Thanks for the help! The remove battery trick didn't work so I have a cmos chip on the way from flea-bay. <$9 to my door! I'll let you know what happens.
Note, there was a guy on klov (here) who was selling adapters that allow you to replace the cmos ram with a battery-backed sram. Great solution because it completely eliminates the need for batteries. You might want to skip the cmos ram and go for something like this. Or at a minimum install a socket so it's easy to switch later.
 
Note, there was a guy on klov (here) who was selling adapters that allow you to replace the cmos ram with a battery-backed sram. Great solution because it completely eliminates the need for batteries. You might want to skip the cmos ram and go for something like this. Or at a minimum install a socket so it's easy to switch later.

If the new chip fixes my problems, that sounds like a good idea! Thanks
 
The self-test checks the CMOS, what does the self-test show? There is a connector on the main board (4 pin if I recall) which the interlock connects to. Remove it to disable the interlock test.

Kirk S.
 
I'm going back on Tuesday to see exacty what the screens says about the cmos and to unplug the interlock switch. Are you talking about the one at the coin door?
 
I'm going back on Tuesday to see exacty what the screens says about the cmos and to unplug the interlock switch. Are you talking about the one at the coin door?

Actually, it is on the large (CPU) board. The interlock is there to prevent game settings from being changed if the game were to somehow get into the book keeping area during use. Unless you plan on putting the game on a location, it is not necessary.

Kirk S.
 
Self test says cmos is good!? And that all ram are good?! If I unplug the 4 pin connector, the games still says that factory settings have been restored and to open the coin door and restart the game. It says that with the door open or closed when powering up , or with the 4 pin, ( 1 wire ), connector removed from board. All kinds of confused now. I think I'm going back Friday for another round after I change the chip.
 
Do you have the original Williams battery holder on the board or have you done the lithium battery mod?

If you are still using the original Williams battery holder, I would say that is also suspect. If you have three batteries in there, you should be reading about 4.5vdc. Many times the posts stop making contact with the batteries and that will break the circuit.

Broken battery holders and dead batteries will also cause that error message.

I highly recommend doing the lithium battery mod that uses a CR2032 lithium battery in place of AA's - no more worries of leaky batteries and acid damage to the pcb once done.
 
Thanks Muel. I've already replaced the holder, it was bad, and now I've replaced the cmos. I hope to get the chance to test it soon, The boss lady has been keeping me very busy lately! Remodleing projects!!
 
In the CMOS protection circuit there are a couple of gates between the memory interlock wire and the CMOS chip. You may need to use a logic probe and make/break the contact to follow the circuit to validate that the gates are acting correctly.

ken
 
Thanks YellowDog! I see a 2 input OR gate at 6E and a 3 input NAND at 6I. Are these the ones in question? I've been down with that nasty stomach bug and am just getting off my ass ( literally ) and back on my feet. I'Ll take the probe with me tomorrow and due some testing. Is it posible to defeat the door switch/OR gate by tying the input high or low?
Once the cmos is set to what you want, can the" NOT WRITE ENABLE" line be pulled to the proper level to not allow re-writeing of the cmos?
 
Those are the ones. I normally just use a jumper cable to clip pin 1 and pin 3 of the memory protect header. It is easier than opening and closing the coin door while testing the board with a logic probe. I put the logic probe on pin 4 of 6E to watch the pin go low when jumpering the mem prot header. Then I check pin 6 of 6E then pin 5 of 6I followed by pin 6 of 6I. That should allow you to walk the whole path to the CMOS write enable.


ken
 
Interesting... When I jumped pins 1 & 3 my probe didn't change at pin 4 of 6E. I used my voltmeter to see if the voltage was changing, it was but from .4 to 1.3, not enough for TTL lo/hi change. With the pins jumped the game booted, but had the reset message so I jumped pin 1 to +5 and voila the game would let me program and when I was done programing it I removed the jumper and it's been working great ever since. I cycled power a few times and have had no issues, even played a few games, much harder than I remember. After further testing I found the door switch to be faulty. Thanks for all the help, Robotron lives on!!
 
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