TECH: Robotron problems

cynic1

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Donor 2011
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Hello,

I was hoping someone on here might be able to help me out. My Robotron is giving a 1-3-8 error code. Sometimes 1-3-1. Even sometimes a 0-6-2. Which is odd because I thought 0 was for Sinistar. Now I've checked the voltages at the RAM. Pin 1 is giving me -5, that's fine. BUT Pin 9 is also giving me a -5 (when it should be a +5). Pin 8 is giving me .02 volts. Far from +12. All voltages are strong at my PS. My ROM's are giving me strong +5. Any help would be greatly appreciated.

Thanks,
Shawn
 
Assuming this was a working machine that just failed?

If that's the case I would start by reflowing the pins on the main PCB, Rom board and possible the sound board.
 
There can be several causes of this:
(1) The RAM chip you are checking may have a little corrosion on it. This will distort the voltage readings.
(2) There may be some corrosion on the header pins of the CPU board.
(3) One (or more) of the filter capacitors (the small electrolytics near the power header, 100mfd at 25V) may be bad and leaking.
(4) There may be a break in one of the wires in the power cable .
(5) One of the wires may have come loose in the power connector.
(6) Your power supply may be providing the correct voltages with no load, but the voltages go lower when the boards ae plugged in. If you have the original linear power supply, watch the 3 LEDs on the power board to see if they are all on when the boards are all plugged in.

ken
 
MonsterBash & YellowDog have the right questions and repair steps, if the machine was working and now is not.

If you got the machine in it's current state, you need to back up and take stock of some things:
1) Is the power supply putting out the correct voltage on the correct pins (unplug from game boards to prevent further damage while testing)
2) What kind of RAM chips are on the CPU board? 4116 or something else, like 4164?

Not sure of your level of experience, so I will recommend the following thread:
http://forums.arcade-museum.com/showthread.php?t=177192
 
Robotron Problems

Hello,

Thanks to everyone who posted responses to help me get my Robotron to live again. That's cool. Okay, here's the current state. This game was converted. I repainted the cabinet and free hand painted the artwork back on, but that's neither here nor there. I bought all boards, a while ago, on Ebay. Posted as working, but... I don't think so. I did desolder and flow new solder to every connector pin on all 4 boards. I have a switcher installed with Arcadeshop's connector. The original 4116 RAM's kept giving me the same 1-3-8 error code. I bought Bob Roberts upgrade to the 4164 RAM's with the adaptor. I removed the RAM socket at 3-8. Installed a new one. Just bought the 4164 from Bob. After all that, fired it up... Same 1-3-8 error code. Same -5 at Pin 9. I'll change the filter caps. That seems to be my last hope for why the board gives -5 at Pin 9 on the RAM and a solid +5 at the ROM on the same damn board. Once again, thanks for everyone's help.

Shawn
 
It has been a while since I looked a one of Bob's adapters, but as I recall, it does not pass -5 to the CPU board at all. Make sure the adapter is in place. It is very easy to pull it off and forget to put it back on (been there done that, got the t-shirt and a tube of dead 4164s).

Otherwise, that sounds suspiciously like one of the address decode chips has gone bad.

ken
 
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