robotron help needed!! garbled scores and reset

Slo

Member

Donor 2011
Joined
Jul 19, 2011
Messages
495
Reaction score
5
Location
Ohio
My Robotron cabaret has developed an issue!!! When the Hi-score table comes up after turning it on it displays garbage. It then cuts to attract mode where the writing is also garbage. When it gets to the title screen it is displayed in fragments and then resets to the carpet pattern. I'm getting 4.7V at the ram. The rom board displays a zero as it should. I have upgraded the ram and battery some time ago. It has the original power supply. Has anybody come across this? Any suggestions? Help!!!
 

Attachments

  • 021913 029.jpg
    021913 029.jpg
    98.7 KB · Views: 24
  • 021913 036.jpg
    021913 036.jpg
    101.5 KB · Views: 16
  • 021913 040.jpg
    021913 040.jpg
    97.6 KB · Views: 12
  • 021913 042.jpg
    021913 042.jpg
    100.8 KB · Views: 12
Very 1st thing I'd do is address the low voltage issue. 4.7V isn't enough.
 
Very 1st thing I'd do is address the low voltage issue. 4.7V isn't enough.

I guess I'll stick a switcher in it for the extra control. I read some where that it's normal for a .5v drop from the ps to the ram. The spec sheets for the ram are 4.5v to 5.5v. The power supply was rebuilt with bobs kit.
 
I guess I'll stick a switcher in it for the extra control. I read some where that it's normal for a .5v drop from the ps to the ram. The spec sheets for the ram are 4.5v to 5.5v. The power supply was rebuilt with bobs kit.

The RAM itself may be fine for 4.5 - 5.5, but most TTL (logic) datasheets say 4.75-5.25. I doubt your voltage is significantly different on nearby TTL chips... which is why I said it sounds low.

Before going through the trouble of changing power supplies... perhaps check/clean the 0.156" pins that bring power; check/re-pin the connector; and make sure the solder joints on the power header aren't cracked. 0.5V drop from the PS to PCB sounds like a bit much to me...
 
The RAM itself may be fine for 4.5 - 5.5, but most TTL (logic) datasheets say 4.75-5.25. I doubt your voltage is significantly different on nearby TTL chips... which is why I said it sounds low.

Before going through the trouble of changing power supplies... perhaps check/clean the 0.156" pins that bring power; check/re-pin the connector; and make sure the solder joints on the power header aren't cracked. 0.5V drop from the PS to PCB sounds like a bit much to me...

Cool. I'll pull the boards and take a look. Thanks for the help.
 
Darren has it on the money. Even if the low voltage isn't the main problem, you can't get far without addressing that first. I would check and/or replace all the power connectors, Bob Roberts sells a kit or Robotron.
 
My Robotron cabaret has developed an issue!!! When the Hi-score table comes up after turning it on it displays garbage. It then cuts to attract mode where the writing is also garbage. When it gets to the title screen it is displayed in fragments and then resets to the carpet pattern. I'm getting 4.7V at the ram. The rom board displays a zero as it should. I have upgraded the ram and battery some time ago. It has the original power supply. Has anybody come across this? Any suggestions? Help!!!

Darren has it on the money. Even if the low voltage isn't the main problem, you can't get far without addressing that first. I would check and/or replace all the power connectors, Bob Roberts sells a kit or Robotron.

Emailing Bob as we speak. I will get the voltage under control and report back. thanks Darren and Logical.
 
Also, pull the batteries - wait 5 minutes - then reinstall and try again. Go into the menu and reset the settings.

Sometimes low battery voltage causes corruption in the CMOS memory and give you garbage on the scores/settings, and sometimes sets the setting at ridiculous levels like 200+ lives, etc...
 
SUCCESS.... sort of

My Robotron lives!!! I'm not sure I fixed it though:( I rebuilt the power supply board and replaced all headers and connectors aside from the rom board ribbon. While I got my voltages back in line, my garbled graphics and resetting persisted. I socketed and replaced 6E, 6J and 4E as well as replacing the transistor at Q1. Still no love. Swapped special chips on the rom board with an untested spare..... no go. I swapped rom boards only to find roms 1, 3 and 4 were bad on the untested board. After replacing the bad roms she fired right up!!!! Swapped rom boards back and she fired right up. I played a couple of games and power cycled a few times.... all is well. Now this has me concerned as I can't duplicate the trouble. I'm thinking the ribbon cable for the rom board may need replacement. If it acts up again I'll probably start there. Anyhow, thanks for the responses DarrenF, Logical Highs and Modessitt. I was definitely starting off on the wrong foot by overlooking my low voltages. Thanks again.
Mike
 
Last edited:
Back
Top Bottom