(Topic ID: 234410)

Gottlieb System 1 not booting, testing MPU - Totem

By shaundburch

4 months ago

Topic Stats

  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 24 days ago by shaundburch
  • No one calls this topic a favorite


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#1 4 months ago

I'm working on a Totem that won't boot. Rebuilt the power supply and all the voltages look great. Walking thru Clay's guide, I also verified the voltages are correct on the MPU (+5 and -12 at the two caps).

Everything looks good up to the point where you're supposed to check for pulses on T1, connections 1 - 13. On the first 5 connections, I get a nice pulse. After that, it's either not pulsing at all or it's pulsing so fast that I can't see it changing. The amber light on my logic tester is just locked on.

From my perspective, it sounds like the board is a goner but I wanted to see if I could get some second opinions before I buy a new board.

Thanks. Any input is appreciated.

#2 4 months ago

Looking through Clays guide I see this for TC1 "This is done at TC1 pins 1-13. Use an o'scope or logic probe looking for pulsing lines. If there's no pulsing, the Rockwell spider chip(s) are bad, and again the story ends here (buy a NiWumpf or Pascal CPU board)."

Sorry looks like that board is done. I've used several pascal boards and they are excellent.

#3 4 months ago

Thanks, appreciate the input! Yep, you are correct....TC1...not T1

I wasn't sure if the "no pulsing" meant a solid light on the logic probe or no light at all. Either way I guess that's not a pulse .....so a new board it is.

3 months later
#4 24 days ago

Just to close this one out. My guess is the previous owner plugged the bottom power supply connection in upside-down.

- The power supply was in bad shape, so I rebuilt that
- The MPU failed the testing steps outlined in Clay's guide...spider chips were bad. I ordered and installed a Ni-Wumpf MPU board.
- The driver board was cooked in one spot, I mean the board was actually blackened and warped. Ordered a rebuilt board from nabours on ebay (great guy), and installed that.
- One of the displays appeared to be dead, so I was worried about having to replace it. I found the information about recharging a display, and gave that a shot with my variable power supply. Wow! Crazy stuff. Felt like Dr. Frankenstein...lol. It came right back to life and looked fantastic. I had to recharge the others after that so they would all look as nice.

I dialed in the power supply and everything came up great. At first I was concerned because it wasn't working properly, then realized I hadn't set the game yet. LOL.

Just for grins, I plugged in the original MPU to see what it was doing. On startup, all the coils immediately locked up and it was in tilt, so confirmed the board is bad.

Thanks to everyone who has made the parts and information available to fix something like this. It really is a credit to the hobby (obsession? sickness?)

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