Ugh. Robotron.

jonathan1138

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Ok - Bit of a mess here.... Need assistance / direction please on this Robotron Mini.

When i got the machine, CMOS error which was not saving settings... sent the board out for repair, just got it back. In the meantime, needed a new monitor - so, during the wait put in a 13 inch WG.

Installed the new boards, along with running that monitor (leads into Iso Transformer / wire this up to the Power supply). The game does not have original Power supply - it has this updated power supply in place.

Turn on the game, see the boards are not getting their juice. There is a Pot on the powersupply that allows me to adjust up to 5 volts. Turn that Pot. Now i have concerns.

I get "Rom ERROR 32" and constant reset, Which, i see can be related to either bad chip (i should swap) OR not getting proper power.

In addition to that, the monitor shows only during an exact mid point of the pot - if i turn that pot to give the boards more power, the picture leans torwards distortion with lots of purple (garbage). Also, the monitor always has this purple line down the center that i dont know how to get rid of...even when at the mid point of the 5 volt pot on the powersupply.

So, some Questions that will hopefully lead to resolve (seems far off!):

1. Could i have damaged the boards (Roms) by adjusting that Pot for voltage? Over volt?

2. Something feels out of place - why is the monitor adjusting the pic when i give it more volts (again, the picture gets more purple when i feed it more volts on the supplies pot). I am guessing the relationship of the power supply voltage is increasing the CPU boards screen output (nothing really to do with the monitor, if that makes sense).

3. How would i remove that line in the center?

Could it be/ does it sound like i have this wired up completely wrong?

Thanks.
 
My recommendation is to get an original linear power supply in there. I had reset problems and drifting voltage problems from the switching power supply a previous owner installed in my robotron. Putting a switching power supply in your cabinet is (IMHO) a bad move.

Here's what I did on mine:

1. Bought the Williams connector kit from Bob Roberts and soldered (not just crimped) new connectors on the wire harness ... those IDC connectors are just not reliable after 30 years.

2. Bought a rebuilt P/S board from YellowDog. He does really nice work, and supports it.

Not a problem on the Robotron since.
 
Thanks for the suggestions guys. I figured there is a wiring issue and the power supply / variable adjustment doesnt feel right.

I am going to spend more time with it today / this week and see if i can get it wired correctly.

As a starting point on the wiring - i see that the output for the isolation transformer doesnt lead anywhere - everything was just wired directly off input of isolation transformer to the power supply. For example the output of the connector for the iso transformer was just left laying in the cab when i got it.

I will report back once i have better results (i can use the power supply from a Stargate mini that is not in use right now and replace that later). Just wondering - is there a chance that i fried any chips when i adjusted the 5 volt power? I just hope i didnt cause any damage....
 
To answer my own question - no, over adjust will not hurt Ram as i just rewired / got it to work. Thanks KLOV.

I need to go back to it and make the wiring permanent - but happy to have it working.
 
Never never never, adjust the power on a switching power supply without a voltmeter on the leads. Some of them will adjust the voltage in excess of 18V, which will fry chips.

ken
 
Yellow dog - thanks for the tip (wanted to know if i could cause damage - sounds like a resounding YES). Fortunately, managed to dodge a bullet on this one.

Going out to finish up the job now and play some Robotron (finally).
 
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