Sega Turbo Power Supply Issues - SOLVED

mykl004

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This is a new venture for me, and I'm needing suggestions on what to try next.
I bought an upright Sega Turbo, and when I plugged it in, the speakers buzzed loudly; the LED displays were going nuts, showing different types of symbols and flashing; and the monitor showed all kinds of numbers and letters in yellow / orange, and the background was a pink / purple color (see attached photo).
I tested the power supply, and it was dead. I installed a new one (Suzo/Happ 80-0064-00), but before connecting the 5V wires, I tested it to make sure it was putting out 5V. It tested 5.2V. I connected the wires, same as the old power supply (Red & Blue on AC, White on -5V, and Yellow on +5V).
I plugged the machine in. The LED on the board lit. I walked around to the front, and the LED's were still going crazy. The monitor was black & white with vertical / squiggly lines. Then, after about 5 or 10 seconds, everything died. The power supply shut down on thermo overload. I disconnected the 5V wires and waited a while. I plugged the unit back in. The power supply was alive and working properly again.
I then reconnected the old power supply. Everything behaved as it did at the beginning.
I removed all removable chips and reseated them. 2 had bent legs, so i thought i was good. No.
I connected the new power supply again and it works well - until i connect the yellow / white wires to +5 / -5. With the 5V wires connected, there isn't any voltage coming from the power supply and the LED on the supply is not lit.
Any ideas?
 

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I think white wires need to be on the logic ground screw, NOT on -5v. There should be +12, +5, -5, Ground/common, and Field Ground on the power supply.

Also, check the header pins on the actual game boards. If they are corroded, take some fine grit sandpaper and sand them till shiny, then put the connectors back on.
 
TimePiloteer, you're right. I switched the white wires to ground and it fired right up. Incredible! Thank you.
I have tall white lights on the side of the road, any idea what that could be? I'll try a search, maybe it's a common problem.
 
If your images are too tall and look stretched, there are adjustment knobs on the boards that care of height. There is a fine adjustment knob and a rough one. Try turning those.
 
Following up on this thread from some time ago for some more instruction from the OPs successful repair.

I haven't seen a good comprehensive thread of power issues for this cab and there's a lot going on with Sega's over engineering. After 120 comes in through the on/off momentary switch and fuses mine is going into a switcher of some sort. It's only showing the 120acv and +5 and -5 used (as it's hooked up—I don't presume that it's hooked up correctly by the last owner so I'll buy that things are not in the correct terminals).

Time piloteer when you guys are speaking above that the white wires are to be on a "pcb logic ground screw" what are you talking about specifically? Ground screw where? Mine is definitely not wired that way but I'm not certain where the ground is supposed to go.

(EDIT—figured this out in case someone reads this post later. The game uses linear power for a bunch of miscellaneous voltages. However the 5vdc comes from a switcher PS. I did not immediately realize it was shipped that way. The white wires go to +5 post and yellows go to ground on the switcher. -5 is not used. The ground tab on the switcher is evidently what the "pcb logic ground screw" in post #2 is referring to).
 
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I want you guys to know that 7 years later, I'm putting in the same part number Suzo Happ supply and was also wondering why the supply was going out. Lo and behold, white wires on GND instead of -5v like they were on the ancient supply Sega had in there. 🙂 Thanks dudes.
 
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