AC inputs to bench test ms pacman board

pinnut

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i have a ms pacman board. i bench tested it with ground and 5 volts to pin 17, works well. however, in the game i turned it on a wisp of smoke came off the board. the trace from Ic1 regulator to the zener burned up, the zener is shorted. after i replace the zener, i'd like to bench test it with 7 volts AC. it looks like the two 7 volts Ac leads could go to pins A and C? is that correct, and all it will need? thanks

Parts SideWire ColorSolder SideWire Color
7 Volt Center Tap (GND)Red-BlackA17 Volt Center Tap (GND)Red-Black
7 Volt Center Tap (GND)Red-BlackB27 Volt Center Tap (GND)Red-Black
7 Volt ACOrangeC37 Volt ACOrange
7 Volt ACGreenD47 Volt ACGreen
 
Galaxian, Pac-Man, and Ms. Pac-Man can all be bench tested with 12v and 5v DC, no mods needed. I've done this many times. You may need to bump up the 5v a little.

If the game worked on your bench with DC, but "smoked" when in the cabinet, then repair it, and retest.

The schematics will confirm the required pinouts.


Scott C.
 
Yeh, for AC input type rails on some boards, I just input DC (current limited - just in case). No mods. Just get the polarity correct. :)
 
i have a ms pacman board. i bench tested it with ground and 5 volts to pin 17, works well. however, in the game i turned it on a wisp of smoke came off the board. the trace from Ic1 regulator to the zener burned up, the zener is shorted. after i replace the zener, i'd like to bench test it with 7 volts AC. it looks like the two 7 volts Ac leads could go to pins A and C? is that correct, and all it will need? thanks

Parts SideWire ColorSolder SideWire Color
7 Volt Center Tap (GND)Red-BlackA17 Volt Center Tap (GND)Red-Black
7 Volt Center Tap (GND)Red-BlackB27 Volt Center Tap (GND)Red-Black
7 Volt ACOrangeC37 Volt ACOrange
7 Volt ACGreenD47 Volt ACGreen
You need both 7VAC and 12VAC on a PacMan board.
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The 7VAC is rectified and is the raw input voltage for the regulated 5VDC. However, its actually the 12VAC input that powers the actual voltage regulator, once rectified. The voltage regulator then controls the D44BM4 pass transistor to actually regulate the 5VDC.
 
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