Question about Jamma Adapters

kpkube

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Purchased 1 Galaxian and 1 Ms pac Jamma adapters.
Is there anything I need to know before I connect these to a Galaxian and Ms pac board?
Any information on these adapters would be very helpful.
Thanks
 
speaker pins are different between the 2 boards, think the rest is much the same, that is the difference between the 2 different adaptors.

Also with both the galaxian and pacman boards they will need there power lines modified when conecting to a jamma loom as there 5 volts and the pac and galax boards are expecting 7v ac so there power regulators will need to be removed.

if its jamma boards in a galax or pac case then they will blow as will be expecting 5v and will get 7vac!
 
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if you have a galaxian board using in a jamma cab then this is the galaxian board modifications. this converts the board to accept the 5v jamma supply voltage, and also allows the 12v to power the sound amplifier as this will be expecting also an ac voltage before modification

Remove IR2 (78GU I.C.)
Remove IR1 (D44VM4 transistor)
Remove R88 (50Ohm 5W resistor)
Replace D4 (A15F diode) with a wire link
Replace D5 (A15F diode) with a wire link
Replace D6 (A14F diode) with a wire link
Replace D7 (A14F diode) with a wire link
Replace R87 (4Ohm 10W resistor) with a wire link

All the wire links added were 1mm solid core domestic wiring cable, rated 15A


I am quite sure pacman boards are the same

regards
Andrew
 
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if you have a galaxian board using in a jamma cab then this is the galaxian board modifications. this converts the board to accept the 5v jamma supply voltage, and also allows the 12v to power the sound amplifier as this will be expecting also an ac voltage before modification

Remove IR2 (78GU I.C.)
Remove IR1 (D44VM4 transistor)
Remove R88 (50Ohm 5W resistor)
Replace D4 (A15F diode) with a wire link
Replace D5 (A15F diode) with a wire link
Replace D6 (A14F diode) with a wire link
Replace D7 (A14F diode) with a wire link
Replace R87 (4Ohm 10W resistor) with a wire link

All the wire links added were 1mm solid core domestic wiring cable, rated 15A


I am quite sure pacman boards are the same

regards
Andrew

You don't need to modify a Ms. Pac board to use it with a JAMMA adapter in a a JAMMA cab. The diodes that turn the AC into DC will just pass the DC through, although you may need to adjust the +5 up a little if the diodes cause it to drop a bit. Altering the PCB will just mean that the PCB can no longer be used in a dedicated cab. I test Pac boards all the time with my JAMMA adapter on my test bench and NEVER alter the PCB prior - and they always work (if the board works).

Not sure if Galaxian is the same, but I'll bet it will work without the mods, too.

Now, if you were using an adapter to play a JAMMA game in a Ms. Pac cab, then you'll need the adapter that converts AC to DC, otherwise you'll kill your JAMMA board...
 
Thanks Guys,
I PM'd channelmanic and was picking his brain. He said the same thing. Where is a good point to check the 5v. He said at the chip. Which one and what pin? My Power supply measures 5.14v at the terminals on the supply.
 
Thanks Guys,
I PM'd channelmanic and was picking his brain. He said the same thing. Where is a good point to check the 5v. He said at the chip. Which one and what pin? My Power supply measures 5.14v at the terminals on the supply.

For a ROM chip, measure the +5 on the pin across from pin 1 on the same end of the chip. For a 24-pin chip, that would be pin 24. For a 40-pin chip, that would be pin 40...
 
Yeah, what mod said is correct. Your +5 may drop a little when going through the rectifier on the pcb but it wont hurt anything. You may need to adjust the switcher up a hair but I have found its usually not needed. On a pac the best(easiest) place to measure +5 is across C3. I dont have a galaxian board handy to look but they should have one or two 470uf caps on them too. Either one should be the +5 line.
 
Thanks Guys. Really appreciate the advice. Couldn't do this without the vast knowledge of the KLOV members. You guys are GREAT...
 
Just watch out if you just turn up the volts to power the board without modification, and then decide to change it back for a jamma board then the volts need to be turned down again or it will likely blow up the jamma board!

as with everything there are several ways to do things, its just deciding which way is best for you.

on a side note, isn't the board powered with 16vac for the sound, then with jamma its 12v and leaving the diodes in its going down to just over 11v, do the sound output amplifiers still work ok without distorting the audio due to low voltage?
 
Just watch out if you just turn up the volts to power the board without modification, and then decide to change it back for a jamma board then the volts need to be turned down again or it will likely blow up the jamma board!
This is exactly why I recommend modifying the boards. They should have been made that way in the first place anyway.

andrew96 said:
on a side note, isn't the board powered with 16vac for the sound, then with jamma its 12v and leaving the diodes in its going down to just over 11v, do the sound output amplifiers still work ok without distorting the audio due to low voltage?
I'm pretty sure they'll work fine at ~11v.
 
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