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mazinkaiser

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hi guys have a question for you i have a astro city with its original power supply i was just checking voltages with my multimeter on the jamma edge under load and im getting perfect 12v and +5v but when i measure the -5 i get -0.008 is this normal i also verified this at the psu connector with and without load still reads the same could any of you check your voltage to see if your getting anything for -5 or is this normal thanks for the help!!
 

mazinkaiser

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Also to add to the question what does -5 power is it used on cps2 boards? Or whats it used mainly for?
 

jassin000

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Only a handful of PCBs actually use -5v, so the majority of JPN power supplies don't provide it PERIOD.
Take for example CPS2 (as you mentioned above) it don't need/want/use -5V whatsoever.
 

Frank_fjs

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Stock Astro power supply has -5V.

Your readings aren't normal.
 

mazinkaiser

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fantastic thanks for clearing that up jassin just wanted to make sure. I always check the psu on a new cab before i plug anything in thank you
 

djsheep

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One of my Astro’s has a fluctuating -5v. I think it’s dependent on the model of the PSU perhaps?
 

jassin000

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I don't have a Astro (never owned one) so I checked just to make sure...
Yup Frank is 100% correct, this is taken right from the manual.


So it should be providing -5volts @ 0.1amp (I incorrectly made the above JPG with 1amp) but if your +5 and +12 lines are stable, it should work fine for CPS2 (because again CPS2 don't use it).
One of my Astro’s has a fluctuating -5v. I think it’s dependent on the model of the PSU perhaps?
Is it like the Wei Ya, and only provides stable power values if used with a 100v step-down?
 
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mazinkaiser

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mine has one of the older psus but still says on the tag -5v


20190502_210446.jpg


You might have hit the nail on the head with the step down let me hook it up to my 100v line and check again
 

mazinkaiser

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after hooking up to my 100v line still reads the same very strange what could be the issue psu has been recapped recently wonder if theres a rectifier out. So is there any chance of me damaging any boards playing like this? Also you mentioned only a handful use -5 which ones would that be?
 

jassin000

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Someone had a handy list of all the boards that required -5v, I think it was @twistedsymphony who posted the link?
What I remember is older PCBs like Bubble Bobble (1986) needed it, and some wacky American PCBs like Mortal Kombat needed it.
But the majority of Japan PCBs made in the 90s onward (CPS1, CPS2, CPS3, MVS) did not.

Also, at least in MK's case... The game still boots without -5v, you just won't get any sound.
 

djsheep

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Is it like the Wei Ya, and only provides stable power values if used with a 100v step-down?
Am actually unsure, I will most likely send it off for a recap to Jomac as I'm assuming that's what the issue most likely is...

Was talking to @xodaraP a while back who hinted that perhaps if there wasn't a load on it / the PCB that it might show a fluctuating value on the multimeter on the Jamma pins?
 

Frank_fjs

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Quite possible that it does need a load on it.

-5V is derived from the +5 or +12V line so if those work generally -5V should be working.
 

xodaraP

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Is it like the Wei Ya, and only provides stable power values if used with a 100v step-down?
Am actually unsure, I will most likely send it off for a recap to Jomac as I'm assuming that's what the issue most likely is...
Was talking to @xodaraP a while back who hinted that perhaps if there wasn't a load on it / the PCB that it might show a fluctuating value on the multimeter on the Jamma pins?
The Astro has a 100V step down (at least in 240v regions) - I have noticed that the -5 isn't stable without a load connected. Unsure why but both @djsheep and I have the same thing happen
 

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after hooking up to my 100v line still reads the same very strange what could be the issue psu has been recapped recently wonder if theres a rectifier out. So is there any chance of me damaging any boards playing like this? Also you mentioned only a handful use -5 which ones would that be?
Older Technos pcb's like Double Dragon, WWF Superstars, etc need -5. I believe it's for the audio. . .
 

Psyko-M1

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after hooking up to my 100v line still reads the same very strange what could be the issue psu has been recapped recently wonder if theres a rectifier out. So is there any chance of me damaging any boards playing like this? Also you mentioned only a handful use -5 which ones would that be?
Older Technos pcb's like Double Dragon, WWF Superstars, etc need -5. I believe it's for the audio. . .
This is correct. I have a WWF Superstars that doesn't play without -5 and I am sad because my 2 cabs are not compatible.
Anybody know if Wrestlefest needs -5?
 

Frank_fjs

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Can always use an external device to generate the negative 5 volts.
 

xodaraP

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If that's the Wolf Unit board then yes it does, all Midway boards need -5

If it's the Technos game, I believe this needs -5 as well. As @Frank_fjs said you can use a Negatron to generate the -5
 

mazinkaiser

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found the wiki about what games use -5 volts i believe this is a partial list but helps alot funny it mentions astro city psu right of the bat must be a common issue

https://wiki.arcadeotaku.com/w/List_of_JAMMA_PCB's_that_require_-5_volts

Also here is another useful thread i found on another forum

http://www.neo-geo.com/forums/showthread.php?167536-Games-that-dont-work-without-5v

Thanks for all the help guys i will try to get ahold of another version of the astro city psu and test will report my findings!!
 

tiff_lee

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My new astro city has the same problem, -5V line is dead. I'll see if I can find the thread I read a while back but there is a particular component on the -5V line which fails, can;t remember if it was a voltage regulator/transistor but it was definitely in a TO-220 package.
 
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