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Question about -5 voltage on astro city

awesome let me know if you can find what regulator it is i can take it off the board and check it order a replacement and test to see if we can document this for posterity.
 
got an update so on several of the -5 lists of compatible games they have combatribes listed as having no sound if your -5 line is not working. A buddy let me borrow his combatribes pcb i plugged it in and have sound!! Also checked the -5v line as i raised and lowered the volume on the pcb and it registered an increase of negative voltage on my multimeter so it went from the .008 to nearly half a volt at .488. Im starting to suspect that this psu does not put out -5v unless it has a load on the -5v and at that point it only provides whats needed just as it was suggested earlier by Frank this makes sense as all psu ive adjusted in the past the +5v and -5 show matching voltages and adjustment since they have the same source. That's why it was strange to me that my +5v was fine usually from what ive seen if theres a problem with +5 you will have a problem with -5 thanks for all the help guys!!
 
Not found the specific thread yet but found this thread:

https://forum.arcadeotaku.com/viewtopic.php?t=32406

in that there is links to drawings for 2 different PSU models:

Sega 400-5198-01Y:
http://i.imgur.com/Ctc1rxc.jpg

Sega 400-5261:
http://i.imgur.com/2oI89Y9.png

referencing both of them there is a voltage regulator on the -5V line (it's the same on both schematics) a 78L05. Ok so I half remembered as it's not a TO-220 package but TO92



mazinkaiser said:
got an update so on several of the -5 lists of compatible games they have combatribes listed as having no sound if your -5 line is not working. A buddy let me borrow his combatribes pcb i plugged it in and have sound!! Also checked the -5v line as i raised and lowered the volume on the pcb and it registered an increase of negative voltage on my multimeter so it went from the .008 to nearly half a volt at .488. Im starting to suspect that this psu does not put out -5v unless it has a load on the -5v and at that point it only provides whats needed just as it was suggested earlier by Frank this makes sense as all psu ive adjusted in the past the +5v and -5 show matching voltages and adjustment since they have the same source. That's why it was strange to me that my +5v was fine usually from what ive seen if theres a problem with +5 you will have a problem with -5 thanks for all the help guys!!
Click to expand...
Yeah that wasn't the case on mine, even when using a board which requires -5V the line is still dead


Edit:

Got it:
https://segamadebaddecisions.wordpress.com/2016/11/22/negative-problems-astro-city-5v-supply-issues/
 
Wow invaluable info tiff thanks for posting it will check that t092 and will report findings!!!
 
I happen to have Superstars, Wrestlefest, and Combatribes PCBs that all work fine in an old woody cab with a switching PSU that I don't think supports -5v.

Now Smash TV requires -5v for the sound (doesn't work sound-wise in the aforementioned woody) so I use my JNX Atlas adapter with a Negatron installed.
 
mazinkaiser said:
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!!
Click to expand...
Those lists are incredibly short. If I had to go by the boards I've owned it would be 3 times longer.
Just in JAMMA I recently repaired Raiden and Kiki Kaikai and those two need -5V for sound.
Then you also have all those classic games (Space Invaders, etc.) where -5V is COMPULSORY for the CPU and the RAM chips. If missing RAMs fry in a couple of minutes. CPU (8080) is generally a lot more tolerant.
 
-5V is mostly used for sound, in particular to power the OP-AMPs in dual-supply configuration.
As for the Astro City PSU it's well known that it's badly engineered especially in the -5V line, they used a weak regulator (78L05) but you can replace it with a more powerful one.
I replaced the PSU in my Astro City with a switching one keeping the original metallic case with all connectors.
 
one of the above links also links to this blog I made years ago:
http://fgaddiction.blogspot.com/2012/05/arcade-psu-debugging.html

essentially if your astro is missing -5v I would check IC3, and like others have said replace it or use a beefier alternative
2012-05-01_19-19-20_260
 
All of my Astros do the same thing. A few locals never believed me until I showed them how the sound works when I plugged in an edge adapter with a Negatron on it and the sound worked. Took it off and plugged the board in, sound didn't work or was all scratchy. I just use the adapter all the time anymore, it was one from Jamma Nation X. I should probably just fix the PSU's at some point though.
 
There's several ways to generate negative voltage, so you can't say "Just buy xx" without detailing the PSU you're using. ;)

During recapping on a New Astro City, 400-5198CE-01Z power supply, I discovered that the regulator of the -5V rail was blown, so I replaced it.
Ratings of the PSU are
+5V 7A
+12V 1,5A
-5V 0,1A, which is the Amp rating of the voltage regulator, a 78L05 in TO-92 package (same package like lots of transistors, but package is not linked to one kind of components).


regula10.jpg


On the NAC PSU I worked on, -5V is generated by a part of the transformer, then regulated by the 78L05. Yes, it is a positive voltage regulator but the ground point used is different than the other power rails. Since it's a linear regulator you may use a load to ensure correct measurements.
 
Have an Astro City PSU with what seems to be a faulty pot on the +5v adjustment. It's sitting dead still, on the higher end (but not burnout levels) on the 5v without any movement on the multimeter when I max the pot high and low.

Anyone here ever needed theirs replaced? Is this a common problem on these PSU? Wondering if I should send it off for repair, or attempt to change out the pot myself.
 
djsheep said:
Have an Astro City PSU with what seems to be a faulty pot on the +5v adjustment. It's sitting dead still, on the higher end (but not burnout levels) on the 5v without any movement on the multimeter when I max the pot high and low.

Anyone here ever needed theirs replaced? Is this a common problem on these PSU? Wondering if I should send it off for repair, or attempt to change out the pot myself.
Click to expand...
You got a multimeter? if you are going to open it up check the pot resistance, according to the circuit diagram it should be 1K. Check that and go from there.
 
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