What's new
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



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!!
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.
 
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!!
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.
 
Hi

I have had the same issue with my Astro City and fixed it by changing at transistor at IC3.
Now happily playing Bubble Bobble again.
 
What did you change the transistor to? Did you replace it with the same type or change it for something else?
 
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.
 
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.
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.
 
  • Like
Reactions: nem
Back
Top