What's new

Regulating -5v?

ptom98

ptom98

Student
Joined
Mar 1, 2025
Messages
33
Reaction score
17
Location
Uk
Having an issue with a Raiden bootleg board on my SuperGun (HAS 4.2 with a RT 125-A PSU) no sound and intermittent crashing.

I've been told that it worked in a cab and it's potentially the SuperGun that's the issue with it not supplying -5v

Having done a quick test at the JAMMA edge I can see it's pulling -5.87v which presumably is too high?
I'm guessing that the issue then is not with the JAMMA board, but with the HAS or the PSU and that the most likely cause is the PSU?

Any recommendations on either a fix or an alternative PSU that offers better regulation on -5v?
 
Robbbert said:
Could try using a 7905 to bring it back to -5 volts.
Click to expand...
Vin must be at least 2V "greater" (in that case lower) than Vout for it to properly operate.
So -7V minimum, at least from the datasheet, it may work with a smaller delta.
 
nem said:
With the Raiden board connected?
Click to expand...
Yes, with it connected.
So, have managed to get it working, but not to sure if it means the issue is elsewhere and the level of -5v is fine.

Tried it on another SuperGun and it worked fine, checked the -5v and that was lower, in the -4v. BUT I use it with my NeoGeo and that has the switch on the audio turned to MVS and not Jamma. Done the same on HAS and that's got the audio working, lowered the voltage from 5v down a bit and that seems to have stopped the crashing.

I'm guessing it's the board that has some issues.
 
You must log in or register to reply here.
Back
Top