I just replaced a really wonky 5v adjustment pot on my New Astro City power supply (400-5261Y), and though the new one is rock solid, it seems there's still an issue with it.
Even with the pot turned down to 0ohm, I only read around 5.45v at the edge with no game connected. This is enough, or more than enough, to get most games working, but on some older PCBs especially I'll get probably 4.80v at best, unable to get it all the way to 5.00. They'll run, but potentially with issues.
What is the expected max/min range of the 5v connection with nothing connected (anyone with a working one, please test for me
)? And does anyone have any idea what components could be the issue?
I'm going by these schematics: https://i.imgur.com/2oI89Y9.png
My first thought of course would be one of the caps. But none of them look even slightly bulgy, so I'm not sure it's the issue, and I don't have the means to "just replace them all".
This article speaks of a common issue with the -5v voltage regulator at IC3.
Mine might have the same problem, because I was barely getting any juice on my -5v connection either, but I'm not seeing any traces of issues around its location, and I'm not sure it could affect the 5v line. But maybe the issue on my PSU is a different one affecting both?
I do see some slight burn marks on the PCB around the pins of the beefy Q1 transistor (2sk2197 MOSFET) connected to a big heat sink. I expect this one gets really hot normally, so I'm not sure how common these marks are, or if they could be the sign of an issue with that component or others near it. I'd like to try replacing it, but I don't know what components would be considered equivalent that are actually accessible to me.
And of course there's the 431L at IC1 which I'm assuming(?) is a power regulator for the 5v line, but I'm not seeing any signs of issues here either.
Any clue where to go from here? Maybe it's a know issue I can't find any documentation about.
Even with the pot turned down to 0ohm, I only read around 5.45v at the edge with no game connected. This is enough, or more than enough, to get most games working, but on some older PCBs especially I'll get probably 4.80v at best, unable to get it all the way to 5.00. They'll run, but potentially with issues.
What is the expected max/min range of the 5v connection with nothing connected (anyone with a working one, please test for me
)? And does anyone have any idea what components could be the issue?I'm going by these schematics: https://i.imgur.com/2oI89Y9.png
My first thought of course would be one of the caps. But none of them look even slightly bulgy, so I'm not sure it's the issue, and I don't have the means to "just replace them all".
This article speaks of a common issue with the -5v voltage regulator at IC3.
Mine might have the same problem, because I was barely getting any juice on my -5v connection either, but I'm not seeing any traces of issues around its location, and I'm not sure it could affect the 5v line. But maybe the issue on my PSU is a different one affecting both?
I do see some slight burn marks on the PCB around the pins of the beefy Q1 transistor (2sk2197 MOSFET) connected to a big heat sink. I expect this one gets really hot normally, so I'm not sure how common these marks are, or if they could be the sign of an issue with that component or others near it. I'd like to try replacing it, but I don't know what components would be considered equivalent that are actually accessible to me.
And of course there's the 431L at IC1 which I'm assuming(?) is a power regulator for the 5v line, but I'm not seeing any signs of issues here either.
Any clue where to go from here? Maybe it's a know issue I can't find any documentation about.
, but the cheapest I can realistically find is about $25 imported from Germany (providing 16V tolerant ones can fit where the 10v ones are supposed to go). That's still not too bad, and worth doing for sure. But I'd still like to start out figuring out what the issue is here rather than just poking blindly.