Hi
Short story - just wired up my first MVS to use an ATX PSU, one of my PSU's works fine with it, the other doesn't. Both PSU's work fine in a PC!
Before I go about consolising my MVS MV1FZ, I thought I'd better go about testing it works before I perform any mods on it.
I've never had any JAMMA stuff before, so it's been a bit of a learning curve, but it seemed quite simple.
I had a good quality HP/Compaq ATX PSU and an ATX 20pin extension lead which I planned to butcher up.
It seemed easy, so I took the extension lead, removed unnecessary cables and decided to solder directly onto the Jamma connector - +5v, +12v, GND. I wired a switch between ATX pin 14 and GND to turn the PSU on and off.
I'm in the UK, so RGB TV is not a problem, so I quickly hardwired an RGB scart lead to the relevant Jamma pins. For now I've just connected up R, G, B, Sync, GND and a wire for +5v to put my TV into RGB mode.
Tried the PSU before plugging it into the MVS, flick the switch and it does indeed switch on, the fan goes around. Plugged it into the MVS, no cart inserted, and my TV switches to the correct channel and goes into RGB mode and tells me it's receiving a 60hz signal. But the screen is blank, power LED on the MVS board is on. Switch it off, switch it back on again and this time I get a few red squares dotted around the screen. Thought I'd try it with a cart anyway, and same again - sometimes the squares are a different colour.
I'd read a post on here that suggested wiring up at least 2 +5v and GND wires from the ATX PSU to the Jamma connector, even though they are linked on the board anyway? So I tried that, still the same.
I was still convinced it was the PSU, even though it was working fine in the PC I had junked the other month.
Powered it up again and measured the voltages on the relevant Jamma contacts, +5v was only reading +4v, and +12v was reading +8v ??? So went away to read a bit more about using an ATX PSU, and found lots of guides about converting one for Lab use which seemed easy enough to follow. Some of them mentioned a sensor wire - a thinner wire, usually orange or brown. But I couldn't really find confirmation of what the sensor wire is for, it's to sense a load and if it doesn't detect one switches the PSU off to prevent it damaging itself?
Anyway, my PSU does have a sensor wire on one of the +3.3v wires, I'd read that sometimes these can be on the +5 and +12v wires, so moved it to one of the +5v wires I'm using. Still no luck though.
Any idea what could be wrong with this PSU, and why it isn't pumping out the correct voltages?
The PSU that I use in my SFF Shuttle PC, which also has a sensor wire on a 3.3v wire, powers the MVS fine though??!! So I'll probably just go ahead and do the 5v only mod once I get a suitable PSU (5v 4a should be enough right?)
Many thanks
Pete
Short story - just wired up my first MVS to use an ATX PSU, one of my PSU's works fine with it, the other doesn't. Both PSU's work fine in a PC!
Before I go about consolising my MVS MV1FZ, I thought I'd better go about testing it works before I perform any mods on it.
I've never had any JAMMA stuff before, so it's been a bit of a learning curve, but it seemed quite simple.
I had a good quality HP/Compaq ATX PSU and an ATX 20pin extension lead which I planned to butcher up.
It seemed easy, so I took the extension lead, removed unnecessary cables and decided to solder directly onto the Jamma connector - +5v, +12v, GND. I wired a switch between ATX pin 14 and GND to turn the PSU on and off.
I'm in the UK, so RGB TV is not a problem, so I quickly hardwired an RGB scart lead to the relevant Jamma pins. For now I've just connected up R, G, B, Sync, GND and a wire for +5v to put my TV into RGB mode.
Tried the PSU before plugging it into the MVS, flick the switch and it does indeed switch on, the fan goes around. Plugged it into the MVS, no cart inserted, and my TV switches to the correct channel and goes into RGB mode and tells me it's receiving a 60hz signal. But the screen is blank, power LED on the MVS board is on. Switch it off, switch it back on again and this time I get a few red squares dotted around the screen. Thought I'd try it with a cart anyway, and same again - sometimes the squares are a different colour.
I'd read a post on here that suggested wiring up at least 2 +5v and GND wires from the ATX PSU to the Jamma connector, even though they are linked on the board anyway? So I tried that, still the same.
I was still convinced it was the PSU, even though it was working fine in the PC I had junked the other month.
Powered it up again and measured the voltages on the relevant Jamma contacts, +5v was only reading +4v, and +12v was reading +8v ??? So went away to read a bit more about using an ATX PSU, and found lots of guides about converting one for Lab use which seemed easy enough to follow. Some of them mentioned a sensor wire - a thinner wire, usually orange or brown. But I couldn't really find confirmation of what the sensor wire is for, it's to sense a load and if it doesn't detect one switches the PSU off to prevent it damaging itself?
Anyway, my PSU does have a sensor wire on one of the +3.3v wires, I'd read that sometimes these can be on the +5 and +12v wires, so moved it to one of the +5v wires I'm using. Still no luck though.
Any idea what could be wrong with this PSU, and why it isn't pumping out the correct voltages?
The PSU that I use in my SFF Shuttle PC, which also has a sensor wire on a 3.3v wire, powers the MVS fine though??!! So I'll probably just go ahead and do the 5v only mod once I get a suitable PSU (5v 4a should be enough right?)
Many thanks
Pete
