Please help: MVS 1-slot producing garbage

Howdy folks,

My MVS 1 slot (MV1A) has been in storage for 2 years in a loft and was working fine when it went in but isn't now. I don't think it's damp because nothing else stored with it showed any even slight signs of that at all.

Problem that's occuring: When I turn on the machine with the MVS in, I get a screen full of flashing green and magenta squares and garbage.

I have tested the machine with other JAMMA boards and they work fine.
I've checked the JAMMA voltages and they are within correct ranges.
I've cleaned the jamma connector somewhat (I have no alcohol but am restocking on Saturday) and have tried 4 cartridges in it and there's no change in the behaviour.
I've reseated the bios.
I've removed the plastic and airdusted the board and it's clean as a whistle visually.
It seems to do the same pattern every time and does it with or without a cartridge inserted.
All DIP switches are set to 0 position.
I have tried setting the test switch to 1 but get nowhere.
I receive no sound.

A video of the problem can be viewed here: WMV AVI

Has anyone seen this behaviour before and can you please help me with some advice?

Many thanks.

Do you have another BIOS you can pop in there to check?

Is there anything suspicious around the battery?

+1 on the battery. My bet is it has leaked while being in storage.

If not, verify that the calender chip is getting +5v and that the crystal is oscillating correctly.

Guys, let this be a reminder to get rid of that dreaded leaky POS and replace it with a lithium and a diode (to prevent it receiving current and blowing).

Thanks for the replies.
I've only got the one MVS so can't try another bios chip but the chip itself seems fine and the board in general, there's no corruption of board or joints at all.
The battery looks fine, it's one of the first things I checked as I've had batteries leak and ruin things before, but it looks good as new.
I can't check the voltage on the calendar chip until tonight as I'm out of the house but I will do later. Which pin on the chip should I check for 5v? And if it's not receiving enough, the battery needs replacing?
Can a dead MVS battery really produce this garbage behaviour?

Vertigo said:

Thanks for the replies.
I've only got the one MVS so can't try another bios chip but the chip itself seems fine and the board in general, there's no corruption of board or joints at all.
The battery looks fine, it's one of the first things I checked as I've had batteries leak and ruin things before, but it looks good as new.
I can't check the voltage on the calendar chip until tonight as I'm out of the house but I will do later. Which pin on the chip should I check for 5v? And if it's not receiving enough, the battery needs replacing?
Can a dead MVS battery really produce this garbage behaviour?

Click to expand...

You'll have to look up the datasheet for the calendar chip, I can't recall the pinout of it.

The chip is powered from the boards main 5v supply. If theres no power to it you have a broken trace. Also check its clock input to ensure the crystal is functioning.

The battery simply keeps the backup ram powered and the calendar running while the system is off. A calendar error is exactly what you are experiencing.

OK, I'm going to replace the battery as there does appear to be a very tiny amount of corrosion to the top surface of the battery and I think it's likely that in 15 years and 2 straight years of inoperation, the battery will have run out.
However, stick vg2430 battery into google and it gives me very few results, in fact all sorts of regional variations of one site: pchub.com.
They want to charge me 35 bucks for a 2 buck part to the UK, so that's a last resort really. So is there any other button battery that's interchangeable with the VG2430?

There are tutorials on battery replacement.

As stated above, I don't recommend replacing it with another rechargable.

Replace it with a CR2032-type lithium battery of the same voltage and a diode. Even if there is no visible corrosion on the board I still suggest cleaning the surrounding area. I use a toothbrush and isopropyl alcohol.

OK, many thanks for all your help, I'll check out the tutorials and go shopping.
I really appreciate the knowledge of you guys.

Hewitson said:

A calendar error is exactly what you are experiencing.

Click to expand...

That's not a calendar error.

Calendar errors either show up as a "CALENDAR ERROR" message or an almost solid green screen - the green screen with the little bit of garbage you see every time you boot your Neo Geo. If it sticks on that green screen then it's a calendar error.

That .wmv file looks like there's a problem with the data getting to the LSPC chip. It looks like it's stuck in some odd video mode. Do you have gouged traces on the board?

RJ

The traces do seem to be fine, it's a very clean board. I did run out of air duster and have ordered a new one so there might be dirt under the chips that's causing a problem.
I do get the solid green screen with the purple dot after the garbage, so it may be a combination of the two.
Will return with an update once I've replaced the battery.
Thanks for your help so far.

OK, I checked the voltage to the calendar chip and it was 0.45v, so clearly the battery was dead. I removed it with no difficulties and half the garbage loop went away, just leaving me on a flickering screen of garbage squares instead.
I had a closer inspection of the underside of the board, searching for traces, and instead found this.
Something's meant to live at PC40, right? It connects to the underside of the chip at MASK4.
On close inspection it looks like it's exploded as there's mild melting of the surface coating and it doesn't look like it's been pushed off as I've seen those pushed off fairly cleanly before.
Can anyone please tell me what I can replace it with? I have no other board to compare the part to. Presumably it's a resistor, but which value, and am I ok to solder it to the two via holes instead of where it was surface mounted?

It's a simple DC filter cap and if it's missing it won't be an issue.

OK, thanks, I'll have more of a look and see what else I can identify as a potential problem.
Which is the LSPC chip? Is it marked as such on the chip itself?

For anyone finding this thread in future, pin 14 on the calendar chip should receive the voltage.

And also, if you're from the future, could you please post the winning lottery numbers from the past, say, five years?

You can PM them straight to me, if you want.

Many thanks,

Ben.