MV1FS P2 controller issues

nikoskon

n00b
Joined
Jan 12, 2021
Posts
13
Hi everyone,

First time poster and and MVS noob, so please be gentle :)

I have just recently got into the MVS thing (GadgetUK to blame here, saw his videos and thought that i need to have one :glee:), so got my first MVS board, being the MV1FS.

In short, i bought it non working, due to battery damage. In fact it was really bad, about 30-35 traces needed to be repaired, but somehow managed to get them all repaired, and now it works!!!:glee: Thanks to all the info on this website, and especially GadgetUK's video repairs (fantastic resource for repairs and heaps of info, even with the waffle :lolz::lolz: Thanks heaps :glee:)

Passes all diagnostic tests (including Z80 tests), and plays all 4 carts i have, but, there is one little problem left.

Player 2 D button does not register at all. All other controls for P2 work fine, just the D button.

The resistor packs are fine, they measure as expected, so i am now leaning towards the fact, that the C1 is buggered.

For the life of me though, i am not sure which pin on C1 the D button goes to. Anyone have any idea which pin it is?

Also, could it be something else, other than the C1 chip? Do C1's fail regularly?

If you need more info/photos, let me know and i can upload.

Look forward to some input, cheers guys :)
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538

nikoskon

n00b
Joined
Jan 12, 2021
Posts
13
The pinout for NEO-C1 is here

https://wiki.neogeodev.org/index.php?title=NEO-C1

There is tons of info on the neogeodev wiki.

Those aren't straight resisters packs, they should be these https://wiki.neogeodev.org/index.php?title=CRE401

I would use a logic probe to verify the signal for P2 D button goes high/low as you test pressing it along the path from the controller port to the NEO-C1.

NEO-C1's can fail, but have also seen button issues caused by a faulty CRE401.

Thanks for that C1 link, have looked at that page before at the pinout, but didn't scroll down far enough to see it has all the buttons listed by pin :hammer:

I'll check that pin out with my logic probe and see what its doing. And the CRE401 does test out fine, as in, one pin reads 1K, and the next 1.3K and so on.

So i assume that if C1 input doesn't go low when i press the D button, it would mean that C1 is faulty?

Edit: Just tested, and the signal goes low from the JAMMA connector to the CRE401, but at the C1, nothing, just stays high. I'll replace the C1 from a junk 1FZ, and see if that fixes it.

Cheers :)
 
Last edited:

nikoskon

n00b
Joined
Jan 12, 2021
Posts
13
Ok, finally fixed it.

Thought i would change out the C1 with a spare from a parts board, but turned out much worse!!! Random colour glitches, BRAM failing, half the controller inputs not working and who knows that else. Not really much of a spare part if you ask me :angry:

Swapped the original C1 back in, then added a bodge wire between C1 pin 68 and CRE401 and, bingo!! P2 D button now works. There must have been a trace cut somewhere along the line under the ferrite beads or the controller ports.

So glad its fixed now :) Very happy boy indeed:glee::glee:
 
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