161 in 1 Cartridge (Rev. 2) not booting on MV-1C but working on MV-1FZ

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
So I checked ROMWAIT, PWAIT0, PWAIT1 and PDTACK going to NEO-DCR continuity is ok.. and all the pull down resistors to ground measure 8k.

Any more hints ? :(
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
I installed a Uni Bios now but I get the same results. Reflowed everything can't really figure out whats wrong.. at the moment the MultiCart will not show the pattern from before but just a blank white screen.

my other 2 original carts are working
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Ok.. we have a FIX :)

So what was the problem ? Actually it seemed that when going through the JAMMA Connectors +5V line it was not able to deliver enough current even though the voltage did not drop and smaller games would work because of less current draw.
A very odd thing that I couldn't figure out is I am measuring a short to ground.. like a 0 Ohm Short (never had that before) but the board works just fine - no hot parts and also the power supply stays cool.
My other MV-1C does not have that behavior and I think it also can't be some weird measurement because of some leftover charge of a cap.

But well if nothing get's hot and everything works how can there really be a 0 Ohm short to ground ?

So in one sentence - if you get a Pattern or white screen when trying to launch big games or multi carts you most likely do in fact have power issues (not enough current going through).
In my case the power supply was strong enough but not the path to the VCC lines.

So glad I could fix it even though the short to ground still leaves me clueless.....
 

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ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
nice, glad you figured out out. Curious, whats creating that url on the MS2 picture?
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
nice, glad you figured out out. Curious, whats creating that url on the MS2 picture?

I think it's because of the rom on the multi cart it might be a hacked version
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Ok short update.. I also kinda fixed the short to ground (that didn't affect the working state of the board).

It seems that something near the JAMMA Connector was causing it - I could not find the issue but I used a cutter knife and ripped off the traces GND and+5V going to the jamma connector and then ran the cables directly.
Now everything is looking as it should be.
I wonder how many layers those MVS boards have ? Sometimes I feel like those aren't just 2 layer boards when measuring. Could it be that those are 4 layer boards ?
 
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