4 slot wont work,jamma plays fine though??

Hi,hope someone out there can help.I've just got my 4 slot mvs cab out of storage and have moved it to my new house,it used to work fine before the move but now all it plays is my jamma boards.When i insert a cartridge into my 4-slot all i seem to get now is a dark blank screen,no sound,no pic,nothing!..not even a garbled screen,just dark.but it continues to play my jamma games fine.
Im wondering if its something to do with the voltage box thing,i noticed the adjustment knob had sunk into the box a bit so i took it apart and pulled it out again,it seems fine,hasnt snapped off or anything,but my mvs games just wont work,really starting to miss them ..any help given is much appreciated.
cheers.

sidekick said:

Hi,hope someone out there can help.I've just got my 4 slot mvs cab out of storage and have moved it to my new house,it used to work fine before the move but now all it plays is my jamma boards.When i insert a cartridge into my 4-slot all i seem to get now is a dark blank screen,no sound,no pic,nothing!..not even a garbled screen,just dark.but it continues to play my jamma games fine.
Im wondering if its something to do with the voltage box thing,i noticed the adjustment knob had sunk into the box a bit so i took it apart and pulled it out again,it seems fine,hasnt snapped off or anything,but my mvs games just wont work,really starting to miss them ..any help given is much appreciated.
cheers.

Click to expand...

Was any changes made to make it play Jamma Boards..?

The voltage from the power supply may be to far off/ low to provide power to the 4 slot mvs.
Did you move that Power supply knob at all.?
You really need to take a voltage test using a Volage/Digi meter..from the power supply.(5V)

I'd say give the 4 slot motherboards edge connector a good cleaning.
Maybe you've spread the connectors in the jamma harness to far out switching to Jamma PCBs
The Jamma harness may be not making good contact with the 4 slot's edge connector.
Clean that too(jamma harness connection)

Did you have a Jamma PCB plugged in the cab while it was in storage.?
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(I wonder what happens when I BIOS chip is not seated properly)Raz..?

Thanks for the response,im not sure what changes have been made originally,i bought it a couple of years ago and havent altered anything.It has always played jamma pcbs and mvs cartridges fine up until now.
I will take the 4 slot off and check the connections and clean its edges aswell,see if that will get me anywhere.
I did alter the voltage knob,yes,to see if it made a difference as i thought this was the reason that the games were not working,but i still cant seem to get anything from my 4 slot apart from a black screen still.
I hope i havent blown anything by doing this,wouldnt even know what to check to see if i have.
I cant remember if a jamma board was left connected while in storage or not,would this of done damage to my 4 slot atall if it was?
Will try and get myself a meter to measure the voltage aswell,will try and do it tommorow.
cheers,any more suggestions very welcome and appreciated.

sidekick said:

Thanks for the response,im not sure what changes have been made originally,i bought it a couple of years ago and havent altered anything.It has always played jamma pcbs and mvs cartridges fine up until now.
I will take the 4 slot off and check the connections and clean its edges aswell,see if that will get me anywhere.
I did alter the voltage knob,yes,to see if it made a difference as i thought this was the reason that the games were not working,but i still cant seem to get anything from my 4 slot apart from a black screen still.
I hope i havent blown anything by doing this,wouldnt even know what to check to see if i have.
I cant remember if a jamma board was left connected while in storage or not,would this of done damage to my 4 slot atall if it was?
Will try and get myself a meter to measure the voltage aswell,will try and do it tommorow.
cheers,any more suggestions very welcome and appreciated.

Click to expand...

I'm going to give an explanation from my own experience..

I started to buy a lot of Jamma PCBs once I got my Candy cab...
Hooked up an -5V line and a plug to switch between Mono and Stereo since I mainly had a 4 slot mother board in it.
( I only wanted to use this cab for Jamma PCBs)

Some PCB's just seem to be much harder to get the Jamma Harness on..
I had one CPSII motherboard that the Jamma harness would slip right on it's edge connector easily..then another one I had would be much harder to get on..
The edge connectors between them would go on differently..One loose one tight.

I started to notice this happening with different PCBs..some were tight others were loose fitting into the harness.

One day after having a Double Dribble PCB in the candy I took it out and plugged in the 4 slot motherboard.
I got no sound and I was ...scared I burnt my 4 slot motherboard out..

I checked the harness pins and noticed some were pressed so far up that they weren't making any connection with the motherboard when the harness was pushed on..and the Jamma harness felt loose going on.

I replaced several pins/luckily I had new ones around..and made sure they all were making contact.
Then I decided not to mess with/buy Jamma PCBs anymore..
Though I have boxes of Jamma harness and parts I'm not looking to mess the harness up in this cab.
I'm not even putting anything in it besides it's 4 slot,.......Hyper and Atomiswave.

I got rid of all my CPSII stuff...and I'm getting rid of all my PCBs.. besides..
Hyper 64
Sega ST-V
Taito F3
Tekken 2
And I'll buy an Atomiswave..

That was what happened to me using Jamma PCBs..
Though I never had a problem with the Tekken 3's cabs harness playing Jamma Pcbs ....the cabs a lot harder to put them in..

http://www.hardmvs.com/images/jamma/JammaEdgeFsm.jpg

Jamma 25/56 crimp on pins
http://www.hardmvs.com/images/projects/neg5volt/jammaPinsSM.jpg


I think you have a power supply problem,...It's either too high or too low..leaning on to low though..