4 slot problem

Pas

Pas

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507
Ok so my 4 slot took a dump on me the other week. when I took it apart I noticed that the bios chip was a windowed eprom instead of the nice original rom. To make matters worse it had nothing covering the window! So I have been on a hunt for a bios chip with no luck yet. None the less I took the bios chip out of another board and put it in there so I could test it further...now it boots ok but there are some graphical issues. The boot screen is messed up, yet the drugs are bad warning is fine, the bios menus and crosshatch and everything are perfect, but there is some seriously messed up graphics in the games...any ideas?
It happens on all games and all slots.

4slot1.jpg

4slot2.jpg

4slot3.jpg

4slot4.jpg

4slot5.jpg

4slot6.jpg
 
channelmaniac

channelmaniac

Mr Neo Fix-it
15 Year Member
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Posts
4,316
That could be....
  • Dirty Slots
  • Dirty Carts
  • Bad chip on top board
  • Bad trace on top board
  • bad trace on bottom board
  • bad chip on bottom board

I doubt it's a RAM chip problem as that should've given an error message when you booted. What BIOS did you put in it to test?

RJ
 
Pas

Pas

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channelmaniac said:
Dirty Slots
Click to expand...
I will try cleaning them...

channelmaniac said:
Dirty Carts
Click to expand...
The carts work fine on my other 4 slot board so I am doubting this one...

channelmaniac said:
Bad chip on top board
Bad trace on top board
bad trace on bottom board
bad chip on bottom board
Click to expand...
I will try swapping top/bottom boards with my working 4 slot and see which board its on.

channelmaniac said:
I doubt it's a RAM chip problem as that should've given an error message when you booted. What BIOS did you put in it to test?
Click to expand...
I took the bios out of my other 4 slot which is working fine. I will still need to get a replacment bios for this board once I figure out its other problems however because the bios was definatly one problem...but sadly not the complete problem.

This board has been sitting in the closet for awhile now but it was working when I put it in there...but that doesnt mean much really since it has been moved around alot and Im not the only one that uses that closet...
 
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Pas

Pas

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Posts
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Ok I just got done swaping out boards and the bios chip (since I only have one to work with). The problem is on the bottom board. I didnt notice anything unusual like bad solder joints or cut traces right off but I guess its time for a closer look and alot of time checking for continuity...unfortuantly I dont have a logic probe or know alot about these four slot boards...so if its a chip I wouldnt even know where to start.
 
mainman

mainman

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I just fixed a four slot last weekend with the same problem. Tell me which version 4 slot is it because I think I know what is wrong
 
Pas

Pas

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mainman said:
I just fixed a four slot last weekend with the same problem. Tell me which version 4 slot is it because I think I know what is wrong
Click to expand...

Its the NEO-MVH MV4.
 
Pas

Pas

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I have looked over this board a few times and didnt find any failed traces, didnt notice any bad solder points, and didnt notice any pins lifted on the surface mounted chips. So I guess I am stuck...who all repairs these boards? Or does anyone have a spare bottom board that they would want to sell?
 
mainman

mainman

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Pas said:
I have looked over this board a few times and didnt find any failed traces, didnt notice any bad solder points, and didnt notice any pins lifted on the surface mounted chips. So I guess I am stuck...who all repairs these boards? Or does anyone have a spare bottom board that they would want to sell?
Click to expand...

I could look at it for you
 
Pas

Pas

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channelmaniac said:
I doubt it's a RAM chip problem as that should've given an error message when you booted.
Click to expand...

Do all bios chips give video ram errors or is it just the unibios?
 
B

bamarquez226

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Pas said:
Do all bios chips give video ram errors or is it just the unibios?
Click to expand...

If you have a legit RAM error (backup, video, etc), you'll see it immediately with the regular BIOS when you power up the board.

And with the UniBIOS, you'll see it on startup as as well in better detail on the menu screens.
 
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Pas

Pas

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Xian Xi said:
Check around the battery area for corrosion.
Click to expand...

OK I removed the anoying hot glue blobs arount the battery and no visable corrosion. What is the best way to remove the foam/paper protector on the bottom of the board? I could just rip it off but then how do you clean all the remaining black foam junk off the board itself that it will no doubt leave?

So far I get no error codes just the messed up graphics. I cant see any broken traces (although it would take me forever to track back and check every one as I dont really know which traces I should be testing). I checked all the surface mount chips and all the connections seem to be good solid connections. I dont see any leaking caps or corrosion anywere on the board, and all the solder points look good. Im thinking there has to be a failed chip somewere on the board but I all I have to work with is a multimeter so I cant really check much.
 
B

bamarquez226

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To remove the foam pads, I found gently warming them with a hairdryer to warm the adhesive up again works pretty well. Start at low and work your way up.

If you have any left over adhesive/foam left, use lighter fluid to remove the rest. I am wary of heavier duty adhesive removers just because there is no way to tell if it will eat through the top coating of the mobo.
 
Pas

Pas

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Posts
507
bamarquez226 said:
To remove the foam pads, I found gently warming them with a hairdryer to warm the adhesive up again works pretty well. Start at low and work your way up.

If you have any left over adhesive/foam left, use lighter fluid to remove the rest. I am wary of heavier duty adhesive removers just because there is no way to tell if it will eat through the top coating of the mobo.
Click to expand...

Funny you should mention a hair dryer. I was looking for one last night for another project I am working on only to find that my wife took it when she moved. I guess the board goes back into the closet until we sell our house here and I move back with her. Oh well...its still up for sale/trade if anyone is interested in fixing this one.
 
K

karlito748

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Mar 2, 2008
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same for me

hi everybody, i need your help.
I've got the same board and the same graphics problems.
Have you got an idea of the problem please ?
Excuse for my english but i'm french.
karl.
 
channelmaniac

channelmaniac

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For scrambled graphics:

If it's on the bottom board there are some 74244 buffer chips that buffer the address lines to the graphic ROMs on the top board. One (or more) of them are bad.

If it's on the top board, same thing...

For vertical lines: Check the 74245 latches on the top and bottom boards related to the specific ROMs in question. These latch the data lines coming from the ROMs to the various data busses on the system. (Video ROM, audio ROM, and program ROM)

RJ
 
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