Bad Luck with my MV-1FZ Mainboards

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furrtek

Super Sidekicks 2
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Check continuity between LSPC2-A2 pin 23 and both RAM5 & RAM6 pins 10.
If the self-tests pass, that should be good.

More plausible: check between LSPC2-A2 pin 112 and cart slot CHA A3 (bottom connector, top row of pins, third pin from the left).
 
RyuX

RyuX

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furrtek said:
Check continuity between LSPC2-A2 pin 23 and both RAM5 & RAM6 pins 10.
If the self-tests pass, that should be good.

More plausible: check between LSPC2-A2 pin 112 and cart slot CHA A3 (bottom connector, top row of pins, third pin from the left).
Click to expand...

Thank you - will try that first thing when I come home.
Also currently I am trying to make an Excel Sheet out of the almost impossible to read schematics for easier troubleshooting (at least for the LSPC Part) and will share that then later with the community as I have not been able to find compiled information that is easy to read.
 

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furrtek

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Cool :) Let me know if it could be linked from the wiki.
Never had the courage to vectorize the schematics.
 
RyuX

RyuX

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furrtek said:
Cool :) Let me know if it could be linked from the wiki.
Never had the courage to vectorize the schematics.
Click to expand...

When I am finished I will have a excel or PDF File.. can I upload it to this forum ? If not I will find another webspace
 
RyuX

RyuX

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Took me the whole morning.. But now the most important things should be covered. I will maybe continue on the 68k etc. but for now I invested enough time for my taste.
 

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RyuX

RyuX

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furrtek said:
Check continuity between LSPC2-A2 pin 23 and both RAM5 & RAM6 pins 10.
If the self-tests pass, that should be good.

More plausible: check between LSPC2-A2 pin 112 and cart slot CHA A3 (bottom connector, top row of pins, third pin from the left).
Click to expand...

Both checks show good continuity. Any more hints ? Otherwise I will have to probe the whole thing I guess :( Even though the board is in good condition and my loupe check didn't show any bad traces
 
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furrtek

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Thanks for the PDF, I'll add a link to it.

Got confused while trying to figure out what was wrong from your pictures. It couldn't have been LSPC2 pin 112...
Apparently 1 out of 2 tiles in sprites are duplicated, so it's like LSPC2 was reading the same VRAM location twice. Can you confirm there are no shorts between A0 and adjacent pins on the slow VRAM (RAM5 and RAM6 I think, the two surface mount ones).

That should have given a VRAM error but I can't think of anything else right now.
 
RyuX

RyuX

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furrtek said:
Thanks for the PDF, I'll add a link to it.

Got confused while trying to figure out what was wrong from your pictures. It couldn't have been LSPC2 pin 112...
Apparently 1 out of 2 tiles in sprites are duplicated, so it's like LSPC2 was reading the same VRAM location twice. Can you confirm there are no shorts between A0 and adjacent pins on the slow VRAM (RAM5 and RAM6 I think, the two surface mount ones).

That should have given a VRAM error but I can't think of anything else right now.
Click to expand...

Yeah man.. your Tip was a Jackpot.. When looking at the pinout again I noticed the corresponding pins are on the backside - usually I always had the Cartridge Adapter Plugged in when tracing the board for mistakes - this time I removed the Adapter to get a better look at the corresponding pins.. and yeah.. there was a solder bridge !!!
I removed it and it worked.. YEEEHA! :buttrock:

Thanks again for your help

After seeing it worked I decided to change all the Caps and the Opamp (TL074) and do the 5V Mod and call it a fix :tickled:

Have a great day
 

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furrtek

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Great !

Took me a while to understand why the bridge wasn't located where I thought.
If anyone is interested: P20 was shorted to ground. It wasn't affecting the tile address directly because it's a pretty high bit, but it was forcing the lower bit of the tilemap index for the shrink lookup in the L0 ROM. So the odd tile numbers were "mapped" to the even ones, duplicating 1 out of 2 tiles.

Definitely adding this to the repair notes, thanks for sharing !
 
RyuX

RyuX

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furrtek said:
Great !

Took me a while to understand why the bridge wasn't located where I thought.
If anyone is interested: P20 was shorted to ground. It wasn't affecting the tile address directly because it's a pretty high bit, but it was forcing the lower bit of the tilemap index for the shrink lookup in the L0 ROM. So the odd tile numbers were "mapped" to the even ones, duplicating 1 out of 2 tiles.

Definitely adding this to the repair notes, thanks for sharing !
Click to expand...

Thanks for the great explanation.
I now have one more board to repair - but this board is "ultra dead" it has low resistance +5V to GND even though I tried to remove all ICs one after another while checking resistance it would not noticeably go up. Also it has many broken traces and the LCSP2-A2 has a broken off pin on the Fast VRAM Enable. Never got it to run - maybe it will be a donor board.
Glad I stocked up on all kinds of RAM chips on mouser. I should be good for some time now :D
 
Dropwire

Dropwire

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Awesome Job!! Glad you got this board up and running.

On your Ultra Dead board with the low resistance, I am working on a similar issue with an MV-1AX board, making some headway. Let you know if I come up with a shortcut to isolate a damaged component.

Once again Congrats on your board repair !!:buttrock::buttrock::buttrock:
 
RyuX

RyuX

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Thanks man! I am glad it worked out so I can continue to wire and consolize that one.
Keep me posted - Like I said I removed all of the parts except the NEO-B1 and still have the low resistance.. so in theory it should be the NEO-B1 but it is the last part - that would be bad luck - so I guess I have some other issue with some traces or solder bridges somewhere. I kept the GND and 5V connected to my multimeter and then removed one part after another with the reflow station and watched the resistance. But yeah.. not much luck with that
 
RyuX

RyuX

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here the 68k pinout now.
 

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RyuX

RyuX

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Finished consolizing this mainboard now..
 

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ack

ack

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Nice job. Glad you got it all working.
 
RyuX

RyuX

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Added the MKL Stereo Sound Mod now.. fits nicely where the Amp used to be.
 

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RyuX

RyuX

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Hey guys.. I have another board and have a weird problem. I get no Errors on the diagnostics bios. The graphics especially texts will be corrupted. I changed many ICs (almost all) and then noticed if I bend the board downward (it means press the middle down and the edges up) it will display correctly. So I might have a broken trace somewhere but looking around with the loupe didn't bring any results. Any hints on where to measure looking at the graphical problems ?

Thanks a ton
 

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RyuX

RyuX

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BIG BEAR said:
000-L0
BB
Click to expand...

Thanks I checked all the traces that go to 000-L0 and replaced the LS245 with the same results. Since I get a "good connection" when bending the boards middle part downwards it must be a broken trace on the top of the board I guess but for the most time it will have a connection so its really hard to measure.. I would have to bend the board the other direction while measuring which is almost impossible for me at this point.

So these graphic glitches will mostly come from the L0 ROM ?
Is there any other explanation possible ?
 
BIG BEAR

BIG BEAR

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From the top in the center would be relative to the ZMC2.
BB
 
RyuX

RyuX

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BIG BEAR said:
From the top in the center would be relative to the ZMC2.
BB
Click to expand...

Another Problem turned up.. the Diagnostic Bios will now drop a "BIOS CRC ERROR".
Not sure why that is happening now..
 
RyuX

RyuX

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I probably ruined something else.. continuity to the 68k from the System ROM is ok.. the normal bios will only boot up to the neo geo screen and then stay black on any game
 

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RyuX

RyuX

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OK I found a bad connection on one of the ICs and could fix the Bios CRC Error. Also the Graphical Error I first had is now fixed.
However I now have another issue with stripes along the screen.

Any hints guys ? We are almost there.. a Fix is in near sight :buttrock:
 

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