MV4 only Crosshatch

Hi guys... I have a 4 slot board (MV4 model) that is stuck in crosshatch and did not recognize any cart.

- I have cecked all the connection on the 4 connectors CN8 - CN9 - CN10 - CN11
I have had to reapir 2 tarces on CN10 due to battery corrosion and an oter MV4 it solved the situation but not here...

-with diagnosti bios all test passed and top board is known well working part as the cartriges are working..

-with Unbios on 0000100 data line I have no NEO-GEO or any indication of reading something from the cart

-on a two slot I solved the problem changing the NEO-GO but here I dont know wich IC drive the cart reading...

many many thanks... this board is driving me creazy....

do you get a cross hatch on all slots?

yes bro.. same at all the 4...

thanks

Normally at that point I would take a known good top board and use it to isolate the issue to either the top/bottom board and go from there. I take it you don't have an known working top board?

On the slot board to the left of each slot there should be 2x LS245 chips, which should be the ones that handle the PROM data lines. On the slot that is active, pin 19 on those 2 chips should be pulsing, while the other slots should have them high.

ack said:

Normally at that point I would take a known good top board and use it to isolate the issue to either the top/bottom board and go from there. I take it you don't have an known working top board?

On the slot board to the left of each slot there should be 2x LS245 chips, which should be the ones that handle the PROM data lines. On the slot that is active, pin 19 on those 2 chips should be pulsing, while the other slots should have them high.

Click to expand...

The top board is perfectly working... I use that from long time just to test the 4 slot so the problem is on the bottom board for sure...

I need help knowing wich IC could cause the "not reading" of the carts or the PROM..

on the two slot I look to the NEO-GO @H2.5 but here on the MV4 I m lost....

Thanks

paoloMVS said:

The top board is perfectly working... I use that from long time just to test the 4 slot so the problem is on the bottom board for sure...

I need help knowing wich IC could cause the "not reading" of the carts or the PROM..

on the two slot I look to the NEO-GO @H2.5 but here on the MV4 I m lost....

Thanks

Click to expand...

I would see if the pin 19 on the 245s is pulsing on the active cart. If its not then work backwards from there by tracing there it comes from. Its may go through multiple ICs on the top board before getting to one (or more) of the top/bottom interconnects. Then from there trace what is feeding those pin(s) from the bottom board.

ack said:

I would see if the pin 19 on the 245s is pulsing on the active cart. If its not then work backwards from there by tracing there it comes from. Its may go through multiple ICs on the top board before getting to one (or more) of the top/bottom interconnects. Then from there trace what is feeding those pin(s) from the bottom board.

Click to expand...

Hi and thanks to the help... I found the problem and was in the two AS244 near the CN10 connector.. change them and now the cart are perfectly reading..

BUT... I have another problem now...I have two upper board for this MV4 and both have different problems

1- no one of the slots read the cart and pin 19 of the two 245s stay high so still cross hatch...
clean the 4 connector and no visible damage...

2-perfect graphic in any slot and no problem but no sound in any of the 4 slot...
clean the contacts and connector but nothing

THANKS

according the 6 slot on neowiki made an image of the upper board divining the "slot connected" IC and what is common... I thing that both of my problems are in the "common section" but where???

paoloMVS said:

1- no one of the slots read the cart and pin 19 of the two 245s stay high so still cross hatch...
clean the 4 connector and no visible damage...

Click to expand...

My previous comment applies to this. You will need to track where pin 19 is fed from. Its likely going to be one of the chips outside the boxed areas in your picture.

paoloMVS said:

2-perfect graphic in any slot and no problem but no sound in any of the 4 slot...
clean the contacts and connector but nothing

Click to expand...

I would suggest doing some additional testing. Unibios 4.0 has a bug where if there is no cart in slot 1, none of the slots will have sound.

With a stock bios, clear backup ram, then retest.

If you have a diag m1 cart, does it pass the z80 tests?

ack said:

My previous comment applies to this. You will need to track where pin 19 is fed from. Its likely going to be one of the chips outside the boxed areas in your picture.

I would suggest doing some additional testing. Unibios 4.0 has a bug where if there is no cart in slot 1, none of the slots will have sound.

With a stock bios, clear backup ram, then retest.

If you have a diag m1 cart, does it pass the z80 tests?

Click to expand...

-abou firstone I focous my attention on the F138 IC that read around is the cause of selection slot and is directly connected to pin 19 of the two 245... will try to change it


-about secondone I already try with stock bios and clear ram but nothing...

with diagnostic bios and M1 cart I have this result..

paoloMVS said:

-abou firstone I focous my attention on the F138 IC that read around is the cause of selection slot and is directly connected to pin 19 of the two 245... will try to change it

Click to expand...

You should consider looking at the data sheet for the IC and use a logic probe to see if its working as it should. Its always possible something upstream from it is broken, or even a cut trace on one of the ICs inputs causing the problem.

paoloMVS said:

-about secondone I already try with stock bios and clear ram but nothing...

with diagnostic bios and M1 cart I have this result..
View attachment 59145

Click to expand...

I've never see anyone actually get that error before. Good news is the z80 is alive and its not a data line issue. I'm a little suspect this error might be bogus and could actually be an upper address line issue. The original diag m1 address line test is broken. If you can, please try using these

https://www.mvs-scans.com/misc/19a00-98f9aad.zip