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Thread: mv1fz backup ram errors (again)

  1. #1
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    mv1fz backup ram errors (again)

    hi
    so my lovely 1fz from time to time throws me this errors :

    Code:
    backup ram error
    Address   00D00000 
    write 5555
    read 8055
    or
    read 8655 / 8455 / 8255


    i've triple checked the RAM 3 / RAM 4 pinout

    Code:
    
    RAM3
    
    1	RAM4 (1), RAM1 (1), RAM2 (1), CPU1 (46), GU5 (33), SP1 (36), CN2 (24A)
    2	RAM4 (2), RAM1 (2), RAM2 (2), CPU1 (44), GU5 (31), SP1 (34), CN2 (22A)
    3	RAM4 (3), RAM1 (3), RAM2 (3), CPU1 (39), GU5 (17), SP1 (28), CN2 (17A)
    4	RAM4 (4), RAM1 (4), RAM2 (4), CPU1 (38), GU5 (16), SP1 (27), CN2 (16A)
    5	RAM4 (5), RAM1 (5), RAM2 (5), CPU1 (37), GU5 (15), SP1 (26), CN2 (15A)
    6	RAM4 (6), RAM1 (6), RAM2 (6), CPU1 (36), GU5 (4), SP1 (25), CN2 (14A)
    7	RAM4 (7), RAM1 (7), RAM2 (7), CPU1 (35), GU5 (3), SP1 (24), CN2 (13A)
    8	RAM4 (8), RAM1 (8), RAM2 (8), CPU1 (34), GU5 (2), SP1 (23), CN2 (12A)
    9	RAM4 (9), RAM1 (9), RAM2 (9), CPU1 (33), GU5 (1), SP1 (22), CN2 (11A)
    10	RAM4 (10), RAM1 (10), RAM2 (10), CPU1 (32), GU5 (64), SP1 (21), CN2 (10A)
    11	RAM2 (11), SP1 (19), CPU1 (5), U8 (18), GU7 (6)
    12	RAM2 (12), SP1 (18), CPU1 (4), U8 (17), GU7 (7)
    13	RAM2 (13), SP1 (17), CPU1 (3), U8 (16), GU7 (8)
    14	GND
    15	RAM2 (15), SP1 (16), CPU1 (2), U8 (15), GU7 (9)
    16	RAM2 (16), SP1 (15), CPU1 (1), U8 (14), GU7 (11)
    17	RAM2 (17), SP1 (14), CPU1 (68), U8 (13), GU7 (12)
    18	RAM2 (18), SP1 (13), CPU1 (67), U8 (12), GU7 (13)
    19	RAM2 (19), SP1 (12), CPU1 (66), U8 (11), GU7 (14)
    20	U17 (2), Q1 (collector)
    21	RAM4 (21), RAM1 (21), RAM2 (21), CPU1 (42), GU5 (20), SP1 (32), CN2 (20A)
    22	GU1 (97)
    23	RAM4 (23), RAM1 (23), RAM2 (23), CPU1 (43), GU5 (21), SP1 (33), CN2 (21A)
    24	RAM4 (24), RAM1 (24), RAM2 (24), CPU1 (41), GU5 (19), SP1 (31), CN2 (19A)
    25	RAM4 (25), RAM1 (25), RAM2 (25), CPU1 (40), GU5 (18), SP1 (29), CN2 (18A)
    26	RAM4 (26), RAM1 (26), RAM2 (26), CPU1 (45), GU5 (32), SP1 (35), CN2 (23A)
    27	U17 (8)
    28	VCC
    
    
    RAM4
    
    1	RAM3 (1), RAM1 (1), RAM2 (1), CPU1 (46), GU5 (33), SP1 (36), CN2 (24A)
    2	RAM3 (2), RAM1 (2), RAM2 (2), CPU1 (44), GU5 (31), SP1 (34), CN2 (22A)
    3	RAM3 (3), RAM1 (3), RAM2 (3), CPU1 (39), GU5 (17), SP1 (28), CN2 (17A)
    4	RAM3 (4), RAM1 (4), RAM2 (4), CPU1 (38), GU5 (16), SP1 (27), CN2 (16A)
    5	RAM3 (5), RAM1 (5), RAM2 (5), CPU1 (37), GU5 (15), SP1 (26), CN2 (15A)
    6	RAM3 (6), RAM1 (6), RAM2 (6), CPU1 (36), GU5 (4), SP1 (25), CN2 (14A)
    7	RAM3 (7), RAM1 (7), RAM2 (7), CPU1 (35), GU5 (3), SP1 (24), CN2 (13A)
    8	RAM3 (8), RAM1 (8), RAM2 (8), CPU1 (34), GU5 (2), SP1 (23), CN2 (12A)
    9	RAM3 (9), RAM1 (9), RAM2 (9), CPU1 (33), GU5 (1), SP1 (22), CN2 (11A)
    10	RAM3 (10), RAM1 (10), RAM2 (10), CPU1 (32), GU5 (64), SP1 (21), CN2 (10A)
    11	RAM1 (11), CPU1 (65), SP1 (10), GU2 (13), CN2 (14B)
    12	RAM1 (12), CPU1 (64), SP1 (9), GU2 (14), CN2 (15B)
    13	RAM1 (13), CPU1 (63), SP1 (8), GU2 (15), CN2 (16B)
    14	GND
    15	RAM1 (15), CPU1 (62), SP1 (7), GU2 (16), CN2 (17B)
    16	RAM1 (16), CPU1 (61), SP1 (6), GU2 (18), CN2 (18B)
    17	RAM1 (17), CPU1 (60), SP1 (5), GU2 (19), CN2 (19B)
    18	RAM1 (18), CPU1 (59), SP1 (4), GU2 (20), CN2 (20B)
    19	RAM1 (19), CPU1 (58), SP1 (3), GU2 (21), CN2 (21B)
    20	U17 (2), Q1 (collector)
    21	RAM1 (21), RAM3 (21), RAM4 (21), CPU1 (42), GU5 (20), SP1 (32), CN2 (20A)
    22	GU1 (13)
    23	RAM3 (23), RAM1 (23), RAM2 (23), CPU1 (43), GU5 (21), SP1 (33), CN2 (21A)
    24	RAM3 (24), RAM1 (24), RAM2 (24), CPU1 (41), GU5 (19), SP1 (31), CN2 (19A)
    25	RAM3 (25), RAM1 (25), RAM2 (25), CPU1 (40), GU5 (18), SP1 (29), CN2 (18A)
    26	RAM3 (26), RAM1 (26), RAM2 (26), CPU1 (45), GU5 (32), SP1 (35), CN2 (23A)
    27	U17 (6)
    28	VCC
    everything is ok , from the errors the issue should be on the RAM4 (i think), or maybe on the two backup ram IC's ?

    this one really is driving me nuts , sometimes the board boots fine without issues
    ... and sometime like on this whole weekend is always stuck on this backup ram errors.
    Funny is that even with the new battery (battery mod, using a new cr one), it never saved nothing, even the date/time
    but that never really bothered me...

    for reference the board haves the +5v mod only+ stereo mod

    Feedback is very welcome.. dunno what should i check next ...


    thanks
    Last edited by dragonpt; 11-13-2016 at 02:12 PM.
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  2. #2
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    Backup RAM errors are not always related to RAM chips. There are some IC's on the backup area region that when they go bad, it gives a Backup Ram error. try to burn a Unibios and see if you can override the error.

  3. #3
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    Check the 74HC32!
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

  4. #4
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    Thanks

    That was the first thing that came to my mind, the ram ic's , probably the 74HC32 , since it's well known the issues it throws ...

    argg guess i need to replace that bastard... im not very handy with small IC soldering ...
    well i guess i need to order some 74HC32 and try my luck...

    Yeah i think it's time to buy an unibios, going to buy it for sure, if the board never gets fixed, i think the unibios should also fit my 4 slot board ...

  5. #5
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    Quote Originally Posted by dragonpt View Post
    Thanks

    That was the first thing that came to my mind, the ram ic's , probably the 74HC32 , since it's well known the issues it throws ...

    argg guess i need to replace that bastard... im not very handy with small IC soldering ...
    well i guess i need to order some 74HC32 and try my luck...

    Yeah i think it's time to buy an unibios, going to buy it for sure, if the board never gets fixed, i think the unibios should also fit my 4 slot board ...
    If you come by, you can use my hot air desoldering station for that job.

  6. #6
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    For sure i'll spam you

    Your way better than me on this things haha ( i suck)
    Im waiting for the unibios / and some 74HC32 that i ordered.

    In the mean time i have to use my huge 4slot...

    Cheers
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  7. #7
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    Quote Originally Posted by GadgetUK View Post
    Check the 74HC32!
    Wow i just saw your youtube videos, great find
    That will help for sure, i saw you had to replace the 74hc32 as well, how did that small one worked for you?

    Impressive
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  8. #8
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    Some updates ..

    Got my unibios 3.3 from Razoola today and i can bypass the errors by forcing to AES
    also got 4 74HC32 that i ordered .. but ... just like what happened with GadgetUK .. i got the smaller ones (smd) .. those are way small for me to try and solder .. damn

    need to get "normal" 74HC32 ugggg damn

    This was the one i got ...

    http://www.ebay.co.uk/itm/5x-74HC32-...IAAOSwl9BWK-NA
    Last edited by dragonpt; 11-17-2016 at 12:22 PM.
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  9. #9
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    More updates

    i managed to soldered the smd 74HC32 , was a bit ugly and i broke a solder point (pin 6 ) but i patched with with a wire to proper RAM pin





    I know this looks like a mess the smd ic was a pain to solder...
    And i lack a desoldering pump


    For the first time, the backup ram seems to work, since now date and time are preserved after power off/on
    (it was always reseting it. and never saved anything)

    but now it's throwing an different backup ram error

    Code:
    backup ram error
    Address   00D00000 
    write 5555
    read b255
    i guess this comes from RAM4 of the backup area, ram4 is faulty?


    oh and dunno why but now i only have PCM sound... no music ... weird
    i guess i need to re-check the small pcb i did for the stereo sound.. weird



    cheers
    Last edited by dragonpt; 11-18-2016 at 04:23 AM.
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  10. #10

  11. #11
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    Looks from that picture that some pads on the 74HC32 might have lifted? 2,5,6,7 and 9? Are you sure all the pins of the chip are connected to the traces you can see on the photo (the one with no chip)? Beyond that, I would be looking at the connections on the SRAM (or probably replacing the SRAM) as Xian Xi has suggested! I managed to fit the smaller chip but its a pretty tight fit - good flux is your friend when soldering SMD! If you want a good example of how easy it can be, check out the Super Mario RPG video I did for the SNES - that chipquik flux makes things like this a breeze!
    Last edited by GadgetUK; 11-19-2016 at 04:21 AM.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

  12. #12
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    Thanks for all the replies and help

    Yeah seems several traces are broken looking at the pics , but tested continuity on all , and only pin 6 wasn't connected (patched it with a wire to pin 27 on RAM1)




    The rest of the 74HC32 ( U17 ) pins looks ok, at least when checking continuity

    Code:
    74HC32  - U17
    
    1.   U6 (2)
    2.   Ram3 (20), Ram4 (20),
    3.   U17 (4), U17 (9)
    4.   U17 (3), U17 (9)
    5.   GU1 (14)
    6.   Ram4 (27),
    7.  GND
    8.   Ram3 (27)
    9.   U17 (3), U17 (4)
    10. GU1 (98)
    11. 22K R2(solder side)
    12. GU3 (93)
    13. GU3 (93)
    14. VCC


    SOUND:
    coincidence or not (?), after soldering the new 74HC32, the board had no sound, i mean no music...
    the pcm sound (coins, etc) where ok.
    I cleaned both cart slots as well as my MVS carts, still the same
    I then checked my small pcb of the stereo mod (the old version based on the circuit of J. Kurtz) and everything was ok also.

    I then start checking the op amp , the solution was soldering (getting) points "A" and "B" (both chanels) directly from the op amp, instead of the points "R36 " and "R37" for some reason continuity became broken from those two points to the OP AMP (???)
    Also had to connect PIN 4 of the OP AMP to +5V, and with this i fixed my sound

    i couldn't find the OP AMP pinout, but i noticied when i was checking continuity on all the pins, when looking for shorts on all the pins,when pin4 was connect to +5v i Immediately had sound on the sound hardware menu, so i just connect it to +5v and all is good

    (Maybe this helps someone with the same issue)








    The board still throws some read xx55 backup ram errors, (currently i can bypass it with unibios- forced AES Mode)
    and yeah i will try to replace RAM4, since the errors comes from it, is there any compatible replacement RAM part that i can order ?
    the SONY ones are hard to find and expensive as hell


    Thank you so much
    Last edited by dragonpt; 11-19-2016 at 11:55 AM.
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  13. #13
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    Any 62256 SRAM in the right package will typically work, something like this:-
    http://www.ebay.co.uk/itm/CY62256-70...IAAOSwNRdX-mg7

    I think I've used 55nS chips before and they work fine.

    Although I think SOIC is the wrong size physically, it needs to be SOP I think.

    EDIT:

    http://www.ebay.co.uk/itm/SRAM-256K-...8AAOxySoJTPxlJ
    Last edited by GadgetUK; 11-19-2016 at 06:30 PM.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

  14. #14
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    Quote Originally Posted by GadgetUK View Post
    Any 62256 SRAM in the right package will typically work, something like this:-
    http://www.ebay.co.uk/itm/CY62256-70...IAAOSwNRdX-mg7

    I think I've used 55nS chips before and they work fine.

    Although I think SOIC is the wrong size physically, it needs to be SOP I think.

    EDIT:

    http://www.ebay.co.uk/itm/SRAM-256K-...8AAOxySoJTPxlJ
    Thanks, just bought two of those ( last link)
    Thanks

    PS: I really ... Really like your videos
    Last edited by dragonpt; 11-19-2016 at 07:22 PM.
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  15. #15
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    Update
    Well finally got the mems ( thanks for the hint GadgetUk)

    Replaced backup ram4 ( since most errors are read xx55)
    Board continues with backup ram errors...

    Read xx55 / 0000/ ff00 , a lot of random errors

    Ugh this is one bastard board lol

    Cheers

    Edit: replaced (again) the 74hc32 ,this time I was extra careful trying not to apply too much heat on those pads for long, and now I get a constant read xx55 backup ram error

    Well if ram4 and the IC are brand new, all pins have good continuity...
    I guess ram3 also needs to be replaced as well
    Last edited by dragonpt; 12-01-2016 at 06:42 PM.
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  16. #16
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    And replaced ram3 as well
    Same thing... Ugg

    So now I've replaced both backup rams (3 and 4) and the 74hc32.
    I guess the only thing left to check on the backup ram circuit is either the NEC ic and the Q1 transistor

    I can't seem to find the NEC IC on eBay, is there any compatible ic that I can use?

    Also, how can I check if the Q1 is faulty?

    This has been an nightmare ...
    Cheers
    Last edited by dragonpt; 12-05-2016 at 05:30 AM.
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  17. #17
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    VICTOLY!!!

    Finally fixed this bastard

    So, short story I had replaced BRAM 3 and 4 for nothing, as well as the 74hc32

    The first 74hc32 was a pain to solder,since it's smaller then the original one, and I suspect the first one I soldered was screw ,probably used too much heat on the pads

    In addition ,also had to patch some vias I broke when I replaced hc32 & the BRAM memories, (lifted some pads) :/
    .....



    Well I ended up checking my faulty mv1b and noticed it had the 74hc32 as well as the NEC D4990A ic

    Replaced those two, and VICTOLY

    Finally

    Btw: this time I tested the (de) soldering on both boards using GadgetUK method, now ... and not only is fast, it ended up very cleaned , awesome.

    Pictures will come
    Cheers
    Last edited by dragonpt; 12-08-2016 at 07:04 PM.
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

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