SNK Neo Geo MV-1FZ (MVS) Repair Part 1 (Backup RAM)

Diagnosing and repairing faults on my SNK Neo Geo MV-1FZ. Totally unorthodox way of removing surface mounted SRAM chips, but it works 😉 References to Universe Bios 3.1, and 161 in 1 multicart.

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It’s worth pointing out that I really wouldn’t recommend removing SMD chips this way, unless you are desperate. Better using hot air or chip qwik. It’s also worth pointing out that using the drag technique with extra flux is the best approach to resoldering new chips. I cringe when watching this video now, just because it’s quite high risk and certainly messy compared to my approach on later videos.

The board started reporting a backup RAM error at address 00D00010, written 5555 read B255.

ChipQuik http://www.chipquikinc.com/
Dangerous Prototypes http://dangerousprototypes.com/open-logic-sniffer/
EEV Blog https://www.youtube.com/user/EEVblog

Connection table courtesey of neo-geo.com forum.

MV1FZ Backup RAM

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