VIDEO RAM ERROR sur MVS 2 Slot

MV-2F

This varies and depends on board revision, firstly:

MV2FS

Work RAM: D3 and D4
Video RAM: C7 and C8 (right next to each other, so really both are kind of at C8 !)
Backup RAM: G1 and G2
Both of these are LH52B256N-70LL  �  28-pin surface mounted, marked as 43256 on the PCB under each chip
Additional Video RAM (fast Video RAM): D9 and C9 (really just below D9)
Both of these are CXK5814P-35L  �  24-pin DIP, marked as 5814 on the PCB under each chip
Colour Palette RAM: B8 and B8 (bunched together)
Both of these are CXK5864BSP-10L  �  28-pin DIP, marked as 4364 on the PCB under each chip
Sound RAM: K11
A single BR6216B-10LL  �  24-pin DIP marked as 6116 on the PCB under the chip

Another revision:

MV2-01

Work RAM: E5 and E6
Video RAM: F13 and G13 (right next to each other, so really both are kind of at C8 !)
Backup RAM: H3 and H4
Both of these are LH52B256N-70LL  �  28-pin surface mounted, marked as 43256 on the PCB under each chip
Additional Video RAM (fast Video RAM): F12 and G12 (really just below D9)
Both of these are CXK5814P-35L  �  24-pin DIP, marked as 5814 on the PCB under each chip
Colour Palette RAM: B9 and C9
Both of these are CXK5864BSP-10L  �  28-pin DIP (narrow body (0.3) or wide body (0.6)), marked as 4364 on the PCB under each chip
Sound RAM: K13
A single BR6216B-10LL  �  24-pin DIP marked as 6116 on the PCB under the chip

The opposite, 0x8000 is the VRAM address, the start of sprite RAM (fast 6116 pair). If the error was at 0x0001-7FFF or 0x8001+ then that would signify a bad chip since the check passed at 0x8000 indicating a good connection. Since the data read is 0x550F, it's the low sprite RAM with connection issues. Since the data should be 0x55, there would be 2 broken and 2 shorted data bus traces in order to return 0x0F... That doesn't happen. If the data returned was 0xFF that would indicate "open-bus" ie a disabled chip, and you'd look at the /CE and /OE pins, but that isn't the case either. I suspect the problem is an address line. The test possibly has written 0x0F on a previous iteration or the RAM powers up to 0x0F and with an open address line the wrong word is being read.

It's the 5814 located at F12. Check the connections:

1 LSPC (146)
2 LSPC (145)
3 LSPC (144)
4 LSPC (143)
5 LSPC (142)
6 LSPC (141)
7 LSPC (140)
8 LSPC (139)
9 LSPC (60)
10 LSPC (61)
11 LSPC (62)
12 GND
13 LSPC (63)
14 LSPC (64)
15 LSPC (65)
16 LSPC (66)
17 LSPC (67)
18 GND
19 LSPC (149)
20 GND
21 LSPC (76)
22 LSPC (148)
23 LSPC (147)
24 VCC

If they're OK, replace the ram.

nic034 a écrit:La classe
"tes ram sont là" ==> (x)
Ok je sorts :p

Kategohi a écrit:

nic034 a écrit:La classe
"tes ram sont là" ==> (x)
Ok je sorts :p

Oui je sais nic034

Kategohi a écrit:A l'adresse de l'erreur la pcb bootera.sinon pour savoir si c'est les autres il faut forcer le demarrage en aes avec l'unibios.