View Full Version : MVS Backup RAM error-hard to fix?
Tupin
01-31-2010, 10:00 PM
I'm looking at a cheap MVS motherboard on eBay, and the auction says it has a backup RAM error. Is fixing this as simple as getting new chips, desoldering the old ones, and soldering in the new ones? Or is there something else?
madman77
02-01-2010, 01:09 AM
It depends...it could be the SRAM, or it could be a trace going to the SRAM that is broken or corroded from battery leakage.
Tupin
02-01-2010, 06:05 PM
So with the former I just change out the chips it gives me an error on, and with the latter I solder new traces?
Does the motherboard start up without a cartridge, or does it need one to start up?
channelmaniac
02-04-2010, 02:26 PM
What's the error message - with the numbers.
That will help me to see if it's a trace problem or a chip problem.
RJ
cesarwalter
04-06-2010, 10:46 AM
Hello channelmaniac i have the same error (Backup Ram Error) and I had replaced IC1, U1, Ram3, Ram4 and Xtal but nothing change :frustrated:.
The numbers are:
ADDRESS 00D00604
WRITE 0604
READ 0644
Can you help me? Please!
Thanks !
Cesar
What's the error message - with the numbers.
That will help me to see if it's a trace problem or a chip problem.
RJ
channelmaniac
04-08-2010, 10:26 PM
Hello channelmaniac i have the same error (Backup Ram Error) and I had replaced IC1, U1, Ram3, Ram4 and Xtal but nothing change :frustrated:.
The numbers are:
ADDRESS 00D00604
WRITE 0604
READ 0644
Can you help me? Please!
Thanks !
Cesar
Post a pic of the board and point out which chips you replaced.
Also, can you post a close-up pic of the area around the battery?
cesarwalter
04-13-2010, 12:47 PM
Ok tomorrow will post some pics !! Thanks
Post a pic of the board and point out which chips you replaced.
Also, can you post a close-up pic of the area around the battery?
cesarwalter
04-14-2010, 08:01 AM
I replaced
U1
IC1
Ram3
Ram4
XT
2 transistors (second pic)
Post a pic of the board and point out which chips you replaced.
Also, can you post a close-up pic of the area around the battery?
channelmaniac
04-16-2010, 02:13 AM
The data lines for the Backup RAM chips are connected directly to the 68000 CPU. Check for continuity between the RAM and the CPU.
Keep in mind that those are 8 bit SRAM chips and the CPU is 16 bits. One SRAM chip is the lower 8 bits of data and the other is the upper 8.
I think you'll find a broken trace on a data line.
RJ
cesarwalter
04-16-2010, 11:34 AM
Ok will check this traces !
The data lines for the Backup RAM chips are connected directly to the 68000 CPU. Check for continuity between the RAM and the CPU.
Keep in mind that those are 8 bit SRAM chips and the CPU is 16 bits. One SRAM chip is the lower 8 bits of data and the other is the upper 8.
I think you'll find a broken trace on a data line.
RJ