UMK3 CMOS U49 Error

XianXi

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Booted fine showing U49 is good. Then I get the screen where it says U49 is bad.

Ordered a replacement and swapped it in, made sure everything is connected good.

Boots the same saying that it's good then says U49 is again bad.

What else could it be?

Version is a 1.0
 
Check power then check the address/data/control lines going to the RAM chip. One or more is missing or is incorrect.

RJ
 
I guess it has a bigger battery, but it's reading 3v. If I take it out the board won't boot. Put it back in and it boots.
 
yea i was looking at pictures just a little taller it looks like, if your getting 3v from the battery i doubt its causing the issue, logic probe or check the traces would be where i'd look next.
 
Well, the reason I suggested it was that I had a board that was giving me the same error. "CMOS Chip U49 bad. Unable to restore factory settings." I replaced the battery and it went away. I have always used CR 2025 or CR 2032 for the batteries. Never used a CR 2325 or CR 2450.
 
Well, the reason I suggested it was that I had a board that was giving me the same error. "CMOS Chip U49 bad. Unable to restore factory settings." I replaced the battery and it went away. I have always used CR 2025 or CR 2032 for the batteries. Never used a CR 2325 or CR 2450.

factory br2325's came in midway/williams boards, cr2325's are the easiest to find exact replacement. difference between 2325 and 2025's is about 3mm of height
 
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Everything is connected good except I can't find where /WE (Pin 12) goes, anyone know? I tried looking at my NBA hangtime and couldn't find it either.
 
I've got a wolf unit here with a good battery yet keeps losing cmos settings as well. 3.2v on the battery. gonna have to check the traces and solder joints.

any luck with your battery/u49 issue?
 
Check the voltage at the SRAM chip with the power off and the battery in circuit.

If that's good then either the SRAM is bad or the control signals to the SRAM are not moving to the proper state to put the chip into low power shutdown mode. See the SRAM's data sheet for more info on that mode.
 
I'm gonna pull the chip and check the control lines to were they go. Also all of a sudden U123 is coming up bad even though it verifies.
 
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