replacing a dead TimeKeeper on a 386 mobo

[CosmicVelocity]

Hi All,

New member here!

Anyways, I recently aquired a Commadore 386 PC and it has a dead ST MK48T87B-24 TimeKeeper NVRAM battery chip that is soldered to the board.
I recently cut it out and unsoldered the remaining pins from the PCB and I was looking at a replacement chip.

Does anyone have any experience with replacing these NVRAM chips with alternatives such as the Dallas ones or external battery versions such as the ones sold on www.exxoshost.co.uk --> https://www.exxoshost.co.uk/atari/last/storenew/falc_rtc.jpg

If I understand it correctly, any of these options should work as a direct drop-in replacement ?

Thanks.

 

[pkhoury]

.....

 

[glitch]

Did you destroy the module in the process of removing it? I've got a bunch of NVRAM/RTC repair boards that allow for the replacement of the top encapsulation with a small circuit board that contains a replacement crystal and battery in a cell holder:

Something like that would work on the MK48T87, though the label would be wrong. I believe the 48T87 is mostly compatible with the DS12887, though in the one board I've repaired with a MK48T87, I had to use a 1287-compatible replacement as it wouldn't work with a newer 12887. I've got repair modules for those as well, and fully assembled/tested GW-12887-1 modules.

 

[pkhoury]

I've seen those before. I tried to be slick and picked up a small supply of DS12887 for some PS/2s and other systems. Semi-NOS (2013 IIRC).

How much are your replacements, glitch?

 

[CosmicVelocity]

Did you destroy the module in the process of removing it? I've got a bunch of NVRAM/RTC repair boards that allow for the replacement of the top encapsulation with a small circuit board that contains a replacement crystal and battery in a cell holder:

Something like that would work on the MK48T87, though the label would be wrong. I believe the 48T87 is mostly compatible with the DS12887, though in the one board I've repaired with a MK48T87, I had to use a 1287-compatible replacement as it wouldn't work with a newer 12887. I've got repair modules for those as well, and fully assembled/tested GW-12887-1 modules.

Yes, the old chip has been destroyed. Right now I just have the empty holes on the board.
Im currently waiting for a new 24 pin IC socket and the NVRAM from that Exxos Atari site..

That said, Im interested in your solution too. How much for it? and where are you located?

 

[glitch]

I'm in the US, the repair boards are $10 (board with battery holder and 32.768 KHz crystal installed, new Renata CR2125 battery included). I typically rebuild the modules for $25 for hobbyists.

 

[CosmicVelocity]

I'm in the US, the repair boards are $10 (board with battery holder and 32.768 KHz crystal installed, new Renata CR2125 battery included). I typically rebuild the modules for $25 for hobbyists.

I actually got the board to work again by using that exxos solution. (next time I find a machine to fix Ill try your chip)