[Coco] MM/1 RTC RIP

Robert Gault robert.gault at worldnet.att.net
Thu Jan 24 20:12:53 EST 2008

Robert Gault wrote:

> Bob Devries wrote:
>> hello, MM/1 users (sorry for the bandwidth usage, you coco chaps)
>> I just found out that the RTC chip in my MM/1 has died. Actually, it's 
>> not the chip, since setting the time will work until the next power 
>> down, so it's the battery. The MM/1 uses a Dallas DS1287 integrated 
>> clock/battery, *and* it is soldered into the IO board. GROAN.
>> What to do?
>> I did some googling and came across this:
>> http://www.mcamafia.de/mcapage0/dsrework.htm
>> This will work, but I still need to desolder the clock chip, or at the 
>> very least do a *very* careful job of gringing the relavant parts. 
>> Sadly I don't own a dremel tool.
>> Does anyone else have experience in this?
> Perhaps you can do something analogous to shat I did with a Dallas 
> DS1216 clock. This was discussed here not too long ago.
> I took a battery, attached two wires to it, and soldered the wires to 
> pins 4 and 8 on the clock chip. The clock then worked like new.
> I don't know if any pins on the DS1287 go directly to the battery. On a 
> DS12885 (drop in replacement) there is a pin for an external battery. If 
> your battery is not completely dead, testing the DS1287 leads with a 
> voltmeter ought to find if there is a connection.
> DS12885 V-Bat pin     package type
>      20                SO PDIP
>      24                PLCC
>      22                TQFP
> -- 

Probably better would be get a DS12887 for a replacement.

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