Repairing a M48T86PC1 RTC chip \ VOGONS

Repairing a M48T86PC1 RTC chip

Topic actions

First post, by targeted

Posted on 2024-10-28, 07:59

targeted Offline

Rank Newbie

Rank: Newbie
Posts: 4
Joined: 2024-10-28, 07:31
Location: Germany

STM M48T86PC1 is an RTC clock package similar to DALLAS 12887 et al. Unfortunately, the existing instructions for DALLAS did not work for it, and I had to drill away the entire case to find out where the wires were.

Now then, here are the instructions on how repair an M48T86PC1 by drilling and attaching an external CR2032 coin battery to it:
https://github.com/targeted/m48t86pc1-rtc-repair

Reply 1 of 6, by Nexxen

Posted on 2024-10-28, 08:23

Nexxen Offline

Rank l33t

Rank: l33t
Posts: 2297
Joined: 2020-03-05, 13:37
Location: Italy

Thanks for sharing!!

PC#1 Pentium 233 MMX - 98SE
PC#2 PIII-1Ghz - 98SE/W2K
"One hates the specialty unobtainium parts, the other laughs in greed listing them under a ridiculous price" - kotel studios

Reply 2 of 6, by mdog69

Posted on 2024-10-28, 20:39

mdog69 Offline

Rank Member

Rank: Member
Posts: 101
Joined: 2019-02-09, 10:42
Location: Coventry, UK

Additional hint: there's a 32.768kHz crystal soldered to two similar pins at the other end of the cap.

Reply 3 of 6, by stamasd

Posted on 2024-10-28, 21:05

stamasd Offline

Rank l33t

Rank: l33t
Posts: 2167
Joined: 2014-08-31, 19:59
Location: Connecticut

I wonder if Necroware's method of using hot air and chipping away at the enbrittlened epoxy would work. It should.

I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O

Reply 4 of 6, by akimmet

Posted on 2024-10-28, 23:00

akimmet Offline

Rank Member

Rank: Member
Posts: 155
Joined: 2024-05-31, 01:16
Location: Ohio, USA

I'm surprised that you didn't come across the sun nvram faq in your research.
https://www.sun3arc.org/FAQ/sun-nvram-hostid.faq.phtml

Reply 5 of 6, by jmarsh

Posted on 2024-10-29, 02:05

jmarsh Offline

Rank Oldbie

Rank: Oldbie
Posts: 1698
Joined: 2014-01-04, 09:17

Why are people still drilling two holes when GND on the battery is connected directly to the GND pin...

Reply 6 of 6, by mdog69

Posted on 2024-10-29, 05:52

mdog69 Offline

Rank Member

Rank: Member
Posts: 101
Joined: 2019-02-09, 10:42
Location: Coventry, UK

jmarsh wrote on 2024-10-29, 02:05:

Why are people still drilling two holes when GND on the battery is connected directly to the GND pin...

Your average 48T device is usually in a socket. Soldering to the ground pin makes it difficult to insert. A flying lead to a convenient earth on the PCB leashes the device to the board.

For DS12887 type devices soldered to a PCB a flying lead is a no brainer when dremelling in-situ.

Go to top of page Go to top of page

Back to General Old Hardware