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AuthorTopic: Amiga 500Plus U12  (Read 122 times)

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Offline scuzzb494

Amiga 500Plus U12
« on: May 22, 2020, 10:47:11 PM »
Hi

It is strange that in most A500Plus computers the battery has chosen to attack component U12 and the adjacent resistor. I can appreciate the resistor cus the legs are so close to the battery end but often only the U12 has been hammered and everything else is generally OK. I guess there is good reason. Don't even know what U12 does.. perhaps someone here knows.

https://www.scuzzscink.com/amiga/scuzzblog_may20_2/car_sbd_190520_28.jpg

https://www.scuzzscink.com/amiga/scuzzblog_may20_2/car_sbd_190520_29.jpg

https://www.scuzzscink.com/amiga/scuzzblog_may20_2/car_sbd_190520_27.jpg


Offline arttu80

Re: Amiga 500Plus U12
« Reply #1 on: May 23, 2020, 10:21:06 AM »
I beg to differ from your opinion. Battery acid can spread on that motherboard to veeery far locations, it just depends on how Amiga was stored. I just revived one, but it needed new Gary socket and even Paula socket was affected too. About that U12, it's only standard logic "glue" chip, which happen to be first in line to take battery attack. Check out where these pins are connected easily at:  http://www.amigapcb.org/

Offline scuzzb494

Re: Amiga 500Plus U12
« Reply #2 on: May 23, 2020, 01:49:44 PM »
Hi

I have removed a bucket full of them. I was intrigued why it hit this little chip first cus basically I didn't know what it did. Even when there appears to be no damage elsewhere this chip seems to have the legs go green.

Below is one dreadful horror and this weeks blog where I am going though eleven of my A500Plus computers reviewing the battery issues from removed batteries.

The horror ..

https://www.scuzzscink.com/amiga/scuzzblog_april20/scuzzblogdapril20_0103.htm

The happy endings .... still three more to show.

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2201.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2202.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2101.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2102.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2001.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_2002.htm

https://www.scuzzscink.com/amiga/scuzzblog_may20/scuzzblogdmay20_1902.htm

I have had damage as far as the Agnus, Gary and the trapdoor expansion plus the back of the board. Dreadful just dreadful.

Thanks for the reply.