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Nathanieltolbert
10th November 2009, 17:43
Hello everyone. I've been looking around to find a replacement for an old RTC clock/battery for an old 486 desktop. I hope to find one, and fix the board so that a friend of mine can use it for his BBS that he likes to play around with. I have looked on the internet but I cannot find anything. I know they can be found but I don't know where to search. But if anyone knows or has one spare (miniscule chance I know) please let me know. The top of the little black box says TH6887A 9350. If anyone can assist me with this I would be appreciative. Thank you in advance.

Nathan

keropi
10th November 2009, 22:11
oh, those are NASTY rtc+battery combo chips... can you get a nice pic of the mobo , and/or it's model/make?

Nathanieltolbert
10th November 2009, 23:54
Yes I believe I have a picture lying around somewhere let me look. I do no appear to have a picture of the motherboard like I thought. When I have time later I will try and take a picture of it. I know it has either 4 pin or six pin attachment to the motherboard though, if that helps.

Nathan

keropi
11th November 2009, 00:12
I am asking for a good pic, as there is a possibility that the motherboard has pins for external battery, so it would be very easy to restore to full operation in 3 seconds :)

rkauer
11th November 2009, 17:55
Another way to make the computer work again locating the battery terminals in that chip and solder a battery holder on it.

Nathanieltolbert
12th November 2009, 07:56
I already did that with help from Ed Jeffries. The problem is that there are no resistors and transistors (I think?) in specific spots that need them to use the actual battery spot and not the RTC Clock/Battery. Unfortunately I haven't found a good enough picture to give to Ed to identify the resistors and transistors that are missing so that we can place them on the board, Hence the reason I'm looking for a replacement of the RTC/Battery. Here are two pictures. As you can see with the first one it used a barrel battery with a 2 pin attachment. Ed wired up a replacement so that the batteries were easily replaceable. The second is a picture of the dreaded RTC/Battery that is already there. The motherboard is an MB-1433-50XXX as I don't know the three letters of the model. It lists 3 different models numbers on boot up like the board itself doesn't know what it is. The chipset is labeled BIOTEQ, which if what I can glean from the internet is an old Biostar motherboard. Can't find much more than that though.

Nathan

-Edit- I should mention that we followed traces to see where the battery connectors went and that's how we found that there weren't resistors and transistors in the right spots. Sorry I didn't mention that.

keropi
12th November 2009, 08:51
seems that external battery won't work then .... I bet this RTC is like the "DALLAS" ones found in mobos of the era , but I cannot be 101% sure of that...

Nathanieltolbert
12th November 2009, 16:12
Not quite certain what a "DALLAS" is. Can you elaborate, please?

keropi
12th November 2009, 16:16
I am talking about THESE (http://www.epower2go.biz/catalog/index.php?main_page=index&cPath=9) , very common in the past... almost every pc board I saw that had such a solution , used those DALLAS chips...

http://www.epower2go.biz/catalog/images/DS12887_blue.jpg


edit: yeap, here is your DIRECT replacement chip: http://www.epower2go.biz/catalog/index.php?main_page=product_info&cPath=9&products_id=33 I would suggest soldering a socket , so you can easily change those chips...

Nathanieltolbert
12th November 2009, 17:48
That's exactly what I needed. 18.00 plus soldering work. Not a bad price. Thank you for the help I really appreciate it.

keropi
12th November 2009, 19:03
glad I could help!