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IBM PS/2 55SX: Which way round for the Dallas DS1287 RTC?

I

interalia

Member
Joined
Dec 16, 2009
Messages
45
Hi Folks

Here goes post number two:

My collection has moved on from a few months ago to just a 5150 (with IBM Midrange network emulation card) and 5151 to:
XT 5160 (with working HD!)
PS/2 50Z (Won't power up unless I take out the 30Mb HD I will sort this out later)
and PS/2 55SX that I have a question on right now.

I have taken out the Dallas RTC and am currently doing the 'piggy back' button cell mod to it
Dimbo though didn't take a note of which way it goes in and so I will have a 50-50 chance of getting it right when I put it back.

Is the white spot on the RTC towards the front of case (processor end) or not? I have the later type of planer.

Regards

Neil

Surrey,UK
 
http://www.mcamafia.de/mcapage0/dsrework.htm maybe? Perhaps a dumb question but there isn't a pin-1 mark on the board or chip? Usually the chip has a mark (dot) on one corner to imply that's pin-1 and they also a lot of times put a mark on the schematic/labeling on the board itself to let you know to pair pin-1 to that point.
 
I've done two of these types of mods. My Dallas Chips both had a white dots which correspond to pin 1. You can see it clearly in the photos of one on the chips in my blog post here.

Tez
 
The dot (or other mark) always indicates pin1 on the device; on the board, if there's a socket it will probably have a notch of some kind in the end where pin1 goes, and maybe a small dot or 1 beside pin 1. As mentioned above, on the solder side the pin1 pad is usually square instead of round like the rest. Pins are counted clockwise looking at it from the bottom (if anyone remembers which way analog clocks moved ;-) )
 
Thanks for the replies.

Well I have tried by moded RTC and although my meter now says I have 3V at the two pins I still get error 162 and 163. I have created a ref disk from rt5565a.exe but this doesn't boot. The floppy drive is accessed during the POST and then again later but no joy. I notice that the HD drive light is on all the time and I did try disconnecting the HD but no change.

Anyone any ideas of where I go next?

Regards

Neil
 
Maybe your floppy drive is bad? I've heard from the PS/2 folk here that those floppy drives like to die a lot.
 
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