Compaq Portable III - help needed with some parts identification

[ppieczul]

Hi,
I am restoring Compaq Portable III. It is a version with cmos battery integrated with the real time clock chip. This chip was missing on my board - probably battery leaked and someone removed it.
I put an MC146818P instead (without integrated battery) and the computer reports no more board error and starts booting.
Still, I have no battery on board. There is a space for a separate battery (XB1-XB4) on the board.
Next to this space there are several components missing, I suppose because there were needed to properly drive the battery with/without power connected.
If I connect the battery directly to the board (XB2-XB3), the current drain is too high and the battery gets hot.

I would like to add the missing parts to the board and whatever parts could have been integrated inside the battery.
I need info on the following parts:
CR2, R38, R39, R40, CR1, Q1 from a board with separate battery.
Alternatively board schematics would be awesome.

Attached is a picture from the Internet with these parts marked - it is too low a quality to judge what they are.


Thanks a lot for your help
Pawel

 

[mediasponge]

A better picture really would help. CR is the prefix for diodes. R is for resistors, Q is for transistors. If you can get the resistor values right by matching the color codes, there are a large number of equivalent parts that could substitute for the diodes and the transistor. Are you sure the MC146818P is the right chip to use? That one has Ram embedded. There are datasheets that give sample circuits that might help. The RTC also needs a crystal. The crystal, battery, and other timing components were likely potted in the original RTC chip. How does the original in this one compare to a Dallas DS12887?

https://www.nxp.com/docs/en/data-sheet/MC146818.pdf

 

[ppieczul]

There are pictures of the boards with separate battery and they have mc146818p installed (e.g. https://www.flickr.com/photos/osr/8143542588).

Exactly, I am looking for the pictures of the board in better quality so I can deduct the missing parts.

Thanks

 

[videofx]

I am looking for the pictures of the board in better quality so I can deduct the missing parts.

My Compaq Portable III arrives this week. Maybe I can help

 

[ppieczul]

Looking forward to it, thanks.

 

[videofx]

OK got my Compaq Portable III today, made some floppies and opened it up and cleaned it out and got everything working! the drive is on its last legs of Course so I have an 80mb coming to replace the 40mb, other that that I have it working 100%!

Tell me what you need and I will send it to you

Anyone know how to get IDE CF working?