VOGONS


DS12887 drop-in replacement

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Reply 160 of 173, by olebakk

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I have assembled a few more of these and to my surprise they do not work (the first two I made seem to work fine still)! I have checked all pins - but I suspect that the chips I use (cheap ebay stuff) is not working properly (same batch as the first two though). Most mainboards just refuse to boot them, but I got an old bord to boot one of them - and noticed that the seconds actually counted to 100! (showing a time of 04:03:89 and so on).

Anyone know of a reliable (but cheap) source of chips?

Reply 161 of 173, by Maeslin

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Shadow Lord wrote:

Hello All,

I have purchased a few of these from Maeslin and they are great! However, I now have a system that uses a DS1497 (basically a DS1495 w/ built in battery). Does anyone know if these would work as a replacement for the DS1497? TIA!

Unfortunately it looks like the logic and adressing on the DS1495/1497 is pretty different from the DS12887. I could make up a similar board using a DS1495 SOIC, 32khz crystal and battery holder but I would have no way to test it.

gottspeed wrote:

Can these still be purchased from Maeslin?

I have a good number of them, unfortunately for single modules the shipping ends up being more expensive than the module itself. If it's a bigger order I might be able to arrange something.

olebakk wrote:

I have assembled a few more of these and to my surprise they do not work (the first two I made seem to work fine still)! I have checked all pins - but I suspect that the chips I use (cheap ebay stuff) is not working properly (same batch as the first two though). Most mainboards just refuse to boot them, but I got an old bord to boot one of them - and noticed that the seconds actually counted to 100! (showing a time of 04:03:89 and so on).

Anyone know of a reliable (but cheap) source of chips?

Counting seconds to 100 is definitely new. Might point to a poorly-done fake.
I think I got a batch of them off aliexpress initially. I'll have to dig through old email and get back to you.

Reply 162 of 173, by Shadow Lord

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Unfortunately it looks like the logic and adressing on the DS1495/1497 is pretty different from the DS12887. I could make up a similar board using a DS1495 SOIC, 32khz crystal and battery holder but I would have no way to test it.

O.k. No worries and thanks for the reply. I believe a member on VCF is already looking into producing a board that can make uses of the DS1495. TIA!

Reply 163 of 173, by feltel

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I probably could need one or two of those Alt12887 replacements as I prefer a clean solution over hacking and glueing an old Dallas module. The Alt12887 should be drop-in compatible with old DS1287 modules used in IBM PS/2s. Unfortunately there seems only sources for this project in the United States as it seems. Is there anyone aware of sources for build modules within Europe? Due to high shipping costs from US to EU and customs a single module would cost nearly fifty Euros, which is a steep price.

Reply 164 of 173, by Tiido

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I actually have a small handful of the PCBs in my hands, in green. I can mail one or two for shipping cost within EU, parts you need to gather yourself though.

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Reply 165 of 173, by feltel

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It would be very kind if you could send me one or two of those PCBs. I actually never tried SMD soldering before but I'm willing to learn on the go. Unfortunately I could not PM you, probably due to my low posting count. Maybe it is working the other way around?

Reply 166 of 173, by Maeslin

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feltel wrote:

It would be very kind if you could send me one or two of those PCBs. I actually never tried SMD soldering before but I'm willing to learn on the go. Unfortunately I could not PM you, probably due to my low posting count. Maybe it is working the other way around?

I went with one of the largest (if not the largest) surface mount footprints specifically to make the job easier. It's doable with just a cheap iron and half-decent solder (just not plumbing solder. don't ask, I've seen it tried) but if you can find a little bottle of liquid flux and some wicking strip (looks like a flat woven copper 'strap') it helps a great deal. I recommend tinning and cleaning the pads before putting the chip on.

To add, if you need to source more PCBs, you can get the whole package of gerber files from the oshpark link and have them made by any fab house of your choice.

Reply 167 of 173, by Tiido

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feltel wrote:

It would be very kind if you could send me one or two of those PCBs. I actually never tried SMD soldering before but I'm willing to learn on the go. Unfortunately I could not PM you, probably due to my low posting count. Maybe it is working the other way around?

You can send an e-mail to me, which can be found in the first link in my signature.
Solering the boards shouldn't be a problem, just have plenty of flux handly and it will go smoothly.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 168 of 173, by matze79

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Works very good!

Thanks for making this Project!

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https://www.retroianer.de - under constructing since ever

Co2 - for a endless Summer

Reply 169 of 173, by Maeslin

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matze79 wrote:

Works very good!

Thanks for making this Project!

Glad you like it!

Word of advice, secure the 32khz crystal to the pcb with a drop of superglue under the case. It doesn't take much to tear it off the pads by accident if they're the only things holding it on.

Reply 170 of 173, by Maeslin

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As a small update, there's now a DS1497 drop-in replacement counterpart to the Alt12887.

I have no way to test the unit since I don't have any systems that use those, but it's a completely passive adapter so issues should only be with assembly.

Reply 172 of 173, by matze79

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Hi,

does anyone use ALT RTC inside IBM PS/2 55SX ?

on each reboot i get Error 163.

CMOS Settings and also Date is saved, but clock starts always again at 12:00:00
it does not save Time.
The ALT12887 works fine in other Systems.

Any suggestions how to fix this ?

https://dosreloaded.de - The German Retro DOS PC Community
https://www.retroianer.de - under constructing since ever

Co2 - for a endless Summer

Reply 173 of 173, by matze79

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It works, one just have to set time with IBM PS/2 reference disc for first time.
if only set from DOS it does not save it.

https://dosreloaded.de - The German Retro DOS PC Community
https://www.retroianer.de - under constructing since ever

Co2 - for a endless Summer