| View previous topic :: View next topic |
| Author |
Message |
ph4nt0m
Joined: 01 Jan 2018
Posts: 812
Location: Europe
|
 Posted: Wed Feb 20, 2019 6:40 pm Post subject: [SOLD] ph4nt0m: IBM 486SLC2 + IBM Opal LX Mainboard |
 |
|
Up for sale a new old stock IBM 486SLC2 50G7262 soldered to an IBM Opal LX mainboard. IBM was restricted by a licence agreement with Intel to selling these CPUs with their mainboards or complete systems. Not to be sold separately under any circumstances. The mainboard comes with the manual.
The 486SLC2 makes use of the 386SX pin-out. What makes it special is the integrated cache of 16Kb. Runs at 50MHz with the 25MHz system bus, though the mainboard supports jumper selectable system bus speeds of 20MHz, 25MHz, 33MHz and 40MHz. Must have a heat sink installed in order to run the CPU at 66MHz or 80MHz. Also takes a regular 387SX compatible math coprocessor.
The mainboard was kept in storage for 25 years. The barrel battery leaked. Had to remove it, clean up and install two aerogel supercapacitors making 1 farad at 5 volts. They never leak and hold enough charge for a couple of days. Any exposed traces were restored and protected with a silver bearing solder.
All sold.
110 USD each with registered worldwide postage included
Last edited by ph4nt0m on Fri Jul 08, 2022 8:42 am; edited 7 times in total |
|
| Back to top |
|
 |
stamasd
Joined: 05 Jun 2014
Posts: 1311
Location: Connecticut
|
| Posted: Thu Feb 21, 2019 7:05 am Post subject: |
|
|
| Very nice and very tempting but I have no money right now so I have to pass. Great idea to use supercapacitors in restoring a leaked battery, I generally use the aux battery connector with a holder for either a CR2032 or 3xAAA. |
|
| Back to top |
|
|
ph4nt0m
Joined: 01 Jan 2018
Posts: 812
Location: Europe
|
| Posted: Thu Feb 21, 2019 7:29 am Post subject: |
|
|
| stamasd wrote: | | Great idea to use supercapacitors in restoring a leaked battery, I generally use the aux battery connector with a holder for either a CR2032 or 3xAAA. |
I have figured out that it's less expensive than to buy a bunch of CR2032 or AAA every year. Got a few bags of these supercaps and slowly upgrading my old mainboards.
BTW supercaps can be used instead of non-rechargeable CR2032 batteries. Use +5V to charge them through a Schottky diode, so they don't discharge into the supply rail when powered off. |
|
| Back to top |
|
|
stamasd
Joined: 05 Jun 2014
Posts: 1311
Location: Connecticut
|
| Posted: Thu Feb 21, 2019 7:35 am Post subject: |
|
|
One downside being that as you mention they hold charge for a few days only. My vintage computers are usually powered down for weeks-months. 
(I have so many of them, can't keep them all running) |
|
| Back to top |
|
|
ph4nt0m
Joined: 01 Jan 2018
Posts: 812
Location: Europe
|
| Posted: Thu Feb 21, 2019 7:45 am Post subject: |
|
|
Supercaps can be combined with external CR2032 or AAA batteries if necessary.
My typical use pattern is to pick up a mainboard, play with it for a few days, then put it back on the shelf for a month or a few. It's alright to run a BIOS setup once picked up from storage. Not alright to do that every time after powering off 
_________________
My Active Sales |
|
| Back to top |
|
|
debs3759
Joined: 18 Jan 2006
Posts: 9477
Location: Northampton, Divided Kingdom
|
| Posted: Fri Feb 22, 2019 3:57 am Post subject: |
|
|
If you are not in a hurry for payment (it would be late April) I will take one. I'll desolder the capacitors and solder in a CR2032 socket. I have plenty of sockets and batteries. I've been looking for a working IBM 486SLC2 system, and adjustable FSB is a deal maker
_________________
My graphics card database can be found at http://www.gpuzoo.com.
I can resist anything except temptation.
Debs |
|
| Back to top |
|
|
Marcin
Joined: 02 Jan 2005
Posts: 8519
Location: Poland
|
| Posted: Fri Feb 22, 2019 4:26 am Post subject: |
|
|
In my opinion is better to use ML2032 it is rechargeable battery like original. You can use it in srandard 2032 socket. Normal CR2032 is short lasting because of overcharging. Supercap is good only when you use it often.
For 10 pcs of Maxell ML2032 include shipping is about 18 USD. I just ordered no name 4 pcs for 4,5 USD include shipping.
_________________
Visit ABC CPU - Virtual CPU Museum. |
|
| Back to top |
|
|
stamasd
Joined: 05 Jun 2014
Posts: 1311
Location: Connecticut
|
| Posted: Fri Feb 22, 2019 4:42 am Post subject: |
|
|
| CR2032 will get overcharged only if you connect it to the original NiMH barrel battery pads. It you use the external battery connector that won't happen, and one lasts several years. |
|
| Back to top |
|
|
Marcin
Joined: 02 Jan 2005
Posts: 8519
Location: Poland
|
| Posted: Fri Feb 22, 2019 4:44 am Post subject: |
|
|
Yes, but externat battery connectors are not present on all boards.
I remember there was a solution to put some kind of diode to + of CR2032 to prevent charging. I cann't find that info now.
_________________
Visit ABC CPU - Virtual CPU Museum. |
|
| Back to top |
|
|
stamasd
Joined: 05 Jun 2014
Posts: 1311
Location: Connecticut
|
| Posted: Fri Feb 22, 2019 5:36 am Post subject: |
|
|
| Marcin wrote: | Yes, but externat battery connectors are not present on all boards.
I remember there was a solution to put some kind of diode to + of CR2032 to prevent charging. I cann't find that info now. |
It's in the third post of this thread. |
|
| Back to top |
|
|
Marcin
Joined: 02 Jan 2005
Posts: 8519
Location: Poland
|
| Posted: Fri Feb 22, 2019 5:38 am Post subject: |
|
|
| stamasd wrote: | | It's in the third post of this thread. |
 To much eye-catching photos 
_________________
Visit ABC CPU - Virtual CPU Museum. |
|
| Back to top |
|
|
ph4nt0m
Joined: 01 Jan 2018
Posts: 812
Location: Europe
|
| Posted: Fri Feb 22, 2019 5:42 am Post subject: |
|
|
| debs3759 wrote: | | If you are not in a hurry for payment (it would be late April) I will take one. I'll desolder the capacitors and solder in a CR2032 socket. I have plenty of sockets and batteries. I've been looking for a working IBM 486SLC2 system, and adjustable FSB is a deal maker |
I can simply sell you one without the supercaps However there's enough space only if a CR2032 is mounted vertically. You have to use a Schottky diode to prevent charging. Anode to the battery, cathode to the mainboard. There is ~0.8V drop across the diode unless you use a high current one, so a single 3V CR2032 may be insufficient. Have to use two CR2032 probably. IMHO it's better to keep the supercaps and connect the batteries to the external connector. It's in the upper left corner behind the keyboard connector.
BTW these mainboards came with the AMI BIOS, but there was an option for the MR BIOS mentioned in the manual. It would be great if someone shares the image with the community.
Last edited by ph4nt0m on Fri Feb 22, 2019 5:48 am; edited 1 time in total |
|
| Back to top |
|
|
H3nrik V!
Joined: 15 Apr 2014
Posts: 1246
Location: Denmark
|
| Posted: Fri Feb 22, 2019 5:47 am Post subject: |
|
|
| ph4nt0m wrote: | | stamasd wrote: | | Great idea to use supercapacitors in restoring a leaked battery, I generally use the aux battery connector with a holder for either a CR2032 or 3xAAA. |
I have figured out that it's less expensive than to buy a bunch of CR2032 or AAA every year. Got a few bags of these supercaps and slowly upgrading my old mainboards.
BTW supercaps can be used instead of non-rechargeable CR2032 batteries. Use +5V to charge them through a Schottky diode, so they don't discharge into the supply rail when powered off. |
Watch out, from where you charge the supercap- some RTCs are not rated for +5V battery voltage. If replacing eg. a 2032, I would charge from +3.3V.
Also bear in mind that supercaps are often not designed for a quick charge. The later, I have been working with, require 3-500 Ohms in series with charging voltage, besides the schottky diode.
Sorry for continuing spamming your sales post, BTW |
|
| Back to top |
|
|
ph4nt0m
Joined: 01 Jan 2018
Posts: 812
Location: Europe
|
| Posted: Fri Feb 22, 2019 6:04 am Post subject: |
|
|
| H3nrik V! wrote: |
Watch out, from where you charge the supercap- some RTCs are not rated for +5V battery voltage. If replacing eg. a 2032, I would charge from +3.3V.
Also bear in mind that supercaps are often not designed for a quick charge. The later, I have been working with, require 3-500 Ohms in series with charging voltage, besides the schottky diode.
Sorry for continuing spamming your sales post, BTW |
Yes, modern RTCs don't like +5V, though those from the 1990's are alright most likely. The supercaps are Cooper Bussmann PB series (Eaton took over Cooper in 2012). There are two of them and each consists internally of two 1F/2.5V caps connected in series. There are also balancing resistors. These supercaps are low ESR, low leakage and suitable for direct battery swap out.
That's alright with spamming as knowledge exchange is no less important than selling |
|
| Back to top |
|
|
stamasd
Joined: 05 Jun 2014
Posts: 1311
Location: Connecticut
|
| Posted: Fri Feb 22, 2019 6:37 am Post subject: |
|
|
| ph4nt0m wrote: | | debs3759 wrote: | | If you are not in a hurry for payment (it would be late April) I will take one. I'll desolder the capacitors and solder in a CR2032 socket. I have plenty of sockets and batteries. I've been looking for a working IBM 486SLC2 system, and adjustable FSB is a deal maker |
I can simply sell you one without the supercaps However there's enough space only if a CR2032 is mounted vertically. You have to use a Schottky diode to prevent charging. Anode to the battery, cathode to the mainboard. There is ~0.8V drop across the diode unless you use a high current one, so a single 3V CR2032 may be insufficient. Have to use two CR2032 probably. IMHO it's better to keep the supercaps and connect the batteries to the external connector. It's in the upper left corner behind the keyboard connector.
BTW these mainboards came with the AMI BIOS, but there was an option for the MR BIOS mentioned in the manual. It would be great if someone shares the image with the community. |
On Semiconductor has some nice (and cheap) Schottkies with much lower Vf. 1N5820 for instance drops 0.37V at 1A, and at currents below 100mA can go as low as 0.2-0.25V. https://www.onsemi.com/pub/Collateral/1N5820-D.PDF |
|
| Back to top |
|
|
|
![[ Hidden ]](https://cdn.cpu-world.com/forum/templates/CPUWorld/images/lang_english/icon_email.gif "[ Hidden ]"){kind=icon}
