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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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13th Jan 2016, 12:19 am | #21 | ||
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,457
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Quote:
It's also thrown up the specs for this series, which state: Quote:
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13th Jan 2016, 11:31 am | #22 |
Octode
Join Date: Aug 2006
Location: Rye, East Sussex, UK.
Posts: 1,647
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Thanks lads, I'd love to say 'Eureka - I've found a battery' - but as my photo and Arjoll's photos show, there is no 'big black AA battery box' nor a penny CR cell, so I presume it must be a Dallas chip with integral lithium battery but as my first photo shows, none of the chips on the rear-most video card, the long main board with Pentium or the base mother-board have user replaceable components or are thick enough for a penny CR cell. The short cards are SCSI, parallel and serial cards.
Just to clarify from my first photo, which are you describing as the I/O board? All that is visible is in my two photos. There is however clearly a board under the mains transformer (2nd photo - about 1/2" cavity) but I can't (yet) see how to easily remove the transformer... ipso facto, this would unlikely be a user-serviceable component hidden away from prying eyes, but I'll have another look-see. The long 'black box' attached to the transformer box with a white, 3-cable connector is for the fan and no visible means of removing it. Yes, Compaq did do some funny things and it is quite possible the RTC battery replacement was a Compaq Service Engineer job... all long since departed! |
13th Jan 2016, 2:02 pm | #23 |
Octode
Join Date: Aug 2006
Location: Rye, East Sussex, UK.
Posts: 1,647
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Update: To gain access to the board under the transformer (for keyboard, VGA etc - the I/O board?) needs a major strip down but the board is visible via an inspection mirror and a torch... there is no obvious battery! However there is a very shallow quite small stacked multi-pin chip which I presume is the Dallas chip (with integral battery) but one clearly not meant to be easily replaced except by an engineer with suitable 'crow-bar and fly-press'. The odds of finding a fully charged replacement are I guess, remote!
At least I now have a functional 3-1/2" drive and - so far - no further 162 messages! I have a spare Compaq 586 (with CR penny battery!) but which is on power all the time the mains is connected - I have replaced the on/off switch but it makes no difference... any ideas?! |
13th Jan 2016, 7:49 pm | #24 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,556
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
If it's a Dallas chip with integral battery, someone posted about a similar device in a Jukebox not long ago and there was mention of chipping bits of the chip away to connect a fresh battery to its innards, etc - but then it was discovered that - against expectations - they were still available from a mainstream supplier.
So, best not to just assume you can't get them any more... there would have been a lot of machines / devices which used these very conveniently packaged RTC / RAM chips and maybe there was a little boom in the manufacturing of originals or equivalents as the batteries in the original ones came to the ends of their lives. |
13th Jan 2016, 8:01 pm | #25 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,943
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
There are several ways to repair them, including attaching flying leads to the power pins or chopping the top off with a Dremel. They weren't intended to be replaceable, and as they haven't been made for a long time any NOS examples kicking around will have very elderly batteries even if they're not completely flat.
The original idea was that these modules would last at least 10 years, which is the standard life of a lot of professional equipment. They've caused lots of problems though, and not only with desktop computers. |
13th Jan 2016, 8:41 pm | #26 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,556
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Actually, the common or garden DS12887A seems to be alive and kicking, although it looks as though Dallas are now a subsidiary of Maxim.
Here it is on RS's website. http://uk.rs-online.com/web/p/real-t...31323838374126 I'm not suggesting that the DS12887A is the actual device which is fitted in brenellic2000's machine, just illustrating that as long as his device is not too obscure, there may still be someone making it (or an equivalent). |
13th Jan 2016, 9:48 pm | #27 | |
Nonode
Join Date: Oct 2014
Location: West Midlands, UK.
Posts: 2,181
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Quote:
As far as running /selecting programs, i used to use a program from Norton 4.5 called BE(.EXE) , with reference to BEDEMO.BAT to bring up a menu at boot up. (You might get a copy here - https://winworldpc.com/download/45AF...5-7054D21A8599) |
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14th Jan 2016, 11:24 am | #28 |
Octode
Join Date: Aug 2006
Location: Rye, East Sussex, UK.
Posts: 1,647
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Thanks Sirius, I managed to track down one via an e-Bay supplier and have ordered one up on the off-chance; from what I've gleaned from the internet, the DS12887A appears to be the most likely replacement. It looks like I need to do do a major strip down to get at it - Oh boy!
Thanks everyone for you help! Barry |
16th Jan 2016, 9:28 pm | #29 |
Heptode
Join Date: Nov 2008
Location: North Walsham, Norfolk, UK.
Posts: 900
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
I was the one with the jukebox error don't buy new old stock as they will already be flat guess how I found out! I found brand new chips with Farnell. On all the ones I have seen there's a date code on most in the week the year format so you can easily tell what the age of the chip is eg 2284 = wk 22 1984
The specs. I read say maximum reliable life of 15 years there's tons of info on Maxims website |
17th Jan 2016, 11:30 am | #30 |
Octode
Join Date: Aug 2006
Location: Rye, East Sussex, UK.
Posts: 1,647
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
Thanks, I did wonder as the packets they came in are a bit dusty! RS have them at the same price while Farnell are considerably dearer.... but Farnell's site won't currently let me register!
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11th May 2016, 6:56 pm | #31 |
Tetrode
Join Date: May 2012
Location: Oxfordshire, UK.
Posts: 69
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Re: 162 set-up error, Compaq Deskpro 66M 486PC
An EISA bus machine stores the configuration of the machine in the CMOS memory. If you replace the CMOS chip (or disconnect the battery) you will need to use a special EISA configuration program run from a bootable floppy and have the configuration files for the expansion cards avaialable - bit like an IBM PS/2
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