Laptop Teardown - Mysterious signatures find? - Page 1
Forum section: electronics / general

author: Syntax Error
author_rank: Frequent Contributor
timestamp: November 06, 2019, 05:20:52 pm
content: There are always interesting discoveries to be made when tearing down old equipment.On the slab was a long defunkedPhillips PCL304business laptop of 1991-1993 vintage. Leading edge in it's day, this business laptop had a black and white TFT screen, 2 meg of RAM, a 40 meg hard drive, a 3.5in floppy disc drive and a 20Mhz-386 CPU with a maths co-processor option. It ran DOS version 5 with a GUI file manager.The battery inside the Dallas clock module had long died, so the Award Bios was stuck forever in January 1970. The battery pack for powering the machine was made from four chunky D-cell Nicads. There was also an pin header for an optional 300 baud modem, just in case the business user needed to dial the company mainframe from their hotel room. On the back were the standard printer and serial ports, with an expansion port for direct access to the bus. The PCB was a mixture of SMD and PTH parts, with chips being a mess of forms factors from DIP to PLCC and SOIC. In the picture the memory module is edge on in SIMM2 with, the power supply, battery charger and screen tube HT supply board, mounted over the hot CPU. The HDD and floppy are under the keyboard.Now the interesting bit... The TFT screen lifted out to reveal embossed in the plastic case a whole set of signatures!So, who were these people? Design engineers at Phillips?

author: ataradov
author_rank: Super Contributor
timestamp: November 06, 2019, 06:08:12 pm
content: It was a common tradition in the old days to put engineer's signatures on the molds. It does not really cost anything and a very cool thing to do.And then design teams became so huge that it stopped making sense. And also companies may not wan to expose names of the engineers working on specific products.The original Macintosh case is probably the best known example of that.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 06, 2019, 06:38:57 pm
content: Yeah. Those were good times, when engineers actually got recognition.These days, it's against most companies' policies. They want to avoid engineers becoming "stars". Star engineers are more likely to: ask more, get offers from competitors, and be less replaceable.

author: Syntax Error
author_rank: Frequent Contributor
timestamp: November 06, 2019, 08:19:31 pm
content: @SiliconWizard - nowadays we just need YouTube to make EE stars.@Ataradov - thanks for that. For a few years it was vogue for engineers to sign their own work like artists sign theirs, as Jobs said. For those playing at home, a link to the Steve Jobs' Macintosh signing party on FolkLore.org :https://www.folklore.org/StoryView.py?story=Signing_Party.txtToday us artists and artesans have to sneak our signatures into the top most bytes of an EEPROM region. Waiting for 2060 when some kid discovers the joy of reading the vintage flash memory chips in their dad's old garage junk.

author: Whales
author_rank: Super Contributor
timestamp: November 06, 2019, 08:56:32 pm
content: N.B. if you want to fix the Dallas clock chip: you can dremel into a couple of very specific locations, hot glue a CR2032 holder ontop and solder a few wires on. Inside the giant plastic prism is a standard (wide) DIP chip and a battery (that you can bypass). I did this mod for a couple of my old machines, there's details on it around the web. Very easy to do.

author: Halcyon
author_rank: Unknown
timestamp: November 08, 2019, 04:54:29 am
content: Quote from: Whales on November 06, 2019, 08:56:32 pmOr you can remove the old Dallas chip altogether and just pop in a new one. They still make brand new replacements for the DS1287's. They'll last another 15+ years.Search for DS1687-5+ for the 5v version or DS1687-3+ for the 3v version.

author: james_s
author_rank: Super Contributor
timestamp: November 08, 2019, 04:59:46 am
content: I prefer to add an external battery. I don't like to support the idiotic practice of potting batteries inside the module by spending my money on them. They should have had a coin cell holder molded into the top.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 08, 2019, 02:28:20 pm
content: Quote from: james_s on November 08, 2019, 04:59:46 amI don't like those potted modules much, and IME they tend to often NOT last nearly as long as they are supposed to. And as they are most often just soldered, on multilayer PCBs, they are a hell to desolder properly without damaging anything.That said, they have some benefits over external batteries. The latter can be prone to oxidation and can leak (although admittedly good primary Lithium batteries can last for very long without leaking...), and sockets can be a problem in harsh environments (but for this, you can always use primary batteries with welded tabs, still much easier to service than those potted modules...)

author: james_s
author_rank: Super Contributor
timestamp: November 08, 2019, 06:14:03 pm
content: They make a surface mount version of many of these in what they call a PowerCap package. It is a non-potted PCB with a snap on cap containing the battery and optionally a crystal. I recently made an adapter to use one of those in place of the potted DS1742W in my TDS3000 scope.

author: Tepe
author_rank: Frequent Contributor
timestamp: November 08, 2019, 10:21:45 pm
content: The inside of an Amiga 1000 case: