I was trained on the X-ray inspection rig last night at work. I was given permission to x-ray circuit boards I bring from home as long as I work on them under the same conditions as before (breaks only).
With that in mind, I'm excited since I can finally see what the hell is wrong with the motherboard from my dead Thinkpad R40. I traced the problem to the area of the northbridge, but because I couldn't see anything, I couldn't fix it. It only had trouble when heated up and would work again with the right pressure on it so I'm thinking a microcrack someplace. It will be interesting to see the result of this.
I'm also looking at doing a bigger project, namely one of those 600MHz upgrades to one of my SGI O2 machines. Since I have the means necessary to do the work, I'm strongly considering it. All I have to do is get a bare RM7000C-600 CPU, one of those SPROM chips and training on the board oven and hot-air rework machines.
Right now, I can do the following to prepare:
switch the resistors around for the voltage mod
have someone at work remove the original CPU or teach me how
clean the pads for the CPU
remove the SPROM and clean the pads
wash the board in preparation for the new CPU and SPROM
If I can make this work efficiently, I could convert more.
Wednesday, September 12, 2007
Sunday, September 9, 2007
Antiquing - Geek style
Right now I'm using my Alienware laptop to do research on a relic I picked up from the local Deseret Industries store. It's a Compaq LTE/286 notebook computer. I'm familiar with this model because I've owned one twice before. The first time, it worked. The second time, it would never work again (I'm looking in your direction, David Orn. Coward.)
This one cost me all of $8 and included a battery pack I'm trying to bring back from the dead as I write this. The battery used in these is odd. It's a D-cell pack with four NiCd cells and a rating of 4.8V at 5Ah capacity. That's a pretty good rating for those days. The advantage with a NiCd pack is they pretty much have an indefinite lifespan as long as they're stored correctly. This one hasn't been, most likely, but I did give it a test boost from a 5VDC 2.5A switched-mode adapter. The adapter is fixed to 12W output, meaning in this case the voltage would drop in proportion to the current requirements. It was pushing 5A into the battery at 1.9VDC. Pretty normal for losses through the leads. I let it idle for a bit like that and then rubber-banded the leads in voltmeter style to check the pack voltage.
Half an hour into a creeping 1.95 to 2.16VDC reading, it jumped to 2.3, then 2.8 and now 3.34V. I am expecting the current input to the pack to be somewhere around 3A. The pack should reach 5VDC soon. The adapter's actual output is 5.25VDC so I won't have to worry about an abysmal charge rate toward the end.
What I don't know is whether the old pack will be able to put out the current I need. I tried to turn the system on with the feed from the adapter, but it would drop the moment the hard disk spindle started. Not unexpected, really. Those motors take a pretty hard kick to start up.
I have a battery case I remember making to power my wife's cellphone when her Lithium cell died. It was okay for that, but what I'm thinking about now more than anything is the fact that the pack is the size of a D-cell. It holds 4 AA cells. If I had four of them, I could run the system for a very long time from 16 NiMh AA cells. That would prove interesting since I have a way of connecting a charge circuit that would make the internal one obsolete.
More likely, I can just put eight AA cells in using packs I have around here already. I'd really much rather put NiMh D-cells in the old pack and alter the charge circuit, though.
My plan for the LTE/286 is to soup it up a bit. Granted, it's going to be nearly impossible to make it anything great, but I can at least make it a killer WordPerfect 5.1 system.
What I want to do, assuming it turns out to work:
1 - Replace the NiCd technology power system with a NiMh one
2 - Replace the EL backlight with an LED one, maybe with the addition of making the display transflective
3 - Replace the hard disk with solid-state Flash storage (very difficult)
4 - Add a keyboard light
5 - Upgrade the RAM
6 - Add some kind of off-storage in the expansion slot where the modem should be
7 - Drive the display as though it's color
1. Insanely easy. Most of the time, NiMh cells are direct replacements you just have to be a bit careful with when letting them charge for a long time.
2. A bit more involved, but the technology is there for an easy conversion. All I have to do is figure out how to spread the light in from the sides the best.
3. This could be a tough one. Some hard disks have to be typed as certain capacities. I'd likely be limited to a 128MB flash device, but that's fine. I already have one. The connector poses a problem as it's a 44-pin IDE connector with the wrong pin spacing. Not quite desktop and not quite notebook IDE.
4. I'm going to have to see if I can tie a Lock LED to a PIC or something to run it.
5. Upgrades are available. I can go to a maximum of 4MB more.
6. I don't know the pinout or whether anything high-speed is available, but I could find out with a lot of footwork.
7. The display used for these laptops is a weird one. I believe it was due to the technology allowing better contrast than the greyscale models. Black is actually a dark navy blue. White is actually an orange-ish white.
I'm now three hours into the project.
I have managed to use a 5VDC 3A power brick to run the computer. It was through this that I found I can connect the top right (from the back of the system) terminal of the power jack to 5VDC and connect the neutral to anywhere on the metal parts of the case in order to power the system just like a battery. I am unsure what the other two leads are for. Going directly from top to bottom or even reversing the polarity did nothing. Likely the neutral/system ground is common while one of the bottom pins is a positive for running the system. The adapter was rather complex with two outputs. I am guessing the system was kept light by keeping the charging system in the adapter.
While I had the system open, I looked for damage to the poorly designed hinges. It was there, especially on the left one, behind the battery pack. The way the hinge is fastened leaves a lot of flex in the stamped steel and with the hinge getting more stiff as it ages, damage is only a matter of time away. The posts where the hinge is anchored are cracked. One is almost gone. I rescued it with cyanoacrylate glue. What I'd really like is to have an epoxy resin buildup like I did with the last one.
I also discovered something that told a bit of the system's story. It was made here in the USA and the casing was molded in January of 1991.
I've discovered why the other LTE/286 had a burned hard disk cable, too. The cable for the drive is routed under the drive and over top of one of the mounting holes for bottom-mounting. The holes in question are not used on this system, with side mounting being the choice here. The mounting holes are, however, touching cushions inside the bottom piece when the system is assembled. That's machined aluminum on a Kapton ribbon cable. Not Kosher. I'm putting paper between the hole and ribbon. I will need that cable when it's time to swap drives.
It's now two days into the project. None of my adapters will properly charge the battery pack, but it wouldn't help, anyway. The pack is dead. It drops itself down to about 1VDC total soon after power is removed. I'll have to rebuild it. I'll also have to find an original AC adapter to do some reverse-engineering. I'd like to put a circuit inside the machine that will allow the system to take a normal two-wire power plug. The insides are rather packed, but it's still do-able with today's technology.
Honestly, what would really be cool is stripping the 286 gear out one day and installing something custom. I'd get a second LTE/286 for that, though. Properly reinforced, too.
I did boot the machine to find DOS already installed on a 40MB hard disk. WordPerfect 5.1 was also there. I don't remember how to use it so I've got a text editor called VDE on there. It's a good one.
This one cost me all of $8 and included a battery pack I'm trying to bring back from the dead as I write this. The battery used in these is odd. It's a D-cell pack with four NiCd cells and a rating of 4.8V at 5Ah capacity. That's a pretty good rating for those days. The advantage with a NiCd pack is they pretty much have an indefinite lifespan as long as they're stored correctly. This one hasn't been, most likely, but I did give it a test boost from a 5VDC 2.5A switched-mode adapter. The adapter is fixed to 12W output, meaning in this case the voltage would drop in proportion to the current requirements. It was pushing 5A into the battery at 1.9VDC. Pretty normal for losses through the leads. I let it idle for a bit like that and then rubber-banded the leads in voltmeter style to check the pack voltage.
Half an hour into a creeping 1.95 to 2.16VDC reading, it jumped to 2.3, then 2.8 and now 3.34V. I am expecting the current input to the pack to be somewhere around 3A. The pack should reach 5VDC soon. The adapter's actual output is 5.25VDC so I won't have to worry about an abysmal charge rate toward the end.
What I don't know is whether the old pack will be able to put out the current I need. I tried to turn the system on with the feed from the adapter, but it would drop the moment the hard disk spindle started. Not unexpected, really. Those motors take a pretty hard kick to start up.
I have a battery case I remember making to power my wife's cellphone when her Lithium cell died. It was okay for that, but what I'm thinking about now more than anything is the fact that the pack is the size of a D-cell. It holds 4 AA cells. If I had four of them, I could run the system for a very long time from 16 NiMh AA cells. That would prove interesting since I have a way of connecting a charge circuit that would make the internal one obsolete.
More likely, I can just put eight AA cells in using packs I have around here already. I'd really much rather put NiMh D-cells in the old pack and alter the charge circuit, though.
My plan for the LTE/286 is to soup it up a bit. Granted, it's going to be nearly impossible to make it anything great, but I can at least make it a killer WordPerfect 5.1 system.
What I want to do, assuming it turns out to work:
1 - Replace the NiCd technology power system with a NiMh one
2 - Replace the EL backlight with an LED one, maybe with the addition of making the display transflective
3 - Replace the hard disk with solid-state Flash storage (very difficult)
4 - Add a keyboard light
5 - Upgrade the RAM
6 - Add some kind of off-storage in the expansion slot where the modem should be
7 - Drive the display as though it's color
1. Insanely easy. Most of the time, NiMh cells are direct replacements you just have to be a bit careful with when letting them charge for a long time.
2. A bit more involved, but the technology is there for an easy conversion. All I have to do is figure out how to spread the light in from the sides the best.
3. This could be a tough one. Some hard disks have to be typed as certain capacities. I'd likely be limited to a 128MB flash device, but that's fine. I already have one. The connector poses a problem as it's a 44-pin IDE connector with the wrong pin spacing. Not quite desktop and not quite notebook IDE.
4. I'm going to have to see if I can tie a Lock LED to a PIC or something to run it.
5. Upgrades are available. I can go to a maximum of 4MB more.
6. I don't know the pinout or whether anything high-speed is available, but I could find out with a lot of footwork.
7. The display used for these laptops is a weird one. I believe it was due to the technology allowing better contrast than the greyscale models. Black is actually a dark navy blue. White is actually an orange-ish white.
I'm now three hours into the project.
I have managed to use a 5VDC 3A power brick to run the computer. It was through this that I found I can connect the top right (from the back of the system) terminal of the power jack to 5VDC and connect the neutral to anywhere on the metal parts of the case in order to power the system just like a battery. I am unsure what the other two leads are for. Going directly from top to bottom or even reversing the polarity did nothing. Likely the neutral/system ground is common while one of the bottom pins is a positive for running the system. The adapter was rather complex with two outputs. I am guessing the system was kept light by keeping the charging system in the adapter.
While I had the system open, I looked for damage to the poorly designed hinges. It was there, especially on the left one, behind the battery pack. The way the hinge is fastened leaves a lot of flex in the stamped steel and with the hinge getting more stiff as it ages, damage is only a matter of time away. The posts where the hinge is anchored are cracked. One is almost gone. I rescued it with cyanoacrylate glue. What I'd really like is to have an epoxy resin buildup like I did with the last one.
I also discovered something that told a bit of the system's story. It was made here in the USA and the casing was molded in January of 1991.
I've discovered why the other LTE/286 had a burned hard disk cable, too. The cable for the drive is routed under the drive and over top of one of the mounting holes for bottom-mounting. The holes in question are not used on this system, with side mounting being the choice here. The mounting holes are, however, touching cushions inside the bottom piece when the system is assembled. That's machined aluminum on a Kapton ribbon cable. Not Kosher. I'm putting paper between the hole and ribbon. I will need that cable when it's time to swap drives.
It's now two days into the project. None of my adapters will properly charge the battery pack, but it wouldn't help, anyway. The pack is dead. It drops itself down to about 1VDC total soon after power is removed. I'll have to rebuild it. I'll also have to find an original AC adapter to do some reverse-engineering. I'd like to put a circuit inside the machine that will allow the system to take a normal two-wire power plug. The insides are rather packed, but it's still do-able with today's technology.
Honestly, what would really be cool is stripping the 286 gear out one day and installing something custom. I'd get a second LTE/286 for that, though. Properly reinforced, too.
I did boot the machine to find DOS already installed on a 40MB hard disk. WordPerfect 5.1 was also there. I don't remember how to use it so I've got a text editor called VDE on there. It's a good one.
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