Re: Help troubleshooting Dell laptop
I just did a kludgy switch repair on an Inspiron 3800 - the original power button was failing. I could not reliably turn it on and off.
Upon disassembly, I found an SMT DPST 5-terminal microswitch on the motherboard. It's similar to the switches commonly found on front panels of printers, faxes and other appliances. However, I could not easily desolder and remove it - I removed the solder with a desoldering braid, but I could not easily lift any of the leads off the pads even with a fine knife. I guess there is a small drop of epoxy holding the switch in place - probably put there just before pick and place during manufacturing.
I then decided to put another switch piggybacked above this one. It would have been too messy with an SMT switch, so I decided to use a through-hole version - and found one in a $0.50 Chinese laser pointer. This is a 4-lead SPST microswitch, but it had the same dimensions as the one in the Inspiron, with the 4 leads conveniently spaced to sit like spider legs above the original SMT microswitch. I checked the continuity on the original microswitch - it's wired like an SPST switch, so a direct parallel connection was feasible. It took nearly two hours to disassemble the board (I removed the PCMCIA socket assembly), carefully position and solder the new switch in place - but in the end everything worked fine. I also carefully cut the plastic on/off switch plunger to size to accommodate the additional height of the piggybacked switch - this has to be done in little increments of about 1 mm each time to get it just right.
It feels great to have the Inspiron running like new - not too bad for a 6+ year old machine. MMC2 mobile PIII Coppermine 700/256, i440BX/MX chipset, ATI Rage Mobility graphics, etc. - the most reliable and dependable platform for Fedora Core (or for that matter any OS/distro).
The engineering on the system is first-class - it's highly modular. It has been value-engineered, but not by bean counters. The charging/PSU circuit is on a separate daughterboard which can be replaced by the end-user - you just need to remove the keyboard to get access to it. Likewise, it just requires the removal of 3 screws to replace the display/hinge assembly in one piece.
All in all, I'd much rather have the PIII Inspiron 3800, rather than the later P4 Inspiron 1100/5100/1150/5150 units. The 3800 is more durable, reliable and maintainable. It also runs cooler and quieter than the P4 units, and has the old PA-6 adapter with the 3-pin square jack. The keyboard has a nicer feel, and it has both a touchpad and a trackpoint. It supports dual-battery operation, and all drives are in removable drive caddies. The CDROM drive caddy can also accomodate a combo CD-RW/DVD drive. The only limitation is the CPU speed - the fastest CPU was the hard-to-find MMC2 PIII/850.
Recommended - pick them off on EBay if the price is right.
I just did a kludgy switch repair on an Inspiron 3800 - the original power button was failing. I could not reliably turn it on and off.
Upon disassembly, I found an SMT DPST 5-terminal microswitch on the motherboard. It's similar to the switches commonly found on front panels of printers, faxes and other appliances. However, I could not easily desolder and remove it - I removed the solder with a desoldering braid, but I could not easily lift any of the leads off the pads even with a fine knife. I guess there is a small drop of epoxy holding the switch in place - probably put there just before pick and place during manufacturing.
I then decided to put another switch piggybacked above this one. It would have been too messy with an SMT switch, so I decided to use a through-hole version - and found one in a $0.50 Chinese laser pointer. This is a 4-lead SPST microswitch, but it had the same dimensions as the one in the Inspiron, with the 4 leads conveniently spaced to sit like spider legs above the original SMT microswitch. I checked the continuity on the original microswitch - it's wired like an SPST switch, so a direct parallel connection was feasible. It took nearly two hours to disassemble the board (I removed the PCMCIA socket assembly), carefully position and solder the new switch in place - but in the end everything worked fine. I also carefully cut the plastic on/off switch plunger to size to accommodate the additional height of the piggybacked switch - this has to be done in little increments of about 1 mm each time to get it just right.
It feels great to have the Inspiron running like new - not too bad for a 6+ year old machine. MMC2 mobile PIII Coppermine 700/256, i440BX/MX chipset, ATI Rage Mobility graphics, etc. - the most reliable and dependable platform for Fedora Core (or for that matter any OS/distro).
The engineering on the system is first-class - it's highly modular. It has been value-engineered, but not by bean counters. The charging/PSU circuit is on a separate daughterboard which can be replaced by the end-user - you just need to remove the keyboard to get access to it. Likewise, it just requires the removal of 3 screws to replace the display/hinge assembly in one piece.
All in all, I'd much rather have the PIII Inspiron 3800, rather than the later P4 Inspiron 1100/5100/1150/5150 units. The 3800 is more durable, reliable and maintainable. It also runs cooler and quieter than the P4 units, and has the old PA-6 adapter with the 3-pin square jack. The keyboard has a nicer feel, and it has both a touchpad and a trackpoint. It supports dual-battery operation, and all drives are in removable drive caddies. The CDROM drive caddy can also accomodate a combo CD-RW/DVD drive. The only limitation is the CPU speed - the fastest CPU was the hard-to-find MMC2 PIII/850.
Recommended - pick them off on EBay if the price is right.
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