NEC ProSpeed SX/20 Issues

[68k]

Howdy!

I picked up this awesome little (lol) laptop today. I LOVE it's design. Thick as a brick... lunchbox carrying handle...removable keyboard... it's fantastic.



I found a compatible power supply and powered it up for the first time in many years (this was on display in a case as a "museum" piece).

The computer beeps twice (CMOS error), seeks floppy for bootable disk, so I know it's working. The LCD, however, has no image. Contrast adjustment doesn't appear to do anything.

The last time I ran into this issue was on a Powerbook 100 and the capacitors were to blame. I changed all of the caps and the issue was resolved.

Does anyone else have this model or any experience with this particular issue? It seems as if every NEC ProSpeed or MultiSpeed I see for sale is broken.

 

[68k]

Well, it's finally working 100%. It was not easy to repair, but here is the repair log:

*Capacitors
-All caps were leaking. Replaced all capacitors on the power supply as well as the mainboards. Cleaned up any electrolytic fluid residue (there was a ton, see below). All issues with screen contrast and power-on reliability were resolved with new capacitors.

*FDD Drive Repair
-The FDD was tested and was determined to be faulty. I disassembled the drive and was displeased to find the remains of a rubber drive belt. I cracked open my arsenal of parts and found a bag of new belts for the Famicom Disk System. I fit one of these belts to the NEC's drive and it worked perfectly. Had this belt not worked I would have been in trouble. The FDD interface is proprietary, so swapping in a new drive isn't an easy option.

*CMOS Battery
-Like many old laptops, the HDD will not function without a valid CMOS configuration. The ProSpeed takes it one step further in that the system will not power on if the battery is disconnected. A NEC model-specific utility is required to configure the CMOS (major props to a VCF member for sending me this utility)

*Plastic Screw Mounts
-The NEC ProSpeed features the now problematic plastic screw mounts with metal inserts. The plastic around the metal will crack causing the screw to break free. The LCD panel had two mounts that needed repair. I melted and molded new plastic around the fractured mounts. It seems sturdy, but only time will tell if the repair will hold up.

Well, that's it! It's no wonder why there aren't many of these systems in working condition today. They require a tremendous amount of work to restore to full functionality, but I felt like this beauty was too cool to part out!

 

[RWallmow]

Nicely done, here, you earned these :bigparty::clap2:

I have 2 laptops I need to tear apart and fix too, not enough free time these days, lol. I have a HP Omnibook 600c and a Toshiba T1600 that are both out of commission, and I am pretty sure both are failures of the internal power regulators, so I am hopeful I can fix them, just a matter of time to get to them.

 

[68k]

You'd be surprised what a simple capacitor change can fix. I've repaired seemingly dead systems my just changing all of the capacitors.

I was fortunate in that this NEC only had about 40 capacitors between the power board and two mainboards...

 

[RWallmow]

You'd be surprised what a simple capacitor change can fix. I've repaired seemingly dead systems my just changing all of the capacitors.

I was fortunate in that this NEC only had about 40 capacitors between the power board and two mainboards...

Yeah, I have re-capped my Mac SE/30, IIci, PB100, and numerous P4 era PCs, so I know all about bad capacitors. That said, I had a cursory look at my dead Toshiba T1600 when I got it, and saw no tell-tale signs of bad caps, but I don't own an ESR meter to actually check the ones on there, just visually checked it, and there's A LOT of discrete components crammed onto its regulator board, and I have no schematics, so it might be a real challenge narrowing its problem down, I will need a really slow weekend to tackle that one, lol.