NEC PC-8201a Adventures – Part Three: Getting Rid of the Dirty

Wel­come back to part three of my res­tor­a­tion and adven­tures with an NEC PC-8201a vin­tage com­puter circa. 1983. Let’s get to it!

Stripping Down

It’s actu­ally not that grungy to look at. Sure, a minor scuff or two, but from the looks of it, this unit is actu­ally quite clean.

So, let’s get it apart and get everything shiny.

Open the Case

Four screws hold the case togeth­er. They come out without any both­er; nice that there are brass fer­rules that they mate to. None of this self-tap­ping into plastic.

Once the back is open, we’ve got a few more screws to free the key­board from the top case.

And we have to care­fully dis­con­nect the key­board con­nect­ors from the main­board. And even­tu­ally remove all boards from the case.

There are two sturdy met­al rails that rein­force the key­board board. These help if you’ve got a tend­ency to pound the key­board as I’ve seen many two-fingered-typ­ing journ­al­ists do. Of note, the Tandy Mod­el 100 only has one met­al rail, the oth­er is plastic.

Ah, There’s the Grunge

Lift­ing the key­board out of the top case shows the fab­ric top lay­er used to keep crumbs and oth­er debris from the cir­cuit board.

Inter­est­ingly, there’s also a soft sponge lay­er cov­er­ing the switches cor­res­pond­ing to the func­tion keys (F1 — F5). This is also absent from the Mod­el 100 and does soften the click sound from those keys.

Remov­ing the fab­ric reveals the cir­cuit board. It’s an ALPS key­board, which is a very good maker of key­boards, back in the day and even today. ALPS keys are much sought after by mech­an­ic­al key­board enthu­si­asts. And it’s a little grungy.

Care­fully remove the oth­er cir­cuit boards and the LCD dis­play mod­ule and set them aside.

Plucking the Keys

Using a key­cap remov­al tool is essen­tial as you don’t want to be pry­ing and apply­ing uneven force against the aged plastic pieces. Even so, I did have a couple of the key retain­ing clips break off a small bit when I extrac­ted the cap — but they seemed fine in sub­sequent testing.

Some keys (Shift, Space, Enter, etc) also have a met­al sup­port bar to rein­force com­monly used keys. These bars just clip into the base of the key­cap and must be care­fully dis­en­gaged before the key­cap is free.

The tri­an­gu­lar arrow keys, the func­tion and stop keys are just inter­est­ing con­fig­ur­a­tions of the same ALPS keys, noth­ing cus­tom or stripped down to save a few pennies.

Into the Bath

I’d pre­vi­ously restored an IBM Mod­el M key­board and learned a bit about clean­ing key­boards. Key­caps all go into a warm bath — basic­ally a jar with warm water and a squeeze or two of Dawn dish soap. They stay in the bath for a day or two, stir­ring once or twice a day.

After remov­ing the LCD and main cir­cuit boards from the top and bot­tom cases, both of those cases get their own warm-to-hot bath in soap (maybe 30 minutes) fol­lowed by a vig­or­ous scrub and a good rinse to remove all the soap/grime residue.

Back to the keycaps

After they’ve soaked for a couple of days, it’s time for a good scrub. This is kind of tedi­ous, but reward­ing. The soak got rid of most of the grime and a few passes over each face with a tooth­brush under run­ning water got rid of the rest. Fol­low with a final rinse.

Out to Dry

The cases were easy to dry with a tow­el, then stand overnight in front of a fan (on low) to ensure they dried.

To dry the keys, just lay them out on a tow­el in front of a fan (on low). Remem­ber to flip them in a few hours to make sure the insides of the key­caps also are dried.

I left them for a few days, flip­ping daily, just to make sure they had dried out completely.

Cleaning the Soft Bits

The fab­ric crumb-catch­er is actu­ally quite sturdy. To clean it you just give it a good soak in dish soap and water, then gently brush while wet. I hung mine on a tow­el rack to dry over night.

The foam Func­tion key cov­er was gently soaked in the same dish soap, then care­fully rinsed and set to dry with the key­caps. Be very care­ful with the foam strip, it’s quite thin and I ima­gine eas­ily torn.

Reassembly

Really it’s just the reverse of the dis­as­sembly pro­cess. Make sure to remem­ber the pos­i­tion of every key (heh, take a photo of the key­board BEFORE you pull off all the key­caps), and care­fully replace the sup­port bars under the Space, Enter etc, keys.

Of course, put the Crumb Pro­tec­tion fab­ric back on BEFORE you start repla­cing the key­caps — some­thing I remembered after about 10 keys in.

Then care­fully remount the boards back into their respect­ive cases, close it up and you’re back in business.

Or so I Thought

After I’d got­ten the board back into the case, I found this small plastic sheet. I did­n’t really remem­ber where it came from, and had to look at my pre-dis­as­sembly pho­tos to find it.

This little sheet pro­tects the key­board cables from being scraped and cut by the sharp solder ends of the key­board (you can see it between the con­nect­ors and the PCB in the photo to the right). I think there was a little adhes­ive on one end of the plastic shield, but it was­n’t tacky now.

So I cleaned it, and used some water-sol­uble glue­stick on that end, and after com­par­ing the pos­i­tion to my pho­tos, glued it back in place. It seems to have worked.

Then it was a simple mat­ter to put the two halves back togeth­er. Power it up and enjoy the squeaky clean feel of a new-ish computer!

Next up: repla­cing the onboard memory pro­tec­tion bat­tery and a look at the REX# enhance­ment chip.