i have a plotter! i can finally be part of #plottertwitter !
Panasonic Penwriter P400C, uses ALPS DPG-1302 plotter mechanism. keyboard needs repairs, original pens mostly dried up but the green still works! has RS-232 built-in so can be controlled from modern devices thru serial
sadly i gotta go back to work now so i can't play with this right now but gosh i'm excited!
okay! managed to make some time to mess with it, and
- think the pens aren't completely dry but rather dried out. been soaking them inside and out with some alcohol and look how great that blue came out!
- definitely will have to replace some nylon gears; losing steps frequently
refilling the pens also doesn't seem like such a difficult task after having opened them up, as long as i can find good water-based pen inks here i should be able to saturate the felt in them and flush out the ballpoint, then hopefully they'll work like new!
so i left the ballpoint tips soaking in alcohol overnight because there's still ink in the pen bodies (my stained paws are proof) but it wasn't getting up to the ballpoint tips. unfortunately not only did this not work, i ended up mechanically breaking the tip for my black pen...
... such that the ballpoint dislodged itself into the pen tip. so considering i can't recover the original pens, i ordered some 0.7mm ballpoints & i'm going to try to devise a way to make them into brand new no-old-parts plotter pens through some 3d printing. digits crossed!
on another note, the gears at first were grinding a lot when returning the carriage, then they started working smoothly, now grinding again. likely the infamous pinion gear but that's gonna have to wait until i have the time to take it all apart. gonna try 3d printing that too
as for the keyboard, it really is just a matter of dirty contacts, the more i've been using it the more i can touch-type it again. gonna try to open it up and clean once i open the machine to replace the gear as well
so i bought some inexpensive fine-tip 0.7mm ballpoint pens (in 10 different colours!) in order to try to fashion new stock for plotters like mine
the first attempt wasn't a success.. however i managed to refill one of the pens with the black ink from those ballpoints!
i still want to try making new pens from scratch later because i want ones in the other colors the ballpoint set i bought came in (like purple and pink), but for now i'm content enough in refilling the ones i have right now
also, just so it's noted i _did_ ruin three pens so far: one of them i didn't notice the ballpoint had vanished, one of them basically crumbled when i tried to take it apart, and the other one i tried a method of getting the ballpoint unstuck and it just dropped into the pen body
the ballpoints in these pens are VERY fine and the tip holding them is plastic, so they're very easy to break. the black pen i have right now is using the tip from one of the gray extra pens (supposedly "correctable" pens, but mine had weird greenish and reddish inks in them)
so after more work yesterday and more frustratingly broken pens, it doesn't look too good for restoring the original pens. i still have black and blue working ok, green sputters but looks like the ballpoint is not getting enough ink, and i have no working tips left to make a red
so the next step is to try and focus more on sourcing new pens through whatever process. there's a place you can still buy them in the US but i'm not in the US and that makes it prohibitive, unless someone wants to donate me some pens for cost of shipping
i won't have much time to work on it today, so maybe this weekend i'll take a look at the gears. those i can get from eBay for a more reasonable price than the pens (because the pens are only sold domestically), but first i'll see if i can do anything to them without replacements
d'you know what? i'm not immediately seeing any split gears, believe it or not
i think they might be grinding for another reason, like the carriage movement resisting too much
i WAS going to try to clean the keyboard from the inside to solve stubborn keys, but check out how thick this metal plate is! nothing i have is strong enough to bend them straight to open it
if i had to guess, they are probably linear spring switches (no tactile feel or click)
this corner isn't so happy
those rubber domes are for the index up and down keys, thankfully they're working fine
i can try to clean up a bit from here but without access to inside the keyboard there's not much i can do about the rust
oh, the switches come off! accidentally pulled one along with a stubborn keycap, turns out they're held in place by plastic clips holding onto the metal plate
i was right about them being linear spring switches!
the switches are pretty easy to take off by paw once you know where the tabs are
unfortunately (fortunately?) this reveals a lot more rust
almost but not quite all clear. can't figure out how to remove from here the switch for the left shift, which has the retainers for the stabilizer bar, the retainers for the space stabilizers, and the caps lock LED. but this already gives me plenty of surface to clean
it took all my strength but i managed to straighten the tabs & free the metal plates! and just in time as well, the rust was starting to get to the membrane, but thankfully nothing had been damaged yet
i got really lucky with this machine, it's in really serviceable condition!
don't have a commercial rust remover readily available so i whipped up a quick baking soda water paste and applied it liberally to both sides of the top plate. seems like most of the surface rust already brushed away anyway
bottom plate is rust-free thankfully
key plate looks almost entirely rust free after scrubbing baking soda off! switches were scrubbed with alcohol to get rid of rust, membrane wiped down as well. the keycaps already looked like they'd never been used but figured i wouldn't do half measures and washed them in soap
as for the carriage mechanism: ended up not taking any pictures of it but all the gears look absolutely fine, only one of them looks slightly "warped" from where it should be, which might be causing the grinding, but none of them are visibly cracked.
i added a shim to keep that gear upright, i don't think the gears need any new lubrication but can do that as well if they seem stuck. haven't tried running it yet with the fix because it currently lacks a keyboard, so it'll have to wait until that
the plate still looks kinda bad in a couple of places on camera but it's a far cry from all that orange surface rust. maybe a better treatment in the future is warranted, but this is what i can offer it right now