The niche 80’s pen plotter

Picked this beauty up at a car boot sale for $2 with a $10 mig welder. If only more of the stalls were full of such interesting stuff. On first power up some of the magic smoke came out of the mains power supply but the scriber worked!  After prying open the worlds cheapest all metal enclosure to see where the smoke originated from in the power supply all seemed fine apart from 30 years of dust on everything.

Behind that small heatsink at the front left is a 4 watt resistor mounted 10mm above the pcb which gets hot and was probably cooking the layer of dust on it before I cleaned board looking for fried components. 

It still worked after that brief smoke release so I pressed on and measured the output voltages just incase it died and I had to replace it to play with the scriber. So the five output wires had +5v, +10.2v and either +26v or -15.8v depending on what pairs you measure. Since it hasn’t failed I just noted down the wire colours and voltages between each wire of the output lead for now.
Listed below for future NC-Scriber users.

• Brown – Gray  15.8v  Brown+
• White – Yellow  5v  White+
• Gray – Green  26v  Green+
• Green – Brown  10.2v  Green

Update:

After someone asked on YouTube about the power requirements to get their own plotter running I did some more in-depth tests and PCB track chasing on the plotter while powered. Can’t guarantee this will work but my NC-50 plotter is supplied with 5v DC and Ground (to power the electronics) and a second pair of wires with 16v DC and ground (to power the motor and solenoid drivers). There is also what looks to be an enable signal wire that turns on the power supply when the rocker switch on the plotter (to the right of the screen) is switched on. The enable wire is held to the electronics ground when the switch is off.

• yellow wire: electronics ground
• White wire: 5v DC for electronics
• Green wire: power supply enable signal
• Grey wire: 16v DC for motor drivers
• Brown wire: motor drivers ground

Anyway, on with the show. I rested a small PC fan on top of the power supply blowing in through the vents and powered up once more.

The oddest thing about the NC-scriber is the instant plotting. Unlike modern label makers which let you type your text, check it, then print the label. This thing puts pen to paper as soon as you hit the keys! Makes for cautious typing as you may notice in the videos. 

With the right pen (not the actual right pen, But a good 0.1 fineliner) wedged into the threaded pen holder the text is remarkably good.

The holder is threaded to mate with rOtrings line of drafting pens with screw on caps like the isograph and rapidograph. I looked for cheap alternatives or used ones but they’re pricey ($30-$90 AUD). So I wrapped the pen I had in A scrap of paper and wedged/twisted it into the threaded holder. Later changed the pink paper out for black electrical tape I had used on the cooling fan.

By the way, the holder is made from a very hard fiber filled plastic.

This thing is really good at what it does. You would attach it to your drawing machine (the big tilted desk with a ruler on an arm that you moved manually around the paper) and positioned the arm so the plotter could write things like scale markers and company details. Thus saving you, the busy  architect or draftsperson from having to neatly write out the same text over and over. What a time to be alive, Right? 

I plan to use it for all future passive aggressive work fridge door notes. 

Or Art. with the motion controlled by modern electronics from the cnc world.

So Yes, It works, But what’s inside?  3 PCB’s, 2 steppers, 1 Solenoid and the motion system used by the Ultimaker 3D printers.

Electronics wise there is a large pcb and two daughter boards, one for the lcd and the other has carbon tracks for the membrane keypad. The mainboard does everything including driving the steppers and solenoid.

I didn’t examine the electronics much as I will bypass all of them if i want to do anything non standard like art with it.

The rest of my photos and videos are in this album https://photos.app.goo.gl/bxMjoecQitkSXCUDA