The HP 7090A is a 3 channel (or two Y and one X) analog plotter and data acquisition unit. The channels are floating (galvanic isolated) which is a very nice smoke reducing feature.
Works also as a GPIB printer with many HP test equipment (emulates the HP 7475A, I think).
There are BNC connectors for an oscilloscope which allows preview before the physical plotting.
If I remember correctly, I have used the 7090A in the past as an analog XY-plotter with an HP 8903B Audio analyzer and a 4192A Impedance analyzer (which requires simultaneous dual Y). And for GPIB plotting the 3585B Spectrum analyzer screens.
-hp-7090a-data-acquisition-recorder-gpib-plotter/?action=dlattach;attach=1740773;image)
Passes self test and my guess would be that it works.
Surprisingly the pens are still manufactured. I think I have a few somewhere but couldn't locate them for further testing.
Cosmetically looks good and has always been stored in a room temperature
It has the usual problem, the plastic lift lever is broken. Can be fixed by drilling a hole and adding a piece of 3mm shaft. Or operated with a screw driver which I did.
The instrument is not as old as you might think, purchased as new in 1997.
-hp-7090a-data-acquisition-recorder-gpib-plotter/?action=dlattach;attach=1740785;image)
Some information:
https://www.eevblog.com/forum/testgear/hp-7090a-measurement-plotting-system/The manual:
https://www.pearl-hifi.com/06_Lit_Archive/15_Mfrs_Publications/20_HP_Agilent/HP_7090A_Measurement_Plotting_System/HP_7090A_Op.pdfThe hard to get pen carousel is included. Also some manuals and a cable shown in the photo.
150 euros, EU only.
Shipping estimate is 15-40 euros depending on your location. Please ask.
Actual postage only, nothing extra. I will pack carefully.
Only for a person who is familiar with the electrical safety regulations and knows how to safely operate and repair professional test equipment.