Tektronix 4662 plotter is Working!

[nikola-wan]

I finally figured out how to get my Tektronix 4662 plotter working with my 4054A computer using GPIB.

There are four rotary switches on the back panel that configure either serial or GPIB capabilities. I finally figured out how to set the switches properly for GPIB from the 4662 service manual. Set A=0, B=0, C=0, D=3 to set the plotter to GPIB address 3 and work with the Tektronix 4050 GPIB MSA codes.

Now any Tektronix program that PRINTs to the screen can be modified to PLOT, by changing the PRINT statements to PRINT @3:

I quickly edited one of my BASIC programs that port Tektronix 4114 terminal graphics to print on the 4050 computer screen, to plot on my 4662.

Here is a video and photo of the first plot: Snoopy, the Red Baron

https://youtu.be/hGmodCc9Hh4

 

[nikola-wan]

This is my setup with my 4054A computer connected to my 4662 (with multi-pen Option 31), right after plotting Snoopy.
You can read the first page of the program - it is all PRINT statements. PRINT @3,21 is a MOVE and PRINT @3,20 is a DRAW to the plotter.

You can see the Faber Castell pen in my 3D printed pen adapter installed in the plotter for that plot.

Next photo shows the Staedtler pen adapter I created to the left of a Tektronix pen and adapter. On the right is the Faber Castell Pitt Artist Pen and adapter I created.
I had purchased two different Staedtler HP Plotter pen sets 20 years ago. Almost all these pens still work. Secret seems to be storing them capped and horizontal.

I purchased the box of Pitt Artist Pens at a Michael's store a couple of weeks ago, plus the XS pen. These pens worked pretty well, although they skipped a little at high speed. The Staedtler pens worked better and didn't skip.

Next photo shows both Staedtler pen sets AND a package of Tektronix plotter pens I had forgotten about. Many of the Tektronix pens still work! I printed Snoopy in the video with a Tektronix blue pen from this package.

The transparent 'pen' at the top of the photo is a Tektronix 4662 digitizing pen. I used this to digitize a Battlestar Galactica starfighter for my "Vipers on Patrol" BASIC program 20 years ago.

Next photo is a closeup of the digitizing pen - you can see the cross-hairs are magnified on the pen package below.

This is a photo of the 11x17 Tektronix plotter paper I bought when I found my 4662 plotter 20 years ago:

I have posted my 3D printed plotter pen adapter STL files on my github Tektronix program repository in a Tektronix 4662 folder:

https://github.com/mmcgraw74/Tektronix-4051-4052-4054-Program-Files

 

[nikola-wan]

Since the Tektronix 4662 Plotter Service Manual scan by the Living Computers Museum in Seattle is now posted on bitsavers.org (thanks Al Kossow!) at:

http://bitsavers.trailing-edge.com/...tive_Digital_Plotter_Service_Manual_Jul83.pdf

I used it to disassemble my 4662 plotter to investigate why the multi-pen carousel stopped working.

I discovered the plastic sprocket on the stepper motor drive shaft for the carousel was split - so the motor was no longer rotating the pens.

I tried superglue on the sprocket but it didn't hold.

I found the sprocket in a google search and am waiting to hear back from the shop on price with shipping.

Another suggestion from Dave Brown at the vintagetek.org museum was to epoxy the broken sprocket to the shaft as he did for their 4662 plotter sprocket:

https://vintagetek.org/repairing-knobs/

 

[nikola-wan]

While my 4662 plotter was open, I took the opportunity to download all four 2732A EPROMs.

These are version -01 firmware and are installed on a separate System Memory board - and the mainboard has no ROMs.

I have uploaded the new ROM images to my github site in the 4662 plotter folder:

Tektronix 4662 Plotter ROMs version -01

In addition I posted photos of the System Memory board with the EPROM's installed:

Here is the top view of my 4662 plotter with the cover removed.
The two ribbon cables from the System Memory board to the Mainboard connect the EPROMs to the 6800 CPU.
The third ribbon cable connects to the Opt 31 multi-pen changer board in the bottom left of the photo.

You can see a whole row of empty sites for ROMs on the Mainboard between the two ribbon cables.
In addition, there are only four 2114L 450 nsec 1Kx4 SRAMs on this version of the Mainboard.

 

[gslick]

I have two 4662 plotters that came with some other Tektronix stuff that I picked up a few years ago (some 4170 CP/M-86 boxes). The plotters are rather grimy. I have never tried to clean them up and see if I could get them working.

I just popped the covers to take a quick look. One has the same EPROM version labels that you have. It looks like all of the SRAM sockets might be populated on that one. The other one has hand written labels on the EPROMs. It is also missing the motor that drives the multi-pen carousel.

Is it easy to remove the plotter bed to get access to the PCBs? I can't get a good look at the hand written EPROM labels without removing the plotter bed. These originally came from a Tektronix engineer and might be pre-production development items.

EDIT: I took another look and realized it is easy to remove just the plotter bed simply by removing four screws. I originally thought the entire pen movement needed to be removed. I'll take a photo of the handwritten EPROM labels and dump them later.

 

[Quagmire]

I finally figured out how to get my Tektronix 4662 plotter working with my 4054A computer using GPIB.

There are four rotary switches on the back panel that configure either serial or GPIB capabilities. I finally figured out how to set the switches properly for GPIB from the 4662 service manual. Set A=0, B=0, C=0, D=3 to set the plotter to GPIB address 3 and work with the Tektronix 4050 GPIB MSA codes.

Now any Tektronix program that PRINTs to the screen can be modified to PLOT, by changing the PRINT statements to PRINT @3:

I quickly edited one of my BASIC programs that port Tektronix 4114 terminal graphics to print on the 4050 computer screen, to plot on my 4662.

Here is a video and photo of the first plot: Snoopy, the Red Baron

https://youtu.be/hGmodCc9Hh4

That Snoopy and the Marilyn M. must have been everywhere back in the day. Your Snoopy looks just line the one our ASR-33 used to put out only it was done with x's & o's. We didn't have access to a plotter.

 

[gslick]

Here are the handwritten EPROM labels on the one 4662 plotter. That one also has a small ATN/DAV HOLDOFF board wired to the main PCB.

 

[nikola-wan]

I have two 4662 plotters that came with some other Tektronix stuff that I picked up a few years ago (some 4170 CP/M-86 boxes). The plotters are rather grimy. I have never tried to clean them up and see if I could get them working.

I just popped the covers to take a quick look. One has the same EPROM version labels that you have. It looks like all of the SRAM sockets might be populated on that one. The other one has hand written labels on the EPROMs. It is also missing the motor that drives the multi-pen carousel.

Is it easy to remove the plotter bed to get access to the PCBs? I can't get a good look at the hand written EPROM labels without removing the plotter bed. These originally came from a Tektronix engineer and might be pre-production development items.

EDIT: I took another look and realized it is easy to remove just the plotter bed simply by removing four screws. I originally thought the entire pen movement needed to be removed. I'll take a photo of the handwritten EPROM labels and dump them later.

All the 4662 and 4663 plotter manuals including service manuals are now posted on bitsavers.org - thanks Al Kossow!!!!

http://bitsavers.trailing-edge.com/pdf/tektronix/466x/

 

[nikola-wan]

I just repaired the sprocket that drives the belt for the multiple pen Option.
This gear broke soon after my video of drawing Snoopy.

I used Dave Brown (vintagetek CEO) instructions to repair the sprocket (left image in the vintagetek link below):
https://vintagetek.org/repairing-knobs/

I used my vintage Unimat SL 1000 model makers lathe to slightly reduce the diameter of the aluminum hub that the sprocket was attached.

The vintagetek article says the plastic (nylon?) sprocket was originally over-molded on the aluminum hub and the plastic shrinks over time and breaks.

I noticed my hub had grooves that were designed to keep the sprocket from slipping on the hub.
I used my lathe to cut off the tops of the grooves until I could slide the sprocket completely over the hub and close the break in the sprocket.

Then I used a super glue brand single-use epoxy to coat the surface of the hub under the sprocket and the inside of the sprocket with a q-tip cut in half as the applicator.

I then clamped the sprocket to the hub with two closepins - one clamping at right angle to the break in the sprocket and the second one clamping the break to the far side of the gear.

I waited 24-hours and just did a test - and the epoxied sprocket worked to select Pen 1 from the carousel.

I now need to adjust the carousel position, because it was unable to dock pen 1 and find a selected pen.

I see that my earlier photos in this thread didn't make the transition from the old website to this one - you will find all those photos on my github repository:
https://github.com/mmcgraw74/Tektronix-4051-4052-4054-Program-Files/tree/master/4662_Plotter

Here are a couple of photos of my repaired sprocket:



The top of the right view shows a couple of gear teeth compressed by the clothespin I used to clamp the broken sprocket - dark line at the bottom of the right photo.
The rest of those two teeth were fine.

Next photo is closeup of the sprocket installed on the servo motor with the drive belt installed. I have not adjusted the belt tension in this photo.


Multi-pen carousel was removed for the repair. This is the view from the plotter side. You can see the pen tips are protected with rubber caps.


Here is the view of the multi-pen carousel from the pen side (the three cables plug in the carousel controller PCB:

 

[syzygy]

This is a really nice story. Thanks for posting. I remember well the HP7475 plotter; used it and others daily for several years.

 

[nikola-wan]

I see my earliest 4662 posts in this thread have attachment links that no longer work.

Most of these links went to my 4662 directory in my Tektronix 4051-4052-4054 repository.
Here is the link to the 4662 directory: 4662_Plotter

The 4662 plotter pen twists into the pen mechanism - so my 3D STL adapters cannot be used with replacement pens.

However, this site says Rapidograph (refillable) pens work with the Tektronix 4662 and 4663 plotters without any adapter! https://www.schwittlick.net/blog/adapters_pens_plotters/

I think I will try a Rapidograph on my plotter.

That website had a photo of the parts of a Rapidograph pen. It has screw threads in the pen body that look the same distance from the tip as the Tektronix plotter pen. There are other models without the threads.

Looks like Koh-I-Noor Rapidograph 3165 pen will work. I see Koh-I-Noor pen kits with a bottle of black ink.

 

[nikola-wan]

I just received my order of a set of four Rapidograph pens with a bottle of PLOTTER INK from EBAY! There are several of these sets on EBAY - this was the only one I saw with Plotter ink.

I also ordered a Koh-I-Noor technical and plotter pen cleaning set with cleaning solution and a squeeze bulb used to clean the tip and to start the ink flowing into the tip (with the transparent adapter in the photo).

The Pen Cleaner instruction page said DO NOT SHAKE THE PLOTTER PEN! It also indicated that the bulb was useful in starting the ink flow - PARTICULARLY FOR PLOTTER PENS - so I guess Plotter Pen Ink may be thicker?



Two of the four pens at the top of the photo had ink on the tip and in the ink tube - so my first job is to use the cleaner to attempt to clean them and then learn how the Rapidograph pen works.

 

[nikola-wan]

Here is my photo of the Koh-I-Noor Rapidograph pen screwed directly into my 4662 multi-pen adapter - next to my photo of the Tektronix brown plotter pen both with and without it being installed in the same adapter.




I was able to clean both of the pens that had been used - one with black ink and one with blue ink. I used a jewelry ultrasonic cleaner on both of the pen 'nibs' after removing the ink capsules and put the capsules in the ultrasonic cleaner. I only put warm water with a little bit of Dawn dish-detergent in the ultrasonic cleaner. I cleaned the nib that had blue ink first and kept using the Cleaner Bulb until the metal shutter (weight?) inside the nib started moving. Then I rinsed out the ultrasonic cleaner with warm water and then put in a little Dawn with warm water and worked on the nib that had been used with black ink. Since the two pens were Gray size 0 (0.35mm) and Brown size 1 (0.5mm) - I also used the tool in the pen kit to disassemble the nibs and wash both the inside with the stainless steel tip plus metal weight and outside.

Tomorrow I will try some of the black Plotter ink that came in the Rapidograph pen set in the pen with the Gray Size 0 0.35mm nib.

 

[nikola-wan]

My experiment using Rapidograph technical drawing pens with my 4662 was almost successful.

The Rapidograph instructions showed the ten different technical pen sizes - my kit had the 0.30mm Yellow, 0.35mm Gray, 0.50mm Brown and 0.60mm Red pens:

1. The Rapidograph pens screwed directly into the 4662 Option 31 multi-pen holder
2. I found the Yellow and Red pen sizes were very clean (maybe unused), but Gray and Brown sizes had been used and needed to be cleaned
   • I used an ultrasonic cleaner to clean the Gray and Brown and would then use the Bulb to try to pull air through the needle at the end of the Nib, repeatedly until the Gray pen was clean enough (I thought)
3. I then put some Plotter ink drops into the ink reservoir, used the Bulb to start ink flow from the Nib, and reassembled the pen without installing the pen holder
4. Next photo shows trying to plot Snoopy with the 0.35mm Gray pen screwed into the multi-pen holder

I apologize for the poor focus but the pen skipped on the paper (laserjet paper).

Since the Gray 0.35 pen was almost the smallest in the kit I decided to try the cleaned Brown 0.50 pen and it also skipped on the paper.

Trying to remove the Rapidograph pens from the multi-pen holder was extremely difficult (I had tried to tighten the pen in the holder thinking it might be too far from the plotter bed) - particularly since I had removed the pen holder. I thought next time I might try gluing the clamp ring to the pen holder - but didn't want to go there yet. The clamp ring holds the ink reservoir against the nib, but with the pen screwed into the multi-pen holder - only a couple of threads of the clamp ring were exposed. I was finally able to get the clamp ring off and started pulling the ink reservoir off and got black India ink on my fingers.

I spent the rest of the day using the ultrasonic cleaner with water and dish soap to clean the two pens. It reminded me of trying to refill Canon Inkjet printer cartridges with third party ink - very messy and not really worth the trouble.



I had also just received a sealed metalized packet of NOS Tektronix 4662/4663 ink pens and found a green pen that appeared to work - but the pen was flowing too quickly and smudged that plot.

I then went back to the Faber Castell black artist pen I had 3D printed and adapter for - and now it was skipping like the Rapidograph pen I had a pack of four more Faber Castell pens S 0.3mm, F 0.5mm, M 0.7mm and B 1.5mm size and until I got to the B 1.5mm size - they all skipped during the plot. The good plot of Snoopy was with the B size pen as in the next photo:



I decided to stop my plotter pen experiments for the day. The photo shows the Faber Castell pens and to the left a set of Staedtler Lumocolor pens size S 0.4mm that I will need to repair my 3D printer and design an adapter in order to try them. They are refillable pens.

I have attached my BASIC program to plot one of my Flash Drive vector PICTURE files to the plotter using GPIB (it might work with Option 01 COMM port by using 40 for the GPIB address).
I inserted two PRINT statements - one to disconnect the Flash Drive and connect the Plotter after loading the PICTURE into RAM and the second to unplug the Plotter and plug in the Flash Drive - since my Flash Drive does not have enough drive current to handle any more GPIB devices. I am still considering adding the TI GPIB ICs to a new version of the Flash Drive to remove that restriction.

NOTE: I manually used the plotter joystick to SET upper left and upper right where the paper was placed in landscape mode, but when I tried to plot Mickey Mouse or Dragon - they went off the 8.5x11 paper and onto the plotter bed - I quickly cleaned up the bed with a damped tissue. Snoopy fit in landscape mode. I need to read the 4662 manual (again) and check out plotter image scaling.

 

[nikola-wan]

One thought I had about the pens skipping - maybe my generic LaserJet paper is the cause?

I have a box of Tektronix 11x17 Plotter paper - but not very many sheets - maybe less than 50. Not enough for demos at VCF SW 2026

I just found and ordered a NOS sealed $5 box of 250 sheets of vintage HP Plotter Paper 17801P from the 1980's on EBAY.

The front of the box states: "NOTE: paper is packed with best drawing side up", so maybe it is coated on the top?

 

[nikola-wan]

RTFM: Here is the page that describes how to scale the plot to where the paper is placed:



I briefly pressed the Lower Left Corner key and should have held it until the Plotter rings the bell. Same with Upper Right corner.

So quickly we forget...

 

[nikola-wan]

I received my 250 sheets of HP Plotter paper and plotted Snoopy with the Faber Castell SX black pen, unloaded the paper and turned it around and plotted Dragon.


Maybe my Faber Castell SX pen has been unused for too many years since the last plot. Dragon looks like less skipping.

Running the PICTURE files in the 4051 Emulator - I see that neither of them is centered on the display. I think if I am demonstrating the plotter at VCF SW 2026 -being able to plot two images per side might be possible on a single plotter sheet.

I compared the profile of the Tektronix multi-pen adapter with my 3D printed Faber Castell adapter and I see room for improvement on my 3D printed pen adapter.

This is an incentive for me to fix my 3D printer. The original Creality CR-10S Pro print head had become stuck with filament - maybe the printhead temperature thermistor had died. I replaced the Creality print head with a Microswiss which is a little longer than the Creality printhead so I have to realign my capacitive sensor to the new printhead position.

Hmm - I think I may need to replace the printhead thermistor first - I just moved it to the Microswiss printhead.

 

[nikola-wan]

I remeasured my Tektronix 4662 multi-pen adapter with my Mitutoyo caliper and see several differences on my 3D printed Faber Castell pen adapter that might be responsible for the pen skipping.

Here are my measurements compared against my 3D printed adapter:



Here is the side view of the 4662 plotter pen holder with the empty Tektronix 4662 adapter inserted:



I am counting the 'rings' on the Tektronix adapter in my list below.

1. I am missing the top ring of the Tektronix adapter - but that ring is above the pen holder - so not needed on my adapter
   • HOWEVER - the 4662 pen holder does clamp the adapter on the second, third and fourth Tek rings and the angled slope between the third and fourth Tek rings
2. Problem 1 - my STL thickness of the 'second Tek ring' is 2 mm while the Tek adapter is 1.75 mm
3. Problem 2 - my STL height of the 'third Tek ring' is 2 mm while the Tek adapter is 0.75 mm
4. Problem 3 - my STL thickness of the 'ramp' below the 'third Tek ring' is 1.5 mm while the Tek adapter is 1.25 mm
5. Problem 4 - my STL thickness of the 'fourth Tek ring' is 2 mm while the Tek adapter is 0.75 mm

So I need to create a version 3 STL for Faber Castell pens - I plan to edit my v2 STL

 

[nikola-wan]

I couldn't edit the STL file in Fusion 360 on the non-commercial hobbyist license. I had created the STL using Autodesk 123D and when I looked at my v2 file I discovered the hole for the pen was way too big for a Faber Castell pen - maybe I was trying to design for a different pen?

Anyway I saved that file to a v3 files and edited the outside shape to match my latest caliper readings, but I still need to fix my 3D printer.

zip of the v3 file attached to this post.

123D Design view of the v3 Faber Castell pen design:

 

[RolexTM]

Hey, nice you are working on your plotter

I had skipping too. I solved it by putting a nut over the pen adapter adapter to give it just a little more weight. It needs to be as close to the base part of the printer as possible though and firmly attached.

I accounted the skipping to the length of the pen. Maybe wrong paper too?


Alex