A Heathkit IO-14 Oscilloscope Project
Page Created June, 2026
Nat Wadsworth's SCELBI Development Lab Desk: 1973 or 1974
Heathkit IO-14 (left) and Prototype SCELBI 8H (right)
Background
My interest with the Heathkit IO-14 was kindled a number of years
ago when I was busy building a series of reproduction SCELBI
computers. A friend of mine who was an incredible researcher
obtained some images of SCELBI developer, Nat Wadsworth's
lab. One of these pictures shows a desk with a Heathkit
IO-14 next to what appears to be the first prototype SCELBI 8H.
The SCELBI system included a interface card that would display 5 lines
of 20 alphanumeric characters on an Oscilloscope. Based on the
evidence of this picture, my friend and I assumed that this interface
card was developed using the IO-14 as the output device. At the
time, I was preoccupied by my work on the core SCELBI system components. I thought it
would be neat to be able to eventually demonstrate my reproduction SCELBI using the
original Heathkit Oscilloscope for output. During the course of
the SCELBI project, I obtained 3 Heathkit IO-14 scopes. These old
scopes were in pretty shabby state and I decided that I would restore
the best one and use the others for parts. By the time the SCELBI
project was over, I had only found time to disassemble one of them, and
never went through it and rebuilt it. I'm now at the point where I
need to do something with them and figure I'll get at least one
working, and move the others on to another owner. This webpage
will be used by me to document the rebuild and repair of the IO-14 I
took apart.
Documentation
Fortunately one of the three IO-14s that I obtained, came with
an assembly manual. The manual is very comprehensive and in a
large 8" x 10" format. Many of the pages fold out into double,
triple or even quad normal size. It contains assembly,
calibration, test and troubleshooting instructions in 147 extensively
illustrated pages. Though I will likely find problems with it as I
rebuild my scope, at first glance this document appears to be an ideal
model for how user documentation should be written. It's a shame
modern products aren't documented like this.
The binding on my manual had failed. Despite a number of loose
sections it was complete and the pages were in good shape. Tucked
into the back of the manual, I found a separate 19 1/2" x 32" page
with the schematics. My first problem on this project was deciding
what to do with the manual. I figured that using it with the
failed binding would probably result in further deterioration. I
searched the internet and could not find a digitized version of it
leaving me the option of using it as is, repairing it or scanning
it. One of the first youtube videos
I found when researching the repair of a perfect bound binding
indicated that the
best approach was to pull it completely apart before re-gluing it.
The binding repair process looked fairly straightforward and I already
had all the needed materials to do it. Since I couldn't find a
digitized version online, I decided I would pull the manual the rest of the way
apart, scan it and create a PDF before
attempting to rebind it. Given the failed state of the binding ,
pulling it apart was remarkably easy. There were some
complications with the
large number of fold out pages in the manual, but I was able to scan and
format the entire 147 pages into a pdf document. This took about 1
and 1/2 days to do. The results can be downloaded from here.
The next step is to bind the manual.
If you have any suggestions, send me an email.
