HP 7044A X-Y Recorder Restoration

It takes another long video full of analog goodness to repair this X-Y recorder beauty, because we end up fixing it twice! We also rejuvenate the pens while we are at it, also using two different methods.

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"Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod

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00:00 Intro, previous HP 7035B restoration
01:06 Inspection and first try
02:42 Disassembly, slide cleaning and platen repair
06:44 A power supply fault?
08:44 X-axis fix
09:30 Y power supply debug and fix
13:07 Y-axis still fails!
13:42 Servo circuits (with elevator music)
18:18 Y servo circuit debug
21:01 It self heals, then self breaks!
22:10 Bad op-amp?
24:55 Root cause, repair, and calibration
28:28 Restoring the pens
32:24 It breaks again!
34:02 Second repair
37:59 Laser L-I curve plot demo

[graemedavidson]

A chart topping plot - high tension, a power struggle, getting locked up, some good travel, a twist with pen testing, catastrophic break down, some more tension and the hero saves the day!

[marcoaurelio]

I find the end part very touching as a latin american undergrad student in engeneering when you talk a little about your routine in the lab... IDK why but i find it "cozy"??? I love to hear older engeneers talk about their day-to-day work... continue with your work, which will certainly inspire many undergrads around the world!

[tekvax]

Excellent Repair again, as always! You have one of the best Electronic channels on the YouTube! You content is always the positive height of my day. Thank you again Marc!

[-r-]

Marc, thank you so much for sharing the documents you acquired and the many pages you have had scanned by the National Archives.

You’re not only working with historical artefacts but also making sure anyone can easily access the information that belongs together with them. Basically growing the understanding and shared knowledge about our technological heritage.

Chapeau!

[projectartichoke]

Always a joy watching you restore these wonderful old devices to their former glory.

[gvii]

I always love these videos. Seeing how this older high precision equipment works. Plus, you get a nice tutorial on various circuits along the way. And Holy Hell, do I miss proper manuals with theory of operations and schematics. Yes, I know a lot of devices today would require a schematic the size of a city block and are often nearly impossible to repair for the average person due to microscopic components and conformal coatings, but still... I do miss them. Lol.

[alnwlsn]

I got my hands on one of the HPIB plotters for the first time recently - the electrostatic paper holder is just crazy, something that I surely wouldn't have thought of if it hadn't already been done. And this was in 1979 (and as I understand it, was used for quite a while before that)

[MichaelEhling]

Is it just me or does anyone else look forward to the elevator music explanations? This week: adding op amps!

[EinChris]

Amazing... I saw the 12 Volts at 19:20 ;-)
(Just for the algorithms.)

I always enjoy those repairy things... so much to learn from them.
From concepts of electronic mechanical engineering, to bug tracking and to conducting real repair work.

Nowadays too many things are just thrown away, because they are unrepairable or no one wants to do it even if possible.

[jlwilliams]

A very satisfying episode! The all-electronic projects are interesting, but there's something tangible about things with moving parts. I really appreciated the demo at the end showing how the instrument was used back in the day.

[ronc]

In the early 1980's I used to build Solid State replacements for vacuum tubes that were getting too expensive. We potted them in JB Weld for strength.

[henrikhalle]

Saw the hole video. Liked it. Understand absolutely nothing of what was happening. But I love when there is people that knows something to a high level.

[TrboRadio-rcol]

5:17 p.m. on July 20, 1969, the eagle has landed. 11:30 p.m. Neil Armstrong stepped on the moon. In Argentina, Brazil, Uruguay and Spain means happy friendship day! Runs the Voice!

[rot_studios]

100% agree with the extortion on old service manuals.

[wizardofeyes]

Thank you very much for the video and the operation/service manual. I have one of these plotters "Awaiting implementation". If it doesn't work when I turn it on, I'll have your experience as a guide!

[SuburbanDon]

I worked at Ford Aerospace in the eighties and part of my job was shuttling test equipment around for calibration etc. i know full well how heavy HP and old Tektronix test equipment is. I remember this plotter well.

[milloons]

Thanks for the hands on course on feedback control, also for the pen tip tips.
Regards!

[aaronr.]

Very cool little demo at the end! I thought this was more the type of stuff physicists would work with. I am surprised you got a chance to work with this in your engineering program. Really cool!

[ronjohnson]

I couldn't find a dull moment on this level.

[hoofie]

For once I beat Marc! When I saw the jump of the Y axis at the bottom my first thought was the resistive track has been lost, it's gone OC and the loop is now open. Another great video showing just how good test gear of that area was.