CuriousMarc and Company Fix an Old Analog Device (an Apollo Hand Controller)

I really liked this repair video (above), not because I will ever fix an Apollo-era hand controller (I won't) but because it illustrates well what can go wrong with older, analog gear.  And how you fix it.  

You watch as Mark and Mike try to figure out what was wrong.  This brings us back to the diagnostic questions that Richard Feynman posed to his neighbors when, as a boy, as he fixed their AM radios back in Brooklyn.  "My God! He fixes radios just by thinking!" exclaimed one amazed customer. 

Once (well, several times) after they thought they had it figured out, they used simple test gear (a DMM) to find the short.  Then they fixed it, and brought the controller back to life. This wasn't easy.  It involved lots of digging (almost literal digging) and put at risk some irreplaceable parts.  But they did it.  Three cheers for the CuriousMarc team. 

BTW:  What was that liquid that Marc used to replace the insulation that had been scraped away to allow for testing? 

Inside the NUVISTOR! Making a 555 Timer with Nuvistors!

This video is very cool.  When I saw them crack open a NUVISTOR, I should have known that this was Eric from CuriousMarc.  And it is!  

Here is the YouTube channel: https://www.youtube.com/@TubeTimeUS

And here is my video about the NUVISTORS in my 2 meter receive convertor: 

https://soldersmoke.blogspot.com/2026/07/my-parks-2-meter-nuvistor-converter-qst.html

Thanks Eric! 

Open Sauce 2026 in San Francisco

CuriousMarc and team were heading to this event.  We look forward to their report.  In the meantime other reports are coming in.  

I do see mention of the WSPR Balloons that circumnavigate the globe.  Want one. Also, I saw at least one CubeSat. 

I wonder (not really) if my homebrew SSB transceivers in wooden cases would make the cut. 

The SolderSmoke homebrew direct conversion receiver (with DISCORD support group!) might fit. 

Eric KK6GZM of CuriousMarc is the Author of Open Circuits

I've been watching the CuriousMarc YouTube channel for a while now.  I am sure that many of you also watch.  We know that Marc is a ham (AJ6JV).  But I didn't know that Eric (who appears on the show a lot) is the author of the Open Circuits book.  This book has a lot of photos of electronic components that are cut or filed open to show what is inside.  I came across the book some time ago, and could not resist.  I didn't know that Eric was an author!  Is Eric also a ham? (With the social media handle TubeTimeUS, there is a good possibility.) 

NOTE:  Our friend Walter KA4KXX checked and found that indeed, Eric is a ham!  He is KK6GZM.  FB! 

Here is what Gemini has to say about this: 

On the CuriousMarc YouTube channel, Eric is Eric Schlaepfer, a highly skilled hardware engineer and hardware reverse-engineering expert who frequently collaborates on the channel's most complex vintage electronics restorations.

Online and on social media, he is widely known by his handle, TubeTime (@TubeTimeUS).

When Marc and the team hit an incredibly stubborn digital or silicon-level roadblock, Eric is often the "reinforcement" they call in. He brings massive engineering expertise to the bench, along with a suite of specialized diagnostic tools.

A few things he is best known for on the channel and in the broader electronics community include:

• Deep-Dive Troubleshooting: He famously helped Marc debug a dead IBM PS/2 Model 77 computer by hookup up a logic analyzer and using Ghidra software to reverse-engineer the custom BIOS down to the binary level, successfully tracking down a deeply hidden motherboard ASIC failure.

• The Open Circuits Book: Eric co-authored the popular book Open Circuits: The Inner Beauty of Electronic Components (with Windell Oskay of Evil Mad Scientist Laboratories). On CuriousMarc, he has featured cross-section videos where he literally slices electronic components—like old resistors, capacitors, and ICs—perfectly in half and polishes them to reveal their intricate internal engineering under a microscope.

• The MOnSter6502: Outside of the channel, he is famous in the retro-computing world for designing and building a fully functional, giant-sized MOS 6502 processor made entirely out of thousands of discrete, individual transistors and surface-mount LEDs so you can visually watch the data flow through the registers.

Whenever Eric shows up in the lab next to Marc, Carl Claunch, and Ken Shirriff, you know the video is about to dive deep into microscopic component analysis, logic analysis, or advanced circuit reverse-engineering.

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Here is the CuriousMarc video about the bad French resistor:

https://www.youtube.com/watch?v=z2UXwW55kAI

Here is the cover of the book: