CuriousMarcWe test a pile of new plugins, and fix the king of them all: the HP 5257A 18 GHz Transfer Oscillator. While we are at it, we demo the HP 5264A Preset Unit and the HP 5262A Time Interval Unit. This completes our repair-a-thon! No kidding, we repaired them all, the main counter and 10 plugins!
00:00 Recap of previous episodes 00:43 New pile of plugins! 01:47 HP 5264A Preset Unit Plugin Test 04:11 HP 5262A Time Interval Unit Test 05:53 HP 5257A Transfer Oscillator Test 08:05 Transfer Oscillator Explanation 13:27 Fault #1 Debug 20:00 Fault #2 Debug 25:14 It works again 26:41 Now part the Apollo setup!
HP 5245L Nixie Counter - Part 7: HP 5264 Preset, HP 5262 Time Interval, HP 5257 Transfer OscillatorCuriousMarc2023-09-25 | We test a pile of new plugins, and fix the king of them all: the HP 5257A 18 GHz Transfer Oscillator. While we are at it, we demo the HP 5264A Preset Unit and the HP 5262A Time Interval Unit. This completes our repair-a-thon! No kidding, we repaired them all, the main counter and 10 plugins!
00:00 Recap of previous episodes 00:43 New pile of plugins! 01:47 HP 5264A Preset Unit Plugin Test 04:11 HP 5262A Time Interval Unit Test 05:53 HP 5257A Transfer Oscillator Test 08:05 Transfer Oscillator Explanation 13:27 Fault #1 Debug 20:00 Fault #2 Debug 25:14 It works again 26:41 Now part the Apollo setup!Apollo Comms Part 34: Trying every function of the Apollo command systemCuriousMarc2024-10-08 | We finally have our Apollo command system all working! Let's understand and try every function so we can hack the Apollo spacecraft the next time they launch it...
Our sponsors - PCBWay: fast turn PCBs, pcbway.com - ElectroRent: electrorent.com - Keysight: test instruments: keysight.com - Samtec: connectors: samtec.com - R&D Microwaves: rdmicrowaves.comCape Canaveral Historic Launch Sites VisitCuriousMarc2024-09-01 | Thanks to Carl and the Cape Canaveral Space Force Museum, we get a very special visit of the cape's historic launch sites, and relive the pioneering days of the Space Race.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutModern Fails: Newall C80 DRO repairCuriousMarc2024-08-20 | My expensive lathe digital readout just failed, and Newall does not want to repair it! So, we reverse engineer it, and find out that the proprietary principle of operation is absolutely genius, involving ball bearings and magnetics, with a readout precision of better than 10 microns. And the fault is quite unexpected. Hint: not a capacitor.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Comms Part 33: Is there something wrong with our NASA Up Data Link transmitter?CuriousMarc2024-07-26 | In the last episode, we managed to send Up Data commands using a PSK transmitter made up of HP equipment. But we were unsuccessful when using our original NASA UDL transmitter. Is there still something wrong with it?
Our sponsors - PCBWay: fast turn PCBs, pcbway.com - ElectroRent: electrorent.com - Keysight: test instruments: keysight.com - Samtec: connectors: samtec.com - R&D Microwaves: rdmicrowaves.comHP 7044A X-Y Recorder RestorationCuriousMarc2024-07-20 | 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.
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 demoVisiting the Computer Museum of AmericaCuriousMarc2024-07-15 | After VCF East, we were invited for a very special visit of the Computer Museum of America, near Atlanta, Georgia. Comes with us for a tour!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Comms Part 32: Breaking the Updata Link CodeCuriousMarc2024-07-12 | We finally crack the Apollo uplink subbit code. And as any good hacker would do, we immediately try to send an abort command to the spacecraft.
Our sponsors - PCBWay: fast turn PCBs, pcbway.com - ElectroRent: electrorent.com - Keysight: test instruments: keysight.com - Samtec: connectors: samtec.com - R&D Microwaves: rdmicrowaves.com1962 Japanese 9-Transistor RadioCuriousMarc2024-07-11 | In this mini video we fix up and admire an early Japanese 9-transistor AM-FM radio, which must have felt like a wonder of miniaturization at the time. It was OEM'ed under dozens of different brand names around the world. Many thanks to Jeri Ellsworth for donating this unit.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Comms Part 31: UDL Grand Opening and Power UpCuriousMarc2024-06-25 | We open up the Up Data Link box, which was the remote control box for the spaceship, and power it up for the first time.
Our sponsors - PCBWay: fast turn PCBs, pcbway.com - ElectroRent: electrorent.com - Keysight: test instruments: keysight.com - Samtec: connectors: samtec.com - R&D Microwaves: rdmicrowaves.comDonated Eskalab SpectrophotometerCuriousMarc2024-06-16 | We got a free spectrophotometer lab instrument from the 1960s! It is a wounded beauty: it's devoid of any online information, is missing tubes, and one of the boards says "BAD" on it. Can we save it?
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutOscars new PDP-10 replica (and PDP-8 and PDP-11 too)CuriousMarc2024-05-31 | Oscar Vermeulen is well-known for his highly accurate, ⅔ scale replicas of DEC's popular PDP computers. Here he shows off the newest member of the family, the PiDP-10, which gets us to retrace the history of MIT's AI lab and the Incompatible Timesharing System.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Comms Part 30: We explain and debug modern (CD4046B) and vintage (Apollo) PLL circuits.CuriousMarc2024-05-11 | We build a Phase Locked Loop (PLL) FM demodulator for extracting the Apollo downvoice from its subcarrier, using the classic 7046B IC. But in the meantime, as luck would have it, NASA's own S-band receiver's PLL seems to have gone bonkers, and we can't lock to the spacecraft microwave downlink anymore! So we'll get very hands on with PLLs in this episode. Expect a healthy dose of PLL elevator music.
Elevator Music Credit: Crinoline Dreams by Kevin MacLeod
Our sponsors - PCBWay: fast turn PCBs, pcbway.com - ElectroRent: electrorent.com - Keysight: test instruments: keysight.com - Samtec: connectors: samtec.com - R&D Microwaves: rdmicrowaves.comMay the 4th Vintage Hack #retro #computer #starwars #maythe4thbewithyouCuriousMarc2024-05-06 | Oh no, I'm one day late! Hopefully it still counts. Original full length video from 2019 here: youtu.be/UNdu0YQfvF0HP 9895A Part 2: Epic Controller Board Repair (and a transparent chip surprise)CuriousMarc2024-05-03 | We restore more HP 9895A dual 8" diskette HP-IB drives, but these will be way more challenging. We'll need a full on logic analyzer assisted repair to debug a really, really nasty fault. It's a long video, but don't miss the intermission where Master Ken inspects a transparent silicon-on-sapphire chip!
Many thanks to HP enthusiast Craig Ruff for the ROM dump and disassembly.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutVisiting the System Source Computer MuseumCuriousMarc2024-04-30 | We get a private tour of the System Source Museum near Baltimore, MD. What a gem of a computer museum!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutWe attend the Vintage Computer Festival (VCF East 2024)CuriousMarc2024-04-24 | We had a great time at VCF East, the annual vintage computer exhibit in Wall, New Jersey. Carl was showing off an IBM 1130 he just restored, and we had a round table about the Apollo Guidance Computer restoration. But there is more: the Vintage Computer Federation museum with its working UNIVAC, a military technology museum, and even a prototype AGC!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutModern Fails: Samsung ML-2525W laser printer double repair: picks up two sheets, does not power onCuriousMarc2024-04-04 | In the Modern Tech Fails series, we tackle the Samsung ML-2525W laser printer, which fails like all its siblings for stupidly simple reasons.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutWe restore the HP 9895 dual 8 diskette to play a Colossal Cave game! (ft. Usagi Electric)CuriousMarc2024-04-02 | We restore a vintage HP 9895A dual 8" diskette HP-IB drive, and put it to good use by playing the Colossal Cave Adventure on the HP 9825 calculator.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutFree Abandoned HP 3478A 5-½ Digit DVM RepairCuriousMarc2024-03-01 | We repair a classic HP 3478A 5-½ digit voltmeter, and admire its ultra complicated A to D converter.
Ken Shirriff’s reverse engineering of the hybrid in Marco Reps’ HP 3458: https://x.com/kenshirriff/status/1448392567167479812?s=61&t=UXfboHQEfahjAKeGVe1J8w
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutF8 Fly-By-Wire System (Apollo Guidance Computer Part 31)CuriousMarc2024-02-19 | We get a chance to inspect the actual Apollo Guidance System that flew in NASA's F8 Digital Fly-By-Wire experimental plane. We explain how it worked, and recover the software from its core rope memory. The result is a bit of a surprise!
00:00 Summary of previous episodes 02:05 The F8 Fly-By-Wire pallet 03:43 Why Digital Fly-By-Wire? 06:24 NASA Dryden Flight Research Center 08:08 NASA's F8 DFBW program 14:10 Shuttle support missions 15:20 Inspecting the pallet 19:05 Apollo SPS engine 20:43 Core rope extraction 24:58 Liquid Nitrogen cooling 25:56 Reading the core ropes 29:22 Running and explaining the recovered software 32:20 Mike's core rope recovery to dateBendix Air Data Computer - Part 5: Restoration Finished, It Works!CuriousMarc2024-01-17 | Our jet fighter analog mechanical computer is operational! We fly the bench at supersonic speeds like it's 1950 all over again.
00:00 Recap of previous episodes 01:34 Bendix computer principle of operation 03:26 First round of repairs 05:44 Depstech endoscope 08:08 First pressure sensor power up 10:58 Angle of attack sensor power up 12:18 Second round of repairs 16:18 It finally works! 16:46 Powering the tester with the Apollo inverter 18:44 Flight instruments 19:52 Demo time! 25:08 Outro and beauty shotsHP 410C Vacuum Tube Voltmeter Part 2: AC ProbeCuriousMarc2024-01-09 | We jury-rig a tube based AC probe for our HP 410C VTVM. Will it do better than our modern Keysight multimeter? (Answer: yes)
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutWall of weird vintage electrical and electronic clocks new year flipCuriousMarc2024-01-01 | We had a pretty low key new year's eve at home this time, so we chilled next to the wall of clocks around midnight. We’ve got some heady clock company in there, including a cesium clock, a flown Soyuz clock and a giant vintage Solari flip clock. Happy New Year 2024 to you all.
My corrected Jingle Bells Teletype score below: ---------- CuriousMarc's Jingle Bells for TTY F stands for FIGS X stands for LTRS Z stands for Space Cr is Carriage Return Lf is Line Feed Other letters are as typed Don’t type the actual spaces, they are just for visual aid ---------- Cr Lf FSFSFSXMFS FSFSXEFSFS FSFFSSXRRY ZFFSFSFSFF SSFSFSFSSS FSFSFSFSXC FSXHFSFSFS XRFSFSFSXI FSFSFSFFSS XSTMASFSFS FSFFSSFSFS FSSSFSFSFS FSXZANFSSS FSFSFSFSXD ZAFSSSFSFS FSFSXZHAFS SSFSFSFSFS FSFSFSSSFS FSFSFSXP FFFSSS FSFSFSFSFF FFFSSSFSFS FSFSFFFFFS SSFSFSFSFS FSFSFSSSFS FSFSFSFFFS XPFSFSFSXY FSFSFSXZFS FSFSFFSSXN EWZYFSFSFS FFSSFSFSFS SSFSFSFSFS XEFSXAFSFS FSXRFSFSFS XZFSFSFSFF SSXTOZALFS FSFSFFSSFS FSFSSSFS FSFSFSXL Cr Lf ----------------
Time stamps:
00:00 The original QST article 01:14 Trying the QST score 03:30 Upgrading to a Teletype orchestra 07:56 Editing the tape 14:18 Corrected tape rehearsal 16:36 Jingle Bells Teletype PerformanceTeletype Christmas Song Duet #vintageelectronics #ChristmasCuriousMarc2023-12-25 | Stuff that supports the channel: - Amazon links for the tools I use in the lab (supports the channel if you buy from there) curiousmarc.com/amazon-links - Channel merch on Teespring: teespring.com/stores/curiousmarcs-store - Support us on Patreon: patreon.com/curiousmarc
"Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Comms Part 29: DownvoiceCuriousMarc2023-12-22 | We back out the last remaining modification from our NASA receiver and return it to its original Apollo voice channel. If we are successful, we'll get to hear the voice from the astronauts the exact same way it was transmitted during the missions. And I hopelessly butchered the name of our hero engineer that left the helpful notes on the equipment, it's Frank Landspurg, not David Landsman! Bravo Mr. Landspurg. His obituary says that he was working for Motorola and supporting the Apollo missions, and passed away in 2014.
00:00 Our Apollo receiver has been modified 05:20 Reverting the modification 07:41 Retuning the filter assembly 11:40 First receiver tests 13:38 How to extract downvoice with a ham radio 15:45 First voice trials, not working! 16:49 Tracking the fault in the spacecraft transmitter 20:35 Receiving downvoice!
Correction: 03:26 Frank Landspurg (not Landsman) Correction: 05:09 Frank Landspurg (not Dave Landsman)TMG-303 Test Message Generator RepairCuriousMarc2023-12-16 | We got a beautiful and complicated CDC TMG-303 Teletype Tester from a viewer. Which does not work and does not have any documentation. But that's not going to stop us, right?
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 410C Vacuum Tube Voltmeter RestorationCuriousMarc2023-11-25 | Another classic Hewlett-Packard instrument saved from the trash bin: the HP 410C VTVM (Vacuum Tube Voltmeter).
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutMITE Tactical Teleprinter - military digital communications from 1958CuriousMarc2023-11-16 | We marvel at a MITE AN/TGC-14A(V) Teleprinter, a miracle of teletype miniaturization from 1958. Imagine, only 41 lbs!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo Core Rope Memory (Apollo Guidance Computer Part 30)CuriousMarc2023-10-27 | Core Rope Memory, which contained the programs that landed man on the Moon in the 1960s, is insanely complicated. But that won't stop Mike from making a custom reader for it, so he can recover Apollo Guidance Computer programs lost to history.
Mike Stewart's Core Rope Visualizer: http://apolloguidance.computer/rope/
00:00 Intro: Apollo Guidance Computer restoration 02:21 What is core rope memory? 05:16 Previous core rope recoveries with our AGC 06:44 Our AGC is sold at auction 07:36 Mike's core rope reader prototype 11:09 Last minute core rope "hack" for Apollo 11 14:04 Software recovered so far 14:48 Trying the reader for the first time and error 17:56 Core rope explanation: data encoding 20:13 Transformer rope is not core rope 21:24 Core rope explanation: reading using bistable cores 26:09 Core rope explanation: molybdenum permalloy cores 28:22 Experimental demo of moly cores 31:49 Core rope explanation: addressing with inhibits 33:59 Apollo core rope simulator, inhibit wires 35:56 Set and reset wires 37:45 Parity wires and the design error 45:02 Mike fixes the reader and tries again 47:38 Success! Congrats Mike!8 Floppy drive final repair and realignment procedure (ft. Usagi Electric)CuriousMarc2023-10-10 | Get your 3D printed parts from PCBWay: pcbway.com/rapid-prototyping/manufacture
Usagi Electric (Electric Bunny in Japanese) is visiting us. And I have the very floppy drive his Centurion minicomputer is missing. In this episode, we repair the head actuator brake with a professionally printed 3D part, and demonstrate how to realign the drive with a professional alignment diskette as well as without it. There will be professional bunnies at the end, promised.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutDiode Sampler MagicCuriousMarc2023-09-29 | The HP plugin we just repaired has a magic RF circuit in it: a diode sampler that goes up to 18 GHz. It is well worth playing a little more with it, and understanding how this extraordinary circuit, which is still relevant today, actually works.
Previous video about the HP 5257A 18 GHz transfer oscillator plugin: youtu.be/sl_Zh-IxVTA
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutWhisper Writer Telex to Radio Teletype ConversionCuriousMarc2023-09-03 | In this revenge-of-the-Teletype episode, we reverse engineer our super-modern (1984!) 3M Whisper Writer Telex machine, and turn it into a fully featured RTTY receiver and Teletype tester. Get your PCBs from our sponsor PCBWay: pcbway.com
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 5245L Nixie Counter - Part 6: HP 5255A 12.4 GHz Plugin RepairCuriousMarc2023-08-15 | We repair a 12.4 GHz Nixie frequency counter plugin, the HP 5255A. It takes a double length episode to get it to behave, and you won't believe what we find at the end.
00:00 Summary of previous episodes 00:53 The very broken 12.4 GHz plugin 02:19 Operating principle (with elevator music) 06:30 Opening the unit 09:35 Faulty video amp? 12:53 Debugging the Automatic Gain Control 15:48 Debugging the bias 17:32 RF self-oscillation hell! 22:11 Nursing the amp back to life 25:00 Debugging the power meter circuits 32:45 Debugging the gate extender 37:56 Finally measuring microwaves! 39:20 Discovery of another video amp issue 42:12 Debugging the weird low frequency suckout 47:37 Plot twist: RF mixer surprise! 52:22 Did we finally repair it? 55:42 Epilogue: comparing with another pluginAdding composite video and sound inputs to a 1976 TV (Panasonic TR-525)CuriousMarc2023-08-06 | We modify a cute Panasonic TR-525 portable TV to accept video and sound inputs, so we can use it as a retro computer monitor.
Theme song: Festive Dinner by Pony MusicBendix Air Data Computer - Part 4: Magnetic Amplifier MagicCuriousMarc2023-08-03 | Thermal Camera TC001(android): amazon.com/gp/product/B0B7LMB22Q (Apply $20 coupon with Prime: $229) Thermal Camera TC002(IOS): amazon.com/dp/B0BYHP8KM9 (Apply $70 coupon:$229)
We power up our analog computer for the first time, and are stumped by evil magnetic amplifiers.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutUnassuming Apollo Panel Has Major Role in Apollo 13CuriousMarc2023-07-31 | In another piece of little known Apollo 13 electronic trivia, we power up a mostly unknown panel that was in the command module, and was responsible for triggering the Main Bus B Undervolt alarm. As usual in all things Apollo, it is more complicated than you'd think.
Support the team on Patreon: patreon.com/curiousmarc Buy shirts on Teespring: teespring.com/stores/curiousmarcs-store Learn more on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 5245L Nixie Counter - Part 5: HP 5261A Video Amplifier PluginCuriousMarc2023-07-24 | Our brand spanking new HP 5261A plugin has been in storage since 1972! Authentic HP vintage unboxing experience awaits. Surely, nothing could be wrong with a quality instrument that has been carefully stored for 51 years. Or could it?
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 5245L Nixie Counter - Part 4: HP 5254A 3 GHz Plugin RepairCuriousMarc2023-07-20 | We repair our 3 GHz Nixie frequency counter plugin, the HP 5254A. 3 gig, not bad for 1964! Things are spicier than with our previous and tamer 500 MHz plugin, so we have to break out the microwave test equipment.
00:00 Summary of previous episodes 01:02 Into the broken 3 GHz plugin 04:05 Mechanical repair 07:52 First try 10:09 Multiplier repair 12:22 Second try 13:36 Multiplier alignment 15:36 Third try 16:27 Second mechanical repair and realignment 22:59 Fourth try - it works! 24:20 Measuring the Apollo S-band transmit frequencyRAF Smiths Pitot Static TesterCuriousMarc2023-06-27 | Straight from her late majesty to us, we get a Royal Air Force pitot-static tester, to help us with our restoration of the Bendix Air Data Computer. Is it old? Yes. Was it cheap? Very much so. Does it work? Sure not. Is it beautiful inside? You are kidding, it's awesome, with stunning steampunk technology from the late 1950's! Are we going to be successful in repairing it? You are going to find out in this video!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 5245L Nixie Counter - Part 3: 500 MHz Plugin Repair (HP 5253A and HP 5253B)CuriousMarc2023-06-12 | It's time to repair our 500 MHz frequency converter plugins, the HP 5253A and HP 5253B. It says in red letters: "CAUTION: DO NOT ATTEMPT DISASSEMBLY OF CAVITY". Really? Guess what we are going to do!
00:00 Summary of previous episodes 01:00 The many plug ins for the HP 5245L 02:25 Making the extender cable 03:06 HP 5253 converter principle of operation (with elevator music) 07:58 Inspection and tryout of our first HP 5253A plugin 10:56 Summary of the first HP 5253B repair 11:27 Taking apart the second HP 5253A 14:02 Stuck gearing repair 15:37 Disassembling the "Do Not Disassemble" microwave cavity 19:13 Coaxial resonant cavity explanation (with elevator music) 23:05 Reassembling the cavity 26:19 Testing the repaired HP 5253A plugin 27:15 Comparing with the second HP 5253B cavity 28:26 Testing the second HP 5253B pluginWe found the shark in the SHARC DSP #Short #InTheRightOrientationCuriousMarc2023-06-08 | Antoine (@SiliconInsid on Twitter) brought some cool chips to decap. Here we open a quad SHARC DSP chip. We think that's where the original recipe for fish and chips comes from!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutApollo 13 accident: understanding Houston’s real time debug (Apollo Comms Part 28)CuriousMarc2023-06-02 | We open up a Block I Apollo AC inverter, which gets us totally sidetracked into the Apollo 13 incident. Using the original schematics, looking how our inverter was hooked up in the power system, we can follow word for word the Apollo 13 raw audio of the debug after the accident. I will go into much more engineering details than what is usually reported, but once you understand this, the flight control loops become both limpid and downright chilling. And then, when we regain our composure and get back to said inverter, more surprises await.
An even better way to listen to the Apollo 13 audio is to go to: apolloinrealtime.org/13 Select "join at launch-1minute", then pause it and go to mission time 55:54. To get an even better listen, go to the Mission Audio Control tab, and click on EECOM. You'll hear even more of the backroom discussion between EECOM and EPS
Support the team on Patreon: patreon.com/curiousmarc Buy shirts on Teespring: teespring.com/stores/curiousmarcs-store Learn more on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutRAF Pitot Static Tester Preview - Guess What This is For! #Short #InTheRightOrientationCuriousMarc2023-05-30 | A quick preview of a mystery instrument I just repaired. Can you guess what what it does? Hint: my minions stole this from the British RAF. Full repair video will follow, that was intense.
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutHP 5245L Nixie Counter - Part 2: Repairing the king of Nixie frequency metersCuriousMarc2023-05-17 | We continue repairing our very broken HP 5245L, and hit some really subtle bugs in this amazing all-transistor machine. Opening the Nixie decoder to reveal its many neons and photo-resistor tree is a special treat.
00:00 Summary of previous episode 01:16 Board A21 gate signal repair 04:10 Why is it still not counting? 06:31 Board A17 fast counter repair 11:19 Still not counting right 12:28 Board A15 counter/display explanation 14:20 Taking apart the Nixie decoder 16:25 Board A15 counter neon bulb debug 19:22 Reset issue discovery 20:48 Nixie decoder reassembly and test 21:56 Board A23 reset debug 23:39 Reset fault cured 25:48 Repaired!HP 5245L Nixie Counter - Part 1: The King of 1960s Frequency MetersCuriousMarc2023-05-11 | We start repairing our very broken HP 5245L. It is arguably the king of the Nixie frequency meters of the 1960s. Equipped with the right plug in, it could count up to 18 GHz. Many of them were used in the Apollo communication ground stations. But this digital instrument does not use a single IC: it's all made with individual transistors inside! It feels like repairing a giant IC, but with access to every transistor. We're sure not complaining about it.
00:00 The HP 5245L, king of 1960s counters 02:06 HP instruments at an Apollo tracking station 03:19 Looking inside and first turn on 06:04 Power supply check 06:30 Crystal oscillator check 08:58 Backplane and previous failed repairs 10:22 10 MHz Multiplier repair 12:25 Board A35 Time Base Repair 15:24 Board A19 Input checkout 16:41 Board A21 Function Control checkout 19:17 Board A21 repair 25:28 The differentiator works! 26:27 Gate signal fault 27:14 Summary of Episode 1 repairsVintage Kollsman Altimeter RepairCuriousMarc2023-05-07 | Our eBay altimeter that we purchased for the Bendix Air Data Computer restoration is very broken. Can we repair it? Not too sure about that, but at least we'll get to see what's inside, and it's very pretty!
Get more technical info on the companion site: curiousmarc.com Contact info: youtube.com/curiousmarc/aboutStar Wars Aware Computer - from 1964CuriousMarc2023-05-04 | Today is May the 4th! May the force stay strong with your vintage computer!