#25: A few tips for working on vintage electronics

[@Lesstroublesleeping]

Very good ‘ground rules’ especially for those just getting their feet wet. Really liked your walk through on visual inspection.Taking pictures before, during and after is also a best practice; someone else’s comment on checking the fuse also helps keep the magic smoke from presenting itself... Lastly never hurts to remind people to resist the urge to plug something in to see what happens - especially if they don’t have the proper setup: isolation transformer, variac, dim bulb tester, etc. Thanks for posting this!

[@poormanselectronicsbench2021]

Thank you for sharing a good plan for working on older electronics equipment.Adding a item to the beginning - Try to avoid turning any knobs and switches until you do a good visual of any switch assemblies after opening, and if the item is light enough, do a "shake and rattle" test to see if there are any loose or broken off pieces of anything inside of the enclosure. I purchased a Heathkit transistor curve tracer, which, had some small pieces of something rattling inside of it. after opening it, I found a few pieces of a brown plastic looking material loose inside. A good further inspection revealed a cracked and broken rotary switch wafer ( most likely broken from an inpact on that switch knob before shipping), and although the switch wasnt salvageable, if I decided to power and test it, I could only guess as to what may have shorted out in the decision to do that. Also, Selenium rectifiers, which when they fail do so with MUCH smoke, are not a deadly toxin, and Selenium is actually a necessary mineral supplement, but it can cause toxicity in high exposures and excessive handling or ingestion of it should be avoided ( it is shown to be a carcinogen in higher exposures to lab mice and rats)

[@allthegearnoidea6752]

Lots of great tips thanks for sharing

[@michaela.ofthenorth4530]

Regarding Toxic substances, some of the older Zenith Tube Radios used a sheet of asbestos (usually white) between the bottom of the chassis and the wood cabinet, apparently to prevent fires if something got too hot above the wood case. (Notably the original Zenith Trans-Oceanic and others.) Restorers either remove it with adequate protection (gloves and respirator) or in some cases seal it with something like shellac, spray clear paint/plastic, etc.

[@drtidrow]

Good to know about the old Trans-Oceanics, I've got a bunch of them on the "to-do" pile.

[@gkseifert]

Interesting and useful video, but for Petes sake (or you own) set that tester back to discharge before you go picking things up by those test leads. You had me cringing a couple of times!

[@tomasvalentin6896]

Great video, very informative

[@Broken_robot1986]

Wish the videos were still coming

[@KX4UL]

Very good information! Exactly what I was looking for. I have a couple of old 'Heathkit' HAM radios I want to restore and this video offers some great tips. Thank you for posting!

[@wallacelawrence8234]

instaBlaster.

[@VintageTechFan]

The german word for "rectifier" is "Gleichrichter" (~equal-steerer .. so, rectifier). We like to call the selenium rectifiers "Gleich-Riecht-Er", which basically translates to "It's going to smell!". It's an old saying, going back to the time they were actually used in production.

[@drtidrow]

"It's going to smell" - nice! :-D

[@dbridger620]

Back in the day, I can remember the terrible smell of a failing selenium rectifier as they would slowly cook right under your nose. Ugh! I never knew they were toxic, though. Also, what were AA5 radio engineers thinking when they switched off the neutral side of the line and left the rest of the chassis hot all the time? In restoring an AA5 radio, use a polarized power cord and rewire the chassis so the HOT side of the line is switched off. I would be curious how many people used these sets in a damp environment, changing the channel while turning on a cold water faucet. Your video has some great information. Thanks!

[@radiophysicsandelectronics6923]

Thanks for the feedback, I’m pleased you liked the video. The AA5 radios were designed before the time when the US had polarized power plugs, so there was a 50-50 chance that the plug would be inserted in one orientation versus another. With the cost constraint of not being able to include a power transformer in the design, it seems like the engineers did about as good as they could have done. That said, I’m sure many people got shocked, and I wonder about the injuries or worse that resulted. I’m glad we live in a word where safety is (usually) engineered into products and where the electrical infrastructure and regulatory codes makes that possible! Of course, there is occasionally stupid engineering in cheap products (and sometimes not-so-cheap products), so the buyer needs to beware!

[@VintageTechFan]

@@radiophysicsandelectronics6923 If I look at old pictures of electric switchboards, like in the early 1900s, the safety culture seems basically to have been: "Hmm, all that high voltage on open metal bars .. if someone touches that, he will be 'well done'?" "Yep, the guy who did that yesterday was. So don't touch it." "The switch I have to use all the time is right beside it..." "The switch has to switch the main power line, and the main power line is right there." If you did have an accident, it was basically seen as your fault and that was it. I don't totally agree with the really idiot-proofed way of today though. Often enough safety mechanisms actually hinder the usability of the device so much that people tamper with them, usually making the device MORE dangerous as it ever was without them.

[@sonotdown998]

Your videos are great! Thanks to your methodical and clear demonstrations and explanations my head hasn’t exploded once from electronics information overload. I stumbled upon your channel earlier today and was shocked to see that you don’t have tens of thousands of views for this (and other) videos. It’s a serious head-scratcher. I do have one question. Can one actually pick up the capacitor without a risk of (substantial) shock when that thing’s still on the leakage test setting and dialed up to 250V? I’m not trying to be the safety police here. I’m actually just curious cos I’m hoping to acquire that model soon. Thanks and keep ‘em comin’!

[@radiophysicsandelectronics6923]

You're correct to question, one should always exercise care when using these units. It's best not to handle the capacitor when it's being tested and/or before it's been discharged; this tester and similar testers are dangerous because it is possible to come into contact with high voltage. I'm glad you like the videos.

[@vinnievintage7725]

He will! Its just a fairly new channel. It takes time to build viewership.

[@johnrieger2461]

Excellent information. I recently retired and plan to restore a life long collection of tube radios. Can you recommend a source to buy replacement parts. ( resistors, capacitors, tubes, etc.) I miss Radio Shack….

[@erin19030]

For the price of a cap checker you could just buy all the caps your ever gonna need. Just recap , even after testing thats what your going tondo.

[@JustShortOf]

Great video...!!!

[@jameslucas6589]

One question I always have had, though various resistors drift, what is the rate of drift and the potential for further drift and how far will they drift? That is an unanswerable question in most cases. But given the fact these resistors are quite old, the rate of further drift may not be hardly worth noticing. The reason I am curious is the out of tolerance resistor could be kept and reused for a higher resistance requirement of help to use for a odd value. The old meters and equipment have a penchant for odd resistors which is very frustrating.

[@VintageTechFan]

They will most likely keep drifting when the get thermally cycled again. Also the drift "upwards" is often corrosion at the leads, which can cause a lot of noise, too. Remember the E-series are laid out they way they are, since the tolerance fields line up then. If you use modern E96 1% types, you should be fine in any case therefore. If it's an old 10% .. use the nearest E12 value and it will be fine.

[@drtidrow]

I've encountered a few that were as much as triple their rated value, IIRC the worst I've found so far was a 470k resistor that measured around 1.5Mohms.

[@danielrine3103]

Hi, As I watch the video, I was just wondering.. I have an Eico 232 VTVM that uses that type of rectifier, should that be changed, the output voltage is reading just a little high, the unit does work fine? Thank you!!

[@GeigerCounterVirtualMuseum]

New sub here. Very helpful video. Great info.

[@radiophysicsandelectronics6923]

Thank you!

[@otavakarjalainen]

Hi there, Thank you for this great content, it is enjoyable and informative. (Good production value!) Do you have any good literature to recommend to a musician/audio engineer who is also a theoretical physics student with interests in DIY electronics and restoration of vintage equipment? :-) I'm thinking of getting the legendary "The Art of Electronics" by Horowitz and Hill, but can you recommend any books specifically about vintage gear (i.e. stuff that uses tubes)? Take care,

[@radiophysicsandelectronics6923]

I'm glad you found the video useful. As for literature for the theoretical physics-minded (which is my background), my advice is to submerge yourself in physics E&M texts: At the undergraduate level, Wagsness is excellent, and at the graduate level, while Jackson is the standard, I find the text by Ramo, Whinnery, and Van Duzer more relevant for communications engineering. As for electronics texts, I like Simpson's "Introductory electronics for scientists and engineers" (Allyn and Bacon, 1974; though it's very dated at this point), and of course Horowitz and Hill's venerable "The art of electronics" is great. To deal with the vintage electronics topics, I suggest beginning with early-1960's versions of the Radio Amateur's Handbook or an undergraduate engineering circuits book from the same era, such as Angelo's "Electronic circuits" (McGraw Hill, 1964). If you're interested in tubed electronics, RCA's "Receiving tube manual" has a very worthwhile introductory chapter, and while dated, Christ's "Radio tube fundamentals" is available in reprint and worth reading. At the very pragmatic level, the Antique Radio Forum's "Test equipment and tools" discussion area is an excellent searchable resource. I hope this helps!

[@otavakarjalainen]

Thank you for your ample reply! I will take a look at the books you listed.

[@kennynvake4hve584]

I have found that just about all 470k resistors are out...strange right.

[@natet3345]

Afrotech? 😳 is that you??