All American Five radio receivers • Hacker News Board

Re: All American Five radio receivers

#11

Post by floren » Wed, Dec 21, 2022, 10:22 PM UTC

123pie123 wrote: post #8

floren wrote: post #3

Earlier quoted context omitted.

Dangerous to poke around inside when plugged in, but quite safe unplugged (unlike say an old TV).

DO NOT ASSUME a CRT MONITOR or 'old' TV IS SAFE to poke around when unplugged!!!!!! https://www.instructables.com/How-to-take-apart-TV/

Read what I wrote again carefully, paying extra attention to the word "unlike"

Re: All American Five radio receivers

#12

Post by 123pie123 » Wed, Dec 21, 2022, 10:27 PM UTC

floren wrote: post #11

123pie123 wrote: post #8

Earlier quoted context omitted.

DO NOT ASSUME a CRT MONITOR or 'old' TV IS SAFE to poke around when unplugged!!!!!! https://www.instructables.com/How-to-take-apart-TV/

Read what I wrote again carefully, paying extra attention to the word "unlike"

"but quite safe unplugged"

a CRT monitor is typically (I would not gamble on it - again!) not safe when unplugged

Re: All American Five radio receivers

#13

Post by dylan604 » Wed, Dec 21, 2022, 10:28 PM UTC

gumboza wrote: post #2

Definitely read the potential hazards section. Dangerous as hell these things.

Slap a "No user serviceable parts inside" sticker on it, and you have an unbeatable liability shield! /s

Re: All American Five radio receivers

#14

Post by greenbit » Wed, Dec 21, 2022, 10:32 PM UTC

pyinstallwoes wrote: post #6

floren wrote: post #3

Earlier quoted context omitted.

Dangerous to poke around inside when plugged in, but quite safe unplugged (unlike say an old TV).

Why is an old tv unsafe?

The CRT acts like a capacitor, storing charge for quite considerable lengths of time. Consider that a B&W would typically run 10kV to 15kV, and color sets easily 25kV, and that should give you some idea of how much energy one of those things can hold. And with those kinds of voltages, you don't even need to make contact to find you've become a discharge path, that stuff will reach out and grab you across considerable air gaps.

Re: All American Five radio receivers

#15

Post by dylan604 » Wed, Dec 21, 2022, 10:32 PM UTC

pyinstallwoes wrote: post #6

floren wrote: post #3

Earlier quoted context omitted.

Dangerous to poke around inside when plugged in, but quite safe unplugged (unlike say an old TV).

Why is an old tv unsafe?

oh, boy. the temptations of telling how to find out on your own are strong!

the capacitors in CRTs could store a charge for a long time. i've seen people that assumed the caps were discharged find out the hard way when they shorted the leads with a tool. the noise alone is enough to make one need clean shorts. the only good thing is that they discharge quickly, but they give you "both barrels" worth to borrow a phrase.

Re: All American Five radio receivers

#16

Post by dekhn » Wed, Dec 21, 2022, 10:35 PM UTC

123pie123 wrote: post #12

floren wrote: post #11

Earlier quoted context omitted.

Read what I wrote again carefully, paying extra attention to the word "unlike"

"but quite safe unplugged" a CRT monitor is typically (I would not gamble on it - again!) not safe when unplugged

yes, you two are in agreement. it's the radio receiver that's safe when unplugged.

Re: All American Five radio receivers

#17

Post by II2II » Wed, Dec 21, 2022, 10:38 PM UTC

123pie123 wrote: post #12

floren wrote: post #11

Earlier quoted context omitted.

Read what I wrote again carefully, paying extra attention to the word "unlike"

"but quite safe unplugged" a CRT monitor is typically (I would not gamble on it - again!) not safe when unplugged

Unlike means not like, so they were effectively saying it was safe to go inside radios but it is not safe to go into old televisions.

Re: All American Five radio receivers

#18

Post by Aloha » Wed, Dec 21, 2022, 10:47 PM UTC

userbinator wrote: post #7

https://www.youtube.com/user/glasslinger is a good YouTube channel that shows the servicing of these and other vintage radios.

She is the absolute best! Though the stuff she works on is typically much older than an AA5, shango066 is also great (though, his politics are somewhere between wacky-wacky-wacky and crazy town express), JordanPier too.

Glassslinger is probably the best bench tech I've ever seen, she has an encyclopedic knowledge of vintage electronics.

Re: All American Five radio receivers

#19

Post by 123pie123 » Wed, Dec 21, 2022, 10:49 PM UTC

floren wrote: post #11

123pie123 wrote: post #8

Earlier quoted context omitted.

DO NOT ASSUME a CRT MONITOR or 'old' TV IS SAFE to poke around when unplugged!!!!!! https://www.instructables.com/How-to-take-apart-TV/

Read what I wrote again carefully, paying extra attention to the word "unlike"

appologies - I just re-read the article (and the other comments). I see where you're coming from

I just saw the words "unplugged" and remembered the word vacuum tube - then massive emotions from my past came rushing through

Re: All American Five radio receivers

#20

Post by II2II » Wed, Dec 21, 2022, 10:52 PM UTC

zhrvoj wrote: post #9

gumboza wrote: post #2

Definitely read the potential hazards section. Dangerous as hell these things.

Yeah, do not attempt to use. High voltage inside. Better to buy any new low voltage piece of shit. Throw this all away. Be very afraid of this old stuff. Hmmm....your Tesla, runs on 3.7V LiIon...safe.

It is better to say that you should not go inside of an old television unless you know what you are doing, and don't assume that you know what you are doing unless you have guidance from someone who is experienced. Reading about or watching someone work inside of high voltage devices should not be considered sufficient since it is easy for either the author or reader to miss important details.

It is also worth noting that electrical safety depends upon far more than voltage. We think of 3.7 V battery operated devices as safe because our bodies are not very good conductors (when dry) and some types of batteries have an internal resistance that will limit the current draw. If I recall correctly, the internal resistance of LiIon batteries is sufficiently low that they are dangerous if not handled correctly (e.g. if you short them).