Videokarma.org TV - Video - Vintage Television & Radio Forums

- Antique Radio (http://www.videokarma.org/forumdisplay.php?f=16)

- - Life span of selenium rectifiers? (http://www.videokarma.org/showthread.php?t=243772)

As an amateur radio operator for 37 years myself, I am well familiar with the concept of the "junk box"; in fact, I had one years ago, when I lived in a Cleveland suburb and collected old TVs from my neighbors' trash. I'd rob parts and tubes from the unrepairable sets to repair the good ones, and literally had boxes full of old parts and tubes in my basement workshop as well, so I almost always had the parts I needed to get and keep my restorable sets working.

There is no reason I can't do the same with older, unrepairable solid-state gear today. In fact, you gave me an idea: When the monitor on my computer finally gasps its last breath and fails (even though it currently works well, the monitor is so old now I won't bother having it fixed when it dies; I'll probably replace it with--gasp!--a flat panel), rather than just throwing the entire unit in the trash, I'll look inside the monitor (after discharging the CRT, of course) for things such as rectifier diodes, capacitors, etc. I'm sure I'll find plenty of those in this and just about any other piece of cast-off electronic gear one finds in trash piles these days, including cast-off personal computers (most of these found in trash piles, however, will be without their hard disks; I think that's the law [to remove the hard drive] when disposing of an old computer). In fact, I have a Sony 60-CD stereo system, found near the trash barrels in back of my apartment a few weeks ago, in which the CD player doesn't seem to work; I'm trying to restore it, but if my efforts fail, I will cannibalize the thing and save whatever good parts I can find. I have nothing to lose; in fact, I'll probably be doing myself a favor if I do cannibalize that stereo, as I already have a good (smaller), if old (nine years) bookshelf stereo system and, to be perfectly honest, I have no room for another one, as I live in a very small apartment.

73,

You can tell if a selenium rectifier is bad if it makes a clunk when you throw it into the trash can.

Here you go:

http://search.digikey.com/scripts/Dk...=1N4007DICT-ND

Choose USPS first class and it is only @ $2 for shipping.

Quote:

Originally Posted by wa2ise (Post 2930036)

I used a bridge rectifier salvaged from an old PC power supply. This will allow the filter caps to be recharged twice every cycle of 60Hz powerline, instead of just once. And tube heaters have less hum leakage when they are at a positive voltage compared to the cathodes, like 50V. And this bridge circuit will make the middle of the heater string look to have such a positive voltage, so I rewired the string so the first audio driver tube sees the least AC ripple and a fairly constant voltage as seen by the heater and cathode voltage difference. But the chassis is hot no matter which way the radio's power plug is connected to the powerline. But this is for advanced hobbyists.

In any event, one can acquire a far amount of usable parts from salvaging tossed computer monitors, power supplies and such. This is an old tradition in ham radio, known as the "junk box". Such junk will likely have usable rectifier diodes.

Clever, I wouldn't have thought to try something like that.

John