Quote:
Originally posted by classicradios
Just started cleaning and taking apart this RCA 14PD8054. The TV is in working condition but needs work. Nice strong CRT but the images are distorted (Squished legs, stretched heads, etc...)
I'll slowly go through and replace the caps. Anyone know the proper replacements for the selenium rectifiers in this set? Of course I don't have the Sam's folder on this one. I'm hoping I can go to Radio Shack and buy diodes as replacements. Any help or tips on restoring this TV is much appreciated.
Jim
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I'd replace those seleniums with silicon diodes ASAP, as you are planning to do. (Replacing those old electrolytic caps won't hurt, either--in fact, your TV will work much better with fresh ones. Many stubborn problems in older sets (sync, AGC, hum bars, etc.) can be directly traced to defective electrolytics.
Remember, however, to use resistors in series with the new diodes to maintain the proper output voltage, i. e. to get the same output from the silicons as you now read at the output of the selenium stacks.
Selenium rectifiers were good in their day, but that day is long gone. Seleniums can short, causing them to release a gas which smells like sulphur or rotten eggs (the smoke may be toxic as well), which could also create a fire hazard if the selenium actually burns. Depending entirely upon which way the AC plug is in the wall socket, seleniums can cause a shock hazard as well.
In view of all the problems these outdated parts can cause, I think you're doing the right thing by replacing your TV's seleniums with modern silicons. Any TV/radio technician will tell you the same thing.
I'm not a technician, but I was an electronics experimenter many years ago. About 30-35 years ago I had a basement full of old TVs, radios and even a couple old phonographs which I experimented with quite a bit, so I've had some experience with these older style power supplies and circuits; the new ones throw me for a loop because I haven't kept up with the technology, but I still enjoy helping these guys on AK with their problems (and reading about the ones I can't help them with). And I enjoy looking at the pics of the old TVs I see here no end. It keeps me close to a hobby I enjoyed for many years, until I moved to a small apartment about four years ago. I am also an amateur radio operator (got my first license in 1972 and just renewed the license last month or thereabouts); one must know one's way around electronics fairly well to pass the written test for the license (at least that's how it used to be when I first got into the hobby; it's much different today).
Good luck and very kind regards,