08-16-2008, 08:38 AM
Hi Dave
Be aware that there are THREE electrolytics in the 42-380.
Two were originally contained in one cardboard tube; the other in its own cardboard tube. Both were mounted together against the chassis (not chase - you work on a chassis; you chase your wife
).
Part (20) contains two 8 uF, 475 volt units, part (61) is a single 18 uF, 475 volt unit.
Neither 8 uF, 18 uF, nor a 475 volt rating are standard anymore. Today, 10 uF is generally used to replace 8 uF, and 22 uF replaces 18 uF.
Normally, you would need to go to 500 VDC rating to replace an old 475 volt condenser. However, please note that on this model, the voltage rating are greatly over-rated; condenser (20A), part of (20), will only "see" around 200 volts (original measurement 195V, I'm allowing for today's higher line voltage and more sensitive multimeters). (20) is only getting around 90V, and (61), probably in the neighborhood of 250 to 300 volts.
Therefore, for these particular parts, you may safely use 450 volt replacement electrolytics, since 500 volt electrolytics are sometimes harder to find, and not needed in this application.
But until you become more well versed in electronics, please do not ever assume you may replace an electrolytic with one rated at a lower voltage - most of the time, you can't. This, however, is one of those occasional instances where you can.
Speaking of learning. Never, ever, plug in and turn on an old radio until it has been checked out for signs of trouble. This includes, but is not limited to, replacing the electrolytics right away before going any further. They are almost always bad, or in the process of going bad. (This is what makes the set hum - the electrolytics are no longer doing their job of filtering the set's high voltage power. In other words, they have failed, and could short at any time.)
Failure to heed this warning could result in one or more of the electrolytics shorting out, taking your set's power transformer with it.
And please understand, I am not trying to criticize you, but merely trying to help and educate you at the same time. This is a great hobby. But safety must be observed, and part of that is to never plug in that radio you just bought without, at the very least, replacing those electrolytics.
Be aware that there are THREE electrolytics in the 42-380.
Two were originally contained in one cardboard tube; the other in its own cardboard tube. Both were mounted together against the chassis (not chase - you work on a chassis; you chase your wife
). Part (20) contains two 8 uF, 475 volt units, part (61) is a single 18 uF, 475 volt unit.
Neither 8 uF, 18 uF, nor a 475 volt rating are standard anymore. Today, 10 uF is generally used to replace 8 uF, and 22 uF replaces 18 uF.
Normally, you would need to go to 500 VDC rating to replace an old 475 volt condenser. However, please note that on this model, the voltage rating are greatly over-rated; condenser (20A), part of (20), will only "see" around 200 volts (original measurement 195V, I'm allowing for today's higher line voltage and more sensitive multimeters). (20) is only getting around 90V, and (61), probably in the neighborhood of 250 to 300 volts.
Therefore, for these particular parts, you may safely use 450 volt replacement electrolytics, since 500 volt electrolytics are sometimes harder to find, and not needed in this application.
But until you become more well versed in electronics, please do not ever assume you may replace an electrolytic with one rated at a lower voltage - most of the time, you can't. This, however, is one of those occasional instances where you can.
Speaking of learning. Never, ever, plug in and turn on an old radio until it has been checked out for signs of trouble. This includes, but is not limited to, replacing the electrolytics right away before going any further. They are almost always bad, or in the process of going bad. (This is what makes the set hum - the electrolytics are no longer doing their job of filtering the set's high voltage power. In other words, they have failed, and could short at any time.)
Failure to heed this warning could result in one or more of the electrolytics shorting out, taking your set's power transformer with it.
And please understand, I am not trying to criticize you, but merely trying to help and educate you at the same time. This is a great hobby. But safety must be observed, and part of that is to never plug in that radio you just bought without, at the very least, replacing those electrolytics.
--
Ron Ramirez
Ferdinand IN
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