I did one of the dumbest things, In my excitment to test out a project, I inadvertantly turned the radio on without the tubes in it. All I get now is hum and no reception. Did I fry all the capacitors and/or resistors? If I change these, will the radio come back to working order? The radio is a five tube RCA, not sure of the model number.

Is it an AC or AC/battery? With AC/battery radios, if you remove all of the tubes and it has a solid state rectifier, the electrolytics will build up high voltages, which will burn out the filaments of the battery type tubes when they are re-inserted. With a tube type rectifier, if you remove all but the rectifier, this will happen, but if you remove the rectifier as well, normally no damage will be done.

If an AC or AC/DC radio, are you sure that you put the tubes in the correct sockets. Normally if you remove ALL tubes, no damage is done. In rare circumstances damage is done. With some AC radios if you remove all but the rectifier, damage can be done.

Condensers and resistors are not normally fried when all of the tubes are removed. If the rectifier is left in and it's a transformer powered AC radio you're dealing with, sometimes condensers can be shorted out. Excessively high voltages can build up without the rest of the tubes to load down the power supply.

A model number or at least a tube line-up and reference to the power supply used in the radio will aid in determining your damages.

Thomas

Figured out the model, it is a RCA 8X541. It is AC only. I replaced the electrolytics and a couple of other capacitors and it works for about five seconds and then goes back to a hum with no reception.

:Is it an AC or AC/battery? With AC/battery radios, if you remove all of the tubes and it has a solid state rectifier, the electrolytics will build up high voltages, which will burn out the filaments of the battery type tubes when they are re-inserted. With a tube type rectifier, if you remove all but the rectifier, this will happen, but if you remove the rectifier as well, normally no damage will be done.
:
:If an AC or AC/DC radio, are you sure that you put the tubes in the correct sockets. Normally if you remove ALL tubes, no damage is done. In rare circumstances damage is done. With some AC radios if you remove all but the rectifier, damage can be done.
:
:Condensers and resistors are not normally fried when all of the tubes are removed. If the rectifier is left in and it's a transformer powered AC radio you're dealing with, sometimes condensers can be shorted out. Excessively high voltages can build up without the rest of the tubes to load down the power supply.
:
:A model number or at least a tube line-up and reference to the power supply used in the radio will aid in determining your damages.
:
:Thomas

Does it do this repeatedly or only once and then it doesn't work? This is actually an AC-DC set, not an AC only set. Since you had the rectifier removed as well, and since no tubes will light if one of them is removed, you probably didn't do damage to the components within the radio-audio circuitry. You may want to check C18 for shorts or leakage. If this condenser shorts, it may damage electrolytics and other components. The set should still make some music even though it's humming, but I've never had one of these short, so I don't know for sure. You'd be feeding the circuits AC instead of DC.

Check other condensers for shorts and leakage. Remember to remove one lead of each condenser which you solder. Leakage even in the millions of ohms is bad. Condensers should have no leakage. Check the tone condenser across the output transformer. If this shorts, it'll cut out audio and cause a loud hum.

Since your problem doesn't happen all the time, finding the problem may be difficult. Sometimes I supply condensers which I suspect of arcing with high DC voltage. Ask me if you'd like advice on this. This will reveal arcing that may not present itself when checking for leakage with your resistance meter alone.

Check all condensers and perhaps check resistors, too. One may be opening up, though this doesn't usually cause a loud hum.

Also check your tubes for element-to-element shorts. If you need advice on this, let me know. If you removed all of the tubes, one or more may have loose elements which were jarred into a short from your moving them around. Placing tubes on a table is enough of a jar to shake elements which aren't mounted properly. Most tubes are well constructed, so don't think that this is a regular occurrance. It is rare. If you do have a faulty tube, though, it could be shorting and unshorting due to thermal expansion. When you turn on the set, the parts within the tube expand from the heat and move around. This could cause a short to occur.

Check all listed above. Leave no stone unturned.

Thomas

Thanks for all the advice. One of the tube pins was not making constant contact with the socket. Now the radio works except when it is turned up to higher volumes, it cuts in and out.

:Does it do this repeatedly or only once and then it doesn't work? This is actually an AC-DC set, not an AC only set. Since you had the rectifier removed as well, and since no tubes will light if one of them is removed, you probably didn't do damage to the components within the radio-audio circuitry. You may want to check C18 for shorts or leakage. If this condenser shorts, it may damage electrolytics and other components. The set should still make some music even though it's humming, but I've never had one of these short, so I don't know for sure. You'd be feeding the circuits AC instead of DC.
:
:Check other condensers for shorts and leakage. Remember to remove one lead of each condenser which you solder. Leakage even in the millions of ohms is bad. Condensers should have no leakage. Check the tone condenser across the output transformer. If this shorts, it'll cut out audio and cause a loud hum.
:
:Since your problem doesn't happen all the time, finding the problem may be difficult. Sometimes I supply condensers which I suspect of arcing with high DC voltage. Ask me if you'd like advice on this. This will reveal arcing that may not present itself when checking for leakage with your resistance meter alone.
:
:Check all condensers and perhaps check resistors, too. One may be opening up, though this doesn't usually cause a loud hum.
:
:Also check your tubes for element-to-element shorts. If you need advice on this, let me know. If you removed all of the tubes, one or more may have loose elements which were jarred into a short from your moving them around. Placing tubes on a table is enough of a jar to shake elements which aren't mounted properly. Most tubes are well constructed, so don't think that this is a regular occurrance. It is rare. If you do have a faulty tube, though, it could be shorting and unshorting due to thermal expansion. When you turn on the set, the parts within the tube expand from the heat and move around. This could cause a short to occur.
:
:Check all listed above. Leave no stone unturned.
:
:Thomas

Thomas...I own one of these RCA's (8X541) and didn't realize it was AC/DC (Learn something new everyday). I didn't know that the AC plug was ment to plug into DC also. After reading the literature, I see that you are correct. Interesting....
Joe Ferris

:Does it do this repeatedly or only once and then it doesn't work? This is actually an AC-DC set, not an AC only set. Since you had the rectifier removed as well, and since no tubes will light if one of them is removed, you probably didn't do damage to the components within the radio-audio circuitry. You may want to check C18 for shorts or leakage. If this condenser shorts, it may damage electrolytics and other components. The set should still make some music even though it's humming, but I've never had one of these short, so I don't know for sure. You'd be feeding the circuits AC instead of DC.
:
:Check other condensers for shorts and leakage. Remember to remove one lead of each condenser which you solder. Leakage even in the millions of ohms is bad. Condensers should have no leakage. Check the tone condenser across the output transformer. If this shorts, it'll cut out audio and cause a loud hum.
:
:Since your problem doesn't happen all the time, finding the problem may be difficult. Sometimes I supply condensers which I suspect of arcing with high DC voltage. Ask me if you'd like advice on this. This will reveal arcing that may not present itself when checking for leakage with your resistance meter alone.
:
:Check all condensers and perhaps check resistors, too. One may be opening up, though this doesn't usually cause a loud hum.
:
:Also check your tubes for element-to-element shorts. If you need advice on this, let me know. If you removed all of the tubes, one or more may have loose elements which were jarred into a short from your moving them around. Placing tubes on a table is enough of a jar to shake elements which aren't mounted properly. Most tubes are well constructed, so don't think that this is a regular occurrance. It is rare. If you do have a faulty tube, though, it could be shorting and unshorting due to thermal expansion. When you turn on the set, the parts within the tube expand from the heat and move around. This could cause a short to occur.
:
:Check all listed above. Leave no stone unturned.
:
:Thomas

Since the radio lacks a power transformer and a clock and a phonograph motor, it may be operated from DC. A power transformer and most clock and phonograph motors must be run from AC current only, and at a specific frequency (like 60 cycles). If you run a power transformer from DC, first of all its DC impedance is low, and it'll burn up, and second, due to the lack of a changing magnetic field that would normally be created from alternating current, it won't generate current in any of the secondaries.

With an AC-DC radio, where there is no power transformer, the tube filaments are strung in series to equal line voltage. They may be operated from AC or DC. With the B supply, a rectifier changes AC to pulsating DC. If you were to feed DC to the radio, it would pass through the rectifier quite well. The radio can only be plugged in one way, though, when operated from DC. Since none of the tubes will allow current to flow backwards through them, the radio won't work if the plug is inserted the wrong way.

Thomas