I have an old Crosley Buddy Boy (Model 58) with new problems. The radio was working fine with its original components and then one day decided it would fizzle out and just go into a staight hum mode in which volume control does not exist. I replaced the 2 8 MFD eletrolytic capacitors. When I turned up the variac close to the working voltage one of the electrolytics popped. I then replaced the cap with one in the opposite direction. When I began to power it up again, I noticed the tube number 80 in the power circuit began to eminate blue light and also overly bright red plates. I turned it off imediately.
Any thoughts on what is happening here? Could it be a possible short in the transformer on one side of the tap?
Thanks
Greg
Something is shorted and drawing too much current. The blue color can also mean your 80 tube is gassy.
Be sure both filter caps are installed correctly. Positive goes toward the 80 filament & choke. Negative to center tap of power transformer high voltage winding. If reversed they will cause overheating and blow.
There may be other caps on the B+ line shorted?
http://www.nostalgiaair.org/PagesByModel/654/M0039654.pdf
Norm
:Hi,
:
:I have an old Crosley Buddy Boy (Model 58) with new problems. The radio was working fine with its original components and then one day decided it would fizzle out and just go into a staight hum mode in which volume control does not exist. I replaced the 2 8 MFD eletrolytic capacitors. When I turned up the variac close to the working voltage one of the electrolytics popped. I then replaced the cap with one in the opposite direction. When I began to power it up again, I noticed the tube number 80 in the power circuit began to eminate blue light and also overly bright red plates. I turned it off imediately.
:
:Any thoughts on what is happening here? Could it be a possible short in the transformer on one side of the tap?
:
:Thanks
:
:Greg
Greg,
Don't leave the old capacitor hooked to the circuit when replacing it with a new one.
Radiodoc
I cannot see any tone condensers in the diagram on the output tube that would cause a malfunction, but then the speaker isn't shown. Only the speaker plug is shown. You need to do some analysis of the circuit to see where the overload starts. Since both B+ and B- go to the speaker plug, I can only assume that the speaker field is powered ACROSS the power supply and not in series with it (series is more common in newer radios). A choke is shown in the diagram. Is this choke mounted to the chassis? You need to disconnect everything after the choke from the choke. Does the choke have a short to the chassis? This would overload the rectifier. Since the speaker wiring has both B+ and B- in it, is there a short in the speaker wiring? Is there a short in the field coil? Does the speaker mount to the chassis? Is there a leak from some B+ charged wire in the speaker to the speaker frame that would short to the chassis? As Radiodoc said, be sure that all positive electrolytic leads point to the #80 cathode and its associated choke. Don't reverse electrolytics. If you've reversed any electrolytics either initially or after the problem, throw them away and put in new ones. If you installed one backwards to begin with, there is a slight possibility that it worked fine for a while and then shorted. Reversing the electrolytic to its proper position won't fix things now. It's ruined. On occasion you can reverse polarize new electrolytics (install them backwards) with success, but usually they overheat and pop.
Whatever the problem is, you need to disconnect things and see what is causing the short. If you remove the field coil from the radio (by unplugging the speaker), you cannot power up the radio. This field coil loads down the power supply a bit. Voltages will climb higher without the field coil in place and may damage other components. Test each component with your multi-meter for leakage and such. New electrolytics should have no leakage. The needle of your meter (when set to the X10,000 setting) should spring up towards zero ohms and then slowly fall back to infinity. With a brand new electrolytic it should go right back to infinity. With older electrolytics (or new electrolytics that have sat on the shelf for a long time), you may have some leakage. Anything under 1 meg is absolutely unacceptable. If a condenser has leakage and you decide to use it, the leakage should go away after it has been "reformed." If it doesn't, or if the condenser gets hot, then it is likely junk. Until you thoroughly understand electrolytics (unless you already do), you shouldn't experiment with possibly bad caps. They can ruin your radio.
Check throughout the radio. Go at it systematically. Disconnect everything from the choke and then reconnect slowly. If you reconnect the wire(s) going to the choke and the short comes back, disconnect say the RF section from B+. If the short stays, then the trouble is in the AF (audio frequency) section (including speaker and field coil, as explained before). If it goes away, then some wiring or other offending component in the RF section is causing trouble.
Thomas
Thomas,
I must give credit to Norm for the mention of making sure the pluses on the caps go to the 80 tube and choke. I just warned about leaving the old caps connected to the circuit.
Radiodoc
Sorry for the delay on this original post. Got tied up on another project. Last night I recapped and re-resistored the entire radio. I think it must have been a short somewhere. When I power it up now, the tube no longer turns blue and seems to be operating properly. On the other hand I am not able to pick up stations anymore. I was able to get sound when I used my AM Transmiter. The radio seems to be functioning but it also seems to only want to pick up very strong signals. I had to touch the radio antenna to the transmitter antenna for it to actually recieve at a decent level. Any thoughts on this?
Thanks
Greg
::Purple meens gas. Blue means overload.
::
::I cannot see any tone condensers in the diagram on the output tube that would cause a malfunction, but then the speaker isn't shown. Only the speaker plug is shown. You need to do some analysis of the circuit to see where the overload starts. Since both B+ and B- go to the speaker plug, I can only assume that the speaker field is powered ACROSS the power supply and not in series with it (series is more common in newer radios). A choke is shown in the diagram. Is this choke mounted to the chassis? You need to disconnect everything after the choke from the choke. Does the choke have a short to the chassis? This would overload the rectifier. Since the speaker wiring has both B+ and B- in it, is there a short in the speaker wiring? Is there a short in the field coil? Does the speaker mount to the chassis? Is there a leak from some B+ charged wire in the speaker to the speaker frame that would short to the chassis? As Radiodoc said, be sure that all positive electrolytic leads point to the #80 cathode and its associated choke. Don't reverse electrolytics. If you've reversed any electrolytics either initially or after the problem, throw them away and put in new ones. If you installed one backwards to begin with, there is a slight possibility that it worked fine for a while and then shorted. Reversing the electrolytic to its proper position won't fix things now. It's ruined. On occasion you can reverse polarize new electrolytics (install them backwards) with success, but usually they overheat and pop.
::
::Whatever the problem is, you need to disconnect things and see what is causing the short. If you remove the field coil from the radio (by unplugging the speaker), you cannot power up the radio. This field coil loads down the power supply a bit. Voltages will climb higher without the field coil in place and may damage other components. Test each component with your multi-meter for leakage and such. New electrolytics should have no leakage. The needle of your meter (when set to the X10,000 setting) should spring up towards zero ohms and then slowly fall back to infinity. With a brand new electrolytic it should go right back to infinity. With older electrolytics (or new electrolytics that have sat on the shelf for a long time), you may have some leakage. Anything under 1 meg is absolutely unacceptable. If a condenser has leakage and you decide to use it, the leakage should go away after it has been "reformed." If it doesn't, or if the condenser gets hot, then it is likely junk. Until you thoroughly understand electrolytics (unless you already do), you shouldn't experiment with possibly bad caps. They can ruin your radio.
::
::Check throughout the radio. Go at it systematically. Disconnect everything from the choke and then reconnect slowly. If you reconnect the wire(s) going to the choke and the short comes back, disconnect say the RF section from B+. If the short stays, then the trouble is in the AF (audio frequency) section (including speaker and field coil, as explained before). If it goes away, then some wiring or other offending component in the RF section is causing trouble.
::
::Thomas
:
:Thomas,
:
:I must give credit to Norm for the mention of making sure the pluses on the caps go to the 80 tube and choke. I just warned about leaving the old caps connected to the circuit.
:
:Radiodoc
:
I would suggest using colored pencils along with the schematic to verify the wiring.
Thomas
As usual thank you all for the info and advise!!
Greg :-)
:Have you wired an external antenna to this radio? I think that this radio requires a long wire external antenna. Most radios of this period did. Connect a long wire to the antenna terminal on the back of your receiver. For starters, you can touch your finger to the terminal. Radios of this period will not work without an external antenna. External antennas usually yield better results than internal ones anyway, but they are an inconvenience. You can string one across your back yard away from wires and sources of interference. Your attic will do well, too. A long wire antenna can never fold back on itself or turn right angles. It must go in one direction and then stop. Any bends or turns will cause signal cancellation, and will ruin the efficiency of your antenna.
:
:Thomas
When replacing caps or resistors, it's real easy to make an error. In the middle of removing a cap, the phone rings and you can forget exactly where you were.
I recommend that after replacing the electrolytic filter caps, to troubleshoot and get the set working, after a fashion. Then after replacing each cap, play the radio to verify that you didn't introduce an error.
When removing an old cap, don't remove the whole thing at once. Lift one lead, leaving the old cap dangling on the other terminal.