Have you measured tube plate & screen voltages? 6K6 pins #3 and #4 must be positive. 6Q7, pin #3, positive. Do you hear a loud hum touching top cap on your 6Q7? If so the audio section is ok.
Pins #3 and #4 positive on 6U7 & 6A8. Pin #6 on 6A8 must also be positive.
Might try peaking IF Transformers by ear?
Norm
:might sound stupid but I must have overlooked something I have a late model crosley 517 that was a real basket case, I've recapped the radio had to rewind some coils, put a 1k ohm resistor to replace the field coil (wish I knew the correct impedance)of the original.. finally got it to where I could hear stations but have no volume, I've checked and changed tubes I used my eico 147 to check the speaker/output transformer and I have little or no difference in the volume, I also find the power trans gets hotter then I remember most being... I also changed the volume control the biggest problem I had with it was adjusting the if transformers I had to use two signal generators and still couldn't get them to adjust to the 455kc properly, ok the eico 320 had to use resonate frequencies because of a bad b band coil and the other one is a no name that might not be calibrated right.. I guess I have to find a 1629 tube so I can use the 147 to check the wattage.. anyone have any ideas I figured after the number of sucesses I had with radios that I'd seen all of the probs guess not... any advice would be greatly apprichiated thanks
:might sound stupid but I must have overlooked something I have a late model crosley 517 that was a real basket case, I've recapped the radio had to rewind some coils, put a 1k ohm resistor to replace the field coil (wish I knew the correct impedance)of the original.. finally got it to where I could hear stations but have no volume, I've checked and changed tubes I used my eico 147 to check the speaker/output transformer and I have little or no difference in the volume, I also find the power trans gets hotter then I remember most being... I also changed the volume control the biggest problem I had with it was adjusting the if transformers I had to use two signal generators and still couldn't get them to adjust to the 455kc properly, ok the eico 320 had to use resonate frequencies because of a bad b band coil and the other one is a no name that might not be calibrated right.. I guess I have to find a 1629 tube so I can use the 147 to check the wattage.. anyone have any ideas I figured after the number of sucesses I had with radios that I'd seen all of the probs guess not... any advice would be greatly apprichiated thanks
http://www.nostalgiaair.org/PagesByModel/375/M0003375.pdf
clearly states that there should be a 35 volt drop across the field. That said, use an appropriate resistance that gives you a 35 volt drop across it, and also yields appropriate voltages at their respective tube pins. Be sure that the transformer is also in good order and that it is putting out proper voltages.
Be absolutely sure that you replaced the volume control with the exact same resistance. Do not put in a 1/2 meg or something smaller than the original 1 meg. This will ruin amplifier sensitivity and bass response. A very simple way to test the amplifier to see how it's doing is to connect a portable CD player across the end terminals of the volume control. If need be, connect a .05 microfarad condenser in series with the center wire of the headphone wire and the "top" end of the volume control. The bottom end of the volume control is the end that connects to ground, the end that the slider reaches when minimum volume is desired, and the terminal which the shielded outer conductor of the headphone wire should be connected to. Plug the headphone wire into your CD player and put on your favorite CD. Turn the volume up to about 7 or 8 if the control goes to 9 or 10. Turn on the radio and listen to the music. If you turn the radio down low and the music still sounds distorted, try reducing the volume of the CD player. Reduce the volume until the distortion goes away. Now advance the volume control of the radio for pleasant listening, and then advance it for loud listening. See that the amplifier is capable of producing a nice powerful sound that a single 6K6 amplifier is normally capable of producing (about 1 to 3 watts, perhaps 4 with distortion). If you have trouble, then you need to check for shorted condensers (leakage even in the millions of ohms), bad connections, bad resistors, transformer, or tubes.
Be sure that the AVC resistor has not drifted. It must be in good order if the set is to perform properly. RF tube bias depends on this resistor. If it drifts high, excess electrons will collect on the RF tube grids by normal operation of the tubes as the electrons flow past the grids from the cathodes, and the set will go quiet. The normal purpose of this resistor is to bias some of the electrons to ground to maintain the grids of the RF tubes at a proper negative value. When a loud station is received, the negatively rectified audio signal is sent through the AVC resistor, and is filtered by the AVC condenser. This forms a mean negative voltage in relation to the audio signal produced. This negative voltage is applied to the RF grids, and causes them to perform less, causing the station to get quieter so that it does not distort--and there you have normal AVC operation. A quiet station will not generate this AVC voltage, and so full tube performance will be employed.
Though you can't test your RF generator's IF frequency (455 KC) on a radio, the other signals that you tune in on the radio you can test on a known good radio (perhaps a digitally tuned radio). You can perhaps check the 455 KC signal on a known good radio with 455 KC IF transformers. They may be slightly off, though, so this does not really tell you anything. Do not expect perfection across the dial when testing the generator against a radio, but your signal generator should reasonably line up with corresponding stations tuned in on the test radio. If the radio is a digitally tuned model, the radio will be more accurate than the signal generator, so if the generator does not match the radio, expect the generator to be at fault. You can touch things up reasonably with the corresponding slugs in the generator. My EICO never matches up perfectly across the dial. This ticks me off, but then, after I'm done doing a "rough" tune-up on a radio, I go and fix things up later, move a few stations around on this end of the dial and that, and then, before you know it, the set tunes perfectly, no thanks to my signal generator.
You say you replaced all the condensers in the radio. One item I always emphasize is the mica condenser. Though they rarely fail, sometimes they do, and sometimes they're not mica! YAY! My whole DeWald BT-100 (RCA 630TS chassis with 10BP4 picture tube) had leaky mica condensers, or at least they all looked like mica condensers with those colored dots and all. The ones across the line cord were just plain shorted out, and got hot and everything. Well, after replacing all of them with new ones, I cracked the old ones open to see what was inside. They were ordinary paper insulated condensers!
Anyway, check the signal generator, and check the radio for the unordinary. Signal generators are not that complicated. You should be able to find a broken wire on the coil for the B band. Mend it, and you should be able to bring it back to life. This is one of the few places where I recommend a digital signal generator, though. I hate digital things. No matter what people say, CDs do not sound better than LPs (except for lack of surface noise as compared to a poorly maintained LP), although the new analog CDs sound better than anything. They're amazing. My digitally tuned JVC car radio sounds like you're listening through a cell phone. It all sucks, but a digital signal generator is your key to accurate happiness.
Thomas
:If you replaced all condensers with proper values (voltage and capacitance), and all other resistors are in good condition, all connections, etc., then the radio should be in good order for doing voltage checks, regardless of RF performance. The discription literature given in the link below:
:
:http://www.nostalgiaair.org/PagesByModel/375/M0003375.pdf
:
:clearly states that there should be a 35 volt drop across the field. That said, use an appropriate resistance that gives you a 35 volt drop across it, and also yields appropriate voltages at their respective tube pins. Be sure that the transformer is also in good order and that it is putting out proper voltages.
:
:Be absolutely sure that you replaced the volume control with the exact same resistance. Do not put in a 1/2 meg or something smaller than the original 1 meg. This will ruin amplifier sensitivity and bass response. A very simple way to test the amplifier to see how it's doing is to connect a portable CD player across the end terminals of the volume control. If need be, connect a .05 microfarad condenser in series with the center wire of the headphone wire and the "top" end of the volume control. The bottom end of the volume control is the end that connects to ground, the end that the slider reaches when minimum volume is desired, and the terminal which the shielded outer conductor of the headphone wire should be connected to. Plug the headphone wire into your CD player and put on your favorite CD. Turn the volume up to about 7 or 8 if the control goes to 9 or 10. Turn on the radio and listen to the music. If you turn the radio down low and the music still sounds distorted, try reducing the volume of the CD player. Reduce the volume until the distortion goes away. Now advance the volume control of the radio for pleasant listening, and then advance it for loud listening. See that the amplifier is capable of producing a nice powerful sound that a single 6K6 amplifier is normally capable of producing (about 1 to 3 watts, perhaps 4 with distortion). If you have trouble, then you need to check for shorted condensers (leakage even in the millions of ohms), bad connections, bad resistors, transformer, or tubes.
:
:Be sure that the AVC resistor has not drifted. It must be in good order if the set is to perform properly. RF tube bias depends on this resistor. If it drifts high, excess electrons will collect on the RF tube grids by normal operation of the tubes as the electrons flow past the grids from the cathodes, and the set will go quiet. The normal purpose of this resistor is to bias some of the electrons to ground to maintain the grids of the RF tubes at a proper negative value. When a loud station is received, the negatively rectified audio signal is sent through the AVC resistor, and is filtered by the AVC condenser. This forms a mean negative voltage in relation to the audio signal produced. This negative voltage is applied to the RF grids, and causes them to perform less, causing the station to get quieter so that it does not distort--and there you have normal AVC operation. A quiet station will not generate this AVC voltage, and so full tube performance will be employed.
:
:Though you can't test your RF generator's IF frequency (455 KC) on a radio, the other signals that you tune in on the radio you can test on a known good radio (perhaps a digitally tuned radio). You can perhaps check the 455 KC signal on a known good radio with 455 KC IF transformers. They may be slightly off, though, so this does not really tell you anything. Do not expect perfection across the dial when testing the generator against a radio, but your signal generator should reasonably line up with corresponding stations tuned in on the test radio. If the radio is a digitally tuned model, the radio will be more accurate than the signal generator, so if the generator does not match the radio, expect the generator to be at fault. You can touch things up reasonably with the corresponding slugs in the generator. My EICO never matches up perfectly across the dial. This ticks me off, but then, after I'm done doing a "rough" tune-up on a radio, I go and fix things up later, move a few stations around on this end of the dial and that, and then, before you know it, the set tunes perfectly, no thanks to my signal generator.
:
:You say you replaced all the condensers in the radio. One item I always emphasize is the mica condenser. Though they rarely fail, sometimes they do, and sometimes they're not mica! YAY! My whole DeWald BT-100 (RCA 630TS chassis with 10BP4 picture tube) had leaky mica condensers, or at least they all looked like mica condensers with those colored dots and all. The ones across the line cord were just plain shorted out, and got hot and everything. Well, after replacing all of them with new ones, I cracked the old ones open to see what was inside. They were ordinary paper insulated condensers!
:
:Anyway, check the signal generator, and check the radio for the unordinary. Signal generators are not that complicated. You should be able to find a broken wire on the coil for the B band. Mend it, and you should be able to bring it back to life. This is one of the few places where I recommend a digital signal generator, though. I hate digital things. No matter what people say, CDs do not sound better than LPs (except for lack of surface noise as compared to a poorly maintained LP), although the new analog CDs sound better than anything. They're amazing. My digitally tuned JVC car radio sounds like you're listening through a cell phone. It all sucks, but a digital signal generator is your key to accurate happiness.
:
:Thomas
Change resistance values back to original values only. Change condenser values back to original only. When testing a condenser or resistor, remove one wire to get an exact reading. The radio worked very well when it was new. People bought it by the thousands. It was designed properly, and should be returned to this original design.
T.
thanks
:Actually, 18 is supposed to be 7,000 ohms, so you should replace it with a 7,000 ohm resistor. If voltages are still off, then you need to check condenser 11 for leakage.
:
:Change resistance values back to original values only. Change condenser values back to original only. When testing a condenser or resistor, remove one wire to get an exact reading. The radio worked very well when it was new. People bought it by the thousands. It was designed properly, and should be returned to this original design.
:
:T.
http://www.nostalgiaair.org/PagesByModel/375/M0003375.pdf
which shows both the early and late version. Wasn't sure which you had. Regardless of which radio you have, the early or late version, the screen grid current is taken AFTER the 18 resistor. Plate voltages are taken BEFORE the 18 resistor. Though it is possible for the plate voltage to go up with more voltage on the screen (screen takes more negative current from cathode, and plate sees less current, so there is more positive voltage lingering at plate), changing the screen grid resistor should have only a little affect on the plates. If your voltages are off at the screen grids regardless of which resistor you use, the early version or the late version, then you really need to look at condenser 11. If this condenser is leaking or shorted, then it will draw down the voltage, and will also overheat the 18 resistor slightly, which aids in drifting its value (carbon resistors drift higher in value when they are heated). If all of the other voltages in the radio are fine but this one is off, then you really need to look at condenser 11. If you cannot achieve proper voltages at the screens with the proper value resistor, early or late, then the condenser is extremely likely to be at fault. Condenser 11 also maintains a steady current on the screen grids so that tube fluctuations caused by the radio signals being sent through them do not affect screen grid voltage like they affect plate voltage. If this condenser is faulty, it will not maintain a proper charge to hold the screen grids steady, and the grids will fluctuate with all tube functions, and you will get your lovely oscillation squeel. All condensers in the radio must have absolutely no leakage in order for the radio to perform incredibly well as it did when it was new. To maintain an attractive look under the chassis, the old condensers may be opened, and the small, tubular, yellow "metalized film" condensers may be placed inside.
Thomas
:humm think were confusing the early version with the late version according to the riders I'm using its a 25k thats on page 9-18, but anyway changed r18 to about 12k now get the propper voltage at the screen but plate voltages went up 17v... louder volume again but not as loud as most others I have and less distortion but less stations can be tuned in and its got a nice high pitched oscilation when you tune in a station...
:
:thanks
:
::Actually, 18 is supposed to be 7,000 ohms, so you should replace it with a 7,000 ohm resistor. If voltages are still off, then you need to check condenser 11 for leakage.
::
::Change resistance values back to original values only. Change condenser values back to original only. When testing a condenser or resistor, remove one wire to get an exact reading. The radio worked very well when it was new. People bought it by the thousands. It was designed properly, and should be returned to this original design.
::
::T.