Many Thanks, Jim
It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
Norm
: I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
: Many Thanks, Jim
Jim
: Hi Jim
: It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
: Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
: What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
: Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
: Norm
:
: : I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
: : Many Thanks, Jim
What is the actual resistance in ohms? If the tube filaments are good and wiring isn't open there should be a reading.
Some meters have a contuinuity check using a tone. Don't use this as it will have a cutoff point. My Fluke cuts off around 400 ohms. Below this point there is a tone, above 400 ohms, nothing.
Norm
: Hi Norm,
: I am useing a Fluke 26III multimeter. I checked myself again after your message and I have the same results.The filaments are all fine. I have one probe on the #5 pin of the 19T8 and I am going in sequence from pin to pin on the filament circuit.
: Jim
: : Hi Jim
: : It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
: : Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
: : What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
: : Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
: : Norm
: :
: : : I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
: : : Many Thanks, Jim
: What is the actual resistance in ohms? If the tube filaments are good and wiring isn't open there should be a reading.
: Some meters have a contuinuity check using a tone. Don't use this as it will have a cutoff point. My Fluke cuts off around 400 ohms. Below this point there is a tone, above 400 ohms, nothing.
: Norm
:
: : Hi Norm,
: : I am useing a Fluke 26III multimeter. I checked myself again after your message and I have the same results.The filaments are all fine. I have one probe on the #5 pin of the 19T8 and I am going in sequence from pin to pin on the filament circuit.
: : Jim
: : : Hi Jim
:
: : : It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
:
: : : Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
:
: : : What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
:
: : : Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
:
: : : Norm
:
: : :
: : : : I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
:
: : : : Many Thanks, Jim
Again many thanks, Jim
: Hi Jim
: What is the actual resistance in ohms? If the tube filaments are good and wiring isn't open there should be a reading.
: Some meters have a contuinuity check using a tone. Don't use this as it will have a cutoff point. My Fluke cuts off around 400 ohms. Below this point there is a tone, above 400 ohms, nothing.
: Norm
:
: : Hi Norm,
: : I am useing a Fluke 26III multimeter. I checked myself again after your message and I have the same results.The filaments are all fine. I have one probe on the #5 pin of the 19T8 and I am going in sequence from pin to pin on the filament circuit.
: : Jim
: : : Hi Jim
:
: : : It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
:
: : : Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
:
: : : What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
:
: : : Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
:
: : : Norm
:
: : :
: : : : I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
:
: : : : Many Thanks, Jim
That's great news! A 1N4001 will supply higher voltage than the original selenium rectifier. An added resistor drops some of this voltage and reduces a surge on turn on. With your radio higher voltage isn't a problem and you already have a 68 ohm resistor for protection.
The "beep" mode has a specific resistance where it cuts off. You must have been testing filaments right around this resistance.
Norm
: Hi Norm,
: Excuse a novice beginner; I had the ohmmeter on the beep mode. I would like to thank you and other contributors for your help for beginners. I have learned a lot from Nostalgia Air!!!!
: I replaced the selenium rectifier with the 1N4004 diode like you said. Replaced a 68-ohm resister and the electrolytic capacitors and the radio plays great. You suggested that I install a low value resister in series with the diode to reduce voltage. Could you explain why and what value?
: Again many thanks, Jim
:
: : Hi Jim
: : What is the actual resistance in ohms? If the tube filaments are good and wiring isn't open there should be a reading.
: : Some meters have a contuinuity check using a tone. Don't use this as it will have a cutoff point. My Fluke cuts off around 400 ohms. Below this point there is a tone, above 400 ohms, nothing.
: : Norm
: :
: : : Hi Norm,
: : : I am useing a Fluke 26III multimeter. I checked myself again after your message and I have the same results.The filaments are all fine. I have one probe on the #5 pin of the 19T8 and I am going in sequence from pin to pin on the filament circuit.
: : : Jim
: : : : Hi Jim
: :
: : : : It's best to use a silicon diode such as 1N4004 as a replacement for the selenium rectifier. The banded end on the silicon diode connects to the + end on the selenium. You may want to install a low value resistor in series with the silicon diode to reduce voltage.
: :
: : : : Check continuity of your tube filaments, removed from the radio. On 7 pin tubes it's pins #3 and #4. On 9 pin tubes pins #4 and #5.
: :
: : : : What are you using for continuity testing? I don't see a reason for the results but you might try reversing leads. If there is a semiconductor in the circuit, such as selenium rectifier, it will only test in one direction.
: :
: : : : Resistors in early radios were usually 1/2 watt. Large ones may be 1 or 2 watts and wire wound 5 or 10 watts.
: :
: : : : Norm
: :
: : : :
: : : : : I have a Motorola model 67XM, chassis HS-64 and the selenium rectifier is bad. Where can I purchase one or I understand that it can be replaced with a silicon diode. How do I determine what diode to use? Also I have a continuity problem I can’t figure out. From the #5 pin on the 19T8 to the #4 pin on the 50B5 is fine but if I check from #5 19T8 to #3 on 50B5 no continuity. Continuity between #4 and #3 pins on 50B5 checks out fine, I’m stumped! And last how do I detemine the wattage of the resistors on this set?
: :
: : : : : Many Thanks, Jim