Thanks, Jim
Pin #5 is the plate of 35Z5 and has reasonable voltage. Pin #8, cathode, is where B+ starts in your radio.
Were the replacement electrolytic caps, C10 & C11, new manufacturer? Even if new, if they were made 30 years ago or longer may have gone bad. They will dry out lose capacity and can short over time.
Have original filter capacitors actually been removed? If left in the circuit they can short and cause the 15 ohm resistor blow.
The 35Z5 could be weak? I don't see any other components in you radio that will cause this low B+ voltage unless the radio is miswired or has a short between circuits.
Norm
: Hi,
: I have an Arvin 444A that I recently acquired and I can’t figure out the problem with it. All of the capacitors had been replaced but the there was a 20 mfd in the place of the 40 mfd. I replaced it and then noticed that the R-11 15 ohm resistor was broke in two and I replaced it. All of the tubes check out ok. All I can get is what seams to be the normal in between station very low hum. Checking the voltages at the 35Z5GT I have 121.5 #2 pin, 113 #3, 75.8 #4, 121.5 #5, 83.5 #7, and 36.5 #8. I can’t figure out why the voltage is low at #8 pin. Can someone point me in the right direction?
: Thanks, Jim
Thanks, Jim
: Hi Jim
: Pin #5 is the plate of 35Z5 and has reasonable voltage. Pin #8, cathode, is where B+ starts in your radio.
: Were the replacement electrolytic caps, C10 & C11, new manufacturer? Even if new, if they were made 30 years ago or longer may have gone bad. They will dry out lose capacity and can short over time.
: Have original filter capacitors actually been removed? If left in the circuit they can short and cause the 15 ohm resistor blow.
: The 35Z5 could be weak? I don't see any other components in you radio that will cause this low B+ voltage unless the radio is miswired or has a short between circuits.
: Norm
:
:
:
: : Hi,
: : I have an Arvin 444A that I recently acquired and I can’t figure out the problem with it. All of the capacitors had been replaced but the there was a 20 mfd in the place of the 40 mfd. I replaced it and then noticed that the R-11 15 ohm resistor was broke in two and I replaced it. All of the tubes check out ok. All I can get is what seams to be the normal in between station very low hum. Checking the voltages at the 35Z5GT I have 121.5 #2 pin, 113 #3, 75.8 #4, 121.5 #5, 83.5 #7, and 36.5 #8. I can’t figure out why the voltage is low at #8 pin. Can someone point me in the right direction?
: : Thanks, Jim
Hum would still indicate a problem with the filters unless something is miswired. With the low voltage it's best to have a 110 volt light wired in series with your radio. This will help protect the rectifier from an overload.
Since I don't know your background I'll start with the basis questions. Are the replacement filter caps wired in the right polarity? The + goes toward the 35Z5GT cathode, pin #8. Newer caps have the negative lead marked rather than positive. Are they rated 150 volts or greater?
Is the negative lead connected to the proper spot in the radio? It does not connect to chassis..
Norm
: Hi Norm,
: The electrolytics were new type and the original filter caps had been removed. I replaced them anyway because I wasn’t pleased with the previous replacement. I checked the 35z5 again and it was fine but to be sure I pulled one out of playing set and put it in its place. Now there is a louder hum and the B+ only measures 3.4 volts at pin #8. It appears that the wiring is correct so I guess it might be a short between circuits. Do you have any pointers; I can’t seem to find any?
: Thanks, Jim
: : Hi Jim
: : Pin #5 is the plate of 35Z5 and has reasonable voltage. Pin #8, cathode, is where B+ starts in your radio.
: : Were the replacement electrolytic caps, C10 & C11, new manufacturer? Even if new, if they were made 30 years ago or longer may have gone bad. They will dry out lose capacity and can short over time.
: : Have original filter capacitors actually been removed? If left in the circuit they can short and cause the 15 ohm resistor blow.
: : The 35Z5 could be weak? I don't see any other components in you radio that will cause this low B+ voltage unless the radio is miswired or has a short between circuits.
: : Norm
: :
: :
: :
: : : Hi,
: : : I have an Arvin 444A that I recently acquired and I can’t figure out the problem with it. All of the capacitors had been replaced but the there was a 20 mfd in the place of the 40 mfd. I replaced it and then noticed that the R-11 15 ohm resistor was broke in two and I replaced it. All of the tubes check out ok. All I can get is what seams to be the normal in between station very low hum. Checking the voltages at the 35Z5GT I have 121.5 #2 pin, 113 #3, 75.8 #4, 121.5 #5, 83.5 #7, and 36.5 #8. I can’t figure out why the voltage is low at #8 pin. Can someone point me in the right direction?
: : : Thanks, Jim
I agree with Norm on verifying the wiring. I would go back and trace out the circuit- I suspect that since all of the caps had been replaced- (especially if they had not been replaced by you), and just verify that the signal can move from one stage to the next. A quick shortcut is to touch a screw driver blade to the oscillator section of the tuning capacitor. If you get a buzz there, focus on the mixer/oscillator, and you can rule out the succeeding stages. If nothing happens- carefully touch a screw driver to the grid of each stage, starting with your final- (35L6) pin 5. You should hear some louder buzzing than before, and just work your way back until the noise stops. At which point you have your area to check out.
You did note that the voltage appeared on the low side- check lead dress and make sure nothing is contacting somewhere where it should not. Also make sure that the new filter cap cans are isolated from chassis contact. Once in a while, a can may come in contact with an internal portion of the capacitor. -Rare- yes, but can occur.
: Hi Jim
: Hum would still indicate a problem with the filters unless something is miswired. With the low voltage it's best to have a 110 volt light wired in series with your radio. This will help protect the rectifier from an overload.
: Since I don't know your background I'll start with the basis questions. Are the replacement filter caps wired in the right polarity? The + goes toward the 35Z5GT cathode, pin #8. Newer caps have the negative lead marked rather than positive. Are they rated 150 volts or greater?
: Is the negative lead connected to the proper spot in the radio? It does not connect to chassis..
: Norm
: : Hi Norm,
: : The electrolytics were new type and the original filter caps had been removed. I replaced them anyway because I wasn’t pleased with the previous replacement. I checked the 35z5 again and it was fine but to be sure I pulled one out of playing set and put it in its place. Now there is a louder hum and the B+ only measures 3.4 volts at pin #8. It appears that the wiring is correct so I guess it might be a short between circuits. Do you have any pointers; I can’t seem to find any?
: : Thanks, Jim
: : : Hi Jim
: : : Pin #5 is the plate of 35Z5 and has reasonable voltage. Pin #8, cathode, is where B+ starts in your radio.
: : : Were the replacement electrolytic caps, C10 & C11, new manufacturer? Even if new, if they were made 30 years ago or longer may have gone bad. They will dry out lose capacity and can short over time.
: : : Have original filter capacitors actually been removed? If left in the circuit they can short and cause the 15 ohm resistor blow.
: : : The 35Z5 could be weak? I don't see any other components in you radio that will cause this low B+ voltage unless the radio is miswired or has a short between circuits.
: : : Norm
: : :
: : :
: : :
: : : : Hi,
: : : : I have an Arvin 444A that I recently acquired and I can’t figure out the problem with it. All of the capacitors had been replaced but the there was a 20 mfd in the place of the 40 mfd. I replaced it and then noticed that the R-11 15 ohm resistor was broke in two and I replaced it. All of the tubes check out ok. All I can get is what seams to be the normal in between station very low hum. Checking the voltages at the 35Z5GT I have 121.5 #2 pin, 113 #3, 75.8 #4, 121.5 #5, 83.5 #7, and 36.5 #8. I can’t figure out why the voltage is low at #8 pin. Can someone point me in the right direction?
: : : : Thanks, Jim
Thanks, Jim
Hi Jim
: Hum would still indicate a problem with the filters unless something is miswired. With the low voltage it's best to have a 110 volt light wired in series with your radio. This will help protect the rectifier from an overload.
: Since I don't know your background I'll start with the basis questions. Are the replacement filter caps wired in the right polarity? The + goes toward the 35Z5GT cathode, pin #8. Newer caps have the negative lead marked rather than positive. Are they rated 150 volts or greater?
: Is the negative lead connected to the proper spot in the radio? It does not connect to chassis..
: Norm
: : Hi Norm,
: : The electrolytics were new type and the original filter caps had been removed. I replaced them anyway because I wasn’t pleased with the previous replacement. I checked the 35z5 again and it was fine but to be sure I pulled one out of playing set and put it in its place. Now there is a louder hum and the B+ only measures 3.4 volts at pin #8. It appears that the wiring is correct so I guess it might be a short between circuits. Do you have any pointers; I can’t seem to find any?
: : Thanks, Jim
: : : Hi Jim
: : : Pin #5 is the plate of 35Z5 and has reasonable voltage. Pin #8, cathode, is where B+ starts in your radio.
: : : Were the replacement electrolytic caps, C10 & C11, new manufacturer? Even if new, if they were made 30 years ago or longer may have gone bad. They will dry out lose capacity and can short over time.
: : : Have original filter capacitors actually been removed? If left in the circuit they can short and cause the 15 ohm resistor blow.
: : : The 35Z5 could be weak? I don't see any other components in you radio that will cause this low B+ voltage unless the radio is miswired or has a short between circuits.
: : : Norm
: : :
: : :
: : :
: : : : Hi,
: : : : I have an Arvin 444A that I recently acquired and I can’t figure out the problem with it. All of the capacitors had been replaced but the there was a 20 mfd in the place of the 40 mfd. I replaced it and then noticed that the R-11 15 ohm resistor was broke in two and I replaced it. All of the tubes check out ok. All I can get is what seams to be the normal in between station very low hum. Checking the voltages at the 35Z5GT I have 121.5 #2 pin, 113 #3, 75.8 #4, 121.5 #5, 83.5 #7, and 36.5 #8. I can’t figure out why the voltage is low at #8 pin. Can someone point me in the right direction?
: : : : Thanks, Jim