Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.

:Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:
Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...

::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::
:Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:
The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.

Dave

Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.

Norm

:::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::
::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::
:The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:

:Dave
:
: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
:
:Norm
:
::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::::
:::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:::
::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
::
:
:
The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.

Dave

A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.

Norm

::Dave
::
:: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
::
::Norm
::
:::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::::
::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::::
:::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:::
::
::
:The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
:

:Dave
:
: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
:
: Norm
:
:::Dave
:::
::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
:::
:::Norm
:::
::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::::::
:::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:::::
::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
::::
:::
:::
::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
::
:
:
Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.

Thanks again.

Dave

Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?

Norm

::Dave
::
:: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
::
:: Norm
::
::::Dave
::::
:::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
::::
::::Norm
::::
:::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::::::
::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::::::
:::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:::::
::::
::::
:::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
:::
::
::
:Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
:
:Thanks again.
:

:Dave
:
: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
:
:Norm
:
:::Dave
:::
::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
:::
::: Norm
:::
:::::Dave
:::::
::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
:::::
:::::Norm
:::::
::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::::::::
:::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:::::::
::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
::::::
:::::
:::::
::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
::::
:::
:::
::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
::
::Thanks again.
::
:Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
:

Dave

Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.

Norm

::Dave
::
:: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
::
::Norm
::
::::Dave
::::
:::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
::::
:::: Norm
::::
::::::Dave
::::::
:::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
::::::
::::::Norm
::::::
:::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::::::::
::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::::::::
:::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:::::::
::::::
::::::
:::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
:::::
::::
::::
:::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
:::
:::Thanks again.
:::
::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
::
:
:

:Dave
:
: Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.
:
:Norm
:
:::Dave
:::
::: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
:::
:::Norm
:::
:::::Dave
:::::
::::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
:::::
::::: Norm
:::::
:::::::Dave
:::::::
::::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
:::::::
:::::::Norm
:::::::
::::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::::::::::
:::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:::::::::
::::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
::::::::
:::::::
:::::::
::::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
::::::
:::::
:::::
::::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
::::
::::Thanks again.
::::
:::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
:::
::
::
:Hello everyone. I rewired the tone arm with a shielded cable, replaced the .001 cap that was running aross the terminals on the cartridge , and now the hum is louder, and I get motorboating when I turn up the volume or bass controls. It is definitely grounded and shielded. Now, this is the 41-608 run 121, and it was "modified" to go with a crystal catridge, there is no longer that transformer box and the beam of light cartridge. I noticed that when this was recapped years ago, and modified, that a 1000MF cap was disconnected from the positive side, it is a bypass cap, not electroltic cap from what I can see, I am not sure if this was intentionally disconnected due to the modification or if it should be connected and perhaps it is contributing to the audio issues. The schematic here does not help me ID this cap to see where it should go. When the band changer is on the broadcast or shortwave, there is a little feedback on the volume and bass controls, but it is crazy on the phono selection. Any suggestions are appreciated.
:

Dave

Sometimes connecting a shield at both ends causes hum. Try connecting one end of the shield only.

Disconnect the tone arm lamp and see what happens? Originally it was driven off of a high frequency oscillator. If connected to filament line might add hum.

The .001 mf cap may be the same one where you mention 1000mf. Must be 1000pf or .001mf.

Norm

::Dave
::
:: Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.
::
::Norm
::
::::Dave
::::
:::: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
::::
::::Norm
::::
::::::Dave
::::::
:::::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
::::::
:::::: Norm
::::::
::::::::Dave
::::::::
:::::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
::::::::
::::::::Norm
::::::::
:::::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::::::::::
::::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::::::::::
:::::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:::::::::
::::::::
::::::::
:::::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
:::::::
::::::
::::::
:::::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
:::::
:::::Thanks again.
:::::
::::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
::::
:::
:::
::Hello everyone. I rewired the tone arm with a shielded cable, replaced the .001 cap that was running aross the terminals on the cartridge , and now the hum is louder, and I get motorboating when I turn up the volume or bass controls. It is definitely grounded and shielded. Now, this is the 41-608 run 121, and it was "modified" to go with a crystal catridge, there is no longer that transformer box and the beam of light cartridge. I noticed that when this was recapped years ago, and modified, that a 1000MF cap was disconnected from the positive side, it is a bypass cap, not electroltic cap from what I can see, I am not sure if this was intentionally disconnected due to the modification or if it should be connected and perhaps it is contributing to the audio issues. The schematic here does not help me ID this cap to see where it should go. When the band changer is on the broadcast or shortwave, there is a little feedback on the volume and bass controls, but it is crazy on the phono selection. Any suggestions are appreciated.
::
:
:

:Dave
:
: Sometimes connecting a shield at both ends causes hum. Try connecting one end of the shield only.
:
: Disconnect the tone arm lamp and see what happens? Originally it was driven off of a high frequency oscillator. If connected to filament line might add hum.
:
: The .001 mf cap may be the same one where you mention 1000mf. Must be 1000pf or .001mf.
:
:Norm
:
:
:
:
:
:::Dave
:::
::: Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.
:::
:::Norm
:::
:::::Dave
:::::
::::: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
:::::
:::::Norm
:::::
:::::::Dave
:::::::
::::::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
:::::::
::::::: Norm
:::::::
:::::::::Dave
:::::::::
::::::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
:::::::::
:::::::::Norm
:::::::::
::::::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
::::::::::::
:::::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
:::::::::::
::::::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
::::::::::
:::::::::
:::::::::
::::::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
::::::::
:::::::
:::::::
::::::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
::::::
::::::Thanks again.
::::::
:::::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
:::::
::::
::::
:::Hello everyone. I rewired the tone arm with a shielded cable, replaced the .001 cap that was running aross the terminals on the cartridge , and now the hum is louder, and I get motorboating when I turn up the volume or bass controls. It is definitely grounded and shielded. Now, this is the 41-608 run 121, and it was "modified" to go with a crystal catridge, there is no longer that transformer box and the beam of light cartridge. I noticed that when this was recapped years ago, and modified, that a 1000MF cap was disconnected from the positive side, it is a bypass cap, not electroltic cap from what I can see, I am not sure if this was intentionally disconnected due to the modification or if it should be connected and perhaps it is contributing to the audio issues. The schematic here does not help me ID this cap to see where it should go. When the band changer is on the broadcast or shortwave, there is a little feedback on the volume and bass controls, but it is crazy on the phono selection. Any suggestions are appreciated.
:::
::
::
:
:
Norm:
I noticed that the hum is almost just as loud when I put the band selector on to the phono position so I believe the issue may be with the 7C6 tube? I am going to substitute it with one in my Bing Crosby Phono and see if it makes a difference. I read here on the forum that the 7C6 can cause this hum. It is very low on the other bands, but very loud on the phono selection.

::Dave
::
:: Sometimes connecting a shield at both ends causes hum. Try connecting one end of the shield only.
::
:: Disconnect the tone arm lamp and see what happens? Originally it was driven off of a high frequency oscillator. If connected to filament line might add hum.
::
:: The .001 mf cap may be the same one where you mention 1000mf. Must be 1000pf or .001mf.
::
::Norm
::
::
::
::
::
::::Dave
::::
:::: Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.
::::
::::Norm
::::
::::::Dave
::::::
:::::: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
::::::
::::::Norm
::::::
::::::::Dave
::::::::
:::::::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
::::::::
:::::::: Norm
::::::::
::::::::::Dave
::::::::::
:::::::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
::::::::::
::::::::::Norm
::::::::::
:::::::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
:::::::::::::
::::::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
::::::::::::
:::::::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
:::::::::::
::::::::::
::::::::::
:::::::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
:::::::::
::::::::
::::::::
:::::::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
:::::::
:::::::Thanks again.
:::::::
::::::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
::::::
:::::
:::::
::::Hello everyone. I rewired the tone arm with a shielded cable, replaced the .001 cap that was running aross the terminals on the cartridge , and now the hum is louder, and I get motorboating when I turn up the volume or bass controls. It is definitely grounded and shielded. Now, this is the 41-608 run 121, and it was "modified" to go with a crystal catridge, there is no longer that transformer box and the beam of light cartridge. I noticed that when this was recapped years ago, and modified, that a 1000MF cap was disconnected from the positive side, it is a bypass cap, not electroltic cap from what I can see, I am not sure if this was intentionally disconnected due to the modification or if it should be connected and perhaps it is contributing to the audio issues. The schematic here does not help me ID this cap to see where it should go. When the band changer is on the broadcast or shortwave, there is a little feedback on the volume and bass controls, but it is crazy on the phono selection. Any suggestions are appreciated.
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:Norm:
: I noticed that the hum is almost just as loud when I put the band selector on to the phono position so I believe the issue may be with the 7C6 tube? I am going to substitute it with one in my Bing Crosby Phono and see if it makes a difference. I read here on the forum that the 7C6 can cause this hum. It is very low on the other bands, but very loud on the phono selection.
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I substituted the 6c6 and other tubes, unfortunately the hum is still present on the "phono" selection regardless of if the phono is connected or not to the amp. Any other suggestions are appreciated, I cannot figure out what is causing this.

Dave

Still must have something to do with shielding? Try shorting center wire to shield on the phono cable. Hum should be gone. If not shield isn't grounded to a proper place.

Norm

:::Dave
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::: Sometimes connecting a shield at both ends causes hum. Try connecting one end of the shield only.
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::: Disconnect the tone arm lamp and see what happens? Originally it was driven off of a high frequency oscillator. If connected to filament line might add hum.
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::: The .001 mf cap may be the same one where you mention 1000mf. Must be 1000pf or .001mf.
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:::Norm
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:::::Dave
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::::: Yes a connecting shielded cable for VCR or DVD player will work as long as it isn't too heavy for the pickup arm.
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:::::Norm
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:::::::Dave
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::::::: Can't see the tab but wonder if it determines size of the record? Maybe has something to do with where a record starts?
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:::::::Norm
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:::::::::Dave
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::::::::: A crystal cratridge is high impedance. Needs shielded wire to keep hum down. If you are going to be keeping the light be sure wires are away from any audio line.
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::::::::: Norm
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:::::::::::Dave
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::::::::::: Are you using shielded wire to the cartridge? Signal line is center with a grounded shield. Otherwise there will be hum.
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:::::::::::Norm
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::::::::::::::Recently recapped my 41-608 radio/phono which had the beam of light changer updated with a crystal cartridge. The changer works fine, but there is a definite AC hum in the phono position. The changer is grounded from what I can see. There is also a small cap across the cartridge, although that is quite old. Any suggestions on how to eliminate the hum? It is not present on any other position.
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:::::::::::::Try grounding out the + side of the cartridge, if it goes away, you could have a shielding problem with the cartridge and may have to run shielded cable...Not sure about that cap you mentioned, try disconnecting that if nothing else helps. I restored one of those Beam of Light set a couple years ago, had Gib at West Tech Services rebuild the original BOL cartridge. Worked pretty good..It was the leading edge of hi-tech back in the day...
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::::::::::::The recapping was the chassis itself, I will see about the cartridge grounding. Unfortunately since the changer was "updated" to remove the BOL and go crystal, it is harder to find the issue.
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::::::::::The wiring that is already in the cartridge from the previous modification is just single cloth wires, white and black. I also have a single bulb cartridge mounted in the head of the tone arm that is wired to the former beam of light wires to power the light. I wanted the tone arm to light up like it used to when it was beam of light.
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::::::::Thanks for the advice, I will work on it. One more question, the turntable has a small metal tab that sticks up thru the flocking. What is this for? It appears to be attached to a metal strip under the platten and sticks up thru a small hole. It is about 1/4 inch in height and very small. Just curious on its purpose.
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::::::::Thanks again.
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:::::::Would an rca cable cord from a DVD or VCR work if cut and spliced at the ends?
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:::::Hello everyone. I rewired the tone arm with a shielded cable, replaced the .001 cap that was running aross the terminals on the cartridge , and now the hum is louder, and I get motorboating when I turn up the volume or bass controls. It is definitely grounded and shielded. Now, this is the 41-608 run 121, and it was "modified" to go with a crystal catridge, there is no longer that transformer box and the beam of light cartridge. I noticed that when this was recapped years ago, and modified, that a 1000MF cap was disconnected from the positive side, it is a bypass cap, not electroltic cap from what I can see, I am not sure if this was intentionally disconnected due to the modification or if it should be connected and perhaps it is contributing to the audio issues. The schematic here does not help me ID this cap to see where it should go. When the band changer is on the broadcast or shortwave, there is a little feedback on the volume and bass controls, but it is crazy on the phono selection. Any suggestions are appreciated.
:::::
::::
::::
:::
:::
::Norm:
:: I noticed that the hum is almost just as loud when I put the band selector on to the phono position so I believe the issue may be with the 7C6 tube? I am going to substitute it with one in my Bing Crosby Phono and see if it makes a difference. I read here on the forum that the 7C6 can cause this hum. It is very low on the other bands, but very loud on the phono selection.
::
:I substituted the 6c6 and other tubes, unfortunately the hum is still present on the "phono" selection regardless of if the phono is connected or not to the amp. Any other suggestions are appreciated, I cannot figure out what is causing this.
: