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Zenith 7H820 How to hook up new C21due to 3 connections???
1/18/2007 9:10:54 PMBob Elbert
C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
Bob
1/18/2007 9:22:33 PMDoug Criner
Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf

On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.

Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.


:C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
:Bob

1/18/2007 9:33:23 PMBob Elbert
I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
:Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
:
:On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
:
:Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
:
:
::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
::Bob
1/18/2007 9:42:24 PMRadiodoc
Bob,

I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.

Radiodoc


:I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
::
::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
::
::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
::
::
:::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
:::Bob

1/18/2007 10:07:01 PMBob Elbert
I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
Bob


:Bob,
:
:I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
:
:Radiodoc
:
:
::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
:::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
:::
:::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
:::
:::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
:::
:::
::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
::::Bob

1/18/2007 10:32:21 PMRadiodoc
Bob,

Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.

Radiodoc


:I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
:It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
:Bob
:
:
::Bob,
::
::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
::
::Radiodoc
::
::
:::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
::::
::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
::::
::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
::::
::::
:::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
:::::Bob

1/18/2007 10:51:45 PMBob Elbert
Oh Noooo...don't send me to Radio Shack!! They won't have it either because there was no demand for it and they quit carrying it or the last roll someone bought 4 years ago and they are expecting it "on the truck" any day now but...but...you should probably stock up on batteries and cheap remote control toys and.. and....

:Bob,
:
:Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.
:
:Radiodoc
:
:
::I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
::It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
::Bob
::
::
:::Bob,
:::
:::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
:::
:::Radiodoc
:::
:::
::::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
:::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
:::::
:::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
:::::
:::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
:::::
:::::
::::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
::::::Bob

1/18/2007 11:22:02 PMRadiodoc
Bob,

The only reason I went to this one was they had a lot of stuff that wasn't Radio Shack. I remember one item real well and that was around 100 Amphenol PL-259 connectors for thirty-five cents each. Let me know how you come out with the lead resoldering on the cap.

Radiodoc


:Oh Noooo...don't send me to Radio Shack!! They won't have it either because there was no demand for it and they quit carrying it or the last roll someone bought 4 years ago and they are expecting it "on the truck" any day now but...but...you should probably stock up on batteries and cheap remote control toys and.. and....
:
::Bob,
::
::Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.
::
::Radiodoc
::
::
:::I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
:::It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
:::Bob
:::
:::
::::Bob,
::::
::::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
::::
::::Radiodoc
::::
::::
:::::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
::::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
::::::
::::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
::::::
::::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
::::::
::::::
:::::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
:::::::Bob

1/18/2007 11:47:24 PMplanigan
Bob: For the foil try an Arts & Crafts store. They have that sort of foil for different prodjects. You could also try (if you can find it) copper flashing for roofing although that may be heavier guage. PL


:Bob,
:
:The only reason I went to this one was they had a lot of stuff that wasn't Radio Shack. I remember one item real well and that was around 100 Amphenol PL-259 connectors for thirty-five cents each. Let me know how you come out with the lead resoldering on the cap.
:
:Radiodoc
:
:
::Oh Noooo...don't send me to Radio Shack!! They won't have it either because there was no demand for it and they quit carrying it or the last roll someone bought 4 years ago and they are expecting it "on the truck" any day now but...but...you should probably stock up on batteries and cheap remote control toys and.. and....
::
:::Bob,
:::
:::Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.
:::
:::Radiodoc
:::
:::
::::I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
::::It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
::::Bob
::::
::::
:::::Bob,
:::::
:::::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
:::::
:::::Radiodoc
:::::
:::::
::::::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
:::::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
:::::::
:::::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
:::::::
:::::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
:::::::
:::::::
::::::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
::::::::Bob

1/18/2007 11:56:21 PMBob Elbert
I will check our local Hobby Lobby and another Hobby store and see if they have it but I am going to keep my fingers crossed for awhile and see if the old cap stands up. I know I will run into that stuff sooner or later. I am in and out of every thrift store and flea market within a 50 mile radius scrounging for whatever as a general rule of thumb.
Bob

:Bob: For the foil try an Arts & Crafts store. They have that sort of foil for different prodjects. You could also try (if you can find it) copper flashing for roofing although that may be heavier guage. PL
:
:
::Bob,
::
::The only reason I went to this one was they had a lot of stuff that wasn't Radio Shack. I remember one item real well and that was around 100 Amphenol PL-259 connectors for thirty-five cents each. Let me know how you come out with the lead resoldering on the cap.
::
::Radiodoc
::
::
:::Oh Noooo...don't send me to Radio Shack!! They won't have it either because there was no demand for it and they quit carrying it or the last roll someone bought 4 years ago and they are expecting it "on the truck" any day now but...but...you should probably stock up on batteries and cheap remote control toys and.. and....
:::
::::Bob,
::::
::::Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.
::::
::::Radiodoc
::::
::::
:::::I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
:::::It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
:::::Bob
:::::
:::::
::::::Bob,
::::::
::::::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
::::::
::::::Radiodoc
::::::
::::::
:::::::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
::::::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
::::::::
::::::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
::::::::
::::::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
::::::::
::::::::
:::::::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
:::::::::Bob

1/18/2007 11:50:39 PMBob Elbert
Rad,
I was able to reconnect C21 and so now its on to bigger and better things. I have all the paper caps replaced (except C21). Now I am going to start in on the electrolytic caps. It's a can with 4 caps in it so this will be interesting for me....stand by :O)
Bob

:Bob,
:
:The only reason I went to this one was they had a lot of stuff that wasn't Radio Shack. I remember one item real well and that was around 100 Amphenol PL-259 connectors for thirty-five cents each. Let me know how you come out with the lead resoldering on the cap.
:
:Radiodoc
:
:
::Oh Noooo...don't send me to Radio Shack!! They won't have it either because there was no demand for it and they quit carrying it or the last roll someone bought 4 years ago and they are expecting it "on the truck" any day now but...but...you should probably stock up on batteries and cheap remote control toys and.. and....
::
:::Bob,
:::
:::Please don't try to get me to swear to it, but I believe it was at Radio Shack, however, I have had the roll for a few years. I bought a bunch of stuff a few years ago from a nearby Radio Shack that went out of business.
:::
:::Radiodoc
:::
:::
::::I only cut one lead so I "think" I can get it reconnected again if I am careful. (major task for me)
::::It measures .3 on my Greenlee DM110 so maybe it will be ok. But where does one find copper foil tape for sale or for scrounge/recycle? I do not remember ever seeing something like that.
::::Bob
::::
::::
:::::Bob,
:::::
:::::I have used copper foil tape to make a couple shielded caps in the high gain preamp stage of a couple Webster-Chicago wire recorders. I just wrapped the tape around the cap and soldered a short wire to the foil tape to ground.
:::::
:::::Radiodoc
:::::
:::::
::::::I clipped it off really to a nub before I realized there was a 3rd connection but I may try both suggestions to first see if it makes much noticeable difference. The cap actally does not look too bad from the outside anyway. How would you suggest actually making a shield? Would it wrap around the cap then connect it to ground? What would I make it out of? Some kind of foil? Thanks for your quick reponse. I will go back and continue changing out more caps and think about this.
:::::::Bob, here's your schematic: http://www.nostalgiaair.org/PagesByModel/307/M0025307.pdf
:::::::
:::::::On the parts list, C21 is listed as "shielded." Try replacing it with a regular .02-uF cap. If there are problems, maybe you can rig up a tinfoil shield connected to ground.
:::::::
:::::::Another approach is to lift one lead, and check the cap (if you have a hi-voltage cap checker). If it's OK, then you could leave it alone.
:::::::
:::::::
::::::::C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
::::::::Bob

1/19/2007 12:00:23 AMeasyrider8
:C21, a .02 cap has an extra tab coming off of it that is hooked to chassis ground coming out nearest the positive side of this cap. The side stamped ground hooks to one of the volume control posts and the other side connects to the grid of the 1st audio 19T8 tube. The schematic shows a dotted square around C21 with one corner of it showing it going to ground. With the replacement having only two leads what do you do about that 3rd connection not being on a standard replacement cap??
______________________________________________________________________

Just replace it with a standard capacitor, the newer ones are constructed differently and it should work fine.

Dave
:Bob

1/19/2007 7:40:56 AMDel in Minnesota
Could he use an old tube shield from a parts radio and screw it to the chassis?


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