Zenith 7A02 Chassis Model 7S529,30,47,58,59 all those..

10/29/2009 8:53:42 PMBob E.

1.
On schematic I note S.W. Antenna in AC Cord (connects to band switch)...Should I replace cord with a 3 wire cord and just leave the SW part attached to the AC as you would buy it? I guess they make standard cords like the small brown extension cords with three wires?
2. I always have trouble with the can caps. Now the negative leads of C18 & C19...can they be connected to the hook up to where the can originally connected to the other negative leads at the old can cap lug or do you need to route that point to a Chassis Ground?

10/29/2009 10:30:20 PMEdd

Sir Bob Eeeeeeeee. . . . .

Never, had particularly noticed that three conductor wire being used on that sets antenna for capacitively coupling
into the AC line for signal pick up.

I know that if I had to repeat the situation on my part, I would be pulling out one of my longest compoter / IEC cord and cutting off the IEC portion and using that end of the wire for the set connection .

Then I would go to its other end and pull out the grounding pin connector completely, thereby leaving a green wire floating, with its set end of that wire getting connected into the band switch.

As for the mentioning of the direct grounding of the C18-C19 junctions to ground . .no . .no . .NO, as on this set the center tap of the high voltage winding of the power transformer does NOT go directly to ground. It makes a circuitous path thru some resistors in order to then be able to develop some negative voltages for biasing purposes.

Look at my blue square routing of that center taps path to ground and you will see a designated source of negative 1st grid bias for the AF output tube, noted by my single green arrow markup. The other point would be the two green arrows on the cathode
of the AF output tube. If you ground those filter points, you are shorting the AF tubes cathode to ground.

Also, I have marked up the proper polaraities of the filters involved around that area.

Sorry for the definition quality of schematic sourced, would have liked to have had a clearer Beitmans to work with, but I just had to make " quickie-quickie " markup.

Thassit

73's de Edd

:1.
:On schematic I note S.W. Antenna in AC Cord (connects to band switch)...Should I replace cord with a 3 wire cord and just leave the SW part attached to the AC as you would buy it? I guess they make standard cords like the small brown extension cords with three wires?
:2. I always have trouble with the can caps. Now the negative leads of C18 & C19...can they be connected to the hook up to where the can originally connected to the other negative leads at the old can cap lug or do you need to route that point to a Chassis Ground?
:

10/30/2009 12:18:40 AMBob E.

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:Sir Bob Eeeeeeeee. . . . .
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:Never, had particularly noticed that three conductor wire being used on that sets antenna for capacitively coupling
:into the AC line for signal pick up.
:
:
:I know that if I had to repeat the situation on my part, I would be pulling out one of my longest compoter / IEC cord and cutting off the IEC portion and using that end of the wire for the set connection .
:
:
:Then I would go to its other end and pull out the grounding pin connector completely, thereby leaving a green wire floating, with its set end of that wire getting connected into the band switch.
:
:
:
:
:
:As for the mentioning of the direct grounding of the C18-C19 junctions to ground . .no . .no . .NO, as on this set the center tap of the high voltage winding of the power transformer does NOT go directly to ground. It makes a circuitous path thru some resistors in order to then be able to develop some negative voltages for biasing purposes.
:
:
:Look at my blue square routing of that center taps path to ground and you will see a designated source of negative 1st grid bias for the AF output tube, noted by my single green arrow markup. The other point would be the two green arrows on the cathode
:of the AF output tube. If you ground those filter points, you are shorting the AF tubes cathode to ground.
:
:
:Also, I have marked up the proper polaraities of the filters involved around that area.
:
:
:Sorry for the definition quality of schematic sourced, would have liked to have had a clearer Beitmans to work with, but I just had to make " quickie-quickie " markup.
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:Thassit
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:73's de Edd
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::1.
::On schematic I note S.W. Antenna in AC Cord (connects to band switch)...Should I replace cord with a 3 wire cord and just leave the SW part attached to the AC as you would buy it? I guess they make standard cords like the small brown extension cords with three wires?
::2. I always have trouble with the can caps. Now the negative leads of C18 & C19...can they be connected to the hook up to where the can originally connected to the other negative leads at the old can cap lug or do you need to route that point to a Chassis Ground?
::
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I think I'm seeing where I hook the neg ends of C18 and C19. I would connect to the minus side of of the .1 C17 on your schematic? The 3 point hook up of that junction includes C17, Wire to pin 7 (K) of 7B4, and wire to vol control which are no longer secured to the lug of the old can.

If that is correct then what about the connections that I still have to the other lug hook-up of the old can?
There are 4 connections:
2 wires to the speaker
C10 .005
C9 (I think) .004
My question is.. can they be left connected to that lug or do they need a terminal strip that I would mount to the chassis nearby? I am leaving the old can in place.
And... I have a good schematic enlarged from the Beitmans 1940 page 204.
10-4 on the cord/antenna info too!
I was very happy to get your response as usual and I am excited about getting this set running as the cabinet is in near pristine condition unlike so many others I have had to refinish. I am lucky also to have two of these sets so I have a set to cannibalize from. "Yum Yum Eat'em Up" as the Mad Man of Borneo said on the Rascals :O)
Bob E.