Zenith 10S690 Volume Control Issues

[vortalexfan]

Originally Posted by Kevin Kuehn

R11 and C2 form the AVC filtering. Take a look at the schematic and you will see that each end of R11 goes to a separate IF can.

Actually I think the schematic is wrong, because in the radio itself both IF cans go to only ONE SIDE of R11, and I didn't touch that wiring except to replace the old dry rotted wire from the 1st IF can and I just wired that wire back to where it was previously, and I didn't touch the wiring to the 2nd IF Transformer because the wiring was fine in it.

[old_coot88]

Have you tried Deoxit'ing the switch yet?

[vortalexfan]

Originally Posted by old_coot88

When you get the newest problem fixed and ready to revisit the original problem, the open is almost certain to be in the radio/phono switch, per the attached sketch. To verify, put a jumper across it and see if the audio is restored and the vol control works correctly.

How do I jumper the Switch? Because I think I definitely have it narrowed down to the switch being faulty, because with the volume control knob turned up completely I figured out that the radio is actually working but with barely any audio.
And when I try to monkey with the mode switch I can't get it to do anything.

[vortalexfan]

Originally Posted by old_coot88

Have you tried Deoxit'ing the switch yet?

Yes I have, 3 times and it hasn't made a difference, if anything its made it worse.

[old_coot88]

To jumper the switch, just trace the wiring. Trace it from where the signal wire exits the 2nd IF can and goes to the switch. And trace from C11 to the switch. Put the jumper across the appropriate two lugs.

If perchance you don't plan on using the phono, just leave the jumper in place.

[vortalexfan]

Originally Posted by old_coot88

To jumper the switch, just trace the wiring. Trace it from where the signal wire exits the 2nd IF can and goes to the switch. And trace from C11 to the switch. Put the jumper across the appropriate two lugs.

If perchance you don't plan on using the phono, just leave the jumper in place.

OK, thanks, I'm assuming the lugs I'm jumping are on the switch itself?

I think it is definitely the switch because I'm not getting anything out of radio when I touch the Grid Cap of the 6F5G Audio Amp tube unless I jiggle the switch several times, and even then the hum from touching the grid cap of the 6F5G tube goes away after awhile.

[vortalexfan]

Originally Posted by old_coot88

To jumper the switch, just trace the wiring. Trace it from where the signal wire exits the 2nd IF can and goes to the switch. And trace from C11 to the switch. Put the jumper across the appropriate two lugs.

If perchance you don't plan on using the phono, just leave the jumper in place.

I think I could probably find a replacement switch over at Mouser or Digikey.

Its just a standard 6 Lug SPDT Switch.

In fact here it is on Mouser. https://www.mouser.com/ProductDetail...6%2FVdLw%3D%3D

[old_coot88]

Dude, I gotta apologize. Been giving you bad info. Come to find the switching is done on the downstream side of C11, not on the upstream as in previous sketch.

Thus to jumper the switch, the wires you would trace would be:

1.) from the top lug of volume control to the switch.

2.) from the downstream side of C11 to the switch.

Jumper would go on the appropriate two lugs of the switch.

Damn, sorry for the screwup

[vortalexfan]

Originally Posted by old_coot88

Dude, I gotta apologize. Been giving you bad info. Come to find the switching is done on the downstream side of C11, not on the upstream as in previous sketch.

Thus to jumper the switch, the wires you would trace would be:

1.) from the top lug of volume control to the switch.

2.) from the downstream side of C11 to the switch.

Jumper would go on the appropriate two lugs of the switch.

Damn, sorry for the screwup

Its ok, so I'll just jump the switch that way.

[old_coot88]

Turns out there's an obscure little subnote to the main schematic, showing the radio/phono switching diagram. It's difficult to decipher, but shows the switch as DPDT (double pole/double throw), with the second section switching B+ on/off to the mixer stage.

I would seriously de-consider replacing the switch as that could turn into a real can of worms.

[vortalexfan]

Originally Posted by old_coot88

Turns out there's an obscure little subnote to the main schematic, showing the radio/phono switching diagram. It's difficult to decipher, but shows the switch as DPDT (double pole/double throw), with the second section switching B+ on/off to the mixer stage.

I would seriously de-consider replacing the switch as that could turn into a real can of worms.

Well I really wanted to use the record player on this thing, as it has a nice modern VM 1200 series record changer installed in it.

[old_coot88]

Right now, can you put a record on and play it without any intermittency when you wiggle the switch?

[dieseljeep]

Originally Posted by vortalexfan

Well I really wanted to use the record player on this thing, as it has a nice modern VM 1200 series record changer installed in it.

It seems like the radio from h*ll. Its hard to believe that you had so much grief with it. You should replace the switch with a decent toggle switch, mounted on the back of the chassis. Easy to get at a bigger hardware store.

[vortalexfan]

Originally Posted by old_coot88

Right now, can you put a record on and play it without any intermittency when you wiggle the switch?

I don't know as I currently don't have the record player hooked up right now because I'm trying to fix the drawer glides because the original drawer glides were bad.

[vortalexfan]

Originally Posted by dieseljeep

It seems like the radio from h*ll. Its hard to believe that you had so much grief with it. You should replace the switch with a decent toggle switch, mounted on the back of the chassis. Easy to get at a bigger hardware store.

I was thinking the same thing, this thing seems like its possessed.

The switch on the back won't look as complete as having the switch in the front like it originally had. I think I found a switch over at mouser that might work in place of the original.