I picked up a new radio at The Chris meet on Saturday. I worked pretty well as received. Not to let that disuade me I had to look inside. It was supposed to have been recapped. It was but a couple of the caps were not changed. I changed them with orange drops. The previous recapping job was badly done. A very messy job. I neatened things up by shortining leads and putting in spaghetti tubing. Well, now it motorboats and howels at about .6 mhz. I can't peak the IF transformers without the oscillations starting. If I set them so it does not oscillate, it has no sensitivity. It was very sensitive before I messed with it. Voltages on the tube pins are all resonable. One tube was weak, I changed it. The schematic on Nostalgia Air is not legible. Anyone point me to a legible schematic, on the web? Any ideas on where I went wrong? I have notticed that touching a screwdriver to the detector variable cap helps sensitivity, for what that's worth. Any generic alignment instructions on the web that may help?

Hi,
Did you align it as specified at the bottom of the page with the schematic? Some Zeniths are touchy about the manner in which they are aligned, yours may be one of them.

If you were following the procedure as described in Riders, then I would go through and check and check for shorted leads, or wires that may have been pushed against something when you were replacing some of the caps. Did all of the leads that you shortened go back to their correct location? Did a resistor lead get pushed against something it should not be contacting? Sometimes too, a small blob of solder will short across two leads, or two terminals on a tube socket. Lead dress can make a big difference. Also check to see if you might not have blades of the tuning condenser touching- There are times when in handling one may get bent slightly and cause trouble too.

I would double check to see that the solder joints are good and sound on the .05 mfd cap (connects between the ground and the coil winding that goes to G4 of the 6A8), and the .1 mfd cap that connects to ground and goes to G2 of the 6K7, (which also ties to grids 3 and 5 of the 6A8 at the terminal for G2 of the 6K7). As well as the other .1 mfd, which ties to ground from the B voltage buss (for the 2 IF coils), and there is a 12.5K ohm resistor that ties between these two caps as well, effectively between the Plate and G2 of the 6K7- Check the value of this resistor, as it may have been affected from heat from the soldering iron.

:I picked up a new radio at The Chris meet on Saturday. I worked pretty well as received. Not to let that disuade me I had to look inside. It was supposed to have been recapped. It was but a couple of the caps were not changed. I changed them with orange drops. The previous recapping job was badly done. A very messy job. I neatened things up by shortining leads and putting in spaghetti tubing. Well, now it motorboats and howels at about .6 mhz. I can't peak the IF transformers without the oscillations starting. If I set them so it does not oscillate, it has no sensitivity. It was very sensitive before I messed with it. Voltages on the tube pins are all resonable. One tube was weak, I changed it. The schematic on Nostalgia Air is not legible. Anyone point me to a legible schematic, on the web? Any ideas on where I went wrong? I have notticed that touching a screwdriver to the detector variable cap helps sensitivity, for what that's worth. Any generic alignment instructions on the web that may help?

:Hi,
:Did you align it as specified at the bottom of the page with the schematic? Some Zeniths are touchy about the manner in which they are aligned, yours may be one of them.
:
:If you were following the procedure as described in Riders, then I would go through and check and check for shorted leads, or wires that may have been pushed against something when you were replacing some of the caps. Did all of the leads that you shortened go back to their correct location? Did a resistor lead get pushed against something it should not be contacting? Sometimes too, a small blob of solder will short across two leads, or two terminals on a tube socket. Lead dress can make a big difference. Also check to see if you might not have blades of the tuning condenser touching- There are times when in handling one may get bent slightly and cause trouble too.
:
:I would double check to see that the solder joints are good and sound on the .05 mfd cap (connects between the ground and the coil winding that goes to G4 of the 6A8), and the .1 mfd cap that connects to ground and goes to G2 of the 6K7, (which also ties to grids 3 and 5 of the 6A8 at the terminal for G2 of the 6K7). As well as the other .1 mfd, which ties to ground from the B voltage buss (for the 2 IF coils), and there is a 12.5K ohm resistor that ties between these two caps as well, effectively between the Plate and G2 of the 6K7- Check the value of this resistor, as it may have been affected from heat from the soldering iron.
:
:
::I picked up a new radio at The Chris meet on Saturday. I worked pretty well as received. Not to let that disuade me I had to look inside. It was supposed to have been recapped. It was but a couple of the caps were not changed. I changed them with orange drops. The previous recapping job was badly done. A very messy job. I neatened things up by shortining leads and putting in spaghetti tubing. Well, now it motorboats and howels at about .6 mhz. I can't peak the IF transformers without the oscillations starting. If I set them so it does not oscillate, it has no sensitivity. It was very sensitive before I messed with it. Voltages on the tube pins are all resonable. One tube was weak, I changed it. The schematic on Nostalgia Air is not legible. Anyone point me to a legible schematic, on the web? Any ideas on where I went wrong? I have notticed that touching a screwdriver to the detector variable cap helps sensitivity, for what that's worth. Any generic alignment instructions on the web that may help?