Zenith K731, My first post

This is the location where I attached the green AM wire. Can anyone tell me if this is correct? It is connected to the same tab the blue wire (looks blue in phot, actually a shade of green) is attached to.

In this position I can make out AM radio stations, but they are very faint and I have to crank the volume up to 100%. There is a lot of static, and if I tap the radio I get more static each time.

Can anyone tell me which pin is #1 on a tube?

Thanks - Brad

[wa2ise]

Originally Posted by OldWolf

I can make out AM radio stations, but they are very faint and I have to crank the volume up to 100%. There is a lot of static, and if I tap the radio I get more static each time.

Check for poor contacts on tube sockets and tube pins, and dirty band switches. Touch the top glass seals of each tube one at a time and wiggle the tube a little. If you can get a burst of static with a particular tube, likely there is a loose contact. Remove the tube (disconnect the power cord too!) and with pliars very gently squeeze the tube socket pin grippers. You just want to tighten a little the tension of the tube socket pin gripper. Practice on a junk socket first.

[Nolan Woodbury]

Aaarg...don't think the link is opening, so we'll try this:

Top location:



Underneath:

[Nolan Woodbury]

Here are two styles of the K731. I like both (what's not to like?) but the "Colonial" style with the shorter legs to me, looks a bit more classy. I'm not much into the "TV console" look, which is what Zenith was after I think.



Other variants of this radio, the T2542 and the T350 are nice sets too. In fact, I have a T350 playing on my desk now, and it's unusual with a brushed metal faceplate that stretches over the dial and the control knobs- neat.

Nolan -
Very nice pictures. It looks like I got my wire into the correct position.

Sigh... ...now I need to figure out what to do next.

Do any of the tube sellers provide the service of testing your tubes prior to purchase?

wa2ise - That is a good idea, tightening the socket pins. My problem started when I removed all the tubes to clean them. When I reinstalled, no AM when I had AM before the cleaning. Maybe this will be an easy fix for the FM too.

Has anyone else noticed all the the flux spattered EVERYWHERE on the inside of the chassis. I thought maybe it was just my radio but then I noticed it on some of the above photos of Nolan's.

I work on the radio tonight and report back.

This forum Rocks!

[wa2ise]

Thanks, but be careful that you don't crush the pin grippers. Maybe a better tool to use is a dental pick that you can leverage the point between the phenolic wafer and the outside of a pin gripper. You just want to tighten it by about 1/64th inch.

Tightening the pin grips made all the difference in the world. First I removed each tube and lightly polished the pins. Next I gently tightened the pin grips. After reinserting the tubes I could hear AM! Still, the radio buzzed too much. Next I snugged up each gripper while the tube pin was inserted. I did this for all the tube pins.

When I turned the radio on, the AM reception was crystal clear! To test the FM I had to reassemble the radio so that I could connect the FM antenna.

With the radio assembled and the FM antenna couple attached to the power cord, I am happy to announce that I now can recieve FM.

No static, no buzzing, just rich and clear music from the two speakers.

For the next 3 hours I listened to a live performance of the North Carolina Symphony on WCPE 87.9 out of Wake Forest, NC. (If you like classical music, Google WCPE and you can listen to this station online).

Thanks for all the tips and pointers everyone. And thanks to wa2ise for the tip that finally got my radio running 100%.

[Nolan Woodbury]

Glad to hear it's among the living Brad. With just a bit of care and concern, the Zeniths of this era can return an amazing amount of service.

Never had an issue with socket tightness, but I've sure found most of them to be dirty...I'll clean the tube pins with a bit of Scotchbrite (red pad) douse the sockets with a blast of electronic cleaner, then (carefully) dry with compressed air. After, I smear just a dab of dielectric (sp?) grease on the pins and shove em' back in. This may have the same effect as tightening, and after considering that for a moment (wiggling the tube back and forth to free it) that might be a great place to first check if the radio isn't working, but isn't humming either.

Enjoy your K731 Brad! Seems you've earned this one-

[Blooze]

Good deal, Brad!! Glad to hear you got her working.

Mine seems to play all right on AM and FM, just some background hum. I still have yet to take the chassis out as I've been too busy with other things. Need to do that so I can replace the caps and see if some new filtering will take care of that hum.

Shane

I've noticed mine drifts out of frequency for about 15 minutes, until the electronics are fully warmed up. The AFC works sorta, but it still drifts, when AFC is on and the system is warming up. Drifting can (is) be typical I understand, but is it a warning of a component failure?

I'm spoiled by the PLL tuning of my digital radios!

[Nolan Woodbury]

If I'm not mistaken, a bit of drifting is common until all the tubes are up to full operating temperature. When I'm getting a set ready to listen to, I'll turn it on with the volume down for five minutes or so, then turn everything up and find my station.

I also think that drifting reception can be a sign of capacitor failure...Chad, is this where you recommend the use of freeze spray to isolate the problem?

I have a Zenith K731 tabletop radio with the green antenna wire to the chassis that is unhooked. I cannot seem to open the photo files in this article to see where this should be connected.

[Nolan Woodbury]

Originally Posted by subwoofer149

I have a Zenith K731 tabletop radio with the green antenna wire to the chassis that is unhooked. I cannot seem to open the photo files in this article to see where this should be connected.

The wire goes to the "F" terminal. The other screw ("G") is for ground.