Zenith 5R086 Radio-Phonograph

LogoI don't know why I haven't mentioned this elsewhere, it's one of the first things I bought when I got serious about this hobby. Bought it off eBay but the seller was local so I picked it up. He had reconditioned the cabinet and made it pretty but it wouldn't play. I didn't know what to do, but the Old Man got it to work.

Since then it's been slowly shutting down on me. First the phono audio died, then later on the whole audio went out completely.

This was made in 1946 and there appear to be two different models: the 5R080 and this 5R086. Going by the photographs on Radiomuseum, the difference is the cabinet style; the 080 was leatherette covered and looked more like luggage; the 086 was bare wood.

Radio Broadcasting magazine, 1929I wanted to get this going again because while I have plenty of AM-broadcast radios, this is the only machine I have that plays 78 rpm records (I've since acquired other record players which handle them). I don't have many 78s but I do have a few and once in a while I feel like hearing one, especially since they aren't songs I have in any other format.

This "project" turned out to be a huge embarassment. I'd put off working on it until the Old Man was visiting, because I was convinced it was going to be part of the phono and I know almost nothing about that.

So we took it out to the bench, fired it off. Deader than Jacob Marley at the beginning of A Christmas Carol. Are any of the tubes lit? No.

It's an All-American 5 style setup, which I had forgotten, so the Old Man suggested I check filaments, which was accomplished with the continuity test on the DMM. The 12SA7 was blown. Swapped it out and the radio came to life.

Okay, what about the phono? I put on a record. Nothing. Zilch. Then as I fiddled I noticed a switch that set the changer mode between manual and auto, and it was set in the middle, which is OFF. I flicked it to Auto and the phono came to life.

So there you are—a bad tube and an OFF switch. Sometimes it amazes me that I can even dial a telephone. Zenith 5R086 Radio/phono Zenith 5R086 Radio/phono - cover open

Current status: no audio in phono mode; the AM works so it's not a dead tube this time.

After much prodding and poking and diassembly, I finally mentioned it to The Old Man, who gave me the equivalent of the fingertip-on-the-wiper-of-the-volume-pot test: Raise the tone arm up and there are two wires coming out of it. With the unit on and the volume cranked up, touch one of them with a screwdriver tip (too tight to get a finger in there) and you should hear a loud hum on one side or the other. If you hear a hum, then you know the trouble is upstream (i.e. the cartridge). If you don't, the trouble is downstream. I got the noise: something wrong with the cartridge.

The guts of this unit are shown in Teardown Tuesday II.