Zenith 12H090 Console. HELP!

[jstout66]

Hello, I have a 1940's Zenith Am/Fm shortwave/ Phono combo I've had about 15 years. It's always been in my living-room, plugged in, and I've always fired it up on occasion. Now I have an odd problem. Recently, the radio (dial lights included) would turn off, just like if you had turned the radio off. The turntable portion still has power tho. It has gotten worse and now the radio won't come on. You give it power and the dial lights come on for about a few seconds and it shuts down. I tested ALL the tubes except the 7W7 which is one of those loctal's. The 6S8 had a few shorts. Would either of these tubes cause this problem??

[Chad Hauris]

Probably bad capacitors, maybe shorted electrolytics. Don't try turning it on again till you fix it or you may destroy your power transformer. You may have an intermittent primary winding in the transformer caused by overheating...most likely cause is due to shorted caps or maybe bad 5Y3.

I would replace all the capacitors in it, paper and electrolytic, and check for bad wiring. I have one of these at my parents house that I bought when I was in high school but it has been a while since I have worked on it. You will need to detach the tuner part and pull it out through the front and take out the amp chassis too. There is also a small sub chassis for the cobra phono preamp.

Start by measuring the resistance on the primary of the power transformer. You should have a few ohms, if there is none you have an open winding.

[toxcrusadr]

Ditto on the capacitors. Around there they almost never get powered up until they are recapped.

Around 1940 Zenith used a lot of rubber coated wire which is hard, brittle and cracking now. Check for shorts. I have a '40 model on my bench now (8S563) that has rubber wire disease. I lifted one end of some of the wires and slipped shrink tubing over the entire wire. A few of them I replaced entirely.