Time capsule needed 4 caps, but electrolytics fine!

[Doug E.]

Hi All,

A few months back I took a chance on an EvilBay listing for a 1964 Zenith M1615LU2 16" portable that was (allegedly) used six times and then stored away. Seller didn't include a picture but indicated that it had the original hang tag, instruction book, and UHF ring antenna. He didn't say anything about whether it was in working condition or had been tried. I was intrigued and decided to bid on it. Needless to say, I got it and when it came it was in the original Zenith box with styrofoam packing and sure looked like it had seldom, if ever, been used. Everything was in pristine, original, clean condition. Chassis and tubes were essentially spotless and the set still had something of that "new" smell. The "to" and "from" addresses on the box indicated that it had been mailed by someone in Portland, OR to their daughter who was apparently attending college in California. There was also a sticker from a storage place in CA.

I figured that I would need to replace at least some of the electrolytics anyway, so I decided "damn the torpedoes" and powered it up. After a few seconds of a shrunken raster, it went to full size and the set gave me a bright, clear picture! Now, here's the interesting part. I discovered that the vertical osc/output section had the usual issues: the vertical hold was out of range, and there was poor linearity and height slump after warmup. Turns out that three caps in the vertical section were leaky/off value and had to be replaced. Also, a ceramic disc cap across the damper that was supposed to have a zero temperature coefficient was causing horizontal shrinkage.

So what interests me the most about this is that it confirms something I've suspected before: sets that got little to no use seem to have more leaky/off value caps than sets that were used a lot. Are there known issues with shelf life for mylar and ceramic caps? It seems like many caps that were subjected to repeated heating/cooling cycles over many years in these little "hot box" portables are actually in BETTER shape 40 years later!

Anyhow, the TV now works really well, since the CRT, tubes, and almost everything else are essentially new.

Doug E.