So I have a 1942 transoceanic bomber, I completely restored this thing in december of '08, using what was considered "the best" capacitors around. Those sprague orange drops have never failed me, I still can't complain about them, they are great caps. However, today for the first time in months, I decide to power up the TO on 120 VAC. (I usually used the battery pack I bought). To my amazement, the radio was humming terribly while receiving stations. Those dang sprague atom lytics are already smoked! :wtf:

Either I got a bad supply of them, or the quality control has slipped big time on those. They were new caps when I put them in with 07 date codes I believe, so they were only 1 year old when they got installed. So basically, 3 years later and they are junk. I'm now considering the use of Nichicon lytics in place of the spragues. Anyone else use atoms recently only to be let down like I did? I guess the biggest annoyance here is that I put so much time and effort into recapping it neatly and correctly, yet it all has to get ripped apart again and done over.

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I havn't pulled the chassis yet to check the surge voltage. The caps are rated at 160 v. I'll check voltages at each cap once the radio is fired up from a cold start. I believe sprague is owned by Vishay but they must keep the original plants in operation in MA when sprague was its own company. I can only guess this because mouser puts the caps into their own marked bags and they all indicate "country of origin: United States". The construction of the lytics look identical to what they were putting out 40+ years ago which is kind of amazing. I'll check to see what cap failed and replace it with another sprague. I think whatever the cap was that finally failed was a little iffy from the start as I recall it having a slight hum that modulated the audio right after I recapped it. It wasn't bad, but enough where it didn't have a clean sound, hence why I always liked using it on the A-B battery pack as it had clean DC power then. If this radio could talk, it probably wouldn't want to see Nichicon capacitors, considering it was built right at the time of Pearl Harbor...

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Aahh, thats so frustating.. Quality control really slipped through the hands of time.

The probability of anything else failing is highly unlikely considering the radio only hums when plugged into AC which narrows it down to the power supply, the tubes have been subbed as well. My first thought initially was a failed rectifier tube but that was not the case. If its something other than a cap, then I'll be surprized.

Earlier this year I figured the cost of recapping one set with Sprague caps would cover recapping three sets with Nichicons. Being on a budget, I've generally stuck with Nichicon caps and have been satisfied so far.

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The nichi's used in those zenith's always seemed to hold up quite well. Some of those very early 70's zeniths had a good number of them and the console stereos were loaded up with them by the late 60's.

Have you checked for heater to cathode leakage in the output tube? This will also cause hum when powered by AC. I have seen this several times on AA5 radios. It may not be the caps.

O course, if the tube heaters on these portable sets are always on DC power(regardless of the main set power supply), this would not be cause.

Very interesting to hear a Sprague failed. They do, on occasion, re-brand other vendors' parts. I bought a load of European box-style caps on eBay that were marked with Sprague's RMA number, but they looked like WIMA's or similar. Also have seen a good number of Asian-style caps with Sprague on them in a printing style not at all like their U.S. made ancestors.

I have no idea where good old Orange Drops are made anymore, but I buy 'em closeout/overstock whenever I can. I'd rather help an industrious eBayer than give my money to a foreign outfit who could care less about us.

I won't mention the brand, but a product I once worked on at the factory was full of .1ufd/500V caps that had "Hongkong" printed on them. This brand of capacitor was once domestically-produced, until a foreign owner bought the name. These caps would literally explode, leaving a bullet-hole in the middle. I finally convinced the person who could suggest a replacement that rather than use 1kV caps, just use Spragues at the same voltage. Never saw one of theirs fail in that app.

There should be some consistancy in quality if you buy your components from the same vendor(s). Mouser is usually my first choice for Vishay/Sprague caps and I can't complain. As for the Atoms I may question them if they are the older stock that are cheese colored with the light colored ends at the positive, but those would be old stock from somewhere else (or in one of my bins).

As for those Xicon branded caps, I think a small percentage of them can be questionable...but they do fit in tight spots. I've had them let go on occasion but I'll still consider them though.

Disregard everything I said. I am an idiot, the capacitor was NOT the problem! It was something totally different and strange. I need to make a new thread to prove sprague is still top notch stuff! This is what happens when you assume and don't cover all basis before opening your mouth:twak:

Geez, and I just flushed all my Spagues down the toilet...