Capacitor Reliability Question - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Capacitor Reliability Question (/showthread.php?tid=3828)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Capacitor Reliability Question (/showthread.php?tid=3828)
Capacitor Reliability Question - wakani - 10-12-2011
First a Sea Story.
1983 I was on a USG trip to China, inter alia, to take a look at their manufactoring capabilities. In one particular factory, I was observing the capacitor production system. At the end of the process were some rather impressive looking capacitor testing machines. But they were testing the capacitors by hand. I watched one young lady testing about 60 units per minute but it seemed she would throw units in the "bad bucket" independent of what the meters on the testor said. When I asked why the reply was something to the effect "...we are very proud of our quality control, we test each unit individually. We are expected to find 10 percent that failed the test, no more no less." Thus the red light blinked bad unit, but it went in the "good bucket" and the green light blinked good and it went into the "bad" bucket. I exagerate somewhat, but in a nutshell that was what was going on.
My question is are there some bad apples as far as capacitors out there, exp electrolytics? Are the high voltage "mini electolytics" okay to use?
I pick on capacitors because I think they are the weak link in those old radios.
Re: Capacitor Reliability Question - TA Forbes - 10-12-2011
As a rule one should replace all electrolytics and wax paper caps in any antique radio that you intend to use. They are 70 or so years old and at best are leaky and at worst have failed. A failed electrolytic filter cap can cause the power transformer to fail.
Modern electrolytics are fine to use, as are mylar and ceramic varieties, when one restores the electronics in an antique radio. As a rule electrolytics are available in values larger than 0.5mFd. Mylar/ceramic, etc varieties are available in large and low value sizes, but for radio work 0.5mFd and smaller are best, as these caps get too large in physical size when above 0.5mFd to be of use when restoring an antique radio.
Make sure that you use a capacitor that is voltage rated equal to or higher than that of the capacitor that you are replacing.
Re: Capacitor Reliability Question - Phlogiston - 10-12-2011
I know for sure that you can by bogus parts from E-pay. I have purchased transistors that had the correct part #, just on the wrong part. Buy any parts from a vendor that you know and trust.
Re: Capacitor Reliability Question - Arran - 10-12-2011
wakani Wrote:First a Sea Story.
1983 I was on a USG trip to China, inter alia, to take a look at their manufactoring capabilities. In one particular factory, I was observing the capacitor production system. At the end of the process were some rather impressive looking capacitor testing machines. But they were testing the capacitors by hand. I watched one young lady testing about 60 units per minute but it seemed she would throw units in the "bad bucket" independent of what the meters on the testor said. When I asked why the reply was something to the effect "...we are very proud of our quality control, we test each unit individually. We are expected to find 10 percent that failed the test, no more no less." Thus the red light blinked bad unit, but it went in the "good bucket" and the green light blinked good and it went into the "bad" bucket. I exagerate somewhat, but in a nutshell that was what was going on.
My question is are there some bad apples as far as capacitors out there, exp electrolytics? Are the high voltage "mini electolytics" okay to use?
I pick on capacitors because I think they are the weak link in those old radios.
Even though that was a while ago it does explain why there is a ten fold difference in worker productivity between a Chinese worker and a U.S worker, it may be changing but indescriminately sorting caps that way is going to cut into the productivity and bottom line of the company making them. I for one never install a cap in a radio without testing it first on a capacitor checker, so far I haven't had any problems with the polyester film caps but have had problems with the odd cap that I bought from a surplus mailorder outfit. Chinese made elctrolytic caps are something that I would stay away from if possible, especially the no-name ones. There were some bogus Nichicon caps around about five years ago that caused a lot of problems but I think that brand or any of the other Japanese, American, or German brand ones would be safe so long as they come from a reputable dealer and not a fleabay seller.
Regards
Arran
Re: Capacitor Reliability Question - Marsupial - 10-12-2011
Not exactly related, but a few years ago there was a LOT of "bad" capacitors on the market. Tons of computer equipment, mainly motherboards and power supplies, were affected.
The capacitors would become leaky quite fast (less than a year of usage) and you guess what that could do to computer motherboard.
I remember seeing some on ebay, people would buy them and recap them. With luck they'd end up good as new.
Modern manufacturing process doesn't believe in quality check. It is cheaper to have to refund the few who cares complaining than having to ensure everything that goes out the doors is valid. Moreso in some asian manufacturing plants.
I think it all started when then invented this motto "no user serviceable parts inside" and started to add "warranty void if seal broken" stickers.
Re: Capacitor Reliability Question - Arran - 10-13-2011
Marsupial Wrote:Not exactly related, but a few years ago there was a LOT of "bad" capacitors on the market. Tons of computer equipment, mainly motherboards and power supplies, were affected.
The capacitors would become leaky quite fast (less than a year of usage) and you guess what that could do to computer motherboard.
I remember seeing some on ebay, people would buy them and recap them. With luck they'd end up good as new.
Modern manufacturing process doesn't believe in quality check. It is cheaper to have to refund the few who cares complaining than having to ensure everything that goes out the doors is valid. Moreso in some asian manufacturing plants.
I think it all started when then invented this motto "no user serviceable parts inside" and started to add "warranty void if seal broken" stickers.
Those caps that you speak of would bulge and sometimes leak but the interesting part is that the capacity would actually go up in value if you tested them. The story I heard is that they were counterfeit caps made with a botched recipe for electrolyte. I have a computer tower here that has a few bulged caps in the motherboard, from what I can tell they didn't leak but I am planning on trying a recap on the board.
Regards
Arran
Re: Capacitor Reliability Question - TA Forbes - 10-18-2011
In response to your question about where to buy caps, I have been using Dave Cantelon at Justradios.com. Excellent selection of caps and resistors, also offers shrink tubing and schematics. I had a Canadian set I was having difficulty finding a schematic for and he had it.