On Friday 28 June 2019 02:14:42 deloptes wrote: > Gene Heskett wrote: > > There was a period a decade back where the capacitors > > were legendarily bad. Your unit may have some of them in it. > > It was around 2004. From a trustful source I understood that the > Chinese manage to steal the formula from Japan, but translated few > things wrongly and the world was flooded with bad caps. In the company > I was in back then, PC caught often even fire. We had to mitigate the > risk or just replace the PC with more reliable once. This was a good > story.
I think your beginning date is likely right, but it took a looong time for those to get flushed out of the supply pipelines. They typically went for 10% of what the good stuff was worth and a lot of buyers with a BOM in hand thought they were getting a good deal. Electrolytic capacitors are a very old tech. I even caused a shortage of American made caps in the middle of the OPEC battle in the '70's. I was at the time a tx supervisor for Nebraska ETV, in charge of a channel 19 site NE of Norfolk NE, getting pretty close to colder weather and needing a barrel of Technical Grade Ethylene Glycol for making a 30% mix for transmitter coolant. As that was a klystron using transmitter, you had to have extremely pure, as in distilled or better coolants else the voltages involved would corrode the plumbing very quickly from galvanic effects. Anyway I ran up quite a phone bill locating a barrel, finally finding it sitting on a shipping dock in Omaha, and bought it on the spot, paying about $14/gallon. I had antifreeze for the winter, but that barrel was the last in the country, and was scheduled to be shipped to Sprague in Lincoln about 3 weeks after I bought it off the dock. Put Sprague out of the cap business for several months and created a nationwide shortage of replacement capacitors for the tv's etc of the day. It was well into the next summer before caps started showing up in the wholesalers shelves again. That rise in energy costs broke a few broadcasters and sounded the death knell of klystron amplifiers. It did take something over a decade to flush them, the last time I was one was in 87 or 88, when I was coerced into going up the WNPB, near Morgantown, one of the State of WV's educational tv stations, to see if I could get them back on the air. Poor operator education caused them to wreck one, and they had no real money to buy a new one at $130,000 or so from Varian. But this was late April or early May, and the legislature had included money for a new transmitter, available after 1 July. So they bought a used one that was full of air, then another used one that might have been usable had the half moons in the shipping crate been reinstalled. But they weren't, so I unpacked it, checked for gas, found very little so it seemed worth dressing it up with its cavities, setting it in the magnet dolly and trying. It wasn't until I was trying to seat it in the dolly that I found it was bent. At that point all the state engineers declared it would not work. But I thought we had one chance, and by then I was convinced I was the only one in the building who actually knew how the darned things worked. So I scouted around and found some masonite and cut a couple pads out that could be wedged between the magnet coils and the corners of the top cavity, and placed them such that the tube was centered in the coils again. Measureing for center, I placed the iron places called wobble plates back on top of the dolly and wheeled it into the cubicle & hooked up the plumbing. Then I set the supply feed to Y which cut the beam voltage to about 10K volts, and raised the accel voltage as high negative as it would go, said a small prayer and brought up beam power. Body current was high so I had a limited time to see if moving the wobble plate would reduce it to a tolerable level, and it did. Then I lowered the accel toward ground, wash, rinse, repeat. Put the beam supply back in delta mode, wash rinse and repeat. About that time I became aware that the beam was catching the gas ions and was carrying them to the collector bucket and probably burying them in the copper. Any way, a few minor tweaks and a tube they only paid 10g's for used was on the air at 85% power and a safe and slowly falling body current. And the other state engineers finally understood they had been watching someone who knew what he was doing. And while I was by then tired, it was about a day before the grin let my ears come back to their normal position. I spent far more time teaching the young operators as they came on duty how to keep it adjusted than I did trying to teach the engineers observing me being a nerd. After all, they'd been to school, had sheepskins on the wall. I've an 8th grade education, but have never stopped learning. They had. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>
