#16
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Doug,
There aren't many new techs that understand tube circuits, heck they don't even understand SS circuits. Most are only monkeys trained well enough to replace circuit boards or modules until the problem goes away. Tracing a fault to an actual board level component is a lost art. You have to know circuits and understand how they work to do that. It takes training and education and a mind not too lazy to want to learn. Same in automotive repair and most everything else now. It is sad. I knew a tech who ran a small TV and electronics service shop where I previously lived and I was visiting him one day. He had a fender guitar amp with P-P 6L6's and couldn't for the life of him figure out the fault. He asked me if I would look at it. As soon as I heard the way it cycled on and then went to fuzzy low power I knew exactly what the problem must be. A grid drain resistor on one output tube had opened. At first the tube could work somewhere in it's linear region but within milliseconds of power applied (actually as the circuit was coming up to voltage the tube would get cut off). I had it fixed in a jiffy. Boy was he impressed, or should I say the boy was impressed. |
#17
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One of the main reasons that component level repair today seems so difficiult is that most of the hardware in modern electronics is in the million+ transistor integrated circuits, not isolated to discrete components as it was 20+years ago. There are usually only a few power supply caps, external coils, and mirco-resistors outside the ICs.
Not only is the failure of one of these difficult to diagnose, finding a replacement after only a few years is harder than finding a part for a 50+ year old radio. Modern electronics is truly designed to be throw-away, not repairable. |
#18
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...
Last edited by andy; 12-07-2021 at 11:16 AM. |
#19
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Quote:
__________________
Charlie Trahan He who dies with the most toys still dies. |
#20
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Andy is correct. The last two modern electronic items that have lost were damaged by power surges from lightning. Both had power surge protectors that did not protect them. One was a 16 year old Mitusbishi TV, I have not been able to find the microprocessor IC that was destroyed. The other was my old HP computer running windows 98-uses non-standard size mother board, not made any more.
Another thing that breaks on modern electronics is the cheap plastic buttons, supports, etc. Both of my sisters have had this kind of problem with modern TV sets. Kind of reminds me of modern cars-great electronic engine control which is much better than the old carb system (and modern cars have much better safety features), but the rest of the car is mostly plastic junk which begins falling apart after 5 years ( at least this has been my experience). |
Audiokarma |
#21
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I have a friend who used to work for Teves-they make braking systems & associated electronics for the automotive industry-& he told me that virtually ALL the parts suppliers follow the same unwritten rule-after demand drops below say, 25K units a year, said part is discontinued,& here's the kicker-most times the tooling is destroyed or sold. Sometimes you can substitute a part, sometimes you can't. When my beloved 1977 Yamaha CA-2010 got zapped by lightning in 2001, we couldn't get it fixed because of a certain transistor just simply wasn't available. People marvel at my 1925 radio-"How on earth did you ever find tubes for something that old ?!?"-they don't understand that '01A tubes were made by the zillions for dozens of years. I pity the guy who has as his pride-'n'-joy a 1992 Lincoln in the year 2027 & one of the innumerable little "black boxes" goes kerflooey on it. Especially when I drive by in my '69 model that has none of that mess on it & wave at him...Listening to my 1925 radio, too...HehHehHeh-Sandy G.
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#22
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There was recently a customer in our body shop with a 92 Mustang, 5.0, 5 speed, nice car. He hit something hard enough to pop the airbags, which requires new front sensors. Ford has discontinued them. Due to liability concerns I have to turn him away. (can't legally repair the car without repairing the SRS system) Many late 80s/early 90s parts just don't exist any longer.
__________________
Bryan |
#23
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Repairing newer TVs, SMD 64 pin chips
For me this is another problem repairing newer electronics. Manfactures who use surface mount devices not because there is not enough room, but because they are cheaper to build by robotic placement, wave soldering, etc. and no thought is given to repairability. Even if you can find the replacement smd. and using a high end Pace solder system it can take you an hour and a half or longer to remove and replace one of those chips. Ok, I feel better now, end of my rant.
Richard. |
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