I had the opportunity to repair high-power audio amplifiers used in high-end systems, that used class AB topology and used multiple pairs of TO-3 power transistors. It was very tough to bring the circuitry into balance.
Couple times found myself burning/smoking the balast resistors & traces. I am glad that Class D, made this amps histry.
I had a friend who fell on a stream with his car.
The day after the car was removed from the stream and my friend asked me to recover the audio power amplifier.
Of course nobody removed the battery connections, so I discovered that the PCB traces were simply dissolved!
Electrolysis, of course.
Being a clumsy klutz, I have three times dropped mobile phones into water. Each time I removed the battery right away, let the phone dry thoroughly in a warm place for a day or so, and every time they have worked.
Being a techie guy, I've had others come with the same problem, but they haven't removed the battery, and you can basically throw the phone away.
In my work I have had TV's and transmitters that have been under water. All of them I fixed. First do not apply power, remove tubes, fill set tub with hot water and dish soap, and wash all circut boards, power packs, transformers like you would wash a pair of BVD's. Be sure you have your engineers license handy. Rinse. Put every thing in an oven at 200F for an hour, then let cool and reassemble. Some plastics may soften. Everything worked.
Many years ago I designed a board that included some braking resistors.
For that use I selected good resistors because the energy had to be absorbed in strong bursts.
All the test went ok and we started production.
The guys of the final test called me: "for each board, the first time we test the braking we gets smoke from the resistors!"
"What do you mean with 'the first time'?"
"I mean that if you repeat the test there is no more smoke."
I was puzzled, so I asked the producer of the resistors.
He explained that the first time the resistors get hot it's normal that the varnish releases a bit of smoke. Once "burnized", the resistor shouldn't smoke anymore.
Unless you overload it, that is.
"If you don't want the smoke we can do the 'burnization' before the shipment, but of course this adds to the cost..."
This to say that not always, where there's smoke, there's a bad design!
Back in my day (an engineer since '82) we called that type of display a "vector" display. I remember old Techtronic workstations (and who could forget the game "asteroids") used that type of display.
The good old days of +5V & +12/15V design, when 20MHz was blazing and you could actually wirewrap the prototype before you committed to a PCB!
" n order to alleviate the size issue, they would sometimes use a "Stroker" (as opposed to "Raster") display"
I came across a Tank game using this type of display in a games arcade in South Africa in the 80's. Although it was monochrome (green) It was an awesome game not least because of the infinite range of sizes of the images, as opposed to a raster display. Put many coins into it over the years.
Blog Make a Frequency Plan Tom Burke 17 comments When designing a printed circuit board, you should develop a frequency plan, something that can be easily overlooked. A frequency plan should be one of your first steps ...