Years ago, my company were advertising for a tech to repair music electronics, guitar amplifiers, effects pedals etc.
One guy applying was a full blown PhD in electronics. When I met him, I said that he was way overqualified for what we were offering, but he was adamant that he needed a job, there was no work.
Ok, I said, and took a 10W guitar amplifier from the repair rack, handing him the amplifier and the service manual. My telephone suddenly started working overtime, and so he was left alone for about 30 minutes. When I finally spoke to him, he said he was totally confused, he could get no gain out of the first stage operational amplifier, and showed me four pages of intense algebra analysing the stage.
What is the supply voltage on pin 8 I asked. He turned red as he measured zero volts; a shorted bridge rectifier had blown the supply fuse.
Kevin