On Sunday 02 March 2014 07:05:06 Alister did opine: > On Sun, 02 Mar 2014 09:16:35 +1100, Chris Angelico wrote: > > On Sat, Mar 1, 2014 at 1:31 AM, Grant Edwards > > <invalid@invalid.invalid> > > > > wrote: > >> You drag out the lab scope, logic analyzer, spectrum analyzer, sweep > >> generator, strip plotter, and the machine that goes "ping". You > >> start to get everything set up to nail that problem securely to the > >> dissecting board. Long before you actually get to that point, the > >> problem becomes intimidated and reveals itself and a solution. > > > > *ALL* my machines go ping. It's fundamental to network debugging. I > > know that's not what you meant, but somehow it comes to the same > > thing. :) > > > > And yep. That is so absolutely right. Problems know when concealment > > becomes pointless. > > > > ChrisA > > As a maintenance engineer I find there is also an opposite factor in > operation. > Equipment manufacturers appear to include an "Engineer Proximity > Detector" in all designs that cause the equipment to work flawlessly > when triggered. > > The issue the customer has been complaining about incessantly never > occurs whilst there is an engineer on site.
Most sensitive when any cover has been opened. It took me 5 years to find an intermittent video insert problem in a piece of Chyron gear, and when I found it, I called the guy at Chyron whose name was on the schematic page and told him in no uncertain terms that the best part of him ran down his mothers leg. He'd used a spare gate in a quad nand gate package as an inverter, a common practice when you need just one more inverter in a design. Nothing at all wrong with the concept, but the idiot left one of the two inputs floating, disconnected. That is an absolute no-no in any digital logic circuit, and will bite somebody on the ass, repeatedly. And since I could only get at it for not more than 20 minutes at a time because of its duties, I am ashamed that it took me 5 years to find it when the fix was half an inch of wire wrapping wire to tie it to the other input pin. There is not a digital logic chip book on the planet that doesn't contain warnings about floating inputs. Yeah, I CAN be one of those to idiots. As Marion Morrison, aka John Wayne was fond of saying in his movies, stupidity should hurt. And this guy deserved to hurt. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> NOTICE: Will pay 100 USD for an HP-4815A defective but complete probe assembly. -- https://mail.python.org/mailman/listinfo/python-list
