20-04-2014, 12:31 PM
Rob's experience does prompt me to state what I've said many times before: as fixers of electronic equipment, there is a strong tendency to neglect the test equipment that Nature has given us and to dive straight in with the test equipment. Yes, by all means take sensible precautions with a piece of unknown kit prior to applying power, e.g. isolation transformer; lamp limiter, etc. And then, having powered the item up, making voltage (and possibly waveform) measurements. But prior to any of that, give the item a good 'visual': the things to look for are too many to list and are well-known to experienced fixers. And using your nose to detect any indications of burnt materials or dampness is a good idea. Then when the item is powered up for the first time, is anything running obviously too hot (e.g. the heat-sinks of power transistors)? Are all the valve filaments glowing? Are there any untoward sounds heard - such as cracking or popping? Advance the A.F. gain control: any sounds heard? Give the item a few gentle taps and knocks: any untoward sounds heard?
A lot of 'history' about an item can be gleaned before power is first applied by using eyes, nose, ears and sense of touch - and doing that first can save a lot of headaches later.
Al.
A lot of 'history' about an item can be gleaned before power is first applied by using eyes, nose, ears and sense of touch - and doing that first can save a lot of headaches later.
Al.
