i started off at the bottom at vari*lite ( as did a lot of people still around ) - fixing broken electronics many years ago - and it broke a lot - probably something like 10% failure rate per show. ( possibly more )

On every show you had to test every piece of equipment together as a system before it went out.

its a tough business - such a harsh environment for electronics - very electrically and physically unstable-
with users are under enormous pressure when things break- equipment on and off trucks every day -

and harsh on software developers too- who arent used to things being in continuous use for days at a time - with one unrepeatable and unmeasurable glitch a day -

its a bit of a miracle it works well enough most of the time-


in most cases the physical failures were electrical - cables - power supplies - connectors - mains - static issues -
electronics blows up really easily if you touch it when there is static electricity around -
and vari*lite built their flight cases with static generating material -
I remember the entire first batch of VL4's blew up when they arrived in london because they hadnt been tested on real 240v power.

then there are the design mistakes and the end user errors - dropping things - vari*lite consoles used to blow up when dropped- the relay which switched between 110 and 240 shorted in a failure mode.
Lamp power supplies had an unsafe failure mode which blew up all the transistors.

equipment that gets connected and disconnected all the time that is constantly shipped around - it breaks.
even the best designed stuff. even the worst designed stuff.

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in my experience - with equipment failure like this - you always look to the electrical and cable conditions first of all.
and you check and double check what people say - because in show confusion accurate information is not easy to come by.