Check for thermo sensitive components. You will have to have a way to heat
and cool the suspect parts and test them. One way of doing this is to heat
the unit up to make it work. Then cool the individual components one by one
to provoke the fault. You can use a product called Freeze-Mist for cooling,
and a heat gun for re-heating. This is available from most electronic
suppliers. Start in the power supply and output stage areas first.

Very basically, the other way is to get the unit in the mode where it does
not work, check all the power supply distribution, and follow through the
signal path to see where the signal stops. Then it is the task of taking
voltage readings, and determining the exact components to test.



--

Greetings,

Jerry Greenberg GLG Technologies GLG
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WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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"weedmonke" wrote in message
45...
Anyone else experience this? If the unit is shut off, (cold), When it is
turned on, all you get in all modes is 60 Hz hum. After about 10-15 min,
audio cuts in, and is fine until unit is turned off and allowed to cool
down again.Any suggestions?
TIA