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Ian Iveson
 
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"mike m" wrote

I'm going nuts trying to get My MK to work properly have 2
identical Dynaco MK3's. Completely rebuilt 6 months ago and both
worked beautifully. Went on vacation for 10 days, came back Sunday
night turned on the system and heard almost nothing from the right
channel
(amp#2)....


...What am I not seeing?
Any suggestions?


I can't remember the last time anyone asked a question about a
specific amp and got a specific reply. Not many round here work on
enough commercial stuff to know many by heart, or to be aware of
their particular foibles.

It generally helps therefore to provide a link to the circuit
diagram. Many can be found in the "schematic index" at

http://www.duncanamps.com/

We are unlikely to know where the test points are unless you tell us
or they are shown on a diagram.

So we don't know quite what you have eliminated.

Assuming *all* DC conditions are correct, then you are looking for
problems which don't effect the DC conditions.

A partly-shorted transformer is one possibility...hence Chris'
suggestion of checking the DC resistance of the OPT. Conversely it
could be a partly open-circuit capacitor but you've checked them.

Resistors in series with capacitors, or in parallel with inductors,
are also suspect, but you've checked them.

No such failures are likely to occur because of your absence, so I
wonder if it could be a dusty input connection or pot...but I guess
you've tried wriggling them.

A knackered OPT is bad news, so I hope you've missed something else.

cheers, Ian