Entertainment Center: TVs, Stereos, VCRs and DVDs - Fender "The Twin" Cahnnel Switching not working
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jl_lensman
05-31-09, 04:34 PM
:wall:
Fender "The Twin" amp - red knob version.
http://www.schematicheaven.com/fenderamps/the_twin.pdf
Amp stuck in parallel mode. Can't switch channels by either footswitch or panel pull pot. Channel LEDs not lighting up either. (Both chanel LEDs should be lit in parallel mode).
Replaced all preamp tubes with new. Switched with know working tubes. Still can't find the problem.
All wiring seems to be correct and good.
Also, I can not get .4v on the bias circuit. The most I can get is .3v.
Fender "The Twin" amp - red knob version.
http://www.schematicheaven.com/fenderamps/the_twin.pdf
Amp stuck in parallel mode. Can't switch channels by either footswitch or panel pull pot. Channel LEDs not lighting up either. (Both chanel LEDs should be lit in parallel mode).
Replaced all preamp tubes with new. Switched with know working tubes. Still can't find the problem.
All wiring seems to be correct and good.
Also, I can not get .4v on the bias circuit. The most I can get is .3v.
Rick Johnston
06-01-09, 05:21 AM
Welcome to the forums.
Are all the test points correct?
I can't find a board layout on The Twin, but if it's typical, Fender used large white rectangular ceramic resistors in that circuit. Check for cold solder joints or discolored areas around those resistors.
Are all the test points correct?
I can't find a board layout on The Twin, but if it's typical, Fender used large white rectangular ceramic resistors in that circuit. Check for cold solder joints or discolored areas around those resistors.