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Old 07-15-2017, 02:53 PM   #1
Rich_13
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Default Amp has power but no functions or sound ?

I have a Laney Prism P20 solid state amp . When you flick the power switch on , you hear a slight click from the speaker as usual when powering on and the LED lights on the controls flash momentarily which suggests there's power getting to the control board at least for an instant , then nothing .
There is power to the speaker because if you listen up close you can hear it buzzing , but none of the functions or volume controls work and the LEDs remain off . It seems like a bad connection somewhere but I can see nothing obvious . I'm no electrician and a bit of a duffer with a multimeter but There seems to be continuity in the cables connecting the internal power supply to and between the circuit boards I am getting a beep from the meter , and I can't see any obviously bad solder ? Any ideas would be appreciated .
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Old 07-15-2017, 04:08 PM   #2
HawkHunt
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I don't even know if this is applicable or not, but some amps (mine included) have an FX-Loop level. If there are no pedals in that loop and there the knob is anywhere above 0 then there wont be any sound coming from the speaker.
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Old 07-15-2017, 05:57 PM   #3
Rich_13
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that feature is not on the amp. It was working fine then I switched it off and came back half an hour or so later and switched on and the problem occurred , no other switches or buttons had been touched other than the power switch . Thank you any way for the idea .
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Old 07-15-2017, 11:55 PM   #4
PKVeazey
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Find another speaker and alligator clip it to the speaker in the cabinet. That will tell you if the voice coil is dead or not. If you hear a loud Buzz, then you want to check the power supply for a bad filter capacitor. I'm guessing something on the amp's circuit board is dead. I've got a perfectly good amp but the signal going to the final stage is dead and nothing comes out the speaker. If I use headphones, I can hear everything perfectly. Did I forget to mention that amp is out in the shed where it belongs.
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Old 07-16-2017, 07:37 AM   #5
Rich_13
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I'm more inclined to suspect the circuit boards too, probably the one wth all the controls, because the LED lights which should remain on when you have the amp powered up, are not . They just flicker once as you flick the power switch.
This circcuit board is connected to one with what looks like a processor on it ,then that's connected to another board with the speaker connections and foot pedal auxilliary jack .
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