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Hi everyone, I have a Laney Pro Bass that has no signal from the front end. I have + & - 15v. I can get some noise from the rear return jack (so main amp looks like it is working), but I could use a schematic that I do not have. Thanks in advance for anyone that can help! ------------------------------OMguy
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I think the model # is PB-150.
Try the send jack to another amp.
Try to isolate the problem.
Preamp or Power amp.
What does "I can get some noise from the rear return jack" mean?
Is it noise or a good signal? -
Sorry Jass P Bass, I got a guitar cord and plugged it into the rear return jack and used my finger to inject a noise signal into the main amp, it appears to be working. I need a drawing to try to see where I lose the signal through all the op-amps. Thank you for your advice on the model number!!! ---------------OMguyComment
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Well, if you want to test the opamps look at pin 1 & pin 7.
The output pins.
Insert a signal (signal generator, plucked guitar string) into the input jack.
Set your DVM to read Volts AC & attach the black lead to the chassis.
A guitar will output 100mv's.
So you should see at least that on the output pins.
I would start with the option controls off.
Parametric Switch: Off
Preshape Switch: Off
Graphics EQ: Off.
Turn the gain control all the way up & see if the "peak" LED lights.
If it does then the problem is after that part of the circuit.Comment
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Laney BC250 Schematic
Maybe this Laney amp is "close".
If nothing else it shows the expected gain voltages at each opamp stage.Comment
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Thank you Jass P Bass, I will try to match up the drawing you sent! I will have to check it tomorrow I have shut it down for today. Thanks ------------------------ OMguyComment
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Hi everyone, I finally got back to this one. After searching around all the opamps trying to find something wrong with the opamps I put a light shining at the top side of preamp board ( with the chassis standing on its side ) so the light would let me see the shadows of the top components and I could follow the copper runs to the next stage! Then I followed the signal to one of the switches and lost it through the switch! The wire from the board to the switch must have vibrated the solder out from the switch! (It is a bass amp!)
Thanks Jass P Bass for your help!!! ------------------OMguyComment
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