How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rusty Your Own Question
Rusty, Music Professional
Category: Electronic Musical Instruments
Satisfied Customers: 6059
Experience:  Sound Engineer, Electrical Issues, Tone Consulting
Type Your Electronic Musical Instruments Question Here...
Rusty is online now

Hi im after some help with a Peavey KB/300 guitar amplifier.4

Customer Question

Hi im after some help with a Peavey KB/300 guitar amplifier.4 channel inputs and can only get 1 of them working,which is channel 2.Ive replaced all the caps on the preamp board and ic,s as theyt were all coroded.Ive injected a signal and tried scoping but getting nothing out of the opamps,so could be a short somewhere.need help.andy
Submitted: 5 years ago.
Category: Electronic Musical Instruments
Expert:  Shantal-Mod replied 5 years ago.


I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!


Customer: replied 5 years ago.
Hi yeah ill wait.cheers
Expert:  Shantal-Mod replied 5 years ago.

Hello Andy,

We will continue to look for a Professional to assist you.


Thank you for your patience,



Expert:  Rusty replied 5 years ago.
Hi Andy, my name is Rusty. Are you reading a short on those inputs? Corrosion can cause a bunch of different problems. Check the solder joints around the corrosion area to make sure there is good contact. If things aren't going through your op amps, check the ohms at the input pins. That should give you a good idea of what's going on.

If you suspect it's the op amps, let me know if you can see a number on them, and what test you did to determine the op amp to be bad.
Customer: replied 5 years ago.

Hi rusty yeah reading a short on all inputs.Ive replaced all op amps as they were coroded and electrolytic caps as some were bulging around channel 1 and 2.I have a schematic if you an email where i can send it.cheers andy

Expert:  Rusty replied 5 years ago.

You can send the schematic to [email protected] and tell them it's for Electronics/Expert-Rusty-the-Tech. Before you do that, disconnect the mixer and pinpoint which board the short is coming from. That way we'll be able to cover more ground in shorter time.