Knight mono block with volume static question, help needed

[SwingModern]

Did you wire the new caps in the correct polarity?

I did. I put the old ones back in and now I'm back to the beginning again. Which is good.

So I get sound when the volume is about 1/4 of the way up. Less and more than that there's no sound, only static. Thanks.

 

[SwingModern]

I'm not sure what your level of experience is with this stuff but do be careful with lethal voltages etc. If you replaced the Sprague electrolytics with proper value caps with the same polarity those should be fine. The power supply caps that would normally be high on the priority list for replacement are the can caps on the top of the chassis, circled below.View attachment 2572451

Thank you! I'll see about ordering those.

 

[SwingModern]

I'm not sure what your level of experience is with this stuff but do be careful with lethal voltages etc. If you replaced the Sprague electrolytics with proper value caps with the same polarity those should be fine. The power supply caps that would normally be high on the priority list for replacement are the can caps on the top of the chassis, circled below.View attachment 2572451

I found can capacitors with the same UF ratings, but the voltage ratings are different.

Can they be used? Thanks.

 

[Selmerdave]

Higher voltage rating is ok, lower is not. They don't have to be replaced with cans, a lot of people use individual caps of the correct value under the chassis, but certainly if you find cans that fit and are the right value that's fine too.

 

[SwingModern]

Higher voltage rating is ok, lower is not. They don't have to be replaced with cans, a lot of people use individual caps of the correct value under the chassis, but certainly if you find cans that fit and are the right value that's fine too.

Thank you for the information! Would these can possibly cause the static?

 

[Selmerdave]

Thank you for the information! Would these can possibly cause the static?

It's hard to say, dirty controls or failing resistors are more commonly sources of noises, but your circuit doesn't work right now. It would be best to do some diagnostic testing to figure out what is going on in your circuit and how to proceed. Again, I'm not sure of your experience level but I'm probably not the best person to walk you through that. If you don't have a lot of experience the best thing to do first would be some reading on how electronic components and tube circuits work. From there you can see what's going on in the amp and assess where to focus your efforts to get it working again. With more specific questions about specific parts of the circuit you'll find there are many here with a great deal of knowledge that can help you through issues you come across, but it's pretty hard to answer questions that are very general.

 

[SwingModern]

It's hard to say, dirty controls or failing resistors are more commonly sources of noises, but your circuit doesn't work right now. It would be best to do some diagnostic testing to figure out what is going on in your circuit and how to proceed. Again, I'm not sure of your experience level but I'm probably not the best person to walk you through that. If you don't have a lot of experience the best thing to do first would be some reading on how electronic components and tube circuits work. From there you can see what's going on in the amp and assess where to focus your efforts to get it working again. With more specific questions about specific parts of the circuit you'll find there are many here with a great deal of knowledge that can help you through issues you come across, but it's pretty hard to answer questions that are very general.

Thanks for the info!

 

[zackthedog]

There have got to be some experienced members in the Denver area who could lend you a hand. I'm to far away in Oregon, but I know I'd love to get a peek at a rare piece like that. It's also not terribly complicated and should be an easy repair for an experienced person.

 

[SwingModern]

Hoping to get some more advice. I replaced the on/off tone pot most recently. I can hear music at a low level, but still get a lot of buzz and static. When I turn the volume up about halfway, there's lots of buzz and static.

Would replacing the can capacitors possible fix this? Thanks

 

[Primotubes]

Hoping to get some more advice. I replaced the on/off tone pot most recently. I can hear music at a low level, but still get a lot of buzz and static. When I turn the volume up about halfway, there's lots of buzz and static.

Would replacing the can capacitors possible fix this? Thanks

Did this amp work normally before or did you just acquire this and are trying to make it work. Since this is a kit amp you need to make sure that the person who put it together did it correctly. That is why it would be good to know if this was working properly before. In the schematic the 12ax7 feeds the volume control. pull that tube out and check if the buzz and static is still there. That would indicate that the noise is from further down the amplification chain. If the noise is gone then it originates in the 12ax7 circuit.

 

[SwingModern]

Did this amp work normally before or did you just acquire this and are trying to make it work. Since this is a kit amp you need to make sure that the person who put it together did it correctly. That is why it would be good to know if this was working properly before. In the schematic the 12ax7 feeds the volume control. pull that tube out and check if the buzz and static is still there. That would indicate that the noise is from further down the amplification chain. If the noise is gone then it originates in the 12ax7 circuit.

I removed that tube and the amp is silent. Does that mean that something's wrong with the wiring connected to the tube socket? Thanks.

 

[Primotubes]

I removed that tube and the amp is silent. Does that mean that something's wrong with the wiring connected to the tube socket? Thanks.

Not necessarily. But look at the schematic and almost every part before the next gain stage which is the tone control section can be a source of noise, including the 12ax7 tube. I would try replacing it with a known quiet tube. If no difference you can tap components in the 12ax7 circuit up until the coupling capacitor for the tone control circuit. If you can't get the noise to act up when the component is prodded you should just do a complete rebuild for that section. In fact, since your photo shows that the resistors and other parts are mostly likely original to this unit, and if you want a long term relationship with this amp you should change all of the old resistors and capacitors .