Quote from: jasper2021 on July 24, 2024, 05:17:23 PM

Quote from: DrGonz78 on July 23, 2024, 08:13:57 PMRemove the speaker from the amp. If there is DC voltage leaking into your speaker it may damage it. Next use a multimeter set to read dc voltage across the speaker leads. What does it read?

Multimeter reads 0.15V across the speaker while it's buzzing..

Good.
To my ears it's too buzzy raspy rather than deep hummy, I suspect you lost some ground between amp input and preamp

What happens if you set Master to 0?

What if you short power amp input terminals together?

Trying to find *where* buzz gets in.

Quote from: DrGonz78 on July 23, 2024, 08:13:57 PMRemove the speaker from the amp. If there is DC voltage leaking into your speaker it may damage it. Next use a multimeter set to read dc voltage across the speaker leads. What does it read?

Multimeter reads 0.15V across the speaker while it's buzzing..

That sounds like poor power supply filtering to me. I'd check caps C30, C31, C26, & C27. First, make sure they are properly soldered to the circuit board. It's quite possible you just have a cracked solder joint on one of the caps.

Remove the speaker from the amp. If there is DC voltage leaking into your speaker it may damage it. Next use a multimeter set to read dc voltage across the speaker leads. What does it read? We don't want to accidentally short them together and definitely remove the speaker. If it is not DC voltage on the output it may be something right in the preamp. But first test the power amp side to be careful.

My Sidekick Reverb started giving me issues out of the blue. Lots of humming with nothing plugged in. Here's a video of the issue.  I found a wiring schematic and I opened it up to see if there was any obvious signs of damage but it all looks OK to my beginner's eyes.

Can anyone help me diagnose this issue?  If anyone can point me in the direction of some good troubleshooting resources, I have yet to find anything on my own.

I know this thread has been dead for a number of years, but in case anyone involved with it is still around, I'm looking for board pics of a freedom brothers amp.  I've got one that's in a state of disrepair from someone who tried to do some work on it and only made it more confusing. Anyway, can seem to find so little about this amp on line so following any threads no matter how thin.
Barry

This topic has been moved to Player's Corner.

https://www.ssguitar.com/index.php?topic=5386.0

A rectifier, including a bridge, will charge supply capacitor to 1.41X AC voltage, so about 24VDC as stayed above.
You can* down regulate it to 16V or whatever this mini amp needs.
Simplest is using a 7815 and a diode or two to rise voltage reference, or use an LM317 which costs cents more and is fully adjustable.
You will need some heatsinking for the regulator , at least of aluminum sheet or rail
 

Think that the power typically takes full Amperes, say 2 - 3 - 5 Amperes, even more on a 100W amplifier.

At a preamp level, each signal transistor takes 1 to 5 *milli* (one thousandth) Amperes, an Op Amp some 2 to 5 milli Amperes and so on.

Only those doing (small) power amp jobs such as reverb tank drivers or active earphone out can take, say, 20 to 50 milliamperes.

In any case way less than any speaker driving stage.

So in general, no big deal
 

I was under the impression that a full-bridge rectifier would drop the voltage?  I guess too much voltage is better than too little as it should be easier to drop it than to increase it.