Hello!
I’m getting a strange noise when flipping from Bypass to Operate.
I need help.
Here’s a short Youtube-video showing the problem:
@Henrik welcome to the forum!
Did this start recently? What’s the history?
This could be a few things; first, simplify your setup. Remove anything in the FX loop and just have a guitar, amp, power station and cab. Make sure that the power station and amp are connected to the same wall socket by an extension plug. This will remove ground loops.
Next we can start to suspect other things, but please report back before we continue.
Hello and thanks 
My PS-100 haven’t been used for about 6 months or so. Before that I used it a couple of times. Maybe 2 gigs and a couple of times at home. Soa couple of days ago I bought a new modeler and wanted to try it with a cab connected to the PS-100. So the only connections on the back is the line in from the modeller, speaker out to a 8 Ohm cab with the switch set to 8 Ohm and the power cord. I let it warm up a couple of minutes. And when I switched from bypass to operate I got the sound from the video. Never happened before. Like a constant burrrrrr.
So the unit is not much used at all. I bought it to record with my MESA amp and to have as a poweramp to my Kemper on gigs. It sounds great but my laziness took over so I’ve been using a smaller power amp for convenience 
. That’s why it’s been unused for a while.
Any ideas on what to do?
Hi Henrik, Will PM you…
I have a PS-2 with the same problem . It buzzes loudly once the standby switch is engaged . The tubes are fine , nothing connected to the loop , the PS-2 has a loud mechanical buzzing - no audio input or output . Any ideas what to do ? Thank you .
It turns out that Henrik’s issue might have been a cabling problem. He took his rig apart and reassembled it and the issue disappeared.
However, your rig sounds very simple; it is just a guitar, amp, PS-2, and cab?
Photo of the back of the PS-2 would help just to confirm, and please check the cables are all good.
Please do a final sanity check and then we take it from there…
Sorry , I do not have a photo of the cabling . The two cables here are fine , one input from a JCM800 speaker jack , one output to an 8 ohm test cabinet , The amp and cabinet work fine together , the PS-2 makes a loud buzzing sound ( sounds like a mechanical relay quickly switching on and off , noise seems to come from a component on or near the jack board )
Sorry , my original post said the buzzing was coming out of the speaker . This PS-2 has a loud mechanical buzzing - no audio input or output . With the power off , the top speaker jack measures open circuit , the bottom one measures a short .
OK this is quite significant. Thanks for clearing that up. So this is more mechanical sound, when in operate and it does not go away by setting toggle switches to flat? And you remove everything from FX loop too to eliminate ground loop. If so sounds like maybe someone should take a look at this.
Correct , standby engaged , the PS-2 produces a loud , electromechanical buzz ( nothing in the loop , just amp and speaker ) . There is no audio output from the PS-2 , just a loud internal buzz near the jack board .
OK, any history of putting it in a rack? Or just stock PS-2. Also PS-2 has two SPKR OUT sockets ,are you using the top one – this must be used first.
It is a PS-2A that has not been racked . I have always used the Main , top output speaker cabinet jack
I just need check, serial number date or purchase and location of purchase and then we can sort out arrange a fix.
It was used , not sure where it was purchased originally - Serial : PSA226048 .
OK, so we need to go the route of getting it to a local tech? Let me PM you to get some personal details…