Marshall amp, strange noise

[tinpan]

I have a solid state Marshall Valvastate VS230, works and plays fine except sometimes inbetween songs it makes this whining sound, it's hard to explain but when nothing is being played, no effects plugged in just straight guitar with a known good cord it makes this sound, similar to hearing when a drill or blender is being used over an AM radio but there is nothing being used. The sound will appear then sort of break up then go away. Im a tv repair tech so if this is something where all I need is a resistor or a cap or IC I can do it myself, I looked at the circuit board and nothing looks burnt and solder joints all look good. Anyone know what this is?

[phatt]

Does it happen at the same time every day?

Phil.

[J M Fahey]

similar to hearing when a drill or blender is being used

Well, *maybe* a drill or blender *is* being used somewhere close and you don't know it.
Computers, TVs and monitors, not excluding switching power supplies (which are everywhere, such as your Cellphone charger) and even Cellphones themselves, which regularly chirp "I'm here" to nearest tower, all contribute to electrical noise.
Something funny that happened to me: I live in La Boca, the ancient Buenos Aires port , less than 100 meters from the waterline.
Once, at different times of the day, I heard *everywhere* (even on my TV and my phone) this "... zzzt ... zzzT ... ZZZT ... click click click ... ZZZT ... zzzT ... zzzt ..." sound.
It was maddening.
A shipowner neighbour visited me, and when he heard it said "are you repairing a Marine Radar .... ?"
Turns out there was this Spanish fishing ship anchored one block away, which was being repaired, testing illegally their Radar.
They have a high power setting for navigation use and a low power one for port use.

[tinpan]

Does it happen at the same time every day?

Phil.

No, not same time. random.

[tinpan]

similar to hearing when a drill or blender is being used

Well, *maybe* a drill or blender *is* being used somewhere close and you don't know it.
Computers, TVs and monitors, not excluding switching power supplies (which are everywhere, such as your Cellphone charger) and even Cellphones themselves, which regularly chirp "I'm here" to nearest tower, all contribute to electrical noise.
Something funny that happened to me: I live in La Boca, the ancient Buenos Aires port , less than 100 meters from the waterline.
Once, at different times of the day, I heard *everywhere* (even on my TV and my phone) this "... zzzt ... zzzT ... ZZZT ... click click click ... ZZZT ... zzzT ... zzzt ..." sound.
It was maddening.
A shipowner neighbour visited me, and when he heard it said "are you repairing a Marine Radar .... ?"
Turns out there was this Spanish fishing ship anchored one block away, which was being repaired, testing illegally their Radar.
They have a high power setting for navigation use and a low power one for port use.

I only use the drill and blender thing as an example, the sound is simlar. however my pc is on as I use it to practice with, I use jam tracks. And altho we are on an island we are miles from any port.

[LJN]

That sounds like some kind of interference to me. My amp does that sometimes, In fact, most of the amps I've owned did odd things like that. I had 2 tube amps that would pick up radio signals. Try putting your amp in a different position, and see if the noise changes. I've found that it helps to move the amp sometimes. I'm pretty sure that's all it is, is interference.