Stand-by pop

[Decerto]

Sorry in advance for the newbie question, but this is my first real tube amp, so I'm not too familiar with them, and not sure what should sound normal. I had a Crate tube amp before this, but only for about 2 weeks, then I decided to upgrade. Anyways, onto the supposed problem: My RM100c is making a loud, bassy pop when I switch it over to stand-by, I don't remember it doing this before. I remember it making a light pop, that was more like a click though. Should I be concerned about this?

Sorry again for my noobness.

 

[raz311]

Make sure your master volume is turned down to zero before you flip the stand by to play position - otherwise you might damage something like your speakers

 

[tonymustang302]

Make sure your master volume is turned down to zero before you flip the stand by to play position - otherwise you might damage something like your speakers

Huh? My master is always set to noon.

 

[Decerto]

That kind of gave me an idea that it may have been one of the preamp tubes or something, but I tried turning the volume down on each channel, and even the master just for the hell of it, and it's still a viciously loud pop. I'm really clueless as to what this could be, and the pop makes me kinda worried for my speakers.

 

[Jaded Faith]

I have the same issue on one of my RM100's. Randall fixed it, but it just came back again a little over a week ago. My work around is to turn the power off first when I'm done playing, then switch it to standby. It only pops when I switch from play to standby, not the other way around so firing it up works as normal (turn the amp on for a while, switch it to play when I am ready). Maybe this will help you?

 

[Soulinsane]

There is a 0.1u capacitor ( C1G ) in parallel with the standby switch. It helps suppress contact arch on the switch and the pop you are hearing. If it goes bad you will hear that pop but it will not hurt anything.

 

[Decerto]

There is a 0.1u capacitor ( C1G ) in parallel with the standby switch. It helps suppress contact arch on the switch and the pop you are hearing. If it goes bad you will hear that pop but it will not hurt anything.

Is this easily replaceable?

 

[TheHunter]

There is a 0.1u capacitor ( C1G ) in parallel with the standby switch. It helps suppress contact arch on the switch and the pop you are hearing. If it goes bad you will hear that pop but it will not hurt anything.

I have this pop to! You are positive it will not damage my speakers? Not that I am holding you to that, but if it is damaging then Im sure the rest of us would love to know how we can fix this issue.

If it not a big deal then whatever, it just annoying as hell.

 

[Soulinsane]

Most amps don't have this snubber cap on the standby. Its a luxuery feature really. The pop is annoying and shouldn't hurt anything, but there is always the chance that the arch could fuse the switch contacts together without this snubber cap. You would have to replace the switch in that case.

The part itself is easy to replace but getting to it is another story. It will require removing the power board ( G board ). The part is in a really tight place with a lot of really dangerous high voltage parts just millimeters away. Mine has a large 0.1u 1KV poly cap.

It might be easier to just cut the cap off the board and solder a replacement cap right on the standby switch terminals ( point to point ). In practice you would want the cap as electrically close to the switch as possible anyways. After thinking about it, I'm going to do that with mine now :idea:

 

[Soulinsane]

One more thing to note about this part. On the stock RM100 schematics from Randall it's listed as a .1u 400V cap, but when proofing those schematics I found that my RM100 actually had a .1u 1KV cap.

If any 400V caps where put into C1G they would fail within a short time since there are over 500+V on that circuit. I don't know if there were any 400V caps actually used but look out. I would at least use a 1KV rated replacement. You could go higher with no problems in this case but poly caps get big really fast.

#1 rule of caps. Operate them below 70% of there max voltage rating.

 

[Decerto]

Hate to bump this, but I'm still very weary about this popping noise, and it's getting much worse. Before it was like a bassy pop, it had some thud to it. Now it's like a mid-high snapping pop - Kinda piercing actually, and a little louder than before. You sure nothing could be wrong with it? Because this just doesn't seem right.

 

[guitarcomet]

I have the same issue on one of my RM100's. Randall fixed it, but it just came back again a little over a week ago. My work around is to turn the power off first when I'm done playing, then switch it to standby. It only pops when I switch from play to standby, not the other way around so firing it up works as normal (turn the amp on for a while, switch it to play when I am ready). Maybe this will help you?

I have a Fender amp that does the same thing.
I just guessed it was the nature of the design.
Turn the power off first, did the trick.

 

[RockStarNick]

could it be a worn or bad or dirty switch?