Effects loop noise?

[Tawlks]

I plugged in my 5150 II after moving it and it was making a very loud hiss/hum/buzz when I turned the effects loop on.

What could be causing this? I haven't been rough when moving the amp or anything.

 

[Tawlks]

Oh c'mon..

 

[Ventura]

Is it a tube buffered FX loop????? Cuz if so............. That's right, it'll be the 12AX7 or whatever's driving that loop.

V.

 

[MrDan666]

Make sure the send and return jacks are clean, try some contact cleaner and see if it fixes the problem. If i remember correctly, the 5150II has just a simple interrupt FX Loop, so if the connections are bad there, it will cause noise/intermittent operation.

 

[Tawlks]

Is it a tube buffered FX loop????? Cuz if so............. That's right, it'll be the 12AX7 or whatever's driving that loop.

V.

I wanted to rule out cables before I did that, but I think it must be, it's a low frequency hum, not a whiney squeak normally asociated with microphonic tubes.

I swapped the cables round, both patch and instrument leads between the front of amp and effects loop (I have pedals in both, 4 instument and 5 patch in total) and the problem remained the same, but it seemed to go away when I put a patch cable in the effects loop.

 

[Jimmie]

Is it a tube buffered FX loop????? Cuz if so............. That's right, it'll be the 12AX7 or whatever's driving that loop.

V.

+1 this, if you know which tube the FX loop is buffered through, try re-seating it or replace it with a known to be good tube of the same value. A word of caution, be sure the amp is off and unpluged before doing either of the suggestions above.

Good luck,
Jimmie

 

[Tawlks]

Is it a tube buffered FX loop????? Cuz if so............. That's right, it'll be the 12AX7 or whatever's driving that loop.

V.

+1 this, if you know which tube the FX loop is buffered through, try re-seating it or replace it with a known to be good tube of the same value. A word of caution, be sure the amp is off and unpluged before doing either of the suggestions above.

Good luck,
Jimmie

Just done exactly that. Turned it off, unplugged it, went away, came back and swapped out V5 with a EHx 12aX7. Let's see how this goes.

 

[MrDan666]

Did you try cleaning the FX Loop jack sockets like i suggested?

As far as i know, the 5150's have a simple insert FX loop, just two jacks without any actual FX loop circuitry. It's not a tube buffered loop. So dirty jacks could cause the problem you're having. Lots of other 5150 users have had the same problem and cleaning the dirty Loop jacks fixes the problem.

 

[TJSlice]

Did you try cleaning the FX Loop jack sockets like i suggested?

As far as i know, the 5150's have a simple insert FX loop, just two jacks without any actual FX loop circuitry. It's not a tube buffered loop. So dirty jacks could cause the problem you're having. Lots of other 5150 users have had the same problem and cleaning the dirty Loop jacks fixes the problem.

+1. Owners of the Rockmaster preamp have the same problem. My old Mesa DC-2 also had that issue now and then. Try some cleaner on a cable end and run it in and out of the jacks...

 

[Tawlks]

Didn't work, does anyone know which 12ax7 is for the loop in a 5150 II? I swear it's the V5. :S I'll try cleaning out the jacks with methylated spirit.

Another thing, the noise is the same regardless of master volume.. maybe a grounding issue?

 

[Code001]

http://www.fjamods.com/5150Models.html

 

[MrDan666]

Didn't work, does anyone know which 12ax7 is for the loop in a 5150 II? I swear it's the V5. :S I'll try cleaning out the jacks with methylated spirit.

Another thing, the noise is the same regardless of master volume.. maybe a grounding issue?

The 5150 doesn't use a tube for the FX Loop, so changing tubes won't do a thing. It's a passive Loop, not a tube Loop. Clean the jacks first and see how you get on

 

[Tawlks]

Didn't work, does anyone know which 12ax7 is for the loop in a 5150 II? I swear it's the V5. :S I'll try cleaning out the jacks with methylated spirit.

Another thing, the noise is the same regardless of master volume.. maybe a grounding issue?

The 5150 doesn't use a tube for the FX Loop, so changing tubes won't do a thing. It's a passive Loop, not a tube Loop. Clean the jacks first and see how you get on

Ahh okay. I've got methylated spirit, no contact cleaner.

 

[MrDan666]

Ahh okay. I've got methylated spirit, no contact cleaner.

Got a Maplins store nearby? They sell contact cleaner spray in a can for cheap, well worth having since you can use it for allsorts of things

 

[Tawlks]

Ahh okay. I've got methylated spirit, no contact cleaner.

Got a Maplins store nearby? They sell contact cleaner spray in a can for cheap, well worth having since you can use it for allsorts of things

I tried it with Methylated spirits and it worked. The buzz is gone! I'm not sure how as I cleaned them a few months ago and the effects loop jacks are always plugged in when I play, very strange that they'd get dirty.

Thanks alot man.

 

[MrDan666]

Awesome, glad it worked for you! Rock on!

 

[Shask]

The 5150 series does use a tube for the FX loop. It is not a simple interrupt.

I was going to say maybe it was the power supply to your pedals in the loop, but it sounds like you found your problem