Mark IV effects loop problem

[holdsworth]

I've recently had my Mark IV serviced and retubed about 2 months ago with Tung Sol's and JJ's and I've never been happier with the tone. One problem I seem to be having though is that very recently the volume keeps on dropping out when I initiate my effects loop, but when I turn the effects loop off the volume pops right back to normal!?

Can anyone diagnose my problem? Is it serious, or do I have a duff tube?

 

[Pinweaver]

Usually its one of the pedals in the loop.

 

[Platypus]

Does it do this when there's nothing in the FX loop as well?

Try replacing V2 if so.

 

[6L6C]

You might also want to leave the loop on and instead of the processor just put in a straigh cable and see if you still get the dropping if so probally something in the amp (so hopefully its not the case)
If not do what Platypus said.

 

[fpoon]

You may have set it up wrong (cables). I too had this problem when I wanted to try putting my wah in the loop (I know it sounds better in front). The sound got super thin and the volume decreased.

 

[holdsworth]

Thanks, I'll try those things out and give it a proper testing over the weekend. This is a puzzling problem because since I posted this thread it is working fine again with no drop-outs, and furthermore the tone is perfect to my ears, no loss of power at all.

Does the V2 effect the FX loop then? I just want to sort this problem out so that it doesn't plague a forthcoming gig.

 

[Platypus]

Thanks, I'll try those things out and give it a proper testing over the weekend. This is a puzzling problem because since I posted this thread it is working fine again with no drop-outs, and furthermore the tone is perfect to my ears, no loss of power at all.

Does the V2 effect the FX loop then? I just want to sort this problem out so that it doesn't plague a forthcoming gig.

V2 controls the FX loop return function

Can you explain what is in your loop when you do this and if you've ever heard this problem with nothing in the loop? It's most likely whatever unit is in the loop that is causing this volume issue if you've never heard it without said unit in the loop.