Marshall tsl fx loop bleed - help needed!

[maejima]

Hi there. I 'm new to this forum and i have a problem that many people seem to have.
I've searched everything on the net and could not find the right thing to do.
I Have a Marshall TSL60 Head made in 2006, the amp plays really well and i had no problems with it at all. The only problem is that now i bought a delay pedal to use in the loop and it just seems useless.

There is as i found out a signal bleed from my main channels to the fx loop and from my FX loop to the output. When i use the delay with the clean channel and i turn the loop off with the footswitch and turn the fx mix knob all the way back the is a slight echo heard through the amp , the problem gets bigger with the crunch and unbearable in the Lead channel. The only fix for the echo to stop is to turn off the delay pedal. The other bigger problem is that when i tried to use the delay and a boost pedal after that in the loop to create a solo sound in the lead channel it immediately starts to feedback like crazy (because i supect of the signal bleed crating a feedback loop) making it unusable.

Some guy suggested the whole fx loop circuit to be moved to a less "noisy" enviroment in the amp chassis , another one suggested the loop to be made Serial instead of parallel but i haven't found out how to do either of these mods.
Does anyone know of a solution to this problem? Is this a crosstalk problem because the cables run together? What should i do? please help

[maejima]

So nobody has the same problem? Nobody knows about a solution?
anyone?

[Mark Black]

Well, I haven't encountered that particular problem but I will say this: All of the DSL/TSL Marshalls suffer from solder cracking at many points, most especially on the "single-sided" PCB's but sometimes also on the "double-sided" main board.

So, just to make sure lousy solder joints aren't part of your problem (and to generally drastically improve time before the next problem) I would suggest you retouch solder joints (whether they look good or not) at EVERY PIN of ALL PCB-mounted: Jacks, Switches, LED's, Tube Sockets, Relays, Large Components (like filter caps), AC inlet connector & fuseholders, and multipin connectors (of which there are many, used to interconnect the several PCB's in the amp). Even if that treatment doesn't cure your immediate problem (which it may, actually) you will have improved the longevity of the amp in other regards.

Just my $0.02

[maejima]

Thanks for the response. I will eventually try that but it seems like a hell lot of soldering as the pcbs have thousands of components on them. I don't think that it would help with my problem though cause the loop and everything else on the amp is working, but it has that bleed that i can't seem to get rid of. I think it is a design flaw (poorly shielded cables , wrong place to fit the loop in the pcb board , i don't really know).
What i need to do is convert it to serial rather than parallel operation and find a way to replace the cables with better shielded cables to reduce crosstalk. I just don't know how is that done.