MG100HCFX "howling"

[ando_assi]

First post...

My MG100HCFX started howling (<1KHz) when ever any cable is plugged into the input Jack.
It is quiet when there is nothing plugged in, it plays AUX input with no problem.

Once i opened the unit L6 was blown on the input PCB. It seems to be an inductor from the -Signal on the cable to the - input on the pcb.
I have tried a few values and nothing seems to fix it, when i put a signal generator on it, the noise is gone.

Any ideas would be greatly appreciated.


HELP

[loudthud]

First post...
I have tried a few values and nothing seems to fix it, when i put a signal generator on it, the noise is gone.

A few values of what? Try a short length of wire.

[ando_assi]

A few values of what? Try a short length of wire.

Sorry, i have tried a few different inductor values from various other electronic projects.

If its 0603 size component and my multi meter says its low R i treat it as a Inductor.
I have also tried 0R resistor (no change)

...and i just tried a 100mm length of wire still NG

any other ideas?

[ando_assi]

Thanks, and sorry for the lack of detail.

I have tried a few Inductor values. (From other electronics just kicking around)
If it is not coloured like a resistor and the Multimeter says really Low R i assume it is a Inductor.



... ok, that is crazy, a small length of wire worked. I have tried a 0R Resistor, other inductor values hmmmm

Well... THANKS

[alexradium]

that should be a 250 uH inductor,those are pretty redundant rf protection that Marshall likes to put in any product because they want to meet all the world requirements regarding emissions.
Does it cause any problem if you just short it?

[Jazz P Bass]

L6 is the component that connects to ground.

Without it, your instrument has no connection to amplifier ground.

I agree, for now run a wire.

(I for one would like to know what toasted that component.)