Need help changing Markbass effects loop from parallel to series.

[B String]

I have an F500. I'd like to change the effects loop from parallel to series. I "think" I have the right pictures of how to do this. After changing one jumper from parallel to series, and taking the other jumper off, I get no volume plugging into the F500 input. (as expected) I plug into my Sansamp and into the effects return. This gives the master volume on the F500, but the preamp still effects the sound. Bass, treble, etc. What gives?? The only thing that should be usable is the master volume.
Any pictures info or thoughts would be VERY helpful.

 

[B String]

So I take it nobody's doing these kinds of mods anymore? I'm gonna bump this up just in case it got missed.

 

[FrankG]

I modded my LM 3 this way. U need to have either no cable connected at all or send and return connected obviously. If i set my erfects to standby, i hear no impact on the amp sound, master volume is independent to it also.

 

[DirkP]

On the older LMII and the F1 this can be done by changing a jumper setting. I guess the F500 is the same.
Invalid Link Removed

 

[allboutbass]

Hi,
I was wondering about the Mark III ... is it necessary to do the second jumper as well ? ... I was wondering what this second jumper does, the first one is pretty clear to me.
Hope some one knows.

 

[Sparky Mark]

Hi,
I was wondering about the Mark III ... is it necessary to do the second jumper as well ? ... I was wondering what this second jumper does, the first one is pretty clear to me.
Hope some one knows.

Firstly apologies that I don't know the answer but it makes sense to me that if you are wanting to break one signal path and reroute it then two jumpers may be required.