Boss RSD-10 front panel defeat when keyboard pitch input utilized

[hangnef]

I have racked my Boss RSD-10 (and RPS-10) and also hooked it up to a patchbay and I discovered that I can't put the keyboard pitch input into the patchbay. Placing a cable into the jack effectively disables the entire front panel.

Is there a straightforward way to get around this, like maybe putting a shorted TS cable or something similar into that jack on the patchbay when not using that functionality?

I'm also comfortable with making mods to the circuit etc if necessary (I've already done the 100% wet mod on it). But the circuit diagram for the input is confusing to me. It seems that both tip and sleeve of the jack are grounded until a connector is inserted (probably mis-interpreting it). If that is the case, I could probably add a front panel switch to control it.



Any ideas on what I could do here? Would like to keep these in the rack and utilizing the patchbay, but I do want to use that Keyboard Pitch input as well.

[duck_arse]

let me say first off, I know nothing about these keyboard things you mention. and you've cut-off part of the circuit that might provide clues - but  - as I read what you've shown, with J6 empty, the tip is shorted to ground and the ring is no connection [and other end indeterminant, but interesting]. when you inplug a mono plug, tip unshorts from ground for signal, and the ring dinger will connect to ground. this might effect the un-shown in the manner causing your problems.

simple test - plug in a stereo jack and the ring won't be grounded.

[hangnef]

let me say first off, I know nothing about these keyboard things you mention. and you've cut-off part of the circuit that might provide clues - but  - as I read what you've shown, with J6 empty, the tip is shorted to ground and the ring is no connection [and other end indeterminant, but interesting]. when you inplug a mono plug, tip unshorts from ground for signal, and the ring dinger will connect to ground. this might effect the un-shown in the manner causing your problems.

simple test - plug in a stereo jack and the ring won't be grounded.

Makes sense, thanks!

The keyboard thing is just an input jack that is used for detecting pitch, and the pitch can control things like delay time.  But when this is done, it disables the use of the front panel.  So, in a patchbay situation, I can never use the front panel with that plugged into the patchbay.  I currently connect to the patchbay w/ a stereo cable and it behaves this way (when connected - no front panel).  I should try a mono.

I've also attached a larger portion of the schematic.


If the tip is shorted to ground, could some kind of dummy plug be used in the patchbay to emulate the same conditions as nothing plugged in?

[duck_arse]

well now, see that extra bit tells the story. un-in-jacked tip is grounded for AC, so won't be doing any controlling. but now we see the ring connection should be high from R99 and turning ON IC 7c via R111. inplugging a MONO plug will pull that line hard LOW via R95, doing "things" to the gate and transistor. so, again by my reading, plugging in a stereo plug, with the [plug] ring not connected to anything, shouldn't change the internal states, but for the tip doing its thing.

[hangnef]

well now, see that extra bit tells the story. un-in-jacked tip is grounded for AC, so won't be doing any controlling. but now we see the ring connection should be high from R99 and turning ON IC 7c via R111. inplugging a MONO plug will pull that line hard LOW via R95, doing "things" to the gate and transistor. so, again by my reading, plugging in a stereo plug, with the [plug] ring not connected to anything, shouldn't change the internal states, but for the tip doing its thing.

Thanks again for the analysis, and you are 100% right, it behaves that way.  Mono cable into the keyboard pitch, no front panel control, stereo I can.  I tested this with the unit removed from the rack and detached from the patchbay and using just TS and TRS cables to test.

However, as I mentioned the cable connecting the Pitch input to a jack in the rear of the patchbay I'm using (A Behringer Ultrapatch pro, which has balanced inputs/outputs) is stereo but it behaves as if I have a mono cable plugged in.  The patchbay does have "normaling" etc, but it is to connect a top jack to a bottom (i.e. for send/returns, inserts, etc).

I would have thought the patchbay would be 'transparent' in connections.   

[duck_arse]

let me say first off, I know nothing about these keyboard things you mention.

so, any light at the end of the tunnel solution wise? special custom made cable, perhaps?

[hangnef]

let me say first off, I know nothing about these keyboard things you mention.

so, any light at the end of the tunnel solution wise? special custom made cable, perhaps?

Hehe, not sure.  I need to figure out the characteristics of the patchbay that is causing the issue.
Another option would be to put a switch on the front panel that acted the same as there being no cable inserted (would probably have to cut a trace as well, not a big deal).

[hangnef]

I think I may have figured out what is going on, would love to hear if it makes sense.

It seems the *length* of the cable comes into play.  Stereo cable works, but not if it is too long.  This particular effect box is run via maybe a 15' stereo cable to the rack.  It doesn't work.
Using a short stereo cable between the device and the patchbay works fine. 

I know I've read in the past about the length of cables increasing capacitance, but I'm not sure if that's the case, and if it were how it affects the circuit.

[PRR]

> if it makes sense.

I doubt it.

[hangnef]

> if it makes sense.

I doubt it.

Good call, it turns out that particular patchbay jack was set to normalled (I've been doing a lot of re-arranging).  Working fine w/ the stereo cable.  Something about the length did have an effect though, very repeatable, but wasn't the actual issue.