Weird patchbay issue

[pucho812]

I have a couple of points on a patchbay that will not pass phantom power unless I stick a dead patch plug in those points. When I do The phantom passes to the mic lines and live room without issue.

phantom is derived at the patchbay via switches feeding 6k81 resistors above the Jackfield for mic lines - mic pre. It only happens on 3 jacks.

i would assume a wiring issue at the Jack field, like the trs Jack and the shorting jacks were wired in reverse.

 

[Brian Roth]

Question.....do I ASSume correctly that it is a "full normal" patchbay with switching jacks on top and bottom row?

Bri

 

[abbey road d enfer]

I would suspect the shorting contacts are shorted to ground.
What side are the resistors wired, mic side or console side?
Where do you have to put the plug?

 

[pucho812]

Patchbay would usually be a full normal. But this setup has it as a half normal. Top row is mic lines, bottom row is mic Pre input. Here is a upside down photo. What should be the top, you can see the push pull switches and red led’s for phantom. In the rear of the switches are 6k81 resistors and voltage drop resistor for the led. Phantom runs across the top there and when assigned per channel how into the row labeled mic lines which run into the studio. Phantom is not assigned via the channel strip. I have been told this was a feature called “remote something” on an mci 600 but this is not an mci desk. Anyway I assume the half normal was done to allow patching in mics from the control room or elsewhere. To get phantom on a condenser in the control room, you patch into the row labeled mic lines. This would get the mic phantom power and still send it to the mic pre on the desk.
On the points I dead patch to get phantom to the live room, I am patching in the top row labeled mic lines. This gets phantom out to the studio while allowing signal to the mic pre on the desk.

 

[abbey road d enfer]

Well you really need to check the wiring. As I said there is something shorting the blades to ground.

 

[pucho812]

Well you really need to check the wiring. As I said there is something shorting the blades to ground.

Wiring checks o.k. The row sending phantom wires up the 6k81 resistors to the Tip and ring solder connections of the mic line row. which is also wiring to the ts and rs jacks on the lower row making the half normal and out to the live room.

 

[abbey road d enfer]

. Anyway I assume the half normal was done to allow patching in mics from the control room or elsewhere.

Full normalled would also allow that. It would also allow.
Full normal makes sense only if the switches are connected to a default apparatus, so plugging in the Studio Line allows diverting the signal to an other apparatus, while disconnected the default apparatus.
Are you sure there is nothing connected on the RS and TS?

On the points I dead patch to get phantom to the live room, I am patching in the top row labeled mic lines.

This tends to ascertain my assumption.

 

[JohnRoberts]

Perhaps use a VOM looking at the patch bay terminals and see exactly what is going on, or not.

JR

 

[pucho812]

Perhaps use a VOM looking at the patch bay terminals and see exactly what is going on, or not.

JR

yes... working t remove heat shrink and do so. the grounds are bussed so makes it a little more of an annoyance to get a jack out and see the real deal

 

[pucho812]

Nothing on the TS and RS for the top row(mic lines), TS and RS are wired on the bottom row(mic pre). Yes it is a half normal.

 

[abbey road d enfer]

TS and RS are wired on the bottom row(mic pre).

They should be wired to the T and R of the upper row; correct?

 

[pucho812]

They should be wired to the T and R of the upper row; correct?

Yes they are wired to tip and ring on the top row. they are connected from tip and ring of the top row to ts and rs on the bottom row. A half normal.