API lunchbox B 6 slot

[haystack]

Hi

One channel of the lunch box (3) is not sending 48v phantom via 512c module to the mic along the rear input
xlr. All others are fine and channel 3 is fine if  I plug a mic into the front xlr socket of the module.
I have checked voltages= all have 48v via pin 2/3 on the output xlr except 3.

I am not too sure about the connections inside as I have had a look, but has anyone fixed pcb/xlr /Dsub connections
in a lunchbox?
thanks Haystack

 

[joaquins]

If a non phantom powered mic is working properly the problem may be in the module, did you tried the module in other slots?

I could think in two sources for that problem, the slot connector or the phantom network going to that input (6k8 resistors, ~220µF cap, ~200Ω resistor, switch) or the connector. If the module works fine in other slot is the network, if other module works bad in that slot is the connector. If non of this is true or both there is something else happening, but I doubt that.

JS

 

[haystack]

Hi Joaquins

Thanks for replying.

The module is fine in other slots - healthy 48v measured with DMM. Other modules do not work in that slot either.
Do you think the connector may be bad - that is the socket that the modules pushes into?
Where is the network - is it on the psu board? So this may be at fault?
thank you
Hay

 

[haystack]

I thought I would add that a module works fine in slot 3 if -

mic is plugged in the front input on the module and output xlr at rear  of lunchbox is connected to AD/D.

Phantom is fine and getting to module (api 512c) but not getting fed through input xlr at rear and therefore  to mic.

Hay  :-\

 

[joaquins]

Does a dynamic mic work properly in that slot? other modules work properly in that slot? (even same level)

If dynamics mics don't work properly there the connector where the card sits into have a problem, if it where the PCB fingers (on the module) I've seen it's recommended to use a pencil eraser to clean it, but for the female, on the main board of the lunchbox you probably should use a contact cleaner and figure out some way to move things around without braking anything, probably a scrap PCB pice, I don't know, probably someone here could recommend a way to do it properly. Start with a contact cleaner and a soft brush and see if that works. The input contacts are in the middle of the connector, so concentrate on those.

JS

 

[ruffrecords]

Check the solder joints on the motherboard connector on that slot. Could be a dry joint. I have also seen PCB traces crack as a result of repeated insertions of modules so that might be the problem. A quick resistance check from the XLR to the motherboard connector pins will help.

Cheers

Ian

 

[haystack]

Thanks Ian and thanks Joaquins.

Going to open it all up again and check that resistance connection etc.