ART PRO MPA 2 - XLR chanel 1 is not working

[mindw0rk]

Hi Guys!

I have got ART PRO MPA 2 preamp and XLR input on channel 1 is not working, the DI (HiZ) of the same channel is working, chanel 2 is ok, I have attached a schematic from the similar thread... I am not sure where I shall look for the issue, I can't read the schematic, is there any chance you can point me out where I shall look for?

 

[moamps]

If the instrument input works on the first channel, then the problem is in the microphone preamp whose schematic is framed by a red rectangle. If you have a multimeter, a fault can be found using the faulty and correct microphone channel comparison method.

 

[Ike Zimbel]

If the instrument input works on the first channel, then the problem is in the microphone preamp whose schematic is framed by a red rectangle. If you have a multimeter, a fault can be found using the faulty and correct microphone channel comparison method.

OR, the switching contacts in the instrument jack have gone bad, a fairly common point of failure in mic-pre's that have an instrument input downstream of the Mic input. Try plugging a jack in-and-out of the instrument input, say ten times, and then see if the mic pre wakes up.