Soundcraft Spirit Mixer stuck in PFL solo mode

[desol]

I just picked up one of these little rac pac mixers three weeks ago, from a guy in Montreal! It's actually really nice and in great shape. When it arrived, it was doing the same thing....my two stereo channels had the solo LED's on, despite the switches being depressed or not.  At first they were on solid, but after a day of the mixer being on continually they started to flicker on and off. I started tapping the chassis in the area of those two stereo faders and it seemed to affect the LED solo lights that were flickering. Since then, it has totally stopped and the mixer is working well. Funny how this thread was right here, with the same thing happening to me.

Has a decent sounding eq. The phantom voltage can really pop if you don't turn all the faders down before engaging.

PS - really happy to see service manual here. downloaded instantly! thanks man!

 

[substitute]

PS - really happy to see service manual here. downloaded instantly! thanks man!

Glad to be of service. I found it on electrotanya I think.

That's wild that your's was having such a similar issue, the switching for the SOLO circuitry is much simpler (to me) on the stereo channels.

 

[substitute]

I replaced Q4, it wasn't fun, really small pads and I had remove a daughter board to get to it.  It's done though, and the prognosis is good, SOLO switching is behaving normally.  The mixer is still in pieces and I want to test it with audio before I put it back together, I can't really get to the jacks but I think I can just clip my function generator to the input circuitry for testing purposes.  I'll let yall know how that pans out, not ready to call it good yet.

Also, I'll poke around and do a bit of reverse engineering to see if we can uncover the Q4, Q3 mystery.

 

[JohnRoberts]

I replaced Q4, it wasn't fun, really small pads and I had remove a daughter board to get to it.  It's done though, and the prognosis is good, SOLO switching is behaving normally.  The mixer is still in pieces and I want to test it with audio before I put it back together, I can't really get to the jacks but I think I can just clip my function generator to the input circuitry for testing purposes.  I'll let yall know how that pans out, not ready to call it good yet.

Also, I'll poke around and do a bit of reverse engineering to see if we can uncover the Q4, Q3 mystery.

be careful... do not harm working circuits by probing too much...

JR

 

[substitute]

Tested good with audio, repair seems to be a success. Thanks for your help John.

As far as the Q3/Q4 junction, it appears that the schematic is accurate to the PCB.