Hello,
I was very curious to know if anyone has ever been inside one of QSC's CP line active PA speakers/monitors. Channel one on my fairly new CP8 is out. I loosely suspect that a huge POPPING issue with our digital mixer may have electrically stressed the channel one input. Channel B works fine so the power supply is still there.
If anyone can tell me what to expect when I open it up for trouble shooting that would be great. Unfortunately, I've found nothing in terms of schematics, articles, forum thread, and not even basic diagrams. I'm an electronic tech by day and have a good test bench set up at home but, no clues what to look out for once I get in this weekend. Channel fuses? Input OP amps?
Anything would be helpful.
Thank you!
Best
Phil D
I was very curious to know if anyone has ever been inside one of QSC's CP line active PA speakers/monitors. Channel one on my fairly new CP8 is out. I loosely suspect that a huge POPPING issue with our digital mixer may have electrically stressed the channel one input. Channel B works fine so the power supply is still there.
If anyone can tell me what to expect when I open it up for trouble shooting that would be great. Unfortunately, I've found nothing in terms of schematics, articles, forum thread, and not even basic diagrams. I'm an electronic tech by day and have a good test bench set up at home but, no clues what to look out for once I get in this weekend. Channel fuses? Input OP amps?
Anything would be helpful.
Thank you!
Best
Phil D
Could only find this.
https://adjuntos.yoreparo.com/default/0006/44/2224fac037f71af6ec7d0898f537a893137e1102.pdf
https://elektrotanya.com/showresult?what=QSC&kategoria=All&kat2=All
Might as well check the input cap if nothing else.
https://adjuntos.yoreparo.com/default/0006/44/2224fac037f71af6ec7d0898f537a893137e1102.pdf
https://elektrotanya.com/showresult?what=QSC&kategoria=All&kat2=All
Might as well check the input cap if nothing else.
Last edited:
Thank you Rayma,
Reading the service manual for K2, it mentions that should a high strength signal be input into a channel, the first thing to probably be effected are the differential resistors. Of course, the longer the signal is the more components related to the input would or could be damaged. So, that's a very good start. I should be able to ohm out the connections to the input of channel A and move on in, apply some sine wave and things.
Thank you very much Rayma,
Best,
Phil D.
Reading the service manual for K2, it mentions that should a high strength signal be input into a channel, the first thing to probably be effected are the differential resistors. Of course, the longer the signal is the more components related to the input would or could be damaged. So, that's a very good start. I should be able to ohm out the connections to the input of channel A and move on in, apply some sine wave and things.
Thank you very much Rayma,
Best,
Phil D.
Good luck, often there is a family resemblance in circuitry among different models of a company.
Hopefully that will be of some help.
Hopefully that will be of some help.
Thank you for feedback on this. For reasons I just can't explain, channel one is functioning. This CP8 was used as my monitor for the last 2-3 gigs of the concert season, and both times, or three times, channel A was tried with no sound, and when the XLR was moved to channel B, I had normal monitor output. That is usually enough tries to be confident that there was a repeatable issue but, by both feeding a sine wave into both the inverting and non-inverting input of the balanced input, and also sending a typical mic pre output to the the channel, all is well. Ha. This is more mystifying than an actual problem.
I'm grateful but, it would have been more resolving to actually have identified a specific reason for the non-output!
Thank you again for coming by, I'll try to make the next issue I have not be such a phantom!
Best,
Phil D.
I'm grateful but, it would have been more resolving to actually have identified a specific reason for the non-output!
Thank you again for coming by, I'll try to make the next issue I have not be such a phantom!
Best,
Phil D.
It could have been a physical connectivity issue. My band did 27 concerts in 5 weeks and much of those gigs had extremely hot and humid climate. We were actually nearly passing out from heat, dizzy and weak. Thinking about that, it’s probably possible that a lot of water got inside the CP8 and began messing with things. Our mixers and digital drum modules were also doing very strange things. Perhaps this CP8 had time for moisture to “gas off” and return to functionality. In work right now, one of our auto defibrillators has ceased production do to failing its own self test, mostly in harsh hot environments. I increased the relative humidity and when it hit 93% the unit would fail it’s self test and not let you defib. So, I’ve recently witnessed first hand what a show stopper humidity in the air can be. We are experimenting with conformal coating on various parts of the unit and it’s board to see if that protects from moisture.
Best
Phil d