PROBLEMS WITH A PIONEER QX-949 AMP SECTION

[JAZZIQUAD]

--I own a PIONEER QX-949, it was working ok, but now it presents the following problems:

1.-The FL channel sometimes goes in an intermittent sound or totally out, curiously it fix up pressing the power switch of a deck connected to one of AC outlets, or with a considerably volume increment.

2.-The FR channel sometimes goes totally unbalanced in relation with the other channels, fixing it increasing the volume or turning off/on the receiver.

3.-The RL channel suddenly never worked again.

4.-The more recent problem is in the protection circuit, I think, and maybe is consequence of the above symptoms: sometimes all the output goes down after a "click" (like the one of the fuse when turning on the unit) and turns on again with a "click" to then repeat it in irregular intervals.
What do you think is the problem? What should I ask from the repair service? Do you think I'll need any parts?HOW COULD I CHECK THAT THE DEMODULATOR AND DECODERS ARE REALLY WORKING?

I'm a very young quadlover so I would thank any answer, advice or help of experienced people like you...
THANKS. JAZZIQUAD.-

 

[The Quadfather]

Protection circuits are usually tripped by an amplifier putting out a DC voltage. This is often caused by a fault in the amplifier, or if a DC voltage from a leaky capacitor is fed to it from the control amp section. With DC coupled amps being popular at the time, that is entirely possible. So, put it on the bench and check the output of each amp where it leaves the amplifier board, when the relay is tripped, and no signal fed. Also, a thermal overload could cause a trip if an amplifier is heating up. Either way, you still have to fix the amp, and if you're not an audio technician, I recommend you find one. This is not an easy type repair. The good news is that the parts should be easy to find. Good luck,

The Quadfather

 

[JAZZIQUAD]

QUADFATHER:
Thanks for your advices, they are very usefull to make suggestion to the tech.
THANKS AND GOOD QUADING!

JAZZIQUAD

 

[The Quadfather]

You're welcome! May the fource be with you!

The Quadfather