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Pioneer QX-949 We have a Pioneer qx-949. It will power up. We hear the relay click like it's going to work for a second. Then it makes a little tick sound and it won't produce sound. We love this unit! Please help us find a solution.

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From Charles (owning a QX 949, still working but with some investment into repairs by myself) :
QX 949 contains a "power protection cirquit". This cirquit reacts aswell on short-cirquit (either within the output-amplifier cirquit {transistors} or by faulty speakers) as on overload (by playing musik toooo loud).
Your QX 949 might therefore either be affected by short-cirquit within one of the four output amplifiers or there might be a problem within the pre-amplifier or power section, causing an AC or DC signal to appear at the inputs of the output-amplifier section and therefore overloading the output, as if music was played too loud. First basic test: does the discribed "tick sound" (which means that after power-up the protection cirquit releases the relais again) also appear when the volume is turned down completely ? If not, the fault must be a signal produced within the pre-amplifier section before the volume regulation. If yes there still could be a pre-amp problem after the volume regulation but it´s more likely to be found within the output-amp section. One won´t get round to measure this section (oscilloscope) at it's signal inputs to exclude a faulty signal to arrive there. If this is not the case I would recommend to disconnect and reconnect the four output-amps from the power supply one after the other, for finding which one causes a short-cirquit. But before doing this: try out what happens if you change QX 949 into 2-channel mode by turning the socket on the rear panel. Doing this the output amps for the rear channels are deactivated. If your QX 949 was working under these conditions it would limit your further search to the amps for the rear channels.
There is also a small chance that the power-protection cirquit as such is faulty or that the power supply contains problems. The power supply has got 6 fuses that you will find underneath the bottom plate. Are they all still ok ? (If one of them is broken then there can be a positive or negative supply to the output-amps as these are receiving + and - DC-currents from the power supply)
Basically: this amplifier is almost about 30 years old. As the lifetime of electrolytic capacitors ends after about 15-25 years there appears the need to replace them all (on all the prints). I did it with my QX 949... but you definitely must love yours to do that, it's quite an investment of patience and time.
And: servicemanuals.net display on their webpage availability of QX 949´s service manual. If you can't find it I might be able to scan some pages.
Charles (Switzerland)

Posted on Mar 28, 2008

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Hello

I have one to, with i think the same problem.
Change the trimmers on the output board, then it works again, my did.

best regards
Torben Schellerup (Denmark)

Posted on May 13, 2009

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I bought this new in the early 70's and love it, but, I now find trouble with the push buttons..They are not working well and I have to push several different buttons and my speakers will pop on and then turn off. Is this a problem with the buttons and can they be cleaned. Also I don't know if the push buttons can be removed for cleaning...Any help would be really appreciated. Thanks Paul

Posted on Mar 11, 2010

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I have a pioneer 949, great amp but I lost the sound. It fires up but won't play sound . Don't want to lose this amp. please help

Posted on Oct 06, 2008

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