aiwa hs-pl50 without audio ..... restored

ok we narrowed the field... most likely the Q9 2sk880 doesn't work well... the red dot is connected to the volume channel that you indicated as not working...
on the blue dot you should have the audio output from BBE.
If you connect the two dots, to test, you should hear normal audio...

 

Let's go for it! Should I check the Q conecting to an amplifier, joint dots and negative to he ground? Maybe this time have to solder both dots and pass the wire to the other side to the pcb in order to performance the test easily

 

So starting from R43 in blue on the left, following the circuit on the other side ... cross the capacitor and get to Q9 on the right ... from the red pin following the circuit back to the left and enter the potentiometer

 

If I understand well , it should have been sound at the red dot of the left side if the Q it`s ok

 

Quick update, I found from an old aiwa a donor Q, desolder the bad one and solder the donor, unfortunately, nothing's change

 

Left channel not any sound from. By the way I decide to desolder the right' Q channel and test the bad one putting at rhe right channel, , no sound, when I solder again the god one at the right channel, not any sound in both channels

 

Not any sound at the BBE outputs, I assume the Q's gone bad during the soldering and desoldering process, or the solder is not well executed, altouhg it seems to be ok. I order 4 new Q's to install fresh ones. Now the only sound is the beep that confirms operation when you press the buttons, play, stop.... But only through right channel, It's confusing. Maybe there is something wrong in the ic. I think the troubles could be caused for a suddenly peak of voltage for not using correct current adaptor

 

I test the pre-amplifier outputs too, the are normal sound

 

and true I have not taken into consideration the audio Beep ( green square )
you should hear it on both channels ... enter where a few photos ago I indicated Amp In ... another test before replacing the cip ... check the welds on the output capacitors

 

I've found in Ali Express a second hand pre- amplifier ic, for 3€, I have ordered, until it arrives, I try to test all I can. I think it's not a weld issue cause before recapping only one channel sound was present. Maybe it woul be a corroded or broken trace. I'll check continuity comparing my other unit to guess where the trouble is located

 

Resoldering the q's , now have the right channel working again, and not any sound or beep at the left channel. Testing with an amplifier, pre and bbe out ok both channels. Compairing with my other unit, R51 had to have sound but don't have, from here R17 and R19 don't have too, However, R52, R18 and R20 ( right channel) have all sound

 

These are the resistors that don't have signal. I'm still have waiting for the pre amplifier ic, meanwhile I keep on testing and seeking for clues

 

HI
the left and right audio signal arrives on the output capacitors of the BBE and enters the MOSFETs (Q10 - Q9) as indicated in the picture as indicated with the arrows... you should have the signal at these points on both channels...
Returning to the previous published photos.. if on the volume input you have only one channel that works...
it means that one of the two Mosfets (Q9) does not work. To test.. you can exclude Q9 and connect pins D and S together (see diagram ) and check if the audio reaches you at the AMP input...
these two Mosfets only have the Muting function, they are like two switches that you open and close the audio when needed... but if you want, you can do without it for now

 

At least some leasure time.

With the Q9 bridged, signal arrives to the input volume, but still not sound at left channel. Since that point I was following the schematic, the cuplrit since to be resistor 17, after it there is not audio signal

 

If I joint this way, skipping the R17, the left channel works

 

Resistor 17 have to gone bad, it's no very usual, I think, a resistor fails.

At that point, the bad news are the right channel has lower volumen than the left one. I was adjusting the gain but not way. The sound pressure in channel right is not loud enough.

Again throught the schematic, I've adjusted the gain at the BBE outputs, R29, R30, to have similar sound level at both channels. From there I was following the signal path, I founded a slightly drop between R50 and R48

 

It seems R48 gone bad, connecting that way both channels have same sound level

 

Hello ..it's been a while ...
I don't recommend connecting the resistors as it is
R48 and R50 are separated by two different functions and connecting them together can be harmful
R17 -C17 -R19 are directly in audio output to the headphones
R17 at a value of 3.3 ohms
If you have replaced the capacitors check that C17 is in place and with the polarity in the right direction i.e. + towards R17

 

the connection you made on R17 and by doing this
you exclude both R17 and Capacitor C17