Wanted to post this as a little project for your eyes and also for anybody who might have similar problems with the amplifier, this or other model of Pioneers SX series.
The main problem was "hissing" sound or somekind of low noise on the right channel. I thought that it was just leaking caps and went right away to change every electrolytic I found.
It was pain in the ass to do, because not all of them were possible to change underside. I needed to remove the amplifierboard and to do that I had to cut the wires or remove them from the taps. I took notes and draw what goes where. After the testing, it wasn't the caps. Noise wasn't still gone, I was getting frustrated already because the unit cost me nothing and some of the caps were pretty pricey.
Then I figured to read some forums on the net that some other guy had the hissing thing too and he was advised to replace all of the noisy NPN transistors, 2sc1344 and 2sc1345. There were 8 pieces of 1344 and two 1345's. I figured that 2sc2240 is better and matching, it also has same leg order. I ordered 15 of 2240's and when they arrived I just checked the B-C-E right, put them right in, cleaned the underside of the board with nailpolish remover (acetone free).
I was so sure that I've made a mistake and thing would explode after I hit the switch but luckily this wasn't the case. I measured voltages from the outputs, that I wouldn't burn my speakers. Everything looked fine and I connected the speakers, luckily I didn't do mistakes and out comes the music!
Some pics of the (almost) finished product for your eyes to feast on! I also changed the old wire with round plug that didn't have grounding to a IEC socket with filtering. Can be seen on the pics.
The thing with black background will be laminated or lacquered on top of the unit because I painted the front black.
The main problem was "hissing" sound or somekind of low noise on the right channel. I thought that it was just leaking caps and went right away to change every electrolytic I found.
It was pain in the ass to do, because not all of them were possible to change underside. I needed to remove the amplifierboard and to do that I had to cut the wires or remove them from the taps. I took notes and draw what goes where. After the testing, it wasn't the caps. Noise wasn't still gone, I was getting frustrated already because the unit cost me nothing and some of the caps were pretty pricey.
Then I figured to read some forums on the net that some other guy had the hissing thing too and he was advised to replace all of the noisy NPN transistors, 2sc1344 and 2sc1345. There were 8 pieces of 1344 and two 1345's. I figured that 2sc2240 is better and matching, it also has same leg order. I ordered 15 of 2240's and when they arrived I just checked the B-C-E right, put them right in, cleaned the underside of the board with nailpolish remover (acetone free).
I was so sure that I've made a mistake and thing would explode after I hit the switch but luckily this wasn't the case. I measured voltages from the outputs, that I wouldn't burn my speakers. Everything looked fine and I connected the speakers, luckily I didn't do mistakes and out comes the music!
Some pics of the (almost) finished product for your eyes to feast on! I also changed the old wire with round plug that didn't have grounding to a IEC socket with filtering. Can be seen on the pics.
The thing with black background will be laminated or lacquered on top of the unit because I painted the front black.
Attached Files
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