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SA-910 (SA-9100) Hiss/static and other issues

R

r_s_guy

New Member
I recently acquired a Pioneer SA-910 integrated amp. This is the Japanese 100V version of the SA-9100. Although it sound OK when I heard it at the seller's place, I realize it has a hiss coming from both speakers at all times, a bit louder on the left channel. The hiss is there even at 0 volume, and gets louder the longer the amp is on. There is more hiss if I turn up the volume to high levels. The hiss is still there and exaggerated when I run the amp in separated pre/power mode but with jumper cables connecting the pre to power. The loudenes of the hiss switches sides when I flip the jumpers between L/R. When I connect an external power amp to pre out the hiss is still there with the same loudness. If I use an external preamp into the power in, the hiss somewhat there but reduced to very faint and only at high volume.

Opening up the unit, there is nothing that is immediately apparant as a faulty component, other than one of the 15000uF filter caps having a slight bulge and feels softer. Is this what's causing the hiss? I thought a failing filter cap would produce a 60hz hum, instead of a hiss.

Anyone have exact steps/pictures to extract and recap the filter caps? All the boards in this unit are secured to the chassis with plastic tabs instead of screws. I can't figure out how to disengage these without snapping it. They seem snap at the slightest tug and squeeze.

Help to resolve this issue would be greatly appreciated!
 

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That soft area on the filter cap is just a plastic cover.

The source of the hiss is most likely caused by noisy transistors in the preamp.

Rob
 
Robisme said:
That soft area on the filter cap is just a plastic cover.

The source of the hiss is most likely caused by noisy transistors in the preamp.

Rob
Click to expand...
Any idea which circuit board I should start with? I've heard some of these pioneer units have a well known problem transistor
 
r_s_guy said:
Any idea which circuit board I should start with? I've heard some of these pioneer units have a well known problem transistor
Click to expand...
All of them! There's 2SC1312's everywhere, and the nasty 2SC1451's on the amp board. And the power supply on this model needs some bigger resistors, the power supply gets really hot. Protection circuit needs the usual mods.
 
So, based on my symptoms, does it sound like I should focus on the 2SC1312s on the Control Amp board (AWH-023-B) first, to locate the faulty one(s) or just dive right into replacing all of those trans?

What are the good replacement for those?
 
Gonna give this one a bump as my 9100 just started with the same issue, hiss. Would love to know a source/ replacement for the transistors.
Thanks!
 
Bump, with a new question. I'm looking to get a complete recap kit for SA-910 but can only find kits for SA-9100 in USA. Are the components and values the same for both units? Or different because one unit is for 100v vs 120v?
 
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