SX-9000 My next project

patra710

Active Member
I pick this up at an auction the other day for $35. The front was in good but the wood cast was rough.
pioneer sx9000-2 006.JPG
I took the cover off and there was 47 years of dust in it. I blew out the dust and clean the pots. I check the DC offset at the speakers outputs and had about 700mV. A bit high but I hook up some junk speakers and it did play. I was a little lost at first till I seen that there was two volume controls, one was a master volume and the other a source volume. First time I seen that. And I got no FM stereo light but I found help on this in the forum here.
pioneer sx9000-2 009.JPG
I like the tone color control it has, it did make a little different but I expect more after a recap. The reverb didn't seem to do anything. the output transistors, one channel has the stock 2SD218 in it, the other channel has SK9237 in it. I took some Windex, an acid brush and a shop vac and got the boards on the top side clean.
pioneer sx9000-2 010.JPG
There is around 20 2SC458 transistors in this stereo that I am planning to replace with KSC1845FTA. I am also thinking about changing out the output transistors with MJ21194G. I don't like the idea of two different brands of output transistors. And I have to pull them out to anyway put fresh grease on them. I can't see the main amp board and I am wondering why someone replace those transistors.
I am starting to put together a parts list for this stereo. Does anyone knows of any other known problems with this stereo?
Thanks
 
The reason you see high DC on the speaker terminals is because that is a cap coupled amp.

That makes it sound different.

TOTL cap coupled Pioneer receiver. The best.

There are other problem transistors in there. 2SC1813? I forget. Bunch of them in the reverb board and I think the preamp or head amp board. Change those too.

There are a billion e-caps.

Once updated it’s going to floor you how good it sounds.
 
Thanks, I have done other Pioneers and I was happy with the results. I put together a list of the transistors from the service manual but still need to compare them with what is really in it. Not all of the caps match the service manual, mostly just a higher voltage. I counted 15 boards in this Pioneer so I got my work ahead of me.
When I got this Pioneer at the auction, there was a silver face Sony that was missing knobs and was only rated at 15 WPC. But someone paid more for it and pass by this Pioneer.
 
The SX-9000 is a sleeper but those damn transistors get noisy.
Every one I've had or seen was noisy.
I've had 2-3, worked on 1-2. Still have a couple more.

The transistors in the reverb can cause noise even when you have the audio off to the reverb.

Restoring those is just as much changing the small transistors as it is changing the e-caps.
If fact, fixing the noise is changing the transistors and there is no reason to not change e-caps while fixing except the owner is cheap.

Oh, fixing the function lamps is a joy too.
They used lamp cartridge type housings.
Since the cartridge is obsolete, you need to carefully take the cartridge out
, then open it and then put a new leaded lamp in, then put it all back together. About an hour time each!

Owning a great SX-9000 is either a very expensive labor cost or a true gift from a friend who will restore it cheap.

Since so few properly restored ones exist, they probably never will get the value they deserve.
 
Thanks again. I did some basic test, I put a square wave in and scope it at the pre-out. The square wave was not to square and the right channel was much stronger then the left channel. Putting a sine wave in and measuring at the pre-outs I got 371 mV AC and 491 mV AC where I expected 500 mV. There are still some switches that I couldn't clean until I take the front off but I don't expect much of a different. I check the output of the main amp with 8 ohm dummy loads and measure 22 V, about 55 watts on the right channel and 16.7 V, about 35 watts on the left channel. I did expect the left to be weaker because of the weaker signal from the pre-amp.
As far as the value goes, I just enjoy working on these things. I am retired and it fills my time. I will sell it in the end and I will make some money on it but no where near what I should. But then I will find another and start all over again.
 
They are a labor of love.
TOTL can be a challenge to work on with all the extra features.
 
I got my parts in, so I am hoping to start this project this weekend. Here is a picture showing the size difference of the 1970 caps and new caps. The big one is 100V 2200uF, the tall skinny on is 35V 2200 uF and the two coupling caps are 50V 2200 uF. Now how am I going to make this look good?
sx9000-1 001.JPG
 
This will be a very interesting build, thanks for the photos. I thought they would have had more filter capacitance for 50wpc.

All the best with it :thumbsup:.
 
Cap coupled outputs, the first one that I have done. I don't quite understand just how they work. My first power output test I got 22 V AC rms across my dummy loads, about 60 watts.
 
I got the power supply board rebuilt on this stereo. I change out all of the transistors.
2SC627----ksc3509
2SC485----KSC2073
2SC968----KSC2383
2SC971----KSC2690
Most of the voltages were good but the two at 86 volts came out at 75 volts and the 90 volt came out at 82 volts. These three go to the main amp so I don't know yet if something is pulling them down.
pioneer sx9000-7 004.JPG

I also got the big caps in. I got a big rubber coupling tube from the hardware store to fit around the caps and still fit in the clamps. I couldn't find a perfect fit so I had to cut some but they are in nice and tight.
pioneer sx9000-7 006.JPG

I got the tone color board done. I replace the 2SC458 with KSC1845. Played some music on it and it is sounding better. While playing music I played with the controls. Turning the mic control on the volume got louder. The same with the reverb but not as bad. So I hook my scope up to the preouts just to see and it increase. But the good news is now both side are more even. Before the left side was much weaker.
pioneer sx9000-9 003.JPG

The control amp will be next.
 
I got the reverb, mic and head boards rebuilt. Researching the transistors on the forum here, almost every transistor I look up was replaced by a KSC1845. The 2sc458, 2sc870, 2sc871 and 2sc734 all were change out for the 1845. There was one PNP transistor on the reverb board, 2sa561 which I used a ksa992.
pioneer sx9000-13 001.JPG
pioneer sx9000-13 002.JPG

On the main amp board
2sc484---ksc2073
2sa484---ksa940
2sc627---ksc3503
2sc870---ksc1845
pioneer sx9000-13 003.JPG
When ordering the parts I look at the schematic for the main amp and it didn't show any 2sc627 and I have no ksc3503 in stock. So now it sits here with a big hole in it till I get the transistors that I need.
pioneer sx9000-14 001.JPG
 
Hello:

I'm starting on one of these myself. Any chance you have a cap list put together I could take a look at for ordering purposes? If not when I build one I will post it for future reference. I'm not seeing a lot of threads on this receiver.

Thanks.
 
Friend asked me to look at his SX-9000. Things crackly like mad on the left... scared the hell out of me... loud enough to take out a speaker. Been through a few threads. Looks like either transistors or caps.. don’t think I want to get into this beast. Any ideas on where to start?
 
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