• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Pioneer SX-690 restoration project

bemboc

bemboc

New Member
Hallo,

I am Gyula from Hungary. I bought an incomplete receiver from a friend. It already works electronically, I replaced the STK0039 integrated circuits and some components. Unfortunately, the front panel is missing. I buyed more parts from ebay, but I haven't found a nice front panel. I would like help with that.

Thank You!
Gyula

(The Pioneer SX-680 front is also said to be good for it.)
 
Register to hide this ad
Welcome Aboard!

The exterior front panel from the SX-680 will work, and is probably much more available:
 
Concur with Watthour. The only real difference between the 680 and 690 is the dial face itself. 680=Silver face with Black lettering. 690 Black face with Silver or White lettering.
 
Unfortunately, so far I have only found a scratched front panel on ebay. I'm also in trouble with the STK, I had to replace it again.
 
The replacement modules linked by @merlynski are all but bullet-proof. They far exceed the performance of the originals, let alone any fake/knock-off modules which might be offered as "new" today.
 
bemboc said:
Thank You!
I probably bought a fake STK. Is original disassembled STK IC reliable?
Click to expand...
I have personally used these DIY modules in a Pioneer SX-780. I acquired the bare boards and heatsink plates, ordered the parts from the BOM, assembled the modules, flattened the heatsink plates, mounted them to the SX-780 internal heatsink, and fired them up, first on a DBT, then on full mains. They worked perfectly. The only thing 'out of the ordinary' is the bias (idle current) adjustment on the board: minimum bias is full clockwise, and you adjust counterclockwise to increase bias. I found they worked great and were completely stable, with excellent sound quality. If you go to the link I posted you will see they have been used successfully to replace multiple different STK modules in different manufacturers amplifiers, including the Pioneer SX-580. I consider them as a significant upgrade from the original STK-0050. And IF you cause one to fail it is repairable.
I gave that SX-780 to my son for a wedding present. Two years later it is still their daily driver.
 
Last edited:
Merlynski. 0050's are full complimentary, the 0039's are quasi comp! Is that going to make a difference????? I was going to suggest RCS16's modules, but double checked the schematics on both 1st.

Larry
 
Larry,
The hbrown/rcs16 replacement for the STK-0050 has been successfully used in the SX-580, which has an STK-0029 in it. The '29 is also a quasi-complimentary architecture. The input side circuitry to the module on the SX-580 and the SX-680 are identical, as far as I can tell (power supply is a bit higher on the SX-680), and the SX-680 has 0.22Ω emitter resistors just like the SX-780. The SX-680 has a higher output stage voltage power supply (±30vdc) than the SX-580 (±28vdc). It should work just fine, IMHO.
 
Thank You. I will trying to get a donor device because of the front panel. I would like to replace STK IC with transistors. I read the things on the link. Why is surrogate circuit more complicated than STK internal circuit? What quality can be brought out of this receiver? A SONY STR-6045 is currently in use with Dual 701 turntable.
 
@bemboc The drawing of the 'internal circuit' of the original STK modules is a simplified equivalent, not an actual exact representation. The schematic of the hbrown/rcs16 STK-0050 custom modules is the actual full schematic of the module, as it is built on the printed circuit board.
 
bemboc said:
I ordered a donor device today because of the front panel. Do you think this could be an original IC? https://www.ebay.com/itm/120985277753
Click to expand...
No, that is not likely an original STK module. It has a third-party label on it. ECG did not make original parts, they bought aftermarket, knockoff or (maybe) surplus inventory, cleaned off or covered the original marking, printed their own label on it, marked up the price, and resold them. It may also be a counterfeit with a fake label printed on it.
 
I put the receiver together. It works, but the volume control crackles. Is it possible to get a new replacement potentiometer?
 
You may be able to find a used replacement, that may not be in any better condition, no new identical ones are generally available. BUT if you get some Deoxit F5 Faderlube you can probably clean it up and get it functioning correctly again. Faderlube will clean and lubricate the resistive surface inside. It may take repeated application squirted inside and much exercising the pot from end to end.
 
Thanks for the reply. I tried to clean the potentiometer with Kontakt spray. He didn't use much. Is the Pioneer SX-3800 potentiometer good for this receiver? I could buy a new from the SX-3800 potentiometer. What is the difference between the SX-690 potentiometer and the SX-3800 potentiometer?
 
You must log in or register to reply here.
Back
Top Bottom