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An Old Friend ;)

My father has gifted me the receiver from my childhood :)

It's a Realistic SA-1000, I used to listen to this with the matching Realistic tape deck or Elac turntable on a pair of Realistic Optimus-5 monkey coffins. The Optimus-5's I refurbished some time ago, re-used the 11" woofers and replaced both midrange and cone tweeter with a single Vifa TG9 and new crossover. They're still in use and sounding pretty good.

This amp isn't the most hifi thing out there, but for nostalgia sake I'm going to breath some life back into it. It's still working, but the knobs and buttons are scratchy, so I'm going to try and find replacement pots and replace a bunch of the caps while I'm at it. It's only a 20Wpc amp, with a single rail power supply so the amp output is capacitor coupled. Just replacing those two coupling caps will probably make it sound like new again I'm sure. It's easy to work in, single sided boards and before the invention of pcb connectors apparently, all the internal wiring is wire-wrapped. My dad kept the manual and even the purchase receipt, great thing is the manual has a complete schematic on the back page.

Looks pretty okay if you ask me, doesn't have VU meters unfortunately, but does have 3 band EQ, loudness button and "Quatravox"!
My opinions are 100% factual
jr@machifisideSilver1omoJasonP4thtrykennyk

Comments

  • That's a gem! Looks mint too. I remember & drooled over that amp at the local Rat Shack as a teenager. I really wanted one - it would have gone perfectly with my Nova 6 speakers. But it was more than I could scrounge at the time. I settled for a little Superscope amp. They sure built gear to last back then. 
    hifiside
  • I have one of those, but one channel is burnt out. Old Quatravox model.
  • I'm guessing the trimpots on the board  are adjust DC offset?
  • It's in great shape for its age, a couple chips off the veneer on one side, and the volume knob is a bit crooked, but I'm planning on replacing that pot anyway.

    I scanned the schematic if anyone wants to look:

    My opinions are 100% factual
  • If you find a suitable replacement for the stacked Vol/Bal pot, let them know over on AudioKarma. I hear they have been nearly impossible to find.
    dcibel
  • edited September 28
    I've no problem with a little maguiver work to use a standard dual pot, but in this particular unit it'll be the thread length that makes these pots nearly irreplaceable. It'll be hard to re-attach the front plate without the long threads. The front circuit board is fixed in place by just the potentiometers, then the front plate goes over top and is fixed in place by a second set of nuts.

    I haven't seen any potentiometers yet that have threads this long.

    Standard replacement is a bit short. I can order them with a long shaft, but it might be hard to find the right ones with long threads.

    R-Carpenter
    My opinions are 100% factual
  • I got my dad's old stuff. A Fisher receiver and Sansui speakers. I used to jam the shit outta them growing up....so did dad 😁
    I feel ya, that's a cool vintage system ya got !!! 🤘🏼
  • The volume pot also has a 4th terminal that is part of the loudness circuit, so even if I do find a suitable replacement, the loudness feature will be lost. :(
    My opinions are 100% factual
  • edited September 28
    Check coupling caps C510a and C510b connected to the volume control wiper arm (0.47uF/50V).   If they are leaky electrolytic types, this could be your noise problem (assuming, of course, by scratchy you mean a noise problem and not just scratched up physically).    
  • A pot for a Pioneer SX-990 or SX-626 look long enough, but not a PCB mount - looks like wire wrap pins or lugs. They are also larger in diameter. Might be a tight squeeze getting one to fit.

    I know I've run into a few older pieces that use threaded collar nuts that screw on the pot to secure the faceplate. I don't know if those still exist, but it might be a simple project if you have a 3d printer.
  • edited September 28
    4thtry said:
    Check coupling caps C510a and C510b connected to the volume control wiper arm (0.47uF/50V).   If they are leaky electrolytic types, this could be your noise problem.   
    Who said anything about a noise problem? The pots are just old, worn and scratchy, and I'd rather find a suitable replacement rather than just cleaning them. Even if just the volume knob as it's the most worn. I think if I just do the volume pot, I can use a normal one, the rest of the pots can hold the faceplate on just fine without having to resort to glue or some other hacky solution.

    Anyway, those small value coupling caps aren't electrolytic. Not sure what they are, they are shaped like tantalums, which aren't the best choice for an audio coupling cap if that's what they are.

    My opinions are 100% factual
  • Well I've ordered a bunch of caps, about $50 to replace all the electrolytics and all coupling caps are replaced with poly type except the 2200uF output caps of course. The pots and switches I will simply clean as they're not in too bad shape apart from the volume pot.

    I'm rolling the dice on what appears to be a knock off Alps pot on eBay with the loudness tap. It was only $5 and will probably take a month to get here from China, some online searches lead me to believe that it's a stepped attenuator internally but might do the trick anyway, well see. Not a big loss if it doesn't work out at only $5. Look up "RH2702" for more detail.

    As an alternative, the guy at www.oldradioparts.net will build me something very close to the original pot, but the cost with shipping to Canada is a bit expensive at USD$48, doubling my restoration cost. Not too sure on that option yet.

    My opinions are 100% factual
  • My mistake, when you used the word "scratchy" I misinterpreted this as a noisy pot.  Good to see that you are replacing all the tantalums.  They are notorious for going bad.  I replaced several of these types on my Dynaco ST400 and Revox A77.  
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