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I Couldn't Believe What Happened...

70.161.216.205
Posted on October 31, 2009 at 14:17:49
ESDI-80
Audiophile

Posts: 359
Location: East Coast
Joined: January 1, 2008
 ...When I went to the electronic scrap junk warehouse sale today. I went in, and sitting toward the front of the place was a Pioneer SX-1980! I snag it and a few other goodies for $20!

Cosmetically it needs some TLC. The Plexiglases on the face is broken, the bass control shaft is missing, and a few knobs are missing. Electrically, it seems to be all there. It does power up, but the speaker relay does not click in. Doing some troubleshooting, I believe the power transistors, 6 per side, may be OK. If I unplug the harnesses going the the output transistors, the relay does not click in, yet if I unplug the entire driver board, the relay does kick in. I am suspecting the DC offset must be out of whack.

Any ideas here?

The tuner appears to be functional. :-)

I want to get this bad boy up and running. This will be a great receiver to use in my main set up. Problem is, I need to build some speakers that can take the 270 watt output!

Anyone know what the sound quality is on one of these?

Mike

RE: I Couldn't Believe What Happened..., posted on November 1, 2009 at 05:18:27
EchoWars
Audiophile

Posts: 305
Location: Left of the Dial
Joined: December 2, 2002
 I have a glass that was made for a 1980 (the faceplate should have real glass installed, not plastic) a while back that never got used. While you can likely have a piece made by your local glass shop for $20, the one I have is tempered, and damned unlikely to break. If you're interested, email me.

At any rate, you can measure the offset by looking at pins 3 and 6 of the power supply board (yellow and green wire). Anything over about 2V will prevent the relay from engaging. But...while you are there, you need to check the remainder of the PS voltages. The Achilles heel of the 1980 is that power supply board, mounted up under the bottom of the chassis where it bakes itself to death. 19 out of 20 failures on the 1980 are due to a failure of one of the +/-80V supplies.

RE: I Couldn't Believe What Happened..., posted on November 1, 2009 at 06:24:34
ESDI-80
Audiophile

Posts: 359
Location: East Coast
Joined: January 1, 2008
 Thanks for the advice. I will keep this in mind.

I know my PS board needs some attention. Just a quick look and I saw caps with shrunken sleeves. A big indicator of over heating.

Look like I need to obtain a service manual in the near future!

Mike

RE: "Problem is, I need to build some speakers that can take the 270 watt output!", posted on November 1, 2009 at 03:06:30
1973shovel
Audiophile

Posts: 2368
Location: Greenville SC
Joined: February 25, 2007
Contributor
  Since: June 17, 2009
 Seriously, that's the least of your problems. Driving speakers with too little power (especially solid state power) has damaged far more speakers than an amp with too much power.

Good luck with your project.

RE: I Couldn't Believe What Happened..., posted on October 31, 2009 at 15:41:18
henrybasstardo
Audiophile

Posts: 1044
Joined: June 25, 2003
 Take the voltage on the relay.
It may be dirty. Most can be taken apart and cleaned.

when G/W opened here, posted on October 31, 2009 at 15:12:16
sober1
Audiophile

Posts: 1325
Joined: August 9, 2000
 some 5 years or so back (no competition) I snagged a mint condition SX-1980 with all the original owner's literature. This freakin monster was so cherry, I brought it home, dropped it into the front room system and played it for over a month without so much as a fart! One of my nephews fell in love with it, so I sold it to him for a killer price. It's still his "center-piece" of his massive, evergrowing audio gear collection.
At present, I find myself slowing building a period correct Pioneer system. I have finished the RT-909 and the TX-5500II. Thursday I dropped off my CFT-1000 for overall at Deltronics. I'm resisting the urge to try and bring back the SX-1980, instead, I have been investigating the Integrateds' from the '77-'79 period (to match the analog sources). Any recommendations Inmates?

pax vobis
RE: when G/W opened here, posted on November 1, 2009 at 05:25:48
Mark W.
Audiophile

Posts: 726
Location: Oregon
Joined: March 13, 2006
 Yes stick with the SA-X500 series rather then the later SA-X800 series eaier to service in the 50 series. A good one to look for without breaking the bank would be an SA-7500 or SA-8500 if you have a little more to spend the 9500 is killer.

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