• 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

New SX-780! Metallica killed (most) all of it : (

B

Boostedbox

New Member
So, I pick up a Pioneer SX-780 the other day on the side of the road for $10! Score right! Well, I take it home, plugged it up, hook a lamp cord to the antenna connections and by gosh the dang thing worked....well even!
So...the radio got old quick, and I had this Gerrard turn table with a Pickering cartridge that I bought at a yard sale a week or three ago and a Whiplash album (yeah, the MEGAFORCE one l..l ) that I've had for years waiting on a TT to play it on. See where this is going?
I hooked it up and....damned if it didn't work too!
So Seek and Destroy here I came! Man it was killing the old junky Marantz speakers I use to test stuff with!
Then on comes Whiplash...I just had to turn it up some (more)...it jammed for about 30 seconds and then disaster struck!
SX lost all balls and honestly I smelled a little smoke of some sort although I never saw it. It still plays music, but zero bass on either channel and the left channel is scratchy as all heck. Pots Buttons and Switches were all cleaned, I've tapped around, changed inputs, A to B, nothing changes.
If it helps, the FM stereo/mono switch seamed to quit working at about this same time. Its Stereo all the time now. FM muting switch does nothing either.
Any ideas what I fried? I had really wanted one of these for a long time now and I'm very sad. Any help will be greatly appreciated.
 
Register to hide this ad
Since you are still getting sound from both speakers you may have gotten lucky and not killed the STK amplifier modules......maybe. NEVER connect/disconnect any wiring while the unit is powered up. Also be very cautious of any stray strands of wire potentially shorting out at the either end of the speaker wires.

Do you get normal sound from other sources like FM or through the AUX or tape monitor inputs ?

Did the sound come back to normal once the unit cooled off ?

There are some threads regarding the SX-780 that discuss bad solder joints especially at the three large resistors near the STK modules.

You might also consider giving the output relay a tap or two to see if that clears things up. Very common for those relay contacts to get corroded and affect the sound as you describe.

Another round of cleaning/lubing the pots and switches won't hurt. Sometimes more than one cleaning may be required.

Good luck, keep us posted.
 
Welcome to AK! Do not despair as most all of us have had a vintage piece crap out or test our patience. Others will come by to offer troubleshooting options and repair possibilities. Search for SX-780 threads, plenty of folks have had them, worked on them, and repaired them.

Also goes to show you that vintage gear needs to be checked out before rockin' out.
 
Hey guys thanks for the replies. I didn't plug any sources up with the unit powered on, but it may have been plugged up. (Probably was plugged up but maybe not, I'm not sure about that) the way the speaker connections are nothing can touch ("stragglys" as I call them) I've installed and serviced security systems for a decade so I try to use decent practices to keep from frying things in general.
I haven't tried other sources yet. Before or after. I tried to try, I had also bought two older pioneer cassette players. A 500 and a 550. Niether of which worked well enough to play one. (Different story for a different thread)
I tapped on everything in it to no avail. (Available from the top side anyway)
I do have other junk that does work. I'll try something else today and get back to you guys.
 
Metallica's newest album probably would have caused far more damage. Consider yourself lucky. In a bid to win the "radio friendly" "loudness war - it was mastered to such a high level that the master tapes were distorted as hell. More info on that debacle here: http://mastering-media.blogspot.co.nz/2008/09/metallica-death-magnetic-clipping.html

Agreed however you may not have blown up the modules if you are still getting sound. If you smelt something you may have some damaged components on the boards inside. Are you able to open it up and take you pictures you could post?
 
Also don't discount the possibility that you damaged your speakers - (or maybe your hearing!)
 
No bass, no mono, sounds like an open ground somewhere. Go back to the radio, does it work with that? If so, could be a bad cable on the turntable.
 
You mean Master of Puppets?
I heard Electra put a few out after that that they paid the band formally known as Metallica to play on. But Master of Puppets is the last album Metallica put out.

...radio too guys. I still haven't managed to try a different source yet. All the fuses "Look" good. I have yet to test those as well though. I will today I promise. Thank you so much for your continued replies!
 
Go through it with your meter on Ohms, power disconnected. Measure the resistance from the common terminals at the 2 big filter caps (the 2 that are connected together) to the chassis and then to every point in the circuit that is supposed to be ground, and to the black speaker connectors. Should read close to 0 Ohms every time.
 
You must log in or register to reply here.
Back
Top Bottom