1. Rest in Peace Paul (Kegger) If you would like to help the family in this time of great sorrow and need, you may donate on their GoFundme page: https://www.gofundme.com/mckechnie-medical-and-funeral-fund?
    Dismiss Notice

Bought SX-1980 Today: Already Broke

Discussion in 'Pioneer Audio' started by danrclem, Mar 20, 2017.

  1. danrclem

    danrclem Super Member

    Messages:
    1,039
    I bought a 1980 today along with a SG-9800 equalizer, CT-F9191 tape deck and a pair of CS-922A speakers.

    I listened to it at the sellers house and it sounded good. I checked the DC offset and the left channel was about 23 mV. The right channel was about 178 mV. I know that's not good on the right channel but I decided to hook them up to my speakers anyway.

    The right channel wasn't working. I knew the controls needed cleaned so I started working them and when I got to the tone toggle some working got the right channel working. My Klipsch Chorus brought it to life and it sounded very good. I played it for less than ten minutes, unhooked my speakers and started checking the DC offset again thinking that maybe the tone control had something to do with the high reading. Well it still read about the same. Some black smoke then came up out of the vent (in the center and maybe a little more to the left facing it from the front) that I wouldn't call a puff but more than a wisp. I don't know if I moved my probe off of the speaker connecter any but I saw an open reading before I was able to shut it down.

    I took the wood case and vent off and wasn't able to see any evidence of anything burnt. It had dust on the inside but was cleaner than most all receivers that I have looked at before cleaning. The 1980 looks good and the CT-F9191, SG-9800 look even better. The CS-922A speakers have some rough spots on them.

    Even though I think I could more than get my money back out of it since I bought it at a good price my stomach still hurts. I don't really have time to work on it but if anybody has any ideas of what it may be please let me know. When I am able to get back to it I'll use this posting for inquiries.

    edit; change mA to mV

    002.JPG

    004.JPG
     
    Last edited: Mar 21, 2017
  2. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Messages:
    8,249
    Location:
    Brooksville, Fl.
    I would try cycling the Filter Switches, high and low, about 50 times with the amp off. Turn on the amp and see if that helped. The filter switches are the last place in the preamp before going to the preamp out/amp in and they a well known for corrosion issues that cut off the signal. Report back and let us know if that helped.
     
    danrclem likes this.
  3. rcs16

    rcs16 Super Member

    Messages:
    2,732
    Location:
    Baldwin, Ontario, Canada
    That should be investigated as to the location/component involved before you apply anymore power. Usually if you see smoke there should be some visual indication as to the source. Use your sniffer noise and eyes.
     
    danrclem likes this.
  4. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

    Messages:
    3,720
    Location:
    Las Vegas Nevada
    If it was out of protection it should of been safe. 178mV is high but usable.
    Start it on the DBT and see if it comes out of protection. 150 watt bulb.

    You know the weakest part of the 1980 is the old crusty power supply?
    Its located upside down on the center bottom of the chassis.

    The sx-1980 is a good investment. Even a broke one, and they can get fixed to the degree.
     
    danrclem likes this.
  5. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,111
    Location:
    Glen Burnie Md.
    1megohm: mention of sale or soliciting another member for a piece of equipment is restricted to the Dollars and sense Forum per forum rules. You'd be better off taking any mention of buying or selling to PM's (conversation) to keep it out o the forum. Just a friendly reminder before/if you bump into a moderator and really get chastised.
     
  6. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    22,440
    Location:
    uk.. the middle bit
    how was your meter set up ? its just you said Ma .. if you did measure milliamps you will have shorted the outputs .
     
    danrclem and Hyperion like this.
  7. danrclem

    danrclem Super Member

    Messages:
    1,039
    Thanks for all of the replies.

    KingBubba; If I have time this weekend I'm going to deoxit it.

    rcs16; That was my thoughts too but after reading zebulon1's post I'm going to try that route. I'm going to take the bottom off and check that out first. Unfortunately my sniffer is not working very well and my eyesight isn't much better. I'm gettin' old.

    zebulon1; If I have time this weekend I'll do that. I have a DBT and I feel stupid that I did not hook it up to it in the first place. I was just excited about listening to it. I did some reading last night and found out where the power supply is and that I need to check that out. Hope I don't have to buy one of the aftermarket power supply boards because they're expensive. Yeah the 1980s are bringing ridiculous prices and that's one reason I bought it because I figured if I didn't like it I could find a buyer for it. What little time I did spend with it I liked it very much and will more than likely keep it if I can get it fixed without running into too much cost. As long as the DBT is hooked up there won't be any more damage done?

    peteHall347; Good catch. That was a typo and I changed it. I did have it set in mV so that's one thing I have going my way.


    This truly is a MONSTER RECEIVER and I love the looks and I think I really loved the sound after just a few minutes of listening pleasure. I guess I would put it in the same class as the old big block muscle cars. Don't need that much power but man is it fun to have and play with.

    I don't have much experience with good stereo equipment but this is the best that I've heard. I'm not saying there isn't anything better because I'm sure there is but I just haven't heard it. I'm going to say this is a keeper barring a repair bill that is unaffordable.
     
  8. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    17,064
    Location:
    SE PA
    I would not plug this unit in again without a DBT. Smoke, even a wisp, is something not so good. Don't want not so good to blossom into fully blowed up.

    Wait for some that will help you figure out what broke and must be replaced before you go trying to listen to this unit. There are a few that know how and will help, some have already responded. It ain't me, just trying to limit the damage so this repair can be made more easily.
     
    danrclem likes this.
  9. danrclem

    danrclem Super Member

    Messages:
    1,039
    I'm definitely not going to power it up without a DBT. I'm going to take the bottom off, clean and then see if I can find something that doesn't look right. If I find something I'll then try to get some help.
     
  10. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

    Messages:
    3,720
    Location:
    Las Vegas Nevada
    It is a chore to figure out the best way to approach the situation the set is in.
    The main priority this is to protect the outputs. Then evaluate the sets base functions.
    If the smoke or whatever you saw was from the center of the set then maybe the amps are OK and the Power Supply should be suspect.

    A thought:
    Visual check of the PS and EQ with a magnifier.
    Unplug both amplifiers boards.
    Power on with the DBT.
    Check all the PS voltages at the Pins.
    When the Power supply dies on these (And maybe most) the set just quits. Stays in protection with no fanfare.
    That new board by "Turbo" is the "Cat's A$$" and worth the money.

    One other note from a 57 year old:
    I get these floaters in my eyes when I'm looking down, and it looks like smoke at the top edge of my vision, and it freaks me out every time I'm checking a set with power on.
     
    danrclem likes this.
  11. ConradH

    ConradH AK Subscriber Subscriber

    Messages:
    6,845
    Location:
    Canandaigua, NY
    If it were on my bench, I'd do a really good visual under bright light with a magnifier, plus a sniff test. Next would be in-circuit checks of all semis, except for the outputs, which I'd pull to test. Then fix whatever's obviously bad. I don't think there's any reason this one can't be brought up to partial voltage with a Variac. I'd slowly do that and look at the outputs (before the relay, if it has one) to see if the power amps were functioning or not. Also see what the supplies are doing. Most older amps and supplies can be run at 20-40 VAC, allowing you to measure critical points and get some idea of what's going on, without drawing enough current to smoke anything. Everybody has different methods that work for them, but that would be my approach.

    +1 on the damn floaters!
     
    danrclem and Imanoldee like this.
  12. danrclem

    danrclem Super Member

    Messages:
    1,039
    I'm going to take the bottom off and inspect the power supply like you guys said and then I'll report back. Probably be able to do it this weekend.

    I have floaters too but unfortunately this wasn't floaters. I wish it was though. lol
     

Share This Page