SX 1250 low on putput

Discussion in 'Pioneer Audio' started by Stock48, Feb 22, 2017.

  1. Stock48

    Stock48 New Member

    Messages:
    6
    Ment to say low on output. Big thumbs lol. Hope I posted in correct place. If not I appoligize. I have a 1250 I saved the other day. Came out of a storage unit and the ppl cleaning it out were going to take it to the dump! She's rough on the outside but cleaned up pretty nice and all the lights etc work. Thing sounds really nice and clean. Only problem is once you get past about half power it peters out and goes to crap. Everything inside looks good , no swolen caps or anything but the idle current, and stabalizer current are low and pretty much unresponsive to adjustment. Idle will not go past 5-6 mv, and Stabilizer 44 mv with pots maxed out. Just looking for tips, or suggestions on other things to check/try. I know how to clean switches, check adjust voltage, replace a swolen cap here and there but beyond that Im pretty much learning. Any info/advice is appreciated. Just want to get this thing going strong so I can see how it stacks up against my other recievers. Sounds like it's really gunna rock once dialed in. Thanks, Jarrett.
     
  2. WE6C

    WE6C Active Member

    Messages:
    465
    Location:
    Colfax, Northern California
    I'm sure the power supply has problems which is why when power is increased it can't keep up. Power supply voltages must be correct before anything else can be properly adjusted. Have you checked any of the power supply voltages?

    When you say "stabilizer" at 44 mV, not sure what you mean since the stabilizer/power supply voltages are, among others, 65 volts, and -65 volts, not mV.

    99% of the time the large 22,000 uF caps have a "bubble" on the bottom of them which means they're beginning to leak.

    Do a search on here about the 1250 power amp boards and trimmers. If the idle current trimmers open up you will smoke the final transistors. Easy preventative for a couple of bucks.

    I'm sure some of the smarter guys here will convince you to NOT power it up anymore until... I agree.

    Wish I could find someone throwing one away! Good find!

    Bob
     
  3. rcs16

    rcs16 Super Member

    Messages:
    2,897
    Location:
    Baldwin, Ontario, Canada
    Nice find. As above check out all the power supply voltages first to see if they are in spec, it not, first thing to fix. Lots of threads on serviceing this unit, lots for you to read.
     
  4. jeffpaletz

    jeffpaletz AK Subscriber Subscriber

    Messages:
    1,034
    Location:
    Minneapolis, MN
    You have a top of the line Pioneer from the best of Pioneer's vintage days. If you aren't really good at working on this type of equipment I urge you to find someone who is who can fix it for you or sell it to someone who wants to spend the money to fix it up. If you fill out your profile so we can see what area you live in someone here might contact you to fix it up. IF you are into vintage stereo equipment and enjoy how great they sound you will really like this receiver once it's been restored.
     
  5. Stock48

    Stock48 New Member

    Messages:
    6
    Thanks for the replies guys! I will check the voltage around power supply etc and we will see. Yes stabilizer was 43v not mv. I goofed that up. I might end up just having a tech look at this thing like said above I hate to mess it up, and Im too busy with work right now to devote a bunch of time to it. Im in central Ca between Bakersfield and Fresno. Small town called Porterville. Do you guys know anyone in the area? I messages a guy Pacific Stereo yesterday and he said it would be 12 months before he could look at it. I don't want to wait that long.
     
  6. Stock48

    Stock48 New Member

    Messages:
    6
    I ended up taking this thing to a shop up in Fresno. After $500.00 and waiting 2 months. All they did was replace the input selector switch for FM, am, aux, phono. One of the Phono switches was stuck and broken but was not interfering with the performance. They did not address the stabilizer board at all. After no luck finding a local tech and no help I decide Fk it and just fix it myself. I ordered all the parts thru Digkey from a list I found on here. Went thru the board and still no luck! I was so pissed I ended up buying another receiver off Ebay for parts. It had a dead lft channel but figured It might have a good stabilizer board and it did! I swapped board into my old receiver and h\walla it worked! I then ended up swapping it back into the parts machine and finding that it had a tweaked relay causing the left channel to be dead. That was a major score! I now had 2 working 1250's with one stabilizer board lol. Curiosity got the best of me and I was determined to repair that old fragged board. Apon comparing the 2 I found that my orig board had one of the 2 80V larger caps installed backwards! It had already been that way before I recapped the board and I just put the new caps in same exact way that the originals were. (I had read that sometimes the indications can be wrong). It appeared to have came that way from the factory or someone turned the cap around and put it back in. It was a factory cap. Anyways that really thru me for a loop. I ended up Having to replace that cap and another cpl along with a cpl diodes and ended up fixing it! So long story short I have 2 complete working 1250's now. lol
     
  7. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Messages:
    8,695
    Location:
    Brooksville, Fl.
    I am sorry to hear about you getting raped at the repair shop. The 1250 is modular that makes for easier repairing. There are numerous AK repair tech gurus and I am sure there are some in your area. Repair isn't cheap but , at least our guys will actually do something. I have paid less than your charge to have a receiver completely rehabbed. Put up a question asking about repair gurus near you. I know blhagstrom and CDFixer are both on your side of the country. You have two of the best. Lucky guy.
     

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