Pioneer SPEC-4 repair and restoration thread!

Discussion in 'Pioneer Audio' started by mattsd, Jun 10, 2012.

  1. OverLoad

    OverLoad High On Solder Fumes

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    Yeah no shit!

    :lmao:
     
  2. mattsd

    mattsd AK Subscriber Subscriber

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    Yeah, they are a little big, aren't they? :D Okay, pictures will be smaller from now on, currently they are 1600x1200.
     
  3. Ed in Tx

    Ed in Tx Super Member

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    Need to do a reduction and some editing of prior posts too. Exceeds my screen resolution of 1280X1024... and takes time to load with slow speed AT&T DSL. Just sayin..!
     
  4. mattsd

    mattsd AK Subscriber Subscriber

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    Fixed!

    And here are the after photos of the filter caps!

    [​IMG]

    [​IMG]
     
  5. mattsd

    mattsd AK Subscriber Subscriber

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    And here is the pair completed and together again! As you can see by the meters, I was rocking out with them. :yes::guitar:

    [​IMG]
     
    Last edited: Jul 11, 2012
  6. laatsch55

    laatsch55 Super Member

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    Dude, 8 watts IS NOT rockin out, this is. Into a set of K-Horns. A recently repaired Spec 2 from Avionics friend in Fort Dodge, being shaken down for a week before it goes back.
     

    Attached Files:

  7. mattsd

    mattsd AK Subscriber Subscriber

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    Hey now, I have to consider my family here, I couldn't get it too loud. As it was the 8 to 10 watt output was doing 108-110dB according to my SPL meter. That is about as high as I can get before I hear complaints. Now if I can get a time when they aren't home....:D

    Sent from my Samsung Galaxy S II
     
  8. Ed in Tx

    Ed in Tx Super Member

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    You also have to consider the peaks in the dynamic range of what you're playing. Playing music averaging 8 to 10 Watts on the meters likely has peaks hitting 8-10 dB, which would be up to 100 Watts on peaks. Much different than displaying a sine wave into a dummy load, which would show full power. Showing full rated power on music there has to be some clipping and distortion going on.
     
  9. laatsch55

    laatsch55 Super Member

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    Why, there can be peaks well above the maximum rated output thgat can be in line with rated distortion. I do it all the time. I now have a digital storage scope to go with my Audio Precision ATS-1, maybe I can plot this.

    Amen Matt. No more kids at my house and the wife loves it loud too, I'm a lucky guy.

    Ed, I think it's the duration of those peaks that would determine the amount of distortion or clip.

    I have occasionally pegged my SPL meter at 130db using the White Oaked Phase Linear 700's. They can get the horns into unknown territory.
     
  10. mattsd

    mattsd AK Subscriber Subscriber

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    Yep, you are both correct, I forgot to mention at the continuous 8 to 10 watts output it was bouncing near 30 watts at times on peaks.

    I've done 123dB continuous with my HPM-100's and SX-1980 before, but nobody was home (it was so loud even with my earplugs in I had to turn it down a little). Meters were at about 50 watts with peaks a little past 100 watts.
     
  11. Ed in Tx

    Ed in Tx Super Member

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    I don't think the duration wouldn't effect the voltage where the outputs flat-top and clip unless the power supply sags under load, but yes of course the harder driven into clipping the higher the percentage of distortion. That's like a wall that's limited by the output transistors and power supply. Rated output at the specified distortion is normally just below that clipping point. 3 dB would be double the rated power which ain't a lot of headroom. More real would be a 250 WPC amp that may put out close to 300 Watts before it clips, But that's less than one dB over rated power. I recall I could run an amplifier into clipping easily visible on an oscilloscope before you really start hearing it. That was into a BPI load box that attenuated the monitor speakers by 20-30 dB so you could hear what the amp was doing at a reasonable sound level without killing your ears! Clipping happens well before some realize it.
     
    Last edited: Jul 12, 2012
  12. wasillaguy

    wasillaguy Technician & Fishin'

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    Just wanted to report, I have an "A" version meter amp board, and C1 & C11 are the values listed in Pioneer manual, not the values mattsd encountered, so apparently not all rev. A's are the same. I'm pretty certain this one has never been messed with.
     
  13. xlbee

    xlbee PIONEERFREQ Subscriber

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    Keep an eye out for C13 on the meter board. The parts layout diagram shows it in the incorrect orientation in the service manual.
     
  14. wasillaguy

    wasillaguy Technician & Fishin'

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    Thanks for the heads up. That was my next step, to compare all with the docs before beginning removals.
     
  15. wasillaguy

    wasillaguy Technician & Fishin'

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    Only other thing of note is that C16- 33ufd/25v, is not represented on the foil side layout drawing. It's on the schematic, but invisible on the artwork drawing.
     
  16. xlbee

    xlbee PIONEERFREQ Subscriber

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  17. wasillaguy

    wasillaguy Technician & Fishin'

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    Indeed you did. Thanks for pointing me to it, you've got a good step by step there of the whole process.
    This was the first thread that my search popped up, and I was moving on with only this info. Should have known to look further here on AK.
     
  18. xlbee

    xlbee PIONEERFREQ Subscriber

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    AK definitely is an awesome resource!!!
     
  19. EchoWars

    EchoWars Hiding in Honduras

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    Spec 4 Relay Swap

    Wanted to do a swap as neatly as possible with an Omron MY2. I think this worked out OK.

    [​IMG]

    I have another channel to do, and I'll document it and start another thread.
     

    Attached Files:

    Last edited: May 7, 2016
  20. laatsch55

    laatsch55 Super Member

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    Yep, that's a neat one. Did some matched KSA992's for the 2SA798, heat shrink them together, very well behaved with lots of gain.
     

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