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Pictorial how to: LED tuner bulbs in SX-x2x (727 used)

Discussion in 'Pioneer Audio' started by Johnny_Law, Aug 19, 2015.

  1. Johnny_Law

    Johnny_Law AK Member Subscriber

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    North Bay, NorCal
    How to install LED backlights in a Pioneer SX-727 (also applicable at least to the 828) - has been covered in the past, hopefully this adds to our collective knowledge as well.

    Tools needed:


    Steps:

    1. Remove the wooden cabinet by removing the 4 screws holding it onto the body. (Not pictured)

    2. Remove the knobs. The knobs can be pulled straight off.

    Use a hex key to remove the tuner knob. There are two screws that need to be loosened. Use your 1/16” hex key.

    [​IMG]

    The bass and treble adjustment knobs each are dual-knobs, each of which is set on different threads. I find that it’s easiest to remove the outer one first, and then the inner, instead of pulling on them both at once.

    [​IMG]

    [​IMG]

    During re-assembly they can be pushed back on.

    [​IMG]

    3. Remove the nuts beneath the speaker, volume, and input knobs. They are only on hand tight, time for the 12mm socket (on the left).

    [​IMG]

    4. Remove the three screws holding the face plate onto the frame.

    [​IMG]

    5. Remove the face plate and set it aside.

    [​IMG]

    [​IMG]

    6. Remove the two screws holding the L-bracket which is clamping the tuner face to the frame.

    [​IMG]

    [​IMG]

    7. Remove the two screws on the left of the tuner gauges, followed by the 4 plastic push-rivets holding the tuner face to the frame. The push-rivets easily push out from behind. I used a small paintbrush handle.

    [​IMG]

    [​IMG]

    8. To access the lamps, slide the tuner face out to the left without disturbing the tuner dial.

    [​IMG]

    Here are my 5 dead bulbs. They are 8V 300mA bulbs and they like to burn out. All 5 were dead in this 727, 3 of them were dead in my 828 which will make an appearance in the last picture.

    [​IMG]

    9. Remove the bulbs WITH CARE. I found the best way was to use a small flat-head screwdriver from above to GENTLY massage them from the brackets. You don’t want to break any of these – clean up will be time consuming.

    [​IMG]

    Cont ...
     
    Last edited: Jun 13, 2016

     

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  2. Johnny_Law

    Johnny_Law AK Member Subscriber

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    10. When they are all out, find your LEDs and place them in the sockets, centering the LED strip and getting them as close to straight up and down as you can.

    [​IMG]

    You can now turn the receiver on to verify everything works and the light is even, sliding the tuner dial back in to double check. Everything looks good on mine!

    [​IMG]

    [​IMG]

    11. Re-assembly is the reverse, I actually took the above pictures in reverse, simply re-install the pieces one by one until you’re up and running. Take care to clean all the pieces and not get finger grease or dirt on anything as it goes back together.

    [​IMG]

    And here’s the 727 on top of the 828 I did first. The 10 LEDs in the $7 pack were perfect to replace the 5 bulbs in each receiver. And YES the dimming function of the 828 still works!

    [​IMG]

    I hope this proves useful to those SX-x2x owners out there who are looking for a cheap and easy way to improve the backlighting with reasonably priced and easily available LEDs.

    Cheers,
    Ryan
     
  3. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    Southern NJ
    Nice write up!

    I have a 626 and a 727 on my pile of things to restore, and I will be bookmarking this thread as the pictures are worth a thousand words.

    Where did you get the LEDs from?

    Lee.
     
  4. Sunoo

    Sunoo New Member

    Messages:
    29
    This is the most helpful write up I've seen on this so far, thanks.

    I've heard some complaints about some LEDs being too bright, have you noticed that at all with the ones you linked to?

    Also, do you have any experience replacing the current input indicator lights? Several of those are out on my SX-626, and it would be nice to fix that when I had it apart to fix the dial lights.
     
  5. audiojones

    audiojones Jonesin' for audio Subscriber

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    Central NJ
    Good job and nice writeup - thanks! Those LED's look much nicer than some I've seen in the past, they actually look "right" instead of piercing blue. Be nice to know which ones they are.
     
  6. Sunoo

    Sunoo New Member

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  7. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Hi Lee - The LEDs are from Amazon. They are from a vendor called "autocarstore" and are intended to be installed in sun visors or the like. I have a Prime account, so the price was right - $7 with free 2-day shipping. http://www.amazon.com/gp/product/B00KUI13C6 (Edit: thanks Sunoo!)

    (1) Objectively, yes, they are pretty bright; subjectively, no, they are not too bright to my eyes. Of course, that's not to say it isn't nice to have the 828's dimming feature, which is nice to have in a dimly-lit room.

    I personally like the brightness as it makes the tuner really pop. That's probably a personal call, as I can see the brightness being too pronounced for some, but not me. My two cents.

    (2) Yes, I also replaced the Stereo bulb while it was apart, but I didn't take pictures of it. Those lights are 5mm bulbs, 8V 50mA with leads. I used a 3.6V LED bulb from Radio Shack with a 100ohm resistor. This bulb I do think is a hair too bright - maybe I'll double the resistance and report back.

    Replacing them is straightforward - they are accessible with the face off, and pull out from behind. Their leads are soldered onto the light board. I will try to remember to take pics when I mess with the resistor on my stereo light.

    Of course it's worth mentioning that you should check your fuses first - located underneath, near the transformer. They are soldered in place in these models.

    Thanks. I love how they look. At $7 for 10, and an hour of time, I would highly recommend them, even if just to see how your eyes like it in person.

    --Ryan
     
    Last edited: Aug 20, 2015
  8. Sunoo

    Sunoo New Member

    Messages:
    29
    I suppose at only $7, it's worth giving them a shot. I've got the SX-626 though, so no dimmer there.

    I thought I saw something about the stereo light being different from the input indicator lights, but I might be wrong there.

    My stereo light, the needle light, and the VU light are all still working, so I'm not sure they're worth the effort to try to replace.

    I'll take a look at the fuses, but I think it's most likely that the 40 year old bulbs have failed. :p
     
  9. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Agreed. I really like the un-dimmed look anyway, it's really sharp.

    You know, the stereo bulb could be different, I couldn't figure it out - the manual is hard to read. P.15 of the repair manual hosted here has the bulb type illegibly written by hand, but the next page doesn't list a separate part # for the stereo bulb: http://www.hifiengine.com/manual_library/pioneer/sx-727.shtml

    The goods news is that they are certainly easy to replace.
     
  10. Sunoo

    Sunoo New Member

    Messages:
    29
    That's a useful site, thanks for the link. I brought up the repair manual for the SX-626 ( http://www.hifiengine.com/manual_library/pioneer/sx-626.shtml ), and that does seem to show a part number for the stereo indicator, though the exploded view seems to indicate that it's the same bulb as the other indicators, so maybe I'm not looking at it right.
     
  11. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Good call - looks like the 626 manual shows that the bulb is different. It's a 6V .03A compared to the others at 8V .05A. Great catch!

    [​IMG]
     

     

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  12. Sunoo

    Sunoo New Member

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    I'll have to figure out what to replace those with at some point. I searched around and it sounds like people on here used to sell kits, but everyone I saw mentioned seems to be gone.
     
  13. audiojones

    audiojones Jonesin' for audio Subscriber

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    Contact AK'er dgwojo, he sells the kits for them. I just finished relamping yet another SX-626 last night with bulbs from him, I recommend him highly. He has the 6 volt grain of wheat bulbs for the stereo light as well as the 8 volt version for the tuner pointer needle. Great guy to deal with too.
     
  14. Sunoo

    Sunoo New Member

    Messages:
    29
    Thanks, I'll do that. Is it worth changing the tuner needle out if mine still works? I haven't been able to find any information on how that one is. It doesn't even seem to be listed in the service manual.
     
  15. jheu02

    jheu02 AK Subscriber Subscriber

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    Not having any of these receivers, I don't have the schematics, but is there any voltage dropping resistor in the ORIGINAL circuit for the incandescent bulbs? If so, you may be able to decrease the brightness of the overall set of LEDs by increasing that original resistor value a bit, running the LEDs on less voltage than you currently are.
     
  16. audiojones

    audiojones Jonesin' for audio Subscriber

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    No, if it's working I'd leave it be. Not only is it a royal PITA to change but its also very easy to break the plastic pointer dial if you're not extremely careful. It's an 8 volt "grain of wheat" style bulb (Dave includes it in the SX-626 lamp kit, it's an 8 volt version of the 6 volt stereo indicator bulb). Wouldn't hurt to have the bulb for it on hand though, they do burn out once in a while.

    So it's OK to use 12vdc LED lamps with unregulated 8 volt AC voltage? I thought LED's had to run on DC only.
     
    Last edited: Aug 21, 2015

     

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  17. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    That's been a technical sticking point of mine - the reverse voltage of LEDS is 5v, so it is possible to stress the leds although a string of 3 of them in the fuse body would be 15v or so which is greater than 7.5vac rms (not peak, that's 1.414x, so 10 -12 volts)
    while a vital 0.6v is lost by adding a regular diode as a safety, and 1.2v if you use a bridge rectifier to get more than a 50% on time per cycle...

    Also the 60hz flicker is present, and strobe effect is noticeable (to me at least) especially when your vision is moving and you catch it in peripheral vision.

    What's REALLY fun with the flicker is when the LEDS have alternate installation direction polarities, so you get a "railroad crossing effect". Some random number of them are on for the first half of the AC cycle, and the reminder are on for the other half of the cycle.
     
  18. Johnny_Law

    Johnny_Law AK Member Subscriber

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    I notice no flicker, but a few have written guides as to how to build a circuit to either increase the frequency of or eliminate it, e.g., http://www.audiokarma.org/forums/showpost.php?p=4393595.

    Edit: Verified up close in a dark room. To my eyes, absolutely no flicker. The light appears constant and even. Edit2: Not totally even. After a few days of looking at the display, it is slightly uneven, but only slightly.
     
    Last edited: Aug 24, 2015
  19. Descartridge

    Descartridge "I hear, therefore I am" Subscriber

    Johnny, thanks for the tutorial and source.
     
  20. gkhashem

    gkhashem Active Member

    Messages:
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    Location:
    Webster, NH
    Guys this is a great thread. But it does not tell one how to get to the lights for the meters. I have a SX-727 with the tuning meter bulb out. How do I get to that bulb? From the rear of the meter?
     

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