AM21 low signal strength

Discussion in 'DIRECTV General Discussion' started by William1, Dec 19, 2018.

  1. William1

    William1 Mentor

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    May 11, 2009
    My AM21 has been working more and more poorly over the last few years to the point where it mostly pixelates. Using OTA and the TV tuner works fine. So I felt the issue must be in the AM21. I am no electronics expert but I now what parts are, how they should look and can easily visually see a burnt resistor, cooked fuse or transformer, bulging and/or leaking capacitor.
    So I figured I'd take a look inside and see if there was anything obvious. To open the AM21 and remove the board, you need a Torx 10 security bit (drilled for the security pin). Both the cover and the board use them. Get the bit.
    As soon as I opened it, I could see four bad capacitors all around the RF tuner. 470UF 10V. All split on top, bulging and oozing. I've ordered replacements @ $2 each delivered. It would be a lot cheaper if I had a local store but I have to do online and shipping. I am not positive this will fix my AM21 but it will not make it worse! Bad caps, circled in red.
    AM21 Bad Tuner Caps.jpg
     
    242424 likes this.
  2. P Smith

    P Smith Mr. FixAnything

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    Good luck !
    I'm anxiously waiting your next post …
    perhaps you could make a BOM this time, while waiting ;)
     
  3. texasbrit

    texasbrit Well-Known Member

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    Why bother? Wait for the LCC to be released and then uou can do a price comparison.
     
  4. William1

    William1 Mentor

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    May 11, 2009
    BOM???
     
  5. P Smith

    P Smith Mr. FixAnything

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    Bill Of Materials
    Silk prints and components: IC/transistors/capacitor/diodes/resistors/etc
     
  6. 242424

    242424 AllStar

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    Good luck and post back how it worked!
     
  7. William1

    William1 Mentor

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    May 11, 2009
    A, I got you. Really depends on where you live. No electronics stores near me, so on line. I've seen quality caps go for under $0.50 each and crappy ones selling for $5.00 each! I selected ones from a name brand manufacturer and rated for high frequency (like a RF section of a radio/TV and not ones designed for low frequency as used in a power supply.
    I paid $8.00 for six, delivered via Amazon. 470UF !0V low ESR
    I'm a beginning HAM and have been reading all the books. I have a slight electronics background. Not enough to design my own circuits, but enough to read a schematic, and do basic troubleshooting. As long as my old eyes do not fail me....
     
    Last edited: Dec 20, 2018
  8. P Smith

    P Smith Mr. FixAnything

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    no, not that
    the BOM is for existing components installed/soldered inside of your AM-21
     
  9. William1

    William1 Mentor

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    May 11, 2009
    Caps arrived this morning. Removing the old ones from the board were tough. Through hole solder and it seemed to be high temp solder as well. One at a time, watching polarity. Took old me close to an hour, just to R&R four caps.Hooked it up, only tuner 2 came to 100% (up from 25%) Tuner 1 was still 25%. Crap. poor workmanship. Apart it came for a resoldering. Resoldered all, ensure flow through the holes. Damn bad eyesight! Reconnected, both tuners to 100% Success!
     
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  10. 242424

    242424 AllStar

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    Sweet!
     
  11. P Smith

    P Smith Mr. FixAnything

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    Good to hear that, you did fix it !

    Now, seems to me,you will have more free time and could make a list of components ;)
     
  12. William1

    William1 Mentor

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    May 11, 2009
    Too many SMD parts that I'd spend hours listing. nothing in it for me. However, if someone wanted to give me a few hundred to meticulously itemize all the parts, orientation, photograph the traces, that would be a different story.
     
  13. DirectMan

    DirectMan AllStar

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    Jul 14, 2007
    You have inspired me to attempt the same repair story. I am waiting for a star torx socket I just bought on ebay to open the box. The box is owned by me so no concern about violating TOS. Until the new LCC's are available I am going to try to repair one of my AM-21s.
     
  14. William1

    William1 Mentor

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    May 11, 2009
    Honestly, The hardest part was removing the old caps. Normally, application of the soldering iron and a solder sucker or solder wick would have the board cleared of old solder enabling the component to just come off. Kind of cool that failed caps are visually bad, makes a repair by a non-tech seem like you know what you are doing. Good luck!
     
  15. P Smith

    P Smith Mr. FixAnything

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    Santa Clause is coming with a few hundred … :D
     
  16. William1

    William1 Mentor

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    May 11, 2009
    The device went back to 25%. While the caps I replaced were bad, something else is bad/wrong as well. Perhaps a SMD part is not making good contact and when I was 'man-handling' it, I made temporary contact and subsequent hot/cold cycles 'broke it' again. I had a friend who is a electronics tech look at it and he said the RF section was outputting a strong signal but that once it got to the tuner processor, without a service manual detailing the digital signals and testing, he was unable to check further.
     
    242424 likes this.
  17. scottchez

    scottchez Icon

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    The really need to release the LCC Local Channel connector and sell it for $50 to anyone that wants it and add the drivers to the HS17 (device info is already there recently).
    Pretty please
    Maybe announce it during CES week, hint hint
     
  18. slice1900

    slice1900 Well-Known Member

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    They are still only about 1/3 done fixing the OTA channel lists in various markets. I think it is safe to say they plan to have that done before the LCC is released. So most likely it will be a few more months, at least.
     

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