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Thread: What are Cylendrical SMT components in Tuner Can?

  1. #1
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    Nov 2002
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    What are Cylindrical SMT Components in Tuner Can?

    Can anyone tell me what the cylindrical SMT components are inside the tuner cans? There are Red, White and Blue ones - I am particularly interested in what the blue ones are.

    Thanks a ton if anyone can help!
    Last edited by Generiq; 07-25-2004 at 01:00 AM.

  2. #2
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    Nov 2002
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    I bought a DSR6000 about a year ago from a guy here in the forums and when it came I could tell it was 'worked on'. The hard drive wasn't even screwed down and there were no case screws. It worked so I kept it and have been using it. Now I went to disconnect it and the coax connector on the back came off in my hand. I opened up the unit and looked in the tuner and it was kind of a mess (previos repair was obvious). I removed the mobo from the Tivo, removed the tuner from the board and cleaned it up a bit. When looking at the other tuner I noticed the one of these blue components looked kind of funky and actually popped off (of course with a little help from me!). This piece looks like it was soldered a bit too much previously in a 'repair' and one end is mostly baked/oxidized (was attatched by a sliver (I guess this is why my signal was never as high on this tuner - just a guess). These are so tiny I could never clean up the end enough to re-use it... I tried.

    Anywhoo, these components arent marked and I can't figure out what they are. I'd like to try and hack a replacement in, so I would appreciate any tips if anyone knows what these cylindrical components are. If I can't figure it out, I will probably remove a good one from the board to see if I can test/figure it out.

    This is a pic of the tuner the coax connector came off (after I cleaned it up a bit).
    Last edited by Generiq; 07-25-2004 at 10:15 AM.

  3. #3
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    One strange thing is those two blue ones under the coaz input on the upper left seem to connect to the same points (although the bottom ones connects through a zig-zag trace (so maybe a diode, but they have no band indicating polarity??).
    Last edited by Generiq; 07-25-2004 at 10:16 AM.

  4. #4
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    Judging from the partial schematic contained in the pic, I would say with 99% certainty that those blue parts are capacitors. The values are probably critical, and judging by the size the "zig zag" which is really an inductor, I would suspect they are quite small probably less than 100pf.
    Capactors should read "open" with an ohm meter. Be sure there are no parallel resistance paths when you measure them with ohm meter. You will have to remove them to check cap value with a cap meter, since parastic capacitance will likely affect the reading.

  5. #5
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    Quote Originally Posted by Tiros
    Judging from the partial schematic contained in the pic, I would say with 99% certainty that those blue parts are capacitors. The values are probably critical, and judging by the size the "zig zag" which is really an inductor, I would suspect they are quite small probably less than 100pf.
    Capactors should read "open" with an ohm meter. Be sure there are no parallel resistance paths when you measure them with ohm meter. You will have to remove them to check cap value with a cap meter, since parastic capacitance will likely affect the reading.

    Yes they are probably caps. Could be inductors too. COuld be diodes.

    One thing for sure is that you CANNOT measure them whilst on the board and get accurate readings.

  6. #6
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    Thanks guys - I do think they are caps. Any of the diodes I've seen in similar packages at least had some band to designate the anode and cathode. I would expect inductors not to have an open resistance through them (please correct me if I am wrong on that) which these do off the board. There is a good number of each of these (red, white and blue). I was thinking they could be jumpers, but they aren't 0 ohms AND the blue ones in the pic I took are going between the LNB IN and GND rails according to the schematics posted here. BTW, how'd you like that pic through the microscope eyepiece - I was surprised it worked!

    They do measure at about .105nf with my meter so right on the nose with the ~ 100pf guestimate. I think I have some 100pf caps around and if not, I know that is a value Radio Shack carries.

    Thanks again for the help and wish me luck!

  7. #7
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    Quote Originally Posted by Generiq
    Thanks guys - I do think they are caps. Any of the diodes I've seen in similar packages at least had some band to designate the anode and cathode. I would expect inductors not to have an open resistance through them (please correct me if I am wrong on that) which these do off the board. There is a good number of each of these (red, white and blue). I was thinking they could be jumpers, but they aren't 0 ohms AND the blue ones in the pic I took are going between the LNB IN and GND rails according to the schematics posted here. BTW, how'd you like that pic through the microscope eyepiece - I was surprised it worked!

    They do measure at about .105nf with my meter so right on the nose with the ~ 100pf guestimate. I think I have some 100pf caps around and if not, I know that is a value Radio Shack carries.

    Thanks again for the help and wish me luck!
    Microscope eh....damn! I thought it ws super macro. Everything in your post above appears correct.

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