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Tivo Series 3 - Bad capacitors in power supply

Discussion in 'TiVo Help Center' started by johnsom, Jul 25, 2011.

  1. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    timhbtr53, I figured out that I had to take the screw out of the back of the meter to get to the battery and amazing as it might seem, the Radio Shack battery that was in the meter did not leak. I put in a new battery and the meter is working. When I touched the 2 leads together in Ohms mode, the meter went to 0. I tested the fuse as you suggested and the meter did move, so I guess that rules out the fuse. By the way, the photo you supplied looks more like the power supplies from the 2 648250B units that I repaired earlier in the year, not the 652160 that I am currently trying to repair - but I get that it shows the general location of the fuse. The power supply does not make any noise when plugged in.

    What should I check next?

    Thanks,
    Amy
     
  2. timhbtr53

    timhbtr53 Grumpy Old Man

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    Apr 24, 2014
    In the Deep...
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    It was just to show you the fuse loction. Can you here a high pitch noise you have to listen real close in a quiet area. Have you treyed to check if your getting any volage out on the +5 volt side or the + 12 volt side? The red is 5 volts the yellow is 12 and there is a 3.3 volt line but i don't remember the color sorry. I lost all my stuff in the "great flood of aug 13 2016' so it sucks not having all my stuff.
     
  3. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    I don't hear anything when it's plugged in - no whining or ticking. I've never tested voltage before, so a quick lesson would help. Also, I don't see anything color coded (as in red or yellow). I can post a photo of the ps, if that would help. I do appreciate the help.

    Thanks,
    Amy
     
  4. HerronScott

    HerronScott Well-Known Member

    5,471
    548
    Jan 1, 2002
    Staunton, VA
    A picture would help but you want to take a picture of the connector where the power supply connects to the main board as that's where you will want to measure the voltage. That cable and connector should have the different color cables that timhbtr53 referred to.

    Scott
     
  5. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    Ahh! Now I understand what I'm looking for. BTW, the 3.3 volt line is the sickly orange color that almost looks red. Here's a photo:
    TiVoHD Power Supply.JPG

    Now that I know what I'm looking for, what am I supposed to do?

    Thanks,
    Amy
     
  6. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    Unitron, HeronScott, timhbtr53 - Any help please?
     
  7. HerronScott

    HerronScott Well-Known Member

    5,471
    548
    Jan 1, 2002
    Staunton, VA
    Hi Amy,

    Sorry but work has kept me quite busy late into the evenings so I had not had time to respond. :(

    So first step is to reinstall the screws for the power supply or at least the 3 at the top of your picture with the grounding rings that ground it to the case. Set your voltmeter to measure DC voltage and autoranging if it has it. You can place the black lead from the meter on one of the screws with the grounding ring. Then just place the red lead from the meter into the back of the connector for each of the colors and read the voltage (Tim indicated red 5V, yellow 12V and you said orange 3.3V?).

    Scott
     
  8. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    Scott, thanks for getting back to me. That work thing keeps getting in the way of doing things I want to do and I hate that :)

    I did what you said - I set the meter to the 25V setting since the yellow wire could be 12V (which is above the 5V setting) and not one of the red, yellow and orange wires had voltage. The needle didn't budge. And I do know that the meter is working, since I tested it by checking the voltage on some batteries to make sure that I understood how to use it.

    Other than meaning that the power supply is not supplying power, is there anything that this points to as the problem?

    Thanks,
    Amy
     
  9. HerronScott

    HerronScott Well-Known Member

    5,471
    548
    Jan 1, 2002
    Staunton, VA
    Does this power supply have a fuse on the input?

    Scott
     
  10. amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    Scott, there is one and timhbtr53 had me check that earlier and it was good (see post 561). Any other thoughts?

    Thanks,
    Amy
     
  11. Jun 2, 2017 #571 of 603
    jmbach

    jmbach der Neuerer

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    Jan 1, 2009
    I would check the voltages on both sides of the fuse to start with. Based on what I can see from the photo, should be 120 VAC. If there is voltage on both sides, then need to start checking voltages downstream by following the traces. For there to be no voltages across any of the output rails, the problem more than likely be upstream.
     
    Last edited: Jun 2, 2017
  12. Jun 3, 2017 #572 of 603
    amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    jmbach, thanks for replying. I checked the voltage on both sides of the fuse and it is the same. I'm not sure what you mean by "follow the traces", so any further help is truly appreciated.

    Thanks,
    Amy
     
  13. Jun 3, 2017 #573 of 603
    jmbach

    jmbach der Neuerer

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    The boards I believe are single layer boards. So the bottom side of the board has copper strips or "traces" that connect the components together.

    With no voltage at all the output rails, this would indicate that the problem is before the voltages are split off.

    One place I would check first is that big transformer. One side is probably 125 VAC and the other side is a lower VAC. See if both sides of the transformer has voltage.
     
  14. Jun 3, 2017 #574 of 603
    amyf

    amyf Member

    50
    5
    Sep 24, 2014
    Central NJ
    jmbach, I was able to check for voltage at the big transformer (both sides) and the little transformer (also both sides). I'm not sure how to continue after that - I can post a picture of the underside, if that would help.

    Thanks,
    Amy
     
  15. Jun 3, 2017 #575 of 603
    jmbach

    jmbach der Neuerer

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    Jan 1, 2009
    Yes that will help.
     
  16. Jun 3, 2017 #576 of 603
    jmbach

    jmbach der Neuerer

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    The next the next thing to check would be the rectifier. Which I think is the yellow box looking object. One side should be AC and the other side DC.
     
  17. Jun 3, 2017 #577 of 603
    amyf

    amyf Member

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    Sep 24, 2014
    Central NJ
    Jmbach, are you referring to the yellow box right next to the transformer. Unless you mean the other yellow box that is past the big capacitor. For what it's worth, I know that there is power through the second transformer.

    Thanks,
    Amy
     
  18. Jun 3, 2017 #578 of 603
    jmbach

    jmbach der Neuerer

    2,080
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    Power plug, inductor (coil), ?rectifier, Inductor (coil).
    I only see one transformer and that is on the far end of the board.
     
  19. Jun 3, 2017 #579 of 603
    jmbach

    jmbach der Neuerer

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    Jan 1, 2009
    Photo of bottom would be helpful to get a better handle on the components.
     
  20. Jun 4, 2017 #580 of 603
    amyf

    amyf Member

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    Sep 24, 2014
    Central NJ
    Jmbach, sorry, but I'm don't know much about electronic parts and pieces. I googled transformer and found what looked like a match to a something on the board. I was able to test the copper coiled around in a circle right after the power plugs into the board, and the second smaller coil that was after the yellow box-like thing (going from left to right in the photo). They both had power on both sides (left and right, both copper wires going into the coil). Here is a picture of the bottom of the board:
    TiVoHD Power Supply bottom.JPG


    Thanks for your help and your patience.
    Amy
     

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