DSR708 Harddisk Upgrade Frequent Freezes

Discussion in 'TiVo Upgrade Center' started by hrt78mw, Jul 4, 2015.

  1. hrt78mw

    hrt78mw New Member

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    Jul 4, 2015

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    I bought a 500 Gb harddisk upgrade from DVRupgrade for my DSR708 DirecTV TiVo recorder and installed it. The machine boots fine but quickly freezes at frequent irregular intervals and can only be reset by disconnecting the powercord. I believe this could be caused by the following:

    - The wrong software version on the harddisk bought which identifies itself as DSR7000/17 rather than DSR708 in the DVR Setup menu.

    - A higher current draw. The new harddisk is a WD5000AUX 500 GB drawing 5VDC 0.70A and 12VDC 0.55A per the label whereas the old harddisk is a WD800 drawing 5VDC 0.35A and 12VDC 0.50A, also per the label. I should add that the power supply in this DVR was replaced maybe three years ago, also from DVR Upgrade. The harddisk is, of course, a SATA harddisk which has an IDE adapter which may also draw some current.

    A third possibility, overheating, can be ruled out since I also removed the DVR cover and put a powerful fan directed at the harddisk and power supply with no effect.

    Last, a problem with the mother board can also be ruled out since I then put the old harddisk back in the unit and the DVR runs fine.

    I believe the power supply is the most likely culprit. Can it in DSR708 be replaced with one allowing higher current draw? If so, which one and where to buy? I am assuming that the new power supply I installed a few years back and purchased from DVRupgrade was an exact replacement for the original one but have no way of checking that now since the old one has long been discarded.

    Thank you.
     
  2. unitron

    unitron Well-Known Member

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    That "new" power supply you bought was probably what's called New Old Stock, or NOS, meaning they manufactured it way back when that model TiVo was being made, and its been sitting on a shelf ever since.

    This means it's just as likely as the one that came in your TiVo to have the bogus capacitors that plague all of the S2 and S3 models.

    So the problem might be your power supply needs repair.

    Simple soldering job, parts relatively inexpensive.
     
  3. hrt78mw

    hrt78mw New Member

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    Jul 4, 2015
    OK, how do I identify any "bogus" capacitors on the power supply?

    Follow-up questions:
    - What is the maximum current draw on the 5V portion of the power supply?
    - What is the maximum current draw on the 12V portion of the power supply?
    - Where can I find a service manual for the DSR708 (or DSR704) DVR?

    Looking at the spec sheet for the DSR708, it seems the maximum power it would use is 40W, thus the power supply would deliver no more than 40W. While the old harddisk draws a little less than 10W, the new harddisk draws 13W.

    Is it possible that the relatively minor difference in 5V current draw for the new harddisk could result in the freezes I described in my original message?

    Is there a third-party power supply that could deliver more juice and fits in the chassis?
     
  4. hrt78mw

    hrt78mw New Member

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    Jul 4, 2015
    I finally looked at the power supply and I should have done this a long time ago, particularly since I swapped the new and the old harddisk out several times...

    I am attaching two pictures where you can clearly see that capacitors in three locations on the power supply board have gone bad... I am surprised that the unit actually still works! I immediately ordered a new power supply from DVRupgrade.

    This may also explain the fact that I have seen severe pixelation on some channels - certain ones being prone to this, others not - yet never been able to tie it to one of the two tuners, nor to one of the two cables coming into the DVR from the splitter in the attic. Swapping cables between tuners, using the channel selector to move between channels did not help me find the reason. Hopefully the defective power supply is the culprit...
     

    Attached Files:

  5. unitron

    unitron Well-Known Member

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    Apr 28, 2006
    semi-coastal NC

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    Actually, from those pictures I don't think one can tell whether there are any bad caps or not.

    (the white stuff is glue used to hold components in place during the soldering phase of the manufacturing process)

    You have to check the tops of the capacitors for absolute flatness.

    The least hint of "doming" and it's bad or at least going bad and only going to get worse. Of course it could also be going bad without any bulging or other visible indication.

    Voltage measurements by someone who knows what they are doing would be the preferred way to see if there's anything wrong with the power supply.

    Of course, in the case of Series 2 and Series 3 TiVo power supplies, there's a very good chance that if the capacitors haven't gone bad yet they will, so you might get good readings today and bad ones next week.


    If you look on the large capacitor (the one in the lower left hand corner in those pictures) there should be a sticker wrapped around it that shows the rated current output at the various output voltages.

    That's the rating of the supply, not the usual current draw of the TiVo.


    TiVo schematics and service manuals tend to be sent out via Unicorn Express. :(

    They may exist, but except for the Series 1 models, I don't think they've ever been seen by mere mortals.

    Fortunately the power supplies are fairly straightforward.


    In addition to that white ribbon cable jumper that connects the power supply to the motherboard, there's another, similar looking ribbon cable that connects the front panel to the motherboard.

    It's very easy, without realizing that you have done so, to bump it and partially dislodge it from the socket on the motherboard into which it plugs, and if it's like that when power is applied it can cause burnout of a small inductor and screw things up.

    Check it to be sure it's fully seated at exactly a right angle to the board before plugging the power cord in anytime you're inside the TiVo.
     

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