about the fan on dm800 hd and the tunner ver J

Discussion in 'DM800HD Hardware troubles and Repair support.' started by sokifar, Apr 26, 2020.

  1. sokifar

    sokifar New Member

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    hello Mr johny.B
    i am rafik from algeria and i am a big admirer of your work and your method of answring members
    thanks a lot for your time
    i have a question pls
    i have a dm 800 pvr and recently i added a 12 volts fan to MB
    for making it running slow. i plug it on the 5 volts pin (number 5 ) on the main voltage pins
    [​IMG]
    but
    i have a doubt that with doing that i will reduce amps for the MB and other equipments such the tunner . knowing that the 12 volt fan will consume more amp if pluged on 5 volt.
    did i do right. or i should stop that and find an other source of power on the Mb
    what do you sugest
    - keep taking 5 volts from the pin5 on main voltages pins
    - taking 5 volts from pin 8 on scart
    - taking 5 volts from inside usb port
    - use a 7805 regulator to convert 12 volt from the main supply to 5 volt
    - stop using fan.

    my 2nd question is
    thanks to your method of repairing glitches on tunner
    i could repair mine by replacing the two 330 uf caps and the 1100 uf cap and adding the 680 uf cap on the side of the tunner's pins and using a 12 v/3 amps PSU.
    the tunner works now after it was unnable to find signal on horizontal fréquences and no signal at all on low freq ( under 11700 mhz)
    now i have signal on V freq at start-up. but it takes 5 to 20 minuts to bring signal on H and LOw freq
    i think it's the time for caps to load and heat-up.
    is my combination of repaired caps is good
    knowing that the reading on the pin 5 and 6 in the main voltage pins are a litle bit under the 5 and 12 v.(= 4.8 and 11.89 v) measured with a china-made low-coast untrustable metrix. hhhhhhh
    or
    is it normal for that old tunner and old unit
    or should i replace all caps even the smalls ones ( 22uf and 220 uf)

    please forgive my bad english and thank you in advance for replaying.
     
    Last edited: Apr 26, 2020
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  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hi,

    As for the 12v fan, connected to a 5v circuit.
    - keep taking 5 volts from the pin5 on main voltages pins
    This is not the best place to take from, because you ballast the U6 with it which is already used by the cpu and other circuits on the box.

    - taking 5 volts from pin 8 on scart
    Basically same as above, I do not recommended.

    - taking 5 volts from inside usb port
    That should be a better choice because this voltage is delivered by the U22 and switched by the U11 and not used by the other circuits.
    Normally a fan would be connected to the P8, which is basically the output of the U22.
    The U22 could bare 3 amps, but the U11 can handle 720mA load per channel.
    In any case, it's wise to use a low amps fan.
    More about the U22 circuit, see this picture.

    - stop using fan.
    Depends on the environment it is, but it's not a bad idea.

    There are also an other idea to use a fan as using a 12vDc to 5vDc step down module which can be very cheap to buy and using the 12v input from the box.
    But than the fan will always run, or you must switch off by the 12v power supply.

    About the question,
    now i have signal but it takes 5 to 20 minutes to bring signal on H and low freq

    I have no idea why this could happen, or you must have used caps with a higher (voltage) range, then it may takes longer to load the cap.
     
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  3. sokifar

    sokifar New Member

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    thaks a lot Mr JOHNNY
    you are a great man.
     
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