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  #11 (permalink)  
Old 11-18-2006
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Re: LNB Power missing

U70 (5-pin ic) seems to be a LT1930, it's purpose is to lift the lnb voltage from 12V to 14 or 18Volts. The specs' says 1A and it has an overload protection. But could it be that Q72 and the 0.5ohm resistor (the big green thing) forms the 500mA current limiter? In that case the 20Volt spec for Q72 would be adequate (20V max), because it's on the 12V side.
Could the LNB current limit be raised to say 700mA by replaceing the 0.5ohm resistor and Q72?

Last edited by jenkki700 : 11-18-2006 at 01:44 AM.
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Old 03-22-2007
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Re: LNB Power missing

HELP, is there somebody who knows where i can buy
the MOSFET transistor nds352ap in the netherlands.

Thanks.
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Old 04-02-2007
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Re: LNB Power missing

Quote:
Originally Posted by AlexVbg
HELP, is there somebody who knows where i can buy
the MOSFET transistor nds352ap in the netherlands.

Thanks.
buy it from Digikey.com!
Why do you have to buy it in Holland? It may take a few days more, but it's all the same isn't it?
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Old 04-03-2007
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Re: LNB Power missing

Quote:
Originally Posted by luie1
I repair two db500 that i thought they had bad tuners but it was Q72 i replace them now working good
Digi-Key Part NumberNDS352APCT-ND
Can u explain the details about the picture? What the 5.89 volts mean????
Is it all three pins must same volts????

Thanks for help and reply.

p/s: I have get same problem.. MISSING LNB POWER
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Old 06-05-2007
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Re: LNB Power missing

I have an orig dm500, just want to ask how will i know if it has a missing LNB power? when a connect the cable to my dreambox, i only get AGC=50% and SNR =60% and BER=1000, if i disconnect the cables its still the same, and i noticed that the SYNC and LOCK doesnt have an X on it, when i tested with other stb, the signal is good... is this an indication that it has no LNB power or is it a tuner problem?

i've searched everywhere but couldnt find any solution..
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Old 10-03-2007
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Re: LNB Power missing

The transistor that fooks up the power supply to the LNB - FAIRCHILD SEMICONDUCTOR NDS352AP (MOSFET, P SOT-23)can be purchased in the UK from Farnell Components - Part number 9846395 and costs 36p each. call Farnell on +44 870 1200 208

The other part LT1930 (DC switching power supply) is from linear technologies of Japan. I am trying to source these but can confirm a datasheet here:

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Old 11-05-2007
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Re: LNB Power missing

hello,is somebody able to say the specifications of the Q71 et Q70.I see on the body 6cw et 1aw but i don't found any informations about it on the net.
Thanks for your help
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Old 2 Days Ago
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Re: LNB Power missing

Quote:
Originally Posted by cargab View Post
I've recently got a DM500 with a supossed tuner problem. I replaced the tuner with one from another box, but there was still no signal or LNB power.
Now the LNB power has nothing to do with the tuner itself and I've traced the problem to a little component identified Q72 on the board (bellow the tuner and to the left of a little inductance) and marked "352Ad" on it's body. Anybody knows what that is or what it could be replaced with? I did fix mine by taking the component from the other box, but I'd like to get one nonetheless.
I'm sure that this might help people who fried their boxes with bad wiring or plugging/unplugging with the power on.

Could you describe this Q72? Is the satelite in and out what you are referring to when you say "tuner" and if so does tis need to be removed to get to the Q72? thank you for your help.....colt29
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