LNB V/H Voltage

[inwo]

Not really. Lets say the LNB needs 18 volts and 1 amp to work. The power supply is putting out 18 volts, but there is something wrong and it only can supply 1/4 of an amp. The LNB can't just "make" the power supply supply the 1 amp it needs just because it is there. It will get voltage but not operate because it does not have the current it needs. That appears as what the problem is with this unit. Power the LNB from another known to work source, and the receiver works fine.

RT.

I know what you're saying.

But if the power supply can't supply the current, the voltage will drop accordingly. (under load)

And lnb only needs maybe 8 volts. 12 at most to work. It is internally regulated at 5 volts often.

It does need more on one polarity to switch however.

 

[RT-Cat]

:up

Meow

 

[FaT Air]

Does this receiver exhibit "No Signal" on any LNBF, any band, any polarity? Or is it limited to one particular LNBF, or polarity?
How about comparing the LNB voltage when powered by another receiver, to the voltage supplied by the "No Signal" receiver?

 

[RT-Cat]

Does this receiver exhibit "No Signal" on any LNBF, any band, any polarity? Or is it limited to one particular LNBF, or polarity?

Yes, any LNB. All I get is "No Signal."

How about comparing the LNB voltage when powered by another receiver, to the voltage supplied by the "No Signal" receiver?

Have not tried that reading yet. If powered by the 920, it works fine.
Another thing I checked today was putting an amp meter in the coax line. This just may be the answer. On the good receiver I get 425 milliamps on the meter. On the "bad" receiver it only shows 125 milliamps. It just is not putting out enough "juice" to "fire" the LNB's. So it must be something with the power supply. (?)

RT.

 

[FaT Air]

If only supplying 125ma, the voltage should, I would think, be a lot lower than 13v, unless the LNB is raising it's "R". I*R=E E/R=I E/I=R, This is not making ¢¢¢, That would suggest the regulator in the LNBF isn't being supplied enough voltage to "turn on" but your measurement say it is(?).
Got a 36?* 10W power resistor? 18v would put 500ma thru it @ 9watts[ewh, warm] (it won't change effective R with different voltages) *4-10? 10W in series wouldn't get as warm.

 

[inwo]

If you have access to a "power passive one leg only" splitter you can power both receivers at the same time, powered from one receiver.

edit.

Looks like you've done that.

 

[Pixl]

Ted,

The 425ma with the good receiver sounds like a lot. That is almost at the max current draw of 500ma most receivers are rated at. In my system, the highest draw I have is a certain selection where I'm going thru a 4 way switch, then 8 way switch, then a 22k ecoda switch that powers two dish lnb's at the same time. Total draw=285ma. even though each switch draws some current along with the juice it passes along to the next. So it adds up, but not to what you are drawing.
Something in your system may be in trouble, as well as the one receiver.

 

[Smith P.]

Yes, any LNB. All I get is "No Signal."

Have not tried that reading yet. If powered by the 920, it works fine.
Another thing I checked today was putting an amp meter in the coax line. This just may be the answer. On the good receiver I get 425 milliamps on the meter. On the "bad" receiver it only shows 125 milliamps. It just is not putting out enough "juice" to "fire" the LNB's. So it must be something with the power supply. (?)


RT.

You reversing a cause and a result.
The measured current is defined by your load (LNBF/switch/cables). NO need to invent 'juice' characteristic...
Voltage by the 'bad' receiver is practically same as other box provide.

Something is wrong in your hands: same load (LNBF,cable,etc) cannot produce different load with same source voltage. There is no such magic.
You need to settle you bench properly .

 

[RT-Cat]

Got a 36?* 10W power resistor?

No, not in my old junk box.

Ted,

The 425ma with the good receiver sounds like a lot. That is almost at the max current draw of 500ma most receivers are rated at.......

I have to agree with you on that. With that meter, I may have had the divide by 2 switch on and that would have made that high reading.(looking at the display wrong)
If that was the case, then the reading would have been 212ma good receiver and 62.5ma for the bad receiver.
Will do more checking Thursday afternoon.

Meow.

 

[RT-Cat]

.....Voltage by the 'bad' receiver is practically same as other box provide.

.....same load (LNBF,cable,etc) cannot produce different load with same source voltage. There is no such magic......

Maybe I have the first magic S9.
Will check all voltages when I find some time.
Too bad you are so far away or I could hand you the receiver. I could use a pro to figure why it does not work.

RT.

 

[Smith P.]

Maybe I have the first magic S9.
Will check all voltages when I find some time.
Too bad you are so far away or I could hand you the receiver. I could use a pro to figure why it does not work.

RT.

Then I would ask for the LNBF and the cable too . If I will check on my LNBFs and cabling OK, you will not happy with your 'weird' config.

 

[RT-Cat]

Been a little busy getting rid of the 10 inches of snow I got very early Saturday morning. I found a few minutes to look at this "funny" S9 again. This power supply gets more odd as time goes by. With a different setup with the amp meter in the coax line, I actually got a picture and sound for a few seconds. With the ground or shield of the coax circuit to the LNB open and waiting for a few seconds, then closing the circuit, the meter would move up to 225 Ma. The picture would move and there was sound. Within a couple of seconds the meter would drop and the picture would freeze and the sound would stop. "No signal" on the screen. The meter would show 50Ma and hold there. Open the circuit for about 10 seconds, reconnect and the process would happen again. Moving picture and sound for a few seconds, then stop. This could be repeated time and time again. I would not think it is the main supply because I swapped my working S9 supply and it made no difference in how this sick S9 would work. ?????

 

[Smith P.]

Now put voltmeter on the center of coax and watch it during connection/viewing time.

 

[RT-Cat]

Now put voltmeter on the center of coax and watch it during connection/viewing time.

With the meter set to volts, I get a constant 14.3 and change channel to change polarity, it jumps to 17.5. The voltage does not drop off like the amps do. Change meter to amps, open the circuit, wait, close, up goes meter, on goes channel, three seconds later amps drop and signal goes off or dead. It is as if the power supply had to "build" up a "charge."

 

[FaT Air]

When you "Change meter to amps" are you re-wiring the voltmeter into the circuit? Ammeters are in series with the load, Voltmeters are parallel with the load. If you are rewiring, Voltage not changing, but current dropping from ~200ma to ~50ma says the problem is in the load. Load resistance increasing by a factor of 4.

 

[Smith P.]

Well, I would go back on the voltage regulator, see if control signal changing; o-scope would best tool, as if there is spike in load and over-current protection kicked with delay ...

 

[RT-Cat]

When you "Change meter to amps" are you re-wiring the voltmeter into the circuit? Ammeters are in series with the load, Voltmeters are parallel with the load. If you are rewiring, Voltage not changing, but current dropping from ~200ma to ~50ma says the problem is in the load. Load resistance increasing by a factor of 4.

Yes, re-wiring was done.

Well, I would go back on the voltage regulator, see if control signal changing; o-scope would best tool, as if there is spike in load and over-current protection kicked with delay ...

No scope. Will continue checking when time allows.....

 

[polgyver]

Yes, re-wiring was done.


No scope. Will continue checking when time allows.....

Sometimes it helps to use 2 meters, if there is no oscilloscope. One used as a voltmeter, the other as an ampmeter. Even an old - fashioned, simple, inexpensive meter could help. Most probably, as Smith,P suggests, the over-current protection kicks in, but there could be 2 reasons : 1. The load (faulty LNB or some parasitic resistance in the wiring), or 2. The over-current protection threshold in the receiver somewhat changed. Would be nice to have a schematic-diagram of your receiver, sadly, in recent times, the manufacturers do not provide it... Cheers, polgyver

 

[RT-Cat]

Sometimes it helps to use 2 meters, if there is no oscilloscope. One used as a voltmeter, the other as an ampmeter. Even an old - fashioned, simple, inexpensive meter could help. Most probably, as Smith,P suggests, the over-current protection kicks in, but there could be 2 reasons : 1. The load (faulty LNB or some parasitic resistance in the wiring), or 2. The over-current protection threshold in the receiver somewhat changed. Would be nice to have a schematic-diagram of your receiver, sadly, in recent times, the manufacturers do not provide it... Cheers, polgyver

I would think that is eliminated because the other S9(the one that works)is put back on that same coax after testing the "bad" one. Bugs in wiring or bad LNB should show up in both receivers.
.
Schematic for an S9. Now that would be something. You can't even get a manual you can see the pictures in.

Meow.

 

[polgyver]

I would think that is eliminated because the other S9(the one that works)is put back on that same coax after testing the "bad" one. Bugs in wiring or bad LNB should show up in both receivers.
.
Schematic for an S9. Now that would be something. You can't even get a manual you can see the pictures in.

Meow.

If I remember correctly, the receiver worked for a few seconds when the amp was in series with the LNB (load) and probably current protection circuit limited the current. Could it be that this little amp resistance (probably a fraction of an Ohm, or 1 to 2 Ohms ...) delayed the start of protection circuit? What would happen, if you connect, instead of an ampmeter, a resistor, say, 3.3 or 4.7 Ohm?