Troubleshooting to a bad Triple LNB

[Majique]

I have access to two Directv non-HD systems. Both systems were working fine until earlier last week when system #2 displayed the Searching for Satellite page. So I began troubleshooting....

1) the dish hasn't moved
2) the D10 is working fine (confirmed on system #1)
3) cable and connectors are good (confirmed on system #1)
4) getting 13vdc and 18vdc to the Phase III triple LNB
5) same symptom regardless of which 4 connectors used on the LNB
6) opened Phase III LNB found fried ICs and circuit board in multiswitcher (replaced RG6 cable and connectors after finding fried LNB multiwitcher, just to make sure they weren't zapped too, eventhough they worked on system #1)
7) obtained a different Phase III LNB, the design is the same but the manufacturer is different (not sure if it was working or not, seller says it was)
8) still get Searching for Satellite with system connected (the symptom is the same even if I disconnect cable from D10, so that leads me to believe the receiver is not "seeing" the LNB)
9) beginning to think I got another bad LNB

Short of taking system #1 LNB off and placing it on system #2 antenna (which is gonna be a pain) and visa-versa, what else can I do? Any suggestions?

~Majique

[veryoldschool]

Get another LNB that works. :)

BTW: Welcome to DBSTalk forums.

[Majique]

Get another LNB that works. :)

BTW: Welcome to DBSTalk forums.

Thanks for the welcome.

I was afraid get a known working LNB was the answer I would get. Was hoping there was a secret troubleshooting procedure for the LNBs as stand alone units. I hesitate swapping the LNB from system #1 to system #2 or visa versa due to the precarious position of the #1 dish, which by the way is more "squared" than the round #2 dish. Surely that wouldn't make a difference in whether the LNB would work or not, would it? They both appear to be 18" or so.

[veryoldschool]

The phase III is an oval dish and uses a triple LNB, where the 18" uses single LNBs.

Here will show you some of the dishes: http://www.solidsignal.com/satellite/directv_dish_antenna_types.asp
Perhaps buying a "new one" [LNB] from them would work.

[Majique]

[QUOTE=veryoldschool;1548222]The phase III is an oval dish and uses a triple LNB, where the 18" uses single LNBs.


Yup, the Phase III is on both systems. #1 system antenna just looks more oval from a distance for some reason. So tomorrow I'll trek up on the roof, replace the #1 LNB with the procured LNB and see if the system works. If it does, it confirms the good LNB. If it doesn't I guess I have another faulty LNB on my hands.

[hdtvfan0001]

I would also do one close inspection of the cable connectors at the LNB side, as the triple has (on occasion) had reports of water damage to the connectors when the LNB arm is not properly seated. You may just need to replace a connector or two.

[Majique]

Update...

Both Sharp brand LNBs work fine on system #1.

Today I noticed both system #1 & #2 antenna dishes have "Multi-Satellite" printed on the dish but #2 also has "Channel Master" printed on it. The zapped LNB also has Channel Master on it and is actually an LNBF. Is there a difference between and LNB and an LNBF? Yet all three of the LNB units state "Triple-Feed Multi-Satellite Compatible with Directv Phase III 18 x 20 Dish Antenna". Upon laying the Channel Master LNBF next to the Sharp LNB I noticed the Channel Master's 3 feed horns are thinner than the Sharp LNBs.

Again, the receiver and cable work good on system #1. The cable between the receiver and the antenna has two new connectors and is putting out 13 vdc at the antenna.

So the faulty LNBF is a Channel Master pn 303013601. At this point I'm wondering if that's been my problem all along; trying to use a Sharp LNB on a Channel Master dish in place of a Channel Master LNBF.

[veryoldschool]

The question that comes to mind: Are the LNB assembles "exactly" the same? Sometimes the mounting arm/dish will vary from one maker to another. If the feed horns aren't in the correct focal point, then they can't pickup the signal.
I had a neighbor that wanted to mount a dual output LNB where he had a single and then use the single on his other dish. It didn't work and a quick look showed the feed horn was in a completely different location [just an inch or two] to to the original one.

[Majique]

The question that comes to mind: Are the LNB assembles "exactly" the same? Sometimes the mounting arm/dish will vary from one maker to another. If the feed horns aren't in the correct focal point, then they can't pickup the signal.
I had a neighbor that wanted to mount a dual output LNB where he had a single and then use the single on his other dish. It didn't work and a quick look showed the feed horn was in a completely different location [just an inch or two] to to the original one.I checked that as well and the LNBs have the same angle where they slide into the mounting arm; translating to the same focal point. The Channel Master LNB is just about 1/8" closer to the dish than the Sharp LNB. Not enough to make a difference IMO.

What I can't figure out is why I'm not getting any signal at all. I would think with an antenna that hasn't moved, a compatible LNB and good cabling I'd at least get some weak signals but as it stands I get ZEROs on all satellites. Based on the fact the symptom is the same (searching for satellite) whether or not the cable is connected at the receiver and I'm getting the required voltage at the antenna the only thing I can deduce is the system "demands" a Channel Master LNBF.

[veryoldschool]

I checked that as well and the LNBs have the same angle where they slide into the mounting arm; translating to the same focal point. The Channel Master LNB is just about 1/8" closer to the dish than the Sharp LNB. Not enough to make a difference IMO.

What I can't figure out is why I'm not getting any signal at all. I would think with an antenna that hasn't moved, a compatible LNB and good cabling I'd at least get some weak signals but as it stands I get ZEROs on all satellites. Based on the fact the symptom is the same (searching for satellite) whether or not the cable is connected at the receiver and I'm getting the required voltage at the antenna the only thing I can deduce is the system "demands" a Channel Master LNBF.
Only a three year old would act that way. :lol:

Seriously, 13, 18 volts and 22 KHz tone or not is all "an" LNB needs. There is no way for an LNB to require "more".
Must now ask: How well is the dish really pointed? I know you said it didn't move, but from what you're posting, it is kind of looking like it has moved.

[eakes]

A slight difference in LNB placement relatively to the dish can make a large difference in alignment, especially in an offset feed arrangement. Mark the present alignment position and adjust elevation (up and down) - it should make a difference!

[Majique]

A slight difference in LNB placement relatively to the dish can make a large difference in alignment, especially in an offset feed arrangement. Mark the present alignment position and adjust elevation (up and down) - it should make a difference!I know the LNB and dish haven't moved because they were welded in place and the base is welded to the house. I got out the transient and shot all the angles and nothing has changed.

[Majique]

I know the LNB and dish haven't moved because they were welded in place and the base is welded to the house. I got out the transient and shot all the angles and nothing has changed.

UNBELIEVEABLE..!!!! It's working now....

We were sitting there and all of a sudden the tv started blaring! All the channels are there, crystal clear.

The fix is what's unbelieveable....the military was nearby for the past week or so and now they're gone. They were conducting electro-jamming exercises and my #1 system was far enough away to not be affected!!!!

But at least now we know the Sharp LNB works in place of the Channel Master LNB.

Thanks to all for your input and assistance!

[crashHD]

<jamaican voice>
Boo war waged against TV.

Hooray Beer!
</jamaican voice>