Strange problem with vertically polarised 19E channels only

[robins]

I wonder if anyone could possibly cast light on this puzzling issue?

I have two Spiderboxes connected up to three LNBs, each pointing towards different satellites and all pulling in strong signals. Spiderbox 1 works flawlessly, but Spiderbox 2 brings in only a broken signal from all of the vertically polarised (FTA) channels on 19E. When I swap the two STBs around, it's clear that cabling, DiSEqC switch and LNB are not faulty, as Spiderbox 2 shows the same problem when connected up in the location of Spiderbox 1: the V channels on 19E break up so much that they're unwatchable.

This suggests to me that Spiderbox 2 is faulty and not switching properly from 18v to 13v for the vertical channels. But what mystifies me is: how can this be the case when reception of the vertically polarised channels on 28E and 13E is perfect? And would a hard reset achieve anything?

Any help with this would be greatly appreciated ...

[jbvid]

Hi
A bit hard to follow but you seem convinced its not an LNB or cableing problem, even I would suspect them first. You can check the voltage switching at the rear of the suspect spiderbox's input 'F' connector to see if its voltages differ between H & V. You need to be carefull if doing this and not short out/across the connectors core and outer thread.
jb

[Roadrunner]

Check the Lnb type in the affected box Is it the same as the one in the box that is working? I think something went wrong during setup and I would begin by checking the above mentioned setting first.

[robins]

Thanks very much for this.

Sorry - it's basically two parallel set-ups in two different rooms: spiderbox in both, each connected via a separate DiSEqC box to different outlets on the selfsame three duo LNBs. Spiderbox 2 shows the same fault (flaky reception or 'no signal' on 19E vertical transponders) in both locations, while Spiderbox 1 functions flawlessly in both. This is what leads me to believe that the cabling, DiSEqC switches and LNBs are not suspect - and in fact I've checked, cleaned and tightened up all connections.

Thanks for pointing out that I can check the output voltage. I'll need to get hold of a voltmeter to do this, but I suspect it will show normal functioning, because it obviously switches properly on 28E and 13E - and when the voltmeter replaces the LNB cable the 19E LNB won't be connected at all. I simply can't get my head around how it can switch voltages for 2 satellites but not for the third - which I agree does seem to point to cabling or LNB.

[robins]

Thanks for this pointer - the only LNB settings I can find are under Satellite Settings > LNB, where the figure is set by default on both boxes to 97500/10600. Or is there another setting for LNB type?
All very frustrating. It's a nearly-new box, but returning it patched doesn't sound a good idea to me. Unless it's possible to remove the patch ? I know Factory Re-set doesn't do this ...

[jbvid]

Hi
All I can suggest now is some elimination. run a new direct cable line bypassing diseqc switches, original cables and fittings etc. LNB to Spider1 then try it on Spider2, then your 2nd LNB to Spider 1 then Spider 2.
As Roadrunner says check all the setup menus on both Spiders for comparison.
jb

[renibacterium]

What is the signal strength? Too much signal will cause picture break-up. If it is this then you may need an attenuator.

[robins]

What is the signal strength? Too much signal will cause picture break-up. If it is this then you may need an attenuator.

I think we can discount this, thanks, as the 19E and 13E LNBs are on a 6-degree bracket, so neither brings in the absolute maximum signal - strength and quality are both around the 75% mark. I'll follow jbvid's advice and try to make some direct connections to the 19E LNB ...

[robins]

Hi
All I can suggest now is some elimination. run a new direct cable line bypassing diseqc switches, original cables and fittings etc. LNB to Spider1 then try it on Spider2, then your 2nd LNB to Spider 1 then Spider 2.
As Roadrunner says check all the setup menus on both Spiders for comparison.
jb

Thanks for this. I've now run a cable direct from the 19E LNB and found that the problem remains exactly the same: Spiderbox 1 registers a full signal for both H & V channels, whereas Spiderbox 2 receives a stable signal on the H channels but produces at best a broken picture (signal bars flickering between green/blue and red) and at worst the message 'no signal' (red bar) on all the V transponders. Immediate suspicions are of a loose connection, but that's not the case - and stable reception of the H channels proves this.

This seems to indicate to me that the LNB, DiSEqC switch and cabling are fine, which leaves either the possibility that (i) the settings on the two boxes are different, or (ii) the box is faulty and not switching properly to the lower voltage.

However,
> (i) the settings that appear on the 'Satellite Settings' page are identical, including the LNB figure - 97500/10600 - so unless there's another LNB setting I'm unaware of, this seems to eliminate # (i) as the problem.
> (ii) I can't actually test the output voltage to the LNB until I get a voltmeter, but there's absolutely no doubt that this box switches perfectly between H and V channels on 13E and 28E. When I test the voltage it won't of course be connected to any LNB, so I don't see how this will take me forward.

Or have I missed something blindingly obvious?
Thanks in advance ...

[jbvid]

When I test the voltage it won't of course be connected to any LNB, so I don't see how this will take me forward.

Or have I missed something blindingly obvious?
Thanks in advance ...
All you can do is compare the switching voltages between both boxes when not connected to an LNB.
The suspect Spider could have a low V switching voltage so not operating 19e's LNB, have you tried another LNB on the 19e single direct cable run?
jb

[robins]

All you can do is compare the switching voltages between both boxes when not connected to an LNB.
The suspect Spider could have a low V switching voltage so not operating 19e's LNB, have you tried another LNB on the 19e single direct cable run?
jb

SOLVED!

I've still not been able to measure the respective voltage outputs, but I took your advice and tried an older LNB in place of the problematic one ... and it looks as though your diagnosis is spot-on, as the old LNB brings in all the V channels. So it seems to be an issue where neither the Spiderbox or the LNB is 'faulty', as such, but the two together don't quite work because the switching voltage on Spider 2 must be just on the periphery of the LNB's range. And the reason why the other two LNBs work fine will no doubt be that they're a different brand that's presumably that bit more tolerant. Seems to me to be a classic case of a little knowledge being a dangerous thing, as I might well have contemplated sending Spider 2 back if we'd not discussed it here. So very many thanks for putting me on the right track. Replacing the LNB is an awful lot simpler than arguing with a retailer who would test the returned STB and no doubt find it working perfectly ...!

[jbvid]

Well, we got there in the end, most problems can eventually be sorted by elimination.
jb