Ikea branded TV? Obscure fault.

[Trevtron]

For years Ikea have had dummy TV sets adorning their living room furniture displays, but I discovered the other day that they actually sell their own brand TV's - at least they do in their Seville branch.
It's model number is 602.566.01. I fully expected it to be Vestel crap, but the menu structure didn't feel Vestel-ish, and the sound quality is better than I would have expected from them too.
Unfortunately it wasn't all good news. This particular set belongs to a German customer who bought the set last year because it has a built-in satellite tuner. Perfect for receiving the myriad German channels available on Astra 1. And it performed this task perfectly well, except for the fact that re-ordering the channel list into a sensible order is right royal PITA.
But my task was to add some English TV channels as he is going to rent out the property in the summer. This is something I am used to doing; a 90cm dish receives a handful of UK channels from Astra 2 and, with an offset LNB, the Astra 1 channels can be switched in via a DiSEqC switch. And this is where it went all pear-shaped. As soon as the DiSEqC switch was introduced, most (not all- could still get RTL) of the Astra 1 channels showed 'No Signal'. I tried swapping ports, 3 different DiSEqC switches, different LNB's but each time with the same result. Bypassing the DiSEqC switch restored normal operation on either satellite. Eventually in desperation (and to prove I wasn't going mad) I tried an external satellite receiver and it worked perfectly first time. Whew!! It wasn't me. It appears the TV is somehow interfering with the DiSEqC switch causing loss of signal.
Now I don't expect anyone on here to have come across this fault - it's a fairly uncommon scenario, but of course I am open to suggestions. The owner really wants to use the TV's internal sat tuner - it's why he chose that set - and of course it cuts down on remote clutter, complications for guests etc. etc. What I would like to know is who made the set, and if anyone has had any luck getting tech. help from Ikea.
I am hoping to prevent a complicated outcome; so far I've only been paid 50% of my bill for installing the dish etc. The customer understandably wants to see his system working, but what can I do if it's his TV that's causing the issues?

[stj]

Re: Ikea branded TV? Obscure fault.

not enough current to drive both LNB's
most diseq switches dont alternate the power, only the RF.
this keeps the LNB's stable for a fast lock when channel hopping.

look at the area near the tuner, find the lnb voltage control and look at the caps.

btw, on big switches that feed 4 or more recievers you often use a seperate psu because of this.

[Trevtron]

Re: Ikea branded TV? Obscure fault.

not enough current to drive both LNB's
most diseq switches dont alternate the power, only the RF.
this keeps the LNB's stable for a fast lock when channel hopping.

look at the area near the tuner, find the lnb voltage control and look at the caps.

btw, on big switches that feed 4 or more recievers you often use a seperate psu because of this.

Well done @stj, I reckon you have hit the nail on the head there, thank you!
I will try disconnecting the 'other' LNB just to confirm, but this makes perfect sense. Actually it a kind of a D'oh! moment for me. Here's hoping it's not raining on Monday.
Opening up the TV is not a preferred option at this stage, it's neatly recessed into the wall (probably thus creating a cap-killing "oven") and will be a real bitch to remove. Guests are arriving in a few days so hopefully a temp. fix will do for now.
I've had LNB voltage issues before (no H) with a long cable run and through that I identified an LNB with a particularly low (80mA) current draw. Hopefully I'll still have a couple of those in the shed.

[stj]

Re: Ikea branded TV? Obscure fault.

some recievers actually have a current limit and a sense circuit to detect cable shorts and protect the drive circuit too.

[Trevtron]

Re: Ikea branded TV? Obscure fault.

some recievers actually have a current limit and a sense circuit to detect cable shorts and protect the drive circuit too.

Yes, I'm sure all modern receivers do. Some self-recover when the short is lifted, others (Technomate TM5402 for instance) need a re-boot to clear the error condition.
Back to the original topic- I took along a 4-way DiSEqC switch, figuring no receiver could be expected to power up 4 LNB's simultaneously. I checked it with a cable-checker and sure enough it only powers up the selected port. Just to be sure I also changed the LNB's for 'Best' branded ones which I know from a previous long-cable issue draw less current (80mA on V) than most, and bingo! Both sat's scanned in and working fine side-by-side. Unfortunately the owner was breathing down my neck (and offering me beer at 10am!!) so I didn't get the chance to check the 2-way DiSEqC before removing it. But I kept it and will definitely check it at some point.

Thanks again for your suggestion stj.