We have one dish with a 4 port LNB with two identical pace digiboxes. One works fine - it has a sky card and it receives most channels - just the odd one or two are a bit dodgy. The other is crap - you can't watch even 'good' channels like BBC and ITV. In fact just about the only channel it gets at all is Sky news. So - same dish, identical boxes. The only difference I can think of is different leads from the LNB to the box and the one which works well has a card in - I don't know if that makes a difference. Anyone got any ideas?

First question is: are you using the same regions for both boxes in your comparisons?
The one with the card may well have differnet regions on 101, 102, 103, 105 to one that has no card in.
Some BBC and ITV regions are on different frequencies, and so if you dont use the same ones reception cannot be compared.

Second: cabling could be an issue. Check for joints and cracks where water could have gotten into the cabling, which can reduce signal.

Third: try another port on the LNB - these can fail.

You should swap the boxes around, and see if the performance changes and that will isolate if it is the cableing / lnb are at fault or its the box...

Fourth: depending on model of box, and its age it is entirely possible that he box and it components are starting to fail...be it age or "power surges" that have damaged components.

Thanks the Guy. I will take the card out of the working box (it is an Irish card so 'regions' don't really count) and see if that shows anything up. Then I will swap the (cardless) boxes to see if that makes a difference. Then I will get my little Romanian friend to crawl around the roof looking at cabling and the LNB

The fact that it is an "Irish card" means that regions DO count! The address where the card is registered defines which is your default BBC 1 station on channel 101 and will be via a transponder delivering Irish regional news and will be different than my card for example which is a NW England registered card hence my 101 is NW region and via a transponder which loses signal most times during the day and is totally unreliable for BBC 1 reception. I therefore use channel 977 which gives me excellent reception. This channel is defined on my EPG as "York/Lincs". If my card was sourced from this geographical area my default 101 channel would be this signal giving me excellent reception and I wouldn't need to select another region.
It's the same for ITV.

Our 101 is RTE1, BBC1 (NI) is on 141 and there are no alternative regions.

When I said Irish I meant seriously Oirish.

Are you saying that your EPG doesn't show any other BBC regions from channel number 971 and upwards?

Correcto.
If you use an ROI / Irish sky card in a box, then BBC1 / 2 regions and some of the other BBC channels do not appear in the EPG at al, and you are allocated RTEs 3e etc on 101 etc.

If the car is registered in Northern Ireland, then you are allocated BBC1 NI and BBC2 NI on 101 and 102,

If you have an irish card amd want BBC channel,s then you need to remove the card, and boot the box without a card, and the box defaults to the UK settings of BBC1 London on 101...

Thanks for that, I've learned something there!
Perhaps a card with a UK address should be considered?