bloody satellites

[Dave W]

According to Wikipedia, the LNB gets powered by 13V DC for vertical polarisation and 18V DC for horizontal. The tingle you feel is due to the receiver not being earthed, and some mains voltage is getting to you via stray capacitance, hopefully not enough to harm you.

Something must be stopping the supply from getting to 18V, and I would think it's your receiving device that's at fault, not the LNB(s).

It might be easier to try a different receiver before fiddling with the LNB. You could earth the receiver metalwork to eliminate those unpleasant shocks.

[Archibald Tarquin Blenkinsopp]

Through a coax cable?

Outer, Inner and one polarisation works anyway.

G4's came after people had to know what they were doing with RF.

AB

[Jim GM4DHJ ...]

suppose ...

[Jim GM4DHJ ...]

definitely NOT static .....

[Jim GM4DHJ ...]

indeed...

[The Natural Philosopher]

A lot of unearathed metalwork floats at 110vAC due to there being RF filter caps to live and neutral from the metal case.

Whilts not a hazard, you can definitely feel this and its capable of blowing circuitry that is earthed if connected to it.

[Brian Gaff]

I'd be a little worried at the shock problem before you replace anything expensive myself. Could be a duff psu something like that. Brian

[Brian Gaff]

tee hee, well i got the impressiont this this was more than the tingle effect we often find on non earthed gear. Try earthing it switch on and see if there is a bang? Brian Brian

[Brian Gaff]

That was when the mustard and Cress geminated I guess. Brian

[Jim GM4DHJ ...]

"tee hee" is copyright me...watch it gaff ...

[Brian Reay]

ROTFL

That is priceless.

[Jim GM4DHJ ...]

we will see....he who laughs last laughs longest....and it is usually me....tee hee

[Jim GM4DHJ ...]

..but probably not in this case :(

[Brian Reay]

It shouldn?t be designed like that, it is pointless. It doubles the Z between L&N to dump noise via the C?s (C?s in series rule) and introducing the stray 110Vac point. As I posted in another group, this situation can arise due to a fault condition if, for example, the earth at the plug (top) is lost or somewhere else before the filter.

Again, it could explain the shock and the failure. Jim would be wise to rule it out before sticking a new lnb in. Even if it works initially, it could fail later and he?s back to square one, missing Love Island ;-)

[The Natural Philosopher]

It isn't pointless from an RF POV. A lot of RF noise is common mode on L & N.

And most RF filters have a L->N cap as well.

e.g.

Yup. an unearthed box and cable could absolutely also pick up static or induceed voltage from nearby lightning strikes that might arc over and fry the LNB.

[Brian Reay]

Read what I posted, carefully. The two C?s would be in series, halving the overall value (assuming they are the same), that doubles the impedance Z to decouple the noise. One C would between L&N would be more effective and avoid the stray 110V AC point.

[Roger Hayter]

It would be more effective for possible differential noise, but totally ineffective for common mode noise, which is more likely. As someone said it is common to have both, as well as coupled series inductors and further capacitors if it is a posh mains filter.

[Terry Casey]

Had this when we moved into a brand new office block.

This was 1970, so all the phones were on key and lamp units which were earthed, of course. Ditto electric typewriteres and our cable TV distibution system.

Anything metal could give you a belt, even something as small as a door handle. I remember getting an unexpectedly hefty belt when I touched a 4-drawer filing cabinet!

I got into the habit of touching anything metal with my finger nails by just flicking my fingers at them - I still heard the click of the discharge but didn't feel anything!

I never could work out why this method worked but work it did and it was rare for me to get a belt after I discovered it!

Similarly, inserting a key into a door lock produced the spark but, again, you didn't feel it.

Things improved after a regular spraying routine was introduced.

[Roger Hayter]

Sorry to disappoint you, but I find it a little difficult to know how you get the DC voltage to appear on the cable outer unless that particular cable is disconnected from the receiver, or one of the receivers is disconnected from the mains. Unless this is the case I am going with the majority and guessing you have a faulty LNB *and* a bit of mains leakage on the receiver chassis. BICBW. See if the tingling goes when you've replaced the LNB?

[The Natural Philosopher]

Nah. that will just blow the lnb

fix the tingle first.

Almost certainly the STB or whatver is not earthed properly