Building Wall Socket for Roof LNB Measures 3V

T

tvriffs

Member
My Satellite Setup
DM800
Astra 28.2E
My Location
UK
Hi, we have a satellite on the roof of the building I live in (~20 flats).

I've been having some problems with the signal from this dish, as some channels stop working after 25min of watching.

I've measured the voltage between the central conductor of the coax and the cable shield, and the central conducter is at 3V relative to the shield. This is from the wall, before the reciever is connected.

I was testing earlier, and it was working fine without the f connector (no connection between shield and reciever) and when I bridged the shield to the box, the signal dropped to 0%. (hope that's clear, ask if not).

Is this the cause of the problem? What is causing this?

Thanks in advance!
 
It isn't uncommon to have a small touch voltage on an outlet, but really as it's a commercial system, I would ask the management company to get someone out to check the system, there isn't much you can do without getting involved with the head end and that could inconvenience the other residents.
 
Thanks for the reply. Do you think this might have something to do with the tuning problems I've been having?

It seems strange it stops working after the same duration each time.
 
It's unlikely, it could well be a dreambox fault, have you tried it on another dish?
 
tvriffs said:
I've measured the voltage between the central conductor of the coax and the cable shield, and the central conducter is at 3V relative to the shield. This is from the wall, before the reciever is connected.
Click to expand...


Any measurement here will be inaccurate, the other end of the cable is terminated to an active multiswitch and may therefore give a small touch voltage briefly mentioned above.



I was testing earlier, and it was working fine without the f connector (no connection between shield and reciever) and when I bridged the shield to the box, the signal dropped to 0%. (hope that's clear, ask if not).
Click to expand...

You need the screen of the cable connected to send a DC voltage to the switch :confused:


Also in addition to trying the box Rolf mentioned on another dish, speak with any other residents in the block to see if they are experiencing the same or similar problems.
 
Losing the signal on a Dreambox after 25 minutes can be indicative of a duff power supply. Although it usually affects DM500s with a Diseqc motor, haven't heard of many DM800s with the problem as the power supply has a higher rating.

As stated above try with another dish before assuming anything.
 
Thanks for the replies guys, I've got the box hooked up to another satellite now, it's working so far, I'll post back in a bit.

The thing about the power supply is interesting, I think I have a multi-output supply I can test with.
 
It's working fine with the other dish, could be the building connection, but I'll test it again tomorrow.
 
Okay, after more testing:

- with direct connection to satellite on balcony receiver works 100%
- with building connection, I lose signal after about 20min, only on some channels.
- after losing connection, if I remove f-connector and only connect central coax it works well (strong signal)

As I understand it, the central cable carries a voltage of 13/18V to power the lnb - correct? When the cable shield is connected, what does this do?
 
Essentially, it carries the reverse direct current. You need both connected and not shorted out in order to control the LNB.
 
PaulR said:
Essentially, it carries the reverse direct current. You need both connected and not shorted out in order to control the LNB.
Click to expand...

So it shouldn't work when the f-connecter is not bridging the shield to the receiver? So why it is working in this case? And any idea why it doesn't work when connected properly?
 
You need both the centre and screen connected to supply the correct DC voltage to the switch. I'd suggest you speak with the management company so they can call in an IRS installer to investigate.
 
As the source is a multiswitch then, strictly speaking, it doesn't need the electrical supply from the various STBs in the building as it will be mains powered. This means that there will be probably be a default of vertical low band available from the wall socket when if the DC connection is faulty.

Which channels do you get? For instance, if my theory is correct you will get all the regions of Channel 4 +1 but none of the Channel 4 non-timeshifted channels.
 
I've been through most of the channels but don't see many fail - Channel 4+1 (london I think, the others work). Kerrang & kiss music channels don't work.
 
tvriffs said:
Kerrang & kiss music channels don't work.
Click to expand...


These have an intermediate frequency of 1880Mhz, which is around the DECT band.
 
problem solved? I've increased the voltage output from the dreambox, channels seem to work okay with f-connecter properly connected. kiss&kerrang music channels are working.
 
tvriffs said:
Thanks! now on to the next problem - trees in the way of 13E signal!
Click to expand...

Chain Saw Hire is inexpensive ................
 
Back
Top