Intermittent Foxsat signal fault

RB211900

Standard Member
Hi All, as the title suggests, i'm having some odd problems with my Humax Freesat HD Box, we were watching E4 last night, the picture began to break up, then displayed "No or Bad Signal", upon checking system diagnostics, both the Signal strength and quality had dropped to 0%, all channels on the same vertical frequency were the same, i also notice that the signal strength and quality were lower than normal on all vertical channels, all horizontal were 100% strength and quality on both feeds from the LNB, i performed a factory reset, switched the Humax off for about 30mins, when i switched it back on, the missing channels were all present and correct at both 100% signal and quality, 3 mins in and the signal crashed to 0% again, retried same sequence and repeated exactly.

Pretty stumped now, initially thought the dish may have moved out of line with strong winds, then thought the LNB Might be damaged.......Stumped, so any help would be appreciated.

Also, testing the output voltage, is it tested from the co-ax core to the shielding??
 

grahamlthompson

Distinguished Member
Assuming it's a Foxsat-HD sounds like you have the electrolytic capacitor failure in the power supply. (The faulty ones will have a bulge). If so the box will fail to boot eventually. Repair is very cheap if you can use a soldering iron.

Google Foxsat HD capacitor.
 

RB211900

Standard Member
Assuming it's a Foxsat-HD sounds like you have the electrolytic capacitor failure in the power supply. (The faulty ones will have a bulge). If so the box will fail to boot eventually. Repair is very cheap if you can use a soldering iron.

Google Foxsat HD capacitor.

Its the Foxsat-HDR
 

grahamlthompson

Distinguished Member
Its the Foxsat-HDR

Oh never heard of a problem with the hdr. Could be time to change the lnb.

Presumably both tuners exhibit the same symptoms ?
 

grahamlthompson

Distinguished Member
Yeah exactly the same with both inputs, odd its the vertical channels only.

Only thing I can think of is the hdr is outputting the lower DC switching voltage at a level that the lnb is mistaking for a request for a horizontal transponder. You haven't somehow turned the higher lnb output voltage setting on in the hdr menus have you ?
 

RB211900

Standard Member
Only thing I can think of is the hdr is outputting the lower DC switching voltage at a level that the lnb is mistaking for a request for a horizontal transponder. You haven't somehow turned the higher lnb output voltage setting on in the hdr menus have you ?

No, ive not been in the setup menus in over a year, but its worth a look though! odd thing is, i've had the HDR on for the last hour and a half, no issue whatsoever, all looking good...............intermittent faults are a pain!
 

REPASSAC

Well-known Member
No, ive not been in the setup menus in over a year, but its worth a look though! odd thing is, i've had the HDR on for the last hour and a half, no issue whatsoever, all looking good...............intermittent faults are a pain!

These sort of problems point to a tempertune releated problem - perhaps with the connection to the LNB - Not sure at all - but I would recheck all LNB connections.
 

RB211900

Standard Member
These sort of problems point to a tempertune releated problem - perhaps with the connection to the LNB - Not sure at all - but I would recheck all LNB connections.

All connections were checked yesterday which were fine, which is why im stumped, most things have already been checked.
 

RB211900

Standard Member
*****Update***** seems you can watch E4 for about 15 mins, then signal breaks up, and complete loss, it's lost until either the unit is fully powered off and back on, or, sometimes after you've been into the PVR menu. Looks like the unit might be on its way out.
 

MartinPickering

Well-known Member
you can watch E4 for about 15 mins, then signal breaks up, and complete loss, it's lost until either the unit is fully powered off and back on

That's a fairly typical symptom of a bad LNB connection. Powering off then on can cause a small current surge that punches through the oxidisation on the connection.

I'm not saying that this is the cause - merely that you can't rule it out. Test your receiver on another dish system.
 

hal8000

Novice Member
If you have a digital multimeter you can test both coax leads. Switch off and unplug humax and unscrew both coax cables at bothe receiver and LNB.

You would need an extra wire with two croc clips to short the inner and outer sheild of the connector. At the opposite end of the cable set the multimeter to DC ohms and measure resistance.

Actual value depends on length of the cable but I'd expect a reading of 1 or 2 ohms or lower. Whatever reading you get e.g. 0.5 ohm, the other cable (which will be same length) should have an identical value.
A different reading may indicate oxide layers or possible water
contamination of outer braid. You may be able to make new terminations.
This may not be the fault, just a way to test the cables.
 

grahamlthompson

Distinguished Member

swedish cook

Novice Member
Seems obvious but to exclude the HDR from the equation it would be best if you could borrow a friends Freesat or Sky receiver and see if the fault is still present.
 

hal8000

Novice Member
Why digital any multimeter will do the job. Simple analogue ones can be bought for peanuts.

example

Analogue Minatuure Multimeter 16 ranges pocket sized. | eBay

Reading very low values can be difficult on analogue multimeters
if values are less than 1 ohm. A digital meter is easier to view values below 1 ohm, but yes in most cases analogue meters would work.
Occasionally supermarkets offer digital meters for under a £5 as well, just dont try cooking with them :D
 

grahamlthompson

Distinguished Member
Reading very low values can be difficult on analogue multimeters
if values are less than 1 ohm. A digital meter is easier to view values below 1 ohm, but yes in most cases analogue meters would work.
Occasionally supermarkets offer digital meters for under a £5 as well, just dont try cooking with them :D

Complete rubbish, every digital meter measuring current, voltage or whatever starts with an analogue measurement and converts it to a digital value using an adc.

Resistance is measured by applying a measured voltage to a circuit and measuring the resultimg current. Accurate sensitive moving coil microammeters have been around for decades.

Potentially the best multimeter ever made the avo, it has been dropped from hundeds of feet from the top of national grid towers and still worked

You are wrong, a proper analogue multimeter can still give accurate readings provided it has the appropriate ranges

Digital metering starts with an analogue measurement. Digital multimeters offer one major advantage over conventional moving coil displays. and at the same time a major disadvantage to the unitiated) they have a very high input impedance so draw insignficant current from the connection to which they are connected.

Try this with your digital multimeter. connect a digital multimeter set either to a ac voltage range or a ac low current range. connected to a 50m coil of mains cable only to the live conductor at one end and at other end the meter connected to the neutral conductor to earth. In both cases you wiil find either a significant current or voltage. Try the same with analogue meter you wiil get zilch.

Whats going on, simply the digital meter draws so little current due to it's enormous imput impedance it measures the minute ac currents passing across the capacitance between the two conductors.

In short without being able understand how you are measuring effects the results means very little.

In the end the fundamental Voltage and Current is an analogue measurement (Digital broadcasting is really analogue, the data is transmitted as an analogue signal, only when the uhf carrier is removed is digital data left)
 
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RB211900

Standard Member
I've ordered a new lnb, will re make the connections on either end too, the problems seems to lay with e4 and the other channels on the same vertical frequency.
 

RB211900

Standard Member
If you have a digital multimeter you can test both coax leads. Switch off and unplug humax and unscrew both coax cables at bothe receiver and LNB.

You would need an extra wire with two croc clips to short the inner and outer sheild of the connector. At the opposite end of the cable set the multimeter to DC ohms and measure resistance.

Actual value depends on length of the cable but I'd expect a reading of 1 or 2 ohms or lower. Whatever reading you get e.g. 0.5 ohm, the other cable (which will be same length) should have an identical value.
A different reading may indicate oxide layers or possible water
contamination of outer braid. You may be able to make new terminations.
This may not be the fault, just a way to test the cables.


So you're basically measuring the outer shielding and inner copper coaxial supply core resistance of I've read that correctly?
 

grahamlthompson

Distinguished Member
So you're basically measuring the outer shielding and inner copper coaxial supply core resistance of I've read that correctly?

You basically have :D

The effect that has on the control DC voltage recieved at the lnb depends entirely on the DC resistance of the coax link and the current drawn by the lnb (Basic Ohms Law). Voltage Difference for a DC current = Current x Resistance. ) 0 current = 0 voltage difference whether the DC resistance is 1 ohm or 10000 ohms, what you measure with a voltmeter (Digital or Analogue).

Only when you draw current through a resistance does the the received voltage fall. This includes the current drawn by the meter and it's internal resistance and the internal resistance of the voltage source.

Simple example a DC series motor when energised is pretty nearly a short circuit (Best example a car starter motor) In theory an infinite current pulse.

It doesn't simply because the lead acid battery itself has an internal low resistance. (Extremely low by other battery standards) so it can deliver a high current without the battery terminal voltage falling significantly.

8 1.5 cells in series can deliver 12V, Thanks to the high internal resistance the more current you draw the more the terminal voltage falls. Would you expect 8 AA cells to start a car.

We are talking basic O level physics here :eek:
 

onthehill

Standard Member
These sort of problems point to a tempertune releated problem - perhaps with the connection to the LNB - Not sure at all - but I would recheck all LNB connections.

Interesting reading guys. Was low temperature ruled out?

I lost one tuner for a short while last week when it was very cold. I haven't seen the problem before or since and the tuner returned when the box restarted.
 

hal8000

Novice Member
So you're basically measuring the outer shielding and inner copper coaxial supply core resistance of I've read that correctly?

No, read the reply in full, you're measuring the loop resistance of the coax with one end of the cable short circuited and comparing its value to the other coax.

Measuring outer and inner coax with no short at the opposite end should not give any resistance reading, as it would be the insulation resistance.
Water damaged coax would give a reading but dry coaxial cable
should be a good insulator.
 

RB211900

Standard Member
Gotta be a problem with the humax, Lnb is fine, coax good, just some of the itv channels and E4, you can be watching them for an hour or so then all of a sudden the signal on both inputs drops from 100% to 0 with the no or bad signal banner
 

Railway

Active Member
Gotta be a problem with the humax, Lnb is fine, coax good, just some of the itv channels and E4, you can be watching them for an hour or so then all of a sudden the signal on both inputs drops from 100% to 0 with the no or bad signal banner

Just a thought, it's not interference from for example DEC phone, wifi etc?

Sounds doubtful to me to be the box if it's only certain channels.
 

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