Very strange reception problems

[TORB]

I have started a new topic as I now think that HDD is not the problem and it may be either the tuner or have something to do with reception. Unfortunately, the info I managed to observe, rather than clarifying the situation, just confuses me even more.

On Friday I was watching the cricket on 7 and during the day the reception was fine. At night reception was poor. For part, and I stress only part of the time, I was recording on the B tuner. (The recorded B program had perfect reception.)

On Saturday I carefully observe the signal strength using tuner A with no other tuners active. (I have direct, uninterrupted line of site to the transmission tower in Bowral/Mittagong NSW with nothing in the way.) The results were….
Prime 7…. (Chanel 46) Strength 67 to 92 mostly between 75 to 80
ABC (Chanel 47) Strength 69 to 84 mostly between 77 to 80
Win 10 (Chanel 48) Strength 100!
SBS (Chanel 49) Strength 77 to 88 consistently around 84
Southern Cross Nine (Chanel 50) 100!

Looks straight forward, but its not. Reception was fine, even when I recorded for 90 minutes on the B tuner. This mornings test (Sunday) confuses things even further!

I bypassed the antenna splitter and plugged the aerial straight into the A tuner. The results were….
Prime 7 went up to 100!
Southern Cross Nine plummeted from 100 to 47.
Win 10 also dropped significantly.

I am completely confused as to what could cause this weird behaviour.

[MrQuade]

Are you sure you are looking at the strength figure and not the quality value?

Is that a powered splitter you were using?

[peteru]

There are two problems that the tuners on a T4 can suffer from. One is the LDO voltage regulator failure, which leads to a pair of tuners disappearing. The other is damage to the motherboard and components as a result of the thermal compound breaking down. The symptoms of this are consistent with your description. This problem can manifest itself even after the voltage regulators have been repaired. I have a T4 where tuner B is unusable and when it's being used it causes tuner A to misbehave too. My workaround for this is to disable tuner B in software.

[TORB]

Is that a powered splitter you were using?
[/quote]

Are you sure you are looking at the strength figure and not the quality value?

Is that a powered splitter you were using?

The numbers quoted are for the lower of the two bars. On some channels the other bar (quality) can be as low as 5/8ths of SFA.

I am using a Digitec power splitter.

[Paul_oz53]

I had a faulty shield connection in one of the aerial PAL connectors that caused similar erratic behaviour. Worth trying it with known good leads to eliminate the possibility that the lead-in is at fault. This can happen at the wall point too but more likely at the splitter.

Otherwise, Peteru's issue sounds like a suspect to be eliminated.

[MrQuade]

The numbers quoted are for the lower of the two bars. On some channels the other bar (quality) can be as low as 5/8ths of SFA.

The bar that is positioned lower on the infobar is actually the quality reading. The upper one is the strength.

[TORB]

The bar that is positioned lower on the infobar is actually the quality reading. The upper one is the strength.

Bugger! In that case things are really strange. Nine and Ten both have signal strength readings in single digit numbers.