More Failed Electrolytic Capacitors ?

My sister had a Conia brand, 19" LCD TV that stopped working after several years.
It has a separate power supply that provided 12Vdc at up to 4A.
A quick test of the TV with a substitute power source provided by a bench power supply, showed that the TV was fine. It was just that the external power supply wasn't able to supply the required current, even though it did appear to work OK superficially.

Before throwing the power supply in the bin, a quick look inside revealed that a couple of the final stage electrolytic capacitors appeared to have swelled, with slightly rounded ends.

These two capacitors were rated at 1000uF and 1500uF, both 16Vdc.
I simply replaced them with slightly larger electrolytic capacitors of 1000uF and 2200uF, with higher voltage rating of 25Vdc.
There was adequate room to fit these slightly larger capacitors; and it seemed a good idea increase the voltage rating of the capacitors because it is likely that they failed because they were too close to their rated voltage.

Another power supply fixed by replacing faulty electrolytics.....

LCD Monitors from the rubbish heap

I was recently given a faulty 19" Acer Monitor.
The monitor has built-in speakers, and these emitted a load and intolerable 50Hz buzz while the Monitor was switched on.

This was very a similar symptom exhibited by another Acer LCD monitor that I'd obtained a year before. In this case, there was a loud buzz, and the monitor didn't actually work.

In both cases the solution was to replace main high voltage electrolytic capacitor in the power supply.
This was an 82uF Capacitor rated at 400V.
In both cases the capacitors showed physical signs of leakage, possibly corroded leads.

As soon as the failed capacitor was replaced, and the LCD monitor reassembled, it was an immediately apparent that the fault was cleared.

The image below shows the leaking capacitor before being replaced. Notice the leaked material on right-hand (+ve) lead.

Conclusions ??
The Acer Monitors were about 6 years old when the main high voltage electrolytic capacitor failed in their power supplies.
These monitors both had built-in speakers, which means that any failure in the filtering on the power supply is immediately apparent due to the loud 50Hz buzz.
If the same failure occurred in an LCD monitor without speakers, then it wouldn't be as immediately clear what the fault was. Perhaps there's an easy fix that can be applied to a few other LCD monitors as well.

Topfield PVR signal breaking up

I have Topfield Masterpiece TRF-2400 and generally I think its great. This is our second Topfield PVR, which was only purchased to provide the high definition capability, that the previous model didn't support.

We had a problem with the signal breaking up, making some channels completely unwatchable.
The inbuilt signal strength and signal quality meter, that appears with the information on each channel, was showing full signal strength, but low signal quality.
On channels that were marginal, the signal quality gauge would vary from about 0% to about 30%.

Our TV antenna was quite old and was made up of two antennas feeding a coax combiner. One antenna was an old VHF antenna, and one a newer UHF model.
So we decide to invest in a new antenna, installed by a professional installer. He suggested that we use a masthead amplifier, and that seemed like a good idea, so we agreed.

The result of the new antenna and masthead amplifier was worse than before.
The marginal channels were even more marginal.

I read an article on a forum discussing a Topfield PVR with a similar problem (in a block of flats with a communal antenna with an amplifier). It appeared that the Topfield PVR was suffering from excessive signal strength, causing distortion in the signals and hence reduced signal quality. Their solution was to use an attenuator to reduce the signal strength, there by allowing the Topfield to behave properly.

I decided to try this, and prepared an attenuator with a value of about 10dB, using scrap cable and resistors. As soon as it was inserted in the antenna cable feeding the Topfield, there was instant improvement.
The signal strength was still full scale on all channels, but now the signal quality gauge was full scale on all channels as well.

In summary: the Topfield Masterpiece TRF-2400 PVR seems to suffer from RF signal overload quite easily. So if the signal strength appears good, but signal quality is low, it could be that the RF front end is saturated and distorting the signal.