Digidome aerial revelation

[Chop!]

Our Slx Digidome aerial failed following a thunderstorm, while looking for a replacement online, I read a buyer's review, he claimed that he had by-passed the 240v transformer and connected direct to the 12v amplifier.

As our aerial was stuffed I decided to strip the transformer down to investigate. Nothing to lose and perhaps a lot to gain.

On stripping it down I found that by connecting 12v to the leads, that had come out of the transformer gubbins, I once again had a lit LED and on re-connecting the aerial leads we got all our channels back.

This was a double result, we were saved from having to buy a replacement and, as it was now 12v, our inverter would not keep 'seeing' it when on eco mode.

[jam]

Should the 12v input not be stabilised ? which the components in your defunct power supply would do.

[StephenA]

I wonder what components are in the metal box - apart from a LED and a couple of resistors?

[Jess--]

2 hours ago, StephenA said:

I wonder what components are in the metal box - apart from a LED and a couple of resistors?

most likely a couple of rf chokes and capacitors being used to feed 12v up the aerial cable to an amplifier mounted on the aerial.

chokes to stop the RF (tv signal) from being fed into the power supply (chokes will pass DC power but will block an AC signal)
capacitors to stop the 12v being fed into the tv's aerial input (small capacitors will pass an AC signal but block a DC one up to a certain point)

Edited August 13, 2018 by Jess--

[Horace42]

My gut reaction is to ask

12 hours ago, Chop! said:

......... our aerial was stuffed I decided to strip the transformer down to investigate. Nothing to lose and perhaps ......................

Except your life!

My gut reaction is to ask how a 12v rated device (that might be DC) works safely when connected to 230v supply (that is probably AC)

[Chewbacka]

14 minutes ago, Horace42 said:

My gut reaction is to ask

Except your life!

My gut reaction is to ask how a 12v rated device (that might be DC) works safely when connected to 230v supply (that is probably AC)

Because it contains an isolating transformer.   So mains in, converts internal to 12v which then powers the aerial 

[Jen-in-Wellies]

I'd suggest a 12V to 12V regulated power supply to convert the variable battery voltage and remove any voltage spikes that might damage the aerial amplifier, or TV. Perhaps something like http://www.poweradaptorsuk.co.uk/800ma_Universal_Regulated_DC_In_Car_Power_Adaptor_p/ea800car2.htm

 

Jen

[Horace42]

 

40 minutes ago, Chewbacka said:

Because it contains an isolating transformer.   So mains in, converts internal to 12v which then powers the aerial 

...but by-passing it means 240v will be stuffed up the aerial - a somewhat dangerous situation if it is only meant for 12v,

[matty40s]

46 minutes ago, Horace42 said:

 

...but by-passing it means 240v will be stuffed up the aerial - a somewhat dangerous situation if it is only meant for 12v,

He has removed the 240v side, it's  ow running on 12v

[dor]

ust for interest, I used to have an amp on my aerial in the old analogue days.  Since going digital, I get better reception and more channels when I connect the aerial directly to the TV and not use the amp.

[Chewbacka]

2 hours ago, matty40s said:

He has removed the 240v side, it's  ow running on 12v

So instead of the little transformer feeding 12v into the aerial amp, the mains stuff has been removed and now 12v is being fed into the unit which then sends 12v to the aerial same as before.  My only concern would be that before the 12v was probably fully floating and isolated from earth and with only a few mA capability, but now the 12v will be referenced to Earth with many amps available (from your batteries) so take care with the aerial coax cable as it could overload the unit if the centre (signal) wire is earthed.

[Chop!]

4 hours ago, Jen-in-Wellies said:

I'd suggest a 12V to 12V regulated power supply to convert the variable battery voltage and remove any voltage spikes that might damage the aerial amplifier, or TV. Perhaps something like http://www.poweradaptorsuk.co.uk/800ma_Universal_Regulated_DC_In_Car_Power_Adaptor_p/ea800car2.htm

 

Jen

Thanks Jen, I was wondering if I could use something like this! ;0)