12v Power Issues & Multi Meter Readings...

[SkipFeeney]

Hi All,

I have a 12v (30a) TV that I am attempting to install in the bathroom. The power supply I recieved with the TV did not have a long enough cable to drop down the wall from the loft so I bought an extension cable (2.1mm Socket to DC Power Extension Lead 3m). I then put the extension cable in/on the wall where it was plastered and tiled over. Now when i have gone to install the tv, it won't switch on If however i don't use the exentsion cable its fine! Its obviously the extension cable so I tested it all with a multi meter and this is where I am stumped...The voltage from the power supply is 12.2...the voltage from the power supply plus extension cable is also 12.2 so why isn't it working?!

Meter reading from Power Supply:

PowerSupply

• SkipFeeney
• 14 Aug 2015

Meter reading from Power Supply plus extension:

Extension

• SkipFeeney
• 14 Aug 2015

If it helps this is the power supply:

Untitled

• SkipFeeney
• 23 Mar 2015
• 1

]


Thanks

 

[sparkymarka]

Did you use a DC connector extension ? It may be that the centre pin hole is larger in the DC extension lead than the power supply and not touching the centre pin on the TV,

 

[sparkymarka]

You could try bending the centre pin to one side ( at your own risk) to make the connection .... Not the thing to do but would prove a point !

 

[ban-all-sheds]

Did you use a DC connector extension ? It may be that the centre pin hole is larger in the DC extension lead than the power supply and not touching the centre pin on the TV,

Surely it would have the same design of connector at each end.

So if the female end is too big, and there's a central pin not making contact, then at the other end the male pin will be too big, and won't go in.

 

[ban-all-sheds]

Skip - get a car indicator bulb, solder some thin wires to it, and see if the voltage drops under load.

 

[sparkymarka]

No because most power supply DC connectors have an insert to grip the centre pin , some extension leads don't , a picture of the end of the connector would confirm it .

 

[GaryGarden]

IMO the bathroom is for Sh1ting, showering, and shaving. I am confused as to why you cant watch TV in the lounge? How bleedin long do you spend in the bath/shower???

 

[ericmark]

30/12 = 2.5A one would hope it could take 2.5A but there may be a volt drop under load. If there is a stand by light which works and the TV does not turn on then volt drop. If the stand by light does not work (assuming it has one) then connector problem. It could be a simple dry joint on the connector pin. I have a lap top like that some times stops working un-plug and plug back in and works again but I am too lazy to strip down to re-solder connection.

 

[SkipFeeney]

No standby light i'm afraid but I have had another look at the connectors. It looks like the extension connector is slightly bigger then the power supply connector, I think that is probably the problem (thanks for the suggestion). I wonder if the extension is 2.5mm and the power is 2.1mm and I haven't noticed, it only looks very slighlty bigger.

Extension connector on the left:

Side View

• SkipFeeney
• 14 Aug 2015

Ends

• SkipFeeney
• 14 Aug 2015

Ends

Maybe i'm a bit strange but i'd like to watch TV in the bath!!! Its one way of getting away from the kids for 30mins!

 

[JohnW2]

I have a 12v (30a) TV ...

Do I take it that you mean 30W, rather than 30A?

If however i don't use the extension cable its fine! Its obviously the extension cable so I tested it all with a multi meter and this is where I am stumped...The voltage from the power supply is 12.2...the voltage from the power supply plus extension cable is also 12.2 so why isn't it working?!

If there were a problem with the extension lead (other than possible 'connection problems', such as has been suggested), it would presumably be due to voltage drop when it was fully loaded. However, your measurements have been with no load, so you would not expect to see any voltage drop.

Would it be possible for you to connect the plug of the extension to the TV with some bits of wire and then measure the voltage at the TV end when the TV was switched off, and then with it switched on?

Kind Regards, John

 

[MattChan]

Id say they look like slightly different bore sizes judging by your photo. I'd guess the one on the left is for a 2.5mm pin and the right a 2.1mm pin as you suspect.

 

[ban-all-sheds]

I missed sparkymarka's reply, but not sure what he means anyway, hence this Q:

If one lead is 2.5/2.5, and the other is 2.1/2.1, how does the 2.5mm pin go into the 2.1mm receptacle?

 

[JohnW2]

If one lead is 2.5/2.5, and the other is 2.1/2.1, how does the 2.5mm pin go into the 2.1mm receptacle?

Ah - but what if it were a 2.5/2.1 lead?

Kind Regards, John

 

[ban-all-sheds]

Then I venture to suggest that if it were sold as an extension lead it would not be fit for purpose.

 

[sparkymarka]

Two pins with a taper to make a good connection