Diode porblem with a 12v TV

[Greenie9657]

Afternoon All,

Ive been diving into a 12v TV for a friend and after some fault finding I've found a Diode that is not doing what it should.(I've bypassed it and the TV works so definite DIODE) I know I can buy them from Maplin for around 50p but Im unsure as to which diode it is.

Ive tried uploading a photo but cant seem to get it on here. If I manage to get it uploaded I will add it later on.

Any idea what type it might be? On the circuit board it looks like a Black Resistor albeit slightly chunkier(definitely a diode).

Thanks

 

[bernardgreen]

How can you be sure it is a diode ?

If bypassing it enables the TV to work then it is open circuit. If it is open circuit how can you tell it is ( was ) a diode.

It might have been a fusible resistor or a suppression choke if it is in the power supply .

Or it might have been a diode intended to protect the TV from reversed polarity supply.

If it was a diode to prevent reverse polarity then a 1N4001 will probably be OK for a small TV ( one amp from the battery )

 

[Greenie9657]

How can you be sure it is a diode ?

If bypassing it enables the TV to work then it is open circuit. If it is open circuit how can you tell it is ( was ) a diode.

It might have been a fusible resistor or a suppression choke if it is in the power supply .

Or it might have been a diode intended to protect the TV from reversed polarity supply.

If it was a diode to prevent reverse polarity then a 1N4001 will probably be OK for a small TV ( one amp from the battery )

Hi Bernard
Sorry I should of said it was open circuit. I think my friend said when he broke the 12v power supply he accidently wired it reverse polarity before he realised the centre pin was ment to be the +ve. That's when he asked for help. So I had a feeling it was the diode, but bypassing it confirms that.

Its nothing to do with the power supply, its just on the circuit board.

 

[Greenie9657]

Saying that, usually there is a line on a Diode annotating which side the Cathode is on, but there isn't.

I really need to get this picture unloaded !!

 

[JohnW2]

Sorry I should of said it was open circuit. I think my friend said when he broke the 12v power supply he accidently wired it reverse polarity before he realised the centre pin was ment to be the +ve. That's when he asked for help. So I had a feeling it was the diode, but bypassing it confirms that.

I (like bernard) still don't really understand how that makes you so sure that the component in question is/was a diode. It's actually quite unlikely that reverse polarity supplied to the TV, per se, would destroy a diode within it - and if it had been a diode there to protect the TV against a reverse polarity supply, it obviously would not be damaged by reverse polarity.

As you say, a picture might possibly help. What is the uploading problem you're having - it's a simple enough process.

Kind Regards, John

 

[Taylortwocities]

I really need to get this picture unloaded !!

Follow the instructions in FORUM INFORMATION
http://www.diynot.com/forums/viewtopic.php?t=129539