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Hyundai HPTD 4202s green light but no picture or sound......

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pharmer:
Hi Everyone first post......I have a Hyundai HPTD 4202S and when its switched on, both relays click and then one of the large capacitors makes a slight noise, then a relay clicks again.  Is this normal or is the relay de-energising? The green LED on the front lights up but then it just sits there.  Any ideas anyone?

 :sign0144:

chrissie jones:
have you checked all caps.

Turnip:
H, Pharmer,

It's an LG,

Is there sound, ?   and if so check Z-sus fuses - Chris.

nouira:

--- Quote from: pharmer on November 01, 2010,17:21:26 ---Hi Everyone first post......I have a Hyundai HPTD 4202S and when its switched on, both relays click and then one of the large capacitors makes a slight noise, then a relay clicks again.  Is this normal or is the relay de-energising? The green LED on the front lights up but then it just sits there.  Any ideas anyone?

 :sign0144:

--- End quote ---

pike:

--- Quote from: pharmer on November 01, 2010,17:21:26 ---Hi Everyone first post......I have a Hyundai HPTD 4202S and when its switched on, both relays click and then one of the large capacitors makes a slight noise, then a relay clicks again.  Is this normal or is the relay de-energising? The green LED on the front lights up but then it just sits there.  Any ideas anyone?

 :sign0144:

--- End quote ---

Just fixed one of these. It's actually a samsung tv inside. With the back off you'll see the main Switch Mode Power supply. I found the circuit easily by googling Samsung V4C. Firstly check (carefully) all the working voltages (think theres 6). Inside my TV (top right) are the voltage's nicely marked on a label. If any of them are not near, chances are that section is dud and you'll get no picture. In my case it was one of the DC-DC convertor circuits. Some of these switching regulators are supposed to prevent self damage even with open feedback (bust opto coupler) but alas they dont. Visually check caps for bulging, and obvious explosions. Typically these boards tend to fail with multiple components failure so double check all associated components in the effected area. The minimum equipment required would be a DMM but if you happen to have power supplies to bench test the board and a CRO to hand, repair, without the risk of further damage will be tricky. Another tip, get all the information on the effect IC's. In my case it was a fairchild switching device. Its only has 4 pins but there's a lot more going on inside the chip that'll stop it oscillating. Hope this helps...

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