Lightning strike Digihome 65240fhdledcntd

[Scoobydo]

Hi, Tv was on at the time and plugged into rooftop aerial. Lightning struck house next door. Other houses 200yds away have blown tv's (with no roof top aerial) and broadband routers OOS. The RCD tripped in the property, fuse in mains lead also blew. Aerial drop lead from the roof frazzled in various place with the conductors melted away.

Got no standy light on the tv. Power board is vestel 17PW-03-9. The internal fuse T 3.15a 250v is open circuit. Can I change this for a cartridge fuse and see if power is restored? Have bridged fuse and checked across the 240v power input in diode mode on DMM and this is open circuit.

Thanks in advance for any help

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

When checking the quality of the uploaded file I noticed that the mosfet on the left I couldn't read the numbers on it

[mmartell]

Re: Lightning strike Digihome 65240fhdledcntd

Wipe it down with a q tip and IPA.

[Sparkey55]

Re: Lightning strike Digihome 65240fhdledcntd

Trying to troubleshoot a lightning strike victim can be very difficult because of multiple entry points for the high voltage, being power line, antenna and near field entering via connecting cables and other wires. Could be a lost cause.

[Andrew F. Ali]

Re: Lightning strike Digihome 65240fhdledcntd

trying to troubleshoot a lightning strike victim can be very difficult because of multiple entry points for the high voltage, being power line, antenna and near field entering via connecting cables and other wires. Could be a lost cause.

+100

[R_J]

Re: Lightning strike Digihome 65240fhdledcntd

When checking the quality of the uploaded file I noticed that the mosfet on the left I couldn't read the numbers on it

What you are looking at are diodes in the secondary, they are dual diodes with a common center pin.

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

Ok what's the chances of just changing the internal fuse and all is ok? Guess 1000/1 as it has blown due to current over it's rated capacity? Thanks

[R_J]

Re: Lightning strike Digihome 65240fhdledcntd

You might get lucky, That blue R100 could be a mov that protected the supply and blew the fuse, Measure the resistance across it. It should measure close to open. If it measures shorted, you can remove it to test the power supply but replace it later for continued protection.
Now looking straight above in the picture, under the heatsink is D105, check the resistance between the two outer legs. it should also be close to open and not shorted.

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

d105 if I have the positve of my multimeter on the leg by the jumper j110 and the negative on the right hand leg I get 967 ohms. If I reverse the leads then it is open.

The MOV I get a reading that reduces down to 979k almost like it discharges so when I first probe it on the 2000k scale it starts around 1200k and then reduces until it settles at 979k on that scale.

Thanks for help

[Andrew F. Ali]

Re: Lightning strike Digihome 65240fhdledcntd

The MOV I get a reading that reduces down to 979k almost like it discharges so when I first probe it on the 2000k scale it starts around 1200k and then reduces until it settles at 979k on that scale.

This seems to be open.

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

@Andrew F. Ali if I read it correctly R_J was saying if shorted then remove and replace fuse and see if it fires up. But you seem to be saying opposite.

Tks

[budm]

Re: Lightning strike Digihome 65240fhdledcntd

Nothing wrong with that MOV, it is not needed for the circuit to operate.
Measure the resistance between the two legs of the main filter caps.
Measure the resistance between the two inner legs of the bridge rectifier.

[Andrew F. Ali]

Re: Lightning strike Digihome 65240fhdledcntd

I am saying it is good.

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

Budm, is the bridge rectifier an IC as I cannot see 4 diodes set up as a rectifier and I guess the caps are nearby this for smoothing but not sure where this is on the board. Sorry for new-b questions.

[budm]

Re: Lightning strike Digihome 65240fhdledcntd

D105 is the 4-LEG bridge rectifier mounted on the black heatsink.

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

Inner legs d105 =969k once it goes stable starts higher and reduces. Tks

[budm]

Re: Lightning strike Digihome 65240fhdledcntd

How about the resistance between the two legs of the main filter cap as requested in post #12?

[Scoobydo]

Re: Lightning strike Digihome 65240fhdledcntd

Sorry dont know where it is I googled as best I could but will need guidance

[R_J]

Re: Lightning strike Digihome 65240fhdledcntd

The main filter cap, are actually 3 on this board, they are 47uf 450volt , labled c101, c102, c103, they are in parallel so measure across any one of them
There is also one for the standby circuit, 10uf 450volts, (next to D123)
If you don't read any short circuit across those capacitors, I would try a fuse and see what happens, if there is still a fault the fuse will open.

[R_J]

Re: Lightning strike Digihome 65240fhdledcntd

If there was a spike on the power line, and the mov handled it, that alone would blow the fuse protecting the rest of the power supply