TV Repair Questions? Ask a TV Technician
I am still waiting for an expert reply????
Hi and sorry for the delay in replying to you.
I`m going to help you with your tv/dvd but first could you please tell me it`s model number ?
Hi - its a Mikomi LDVD1535 15" LCD TV/DVD Combi serial No MO7B01042.
Can you tell me if that red light flashes or is on steady ?
Are you able to open the dvd tray?
The red light is steady but the set will not power up and therefore I cannot open the dvd tray.
O.k then i have another question:
Do you wish to repair this yourself ?
If so then the next step would be to remove the back cover to take a look and see if you can find this circuit board:
Yes I will repair this myself - will take the back off and look for the board.
I`ve circled some capacitors this time.
Can you tell me if they appear swollen/rounded tops ?
No, they look ok Jack.
Was asking because it is often the case in lcd tv`s and that is what causes the problem(often) for the power circuit.
But it does not mean that it is not the problem .
Which brings us to the next steps:
This board cost 30 pounds and i could give you an address where to get it in the UK.
Or if you can get a hold of a voltmeter we could take some measurements that could confirm its demise(or health).
And perhaps another option would be to remove it and have it tested at a local repair shop although it is sometimes difficult to test it outside the tv set.
If it is found to be operating properly the next suspect would be the main board.
I have a voltmeter.
O.k thenFirst be careful not put your fingers on the heathsink closest to the a.c connector as it is often at line voltage.
The first thing to do is to find a standby 5 volts in that connector near those capacitors.
Not 4.5 or 4.7 but 5 volts or 5.1 volts +
ok will try.
I have 5+ volts between the top (-ve) pin and the second, third and fouth pin.
I would guess this is in reference to ground.
Should have mentioned that you can use the tv chassis for ground reference(black probe)
I have to take off for about an hour but i would have more testing for you when i come back ?
thanks jack but its getting late in the UK - i will sign back on tomorrow night if thats ok?
You still out there?
As a matter of fact i just came back.
What time is it for you , 8:00 PM ?
Still got your meter handy ?
Yep - on both counts!
On your power supply board there are some writings beside the large connector that goes to the main board.
These are the output/input voltages identification/pinout for that connector.
Can you tell me if one of them has something that looks like P-ON or the ON word associated to it ?
That would be the startup signal coming from the main board and should be at around 3 to 4 volts when the power button is pressed.
Doesn`t make sense as there has to be at least a 24volts in there for the backlight inverter board.
And that board should be switched.
Unless there is another or sub-power supply.
Then can you tell me if that 12 volts is there ?
The ones marked 12V are reading about 15.5 volts and the ones marked 5V are reading 5.2 volts.
There is another board fed from the power board. This board is smaller and has two high voltage coils on it. Any help?
That would be the inverter board.
We cross/posted, did you see my reply above ?
Guess not , looks like it got lost in the great internet beyond.
I was saying that at this point i believe the problem to be the main board.
Unfortunately i could not find it anywhere for now.
The only thing i could find is used and new sets of your model that goes between 50 and 100 pounds.
So even if we can find your main board, it probably will sell for around 60 pounds, which doesn`t really makes it economically viable ?
This was my reply to you that i sent to another customer who must be wondering ; what the heck is he talking about :)
O.k then it would make sense as i was thinking that your set is a 15" model and the 24 volts may not be needed or is built in the inverter board.
So your power supply is constant and not switched, the main board does its switching internally.
In that case i`m afraid the problem is more serious than a power supply board and unfortunately could have to do with the main board.
I took a look and at this point i could not find the main board.
The only thing that i could see is on ebay.UK that had used sets of your model and also the 1538 models for between 50 and 100 pounds used and new.
As the main board if it can be found could go for around 60 pounds i`m not sure if it is economically viable ?
Ok Jack, thanks.
Looks like it will be asigned to the scrap heap - pity, but I must admit I was begining to suspect something economically terminal. I will see if I can get a cheap main board but I don't hold out much hope.
Thanks for your time and efforts.
O.k then and let me know if you find anything interesting.