32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

[rmg_hrr]

Recently My Onida TV become problematic after 1.5 years of service.
It has MLT688 rev 1.6 Power board.

I kept the TV in Box for 4 days and when i connected it back it was showing picture but after some 2 minutes of time it turned of with flickering image.

Again after some 20 mins, I switched it on and it started pictures but same thing happened and it turned off.

I opened the case and cleaned the power board soldered surface and looked for bulged capacitors and found none.

Any help how to fix it?

[ben7]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Recently My Onida TV become problematic after 1.5 years of service.
It has MLT688 rev 1.6 Power board.

I kept the TV in Box for 4 days and when i connected it back it was showing picture but after some 2 minutes of time it turned of with flickering image.

Again after some 20 mins, I switched it on and it started pictures but same thing happened and it turned off.

I opened the case and cleaned the power board soldered surface and looked for bulged capacitors and found none.

Any help how to fix it?

What brands are the capacitors in the power supply?

And why was it in a box? Did you move it? Vibration could have broken a poor quality solder joint.

[rmg_hrr]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Hi Ben,
The capacitors are all 105 degree C

The original caps are from (JH)
470uf 35v total five are present on board Printed CD287 (JH) on Capacitor
22uf 50v total three CD 263 (JH)


Inside heat sink (BOX) 5 Capas are present

470uf 35v two
470uf 16v, one
1000uf 10v two

I guess the heat sink is for the transistors/IC fitted around it.

I replaced the original 470 35v ones with some other Brand called Elna
and with CapXON for 22uf 50

Attaching the board pictures with Capacitor values

Before replacing the capacitors I hear some chattering kind of noise where the two 470uf 35v are present at top but after replacing the caps it has reduced and only fraction of noise still exist.

After replacing the caps The TV still in Black and no picture.

I am planing to put all the original capacitors back as at least The LCD worked for 2 minutes.

[ben7]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Hi Ben,
The capacitors are all 105 degree C

The original caps are from (JH)
470uf 35v total five are present on board Printed CD287 (JH) on Capacitor
22uf 50v total three CD 263 (JH)


Inside heat sink (BOX) 5 Capas are present

470uf 35v two
470uf 16v, one
1000uf 10v two

I guess the heat sink is for the transistors/IC fitted around it.

I replaced the original 470 35v ones with some other Brand called Elna
and with CapXON for 22uf 50

Attaching the board pictures with Capacitor values

Before replacing the capacitors I hear some chattering kind of noise where the two 470uf 35v are present at top but after replacing the caps it has reduced and only fraction of noise still exist.

After replacing the caps The TV still in Black and no picture.

I am planing to put all the original capacitors back as at least The LCD worked for 2 minutes.

JH?

Those are crap.

CapXon is just as bad.

Elna is good, but you will need better caps in the psu, those wont last!

Probably a better idea to get some new caps, panasonic, nichicon or NCC ones

[rmg_hrr]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Where can I buy Panasonic or Nichicon or NCC capacitors in India, Bangalore city?

Is there by any chance that some of the Diodes or transistors also require replacement?

Any one got block diagram of the MLT688 rev 1.6 Board?

[ben7]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Where can I buy Panasonic or Nichicon or NCC capacitors in India, Bangalore city?

Is there by any chance that some of the Diodes or transistors also require replacement?

Any one got block diagram of the MLT688 rev 1.6 Board?

Yes some of the transistors might need replacement, but we will see if the thing will work or not with better caps.

I am sorry, Im afraid I can't help you find the parts, I live in the USA

[rmg_hrr]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Hi Ben, I replaced all the CAPS except the largest capacitor on board, but no luck.

Looks like some other part also got affected.

The voltage out puts from PSU are very low like 2 -6 volts instead of 24 volts at some points which drives other logic board on the LCD.

I have asked for Service from manufacturer, will post the update.

[anmol]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

remove supply socket from invertor board and check all voltage there.

what is the voltage reading at 5v. 12v and 24v ?

keltron cap. are good .

Regard.

[ben7]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

Hi Ben, I replaced all the CAPS except the largest capacitor on board, but no luck.

Looks like some other part also got affected.

The voltage out puts from PSU are very low like 2 -6 volts instead of 24 volts at some points which drives other logic board on the LCD.

I have asked for Service from manufacturer, will post the update.

Measure the voltage on the big capacitor C102, it should be around 300v.

[rmg_hrr]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

The Service Guy came and replaced the entire PSU.
He said capacitors are not the problem on this board, but some of the switching IC's five or six of them ( I think they are Schottky diodes) located at various places are the ones which are fitted with heat sinks require replacement.

But he did not bothered to check any of the IC and Voltages etc, but inserted new PSU board, I will get one month warranty for the new board.

Here in India i think its hard to get parts, I don't exactly know the part no but looks even many shops do not keep good quality branded capacitors 105 C.

Now its working like before.

On this repair cost me 10% of Total cost of TV set

[days]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

i have onida ky rock tecqunition says display has gone but i am sure it some other problem th red power light get on but tv dosent get on while trying i have checked powerboard there is shorted current on power board is that in diode problen can any one geve me the reading of megmeet MLT688 rev 1.6 power board.

[Doom2pro]

Re: 32 Inch LCD (Onida) issues, MLT688 rev 1.6 Power board

JH Capacitors will fail looking pristine, no bulging or discoloring, their failure is a massive increase in ESR and heating them with a soldering iron or heat gun will make their ESR go down a bit which might make the device power up or function properly which can help aid in finding the suspect device if you don't have an ESR meter.

It's best to replace all of them, even any that have not failed with equivalent brand name capacitors, like Rubycon, Nichicon, Panasonic etc....