SANYO DP19640 back light out...

[RAMSELECTRONICS]

I have a SANYO DP19640.

When I turn on it did turned on the back light then in few seconds then off the back light but I can bare to see the LCD screen seem working but no light..

I opened back panel and I see the board has built in power supply and inverted together.

See the pictures in attached files.

I checked all caps are good...

I suspecting the two chips something.. Q7004 and IC7001

Any idea where caused the problem with back light? OR anyone have fixed it before?
thanks!

[budm]

Re: SANYO DP19640 back light out...

That MOSFET Q7004 got very hot, did you check the capacitance and ESR of the filter caps? Hopefully the Inverter transformer or the MOSFET is not damaged, you need to get the P/N of Q7004 to check the resistance between Source and Drain.
If the lamps are worn out they can also cause too much current DRAIN, so there are many things you need to check.

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Okay thanks!! which Caps you want me to check? maybe you can circle on the picture.

I see AliExpress sell the 20 Chips for $10.00

thanks again!

[budm]

Re: SANYO DP19640 back light out...

Did you get the P/N of Q7004? That should be checked first.

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Yup it's TPC8218 H

Here what I found:
http://www.aliexpress.com/item/TPC82...339305292.html

[budm]

Re: SANYO DP19640 back light out...

TPC8218 Dual MOSFETs. Check the resistance between Source pins and Drain pins

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

I measurement Source and Drain looks like all open.

Of Course I desoldered the chip to out then measurement

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

I am thinking to make different to the TO-220....


Here for example: http://www.semicon.toshiba.co.jp/inf...&pid=TK72E08N1

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Back here again... I got new the Power Supply board from eBay and replaced it. but the issue are the same... uhhhh????

I saw on the screen when happening.... When I turned on the power, screen show "Please wait" show red then change to "HDMI" display show red become to white then picture looks great for less 3 seconds then back light shutdown but the green light still on and I hardly to see the screen picture is still there.

Possible bad CFL tube light inside the back-light? BUT short time turned on looks perfect??

thanks!

[RJARRRPCGP]

Re: SANYO DP19640 back light out...

Back here again... I got new the Power Supply board from eBay and replaced it. but the issue are the same... uhhhh????

I saw on the screen when happening.... When I turned on the power, screen show "Please wait" show red then change to "HDMI" display show red become to white then picture looks great for less 3 seconds then back light shutdown but the green light still on and I hardly to see the screen picture is still there.

Possible bad CFL tube light inside the back-light? BUT short time turned on looks perfect??

thanks!

Possibly a bad CCFL bulb.

I also saw a T5 fixture at HCRS with a bad T5 fluorescent tube do the same kind of thing.
Any bad fluorescent tube in the same circuit will result in the ballast also shutting off the good bulb, too!

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Here I made a video... see the color.. red... then white... umm.. for sure bad one? where I get it.?
SHOOT video not working... let me try other way

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Here
https://youtu.be/AGADb5_yIdE

[budm]

Re: SANYO DP19640 back light out...

You have bad lamp, you can also see the ends of the lamp are blackened. Do not keep on using it, it will draw too much current and take out the inverter transformer and the MOSFETs if the over current protection circuit does not kick in.

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

okay I will order new CCFL from eBay.
http://www.ebay.com/itm/2PCS-19-inch...EAAOSwR0JUUZ9p

[RAMSELECTRONICS]

Re: SANYO DP19640 back light out...

Geez forgot leave a message.. I got replaced lamps and it's worked perfect! thanks!