Dynex DX-LCD26-09 ---- NO 12V

[saintlouis74]

I Have a Dynex unit, as soon as i plug the power cord up i get 6 blinking red light then when i press the power button it turns green and screen stays black.. I dont hear any clicking from relays.. i tested all diodes and resistors everything looked good.. VCC tested ok
But the 12v reading isnt solid, i get a high reading then it starts dropping. could be the cheap multi meter im useing.. but i cant seem to find the 12volts

any help in guiding me in the right direction would be appreciated alot thanks

[budm]

Re: Dynex DX-LCD26-09 ---- NO 12V

Is the 24VDC out to the inverter board steady? The 12V and 24V are generated by the same big transformer, the 12V is down converted by BUCK CONVERTER IC904 that converts 24V to 12V.
Try disconnecting the inverter board to see if the 12V becomes stable.
http://www.shopjimmy.com/insignia-ad...pply-unit.htm#

[saintlouis74]

Re: Dynex DX-LCD26-09 ---- NO 12V

Is the 24VDC out to the inverter board steady? The 12V and 24V are generated by the same big transformer, the 12V is down converted by BUCK CONVERTER IC904 that converts 24V to 12V.
Try disconnecting the inverter board to see if the 12V becomes stable.
http://www.shopjimmy.com/insignia-ad...pply-unit.htm#

the 24v is not steady just keeps decreasing, unplugged the inverter and still no steady 12v

[budm]

Re: Dynex DX-LCD26-09 ---- NO 12V

That is what I expect as I explain that the power source for the 12V and the 24V is from the same power transformer.
Lets see if the PFC Voltage booster is OK or not, you will be working in the primary deadly side of the circuit so do not touch anything with your hands, you need to check the DCV between the two legs for the main filter cap (100uF 450VDC) to see if it has >360VDC when power switch is activated, it should be quite steady Voltage.
You can also try heating the whole board with hair dryer for 2~3 minutes to see if the 12V/24V will become steady.

[saintlouis74]

Re: Dynex DX-LCD26-09 ---- NO 12V

that is what i expect as i explain that the power source for the 12v and the 24v is from the same power transformer.
Lets see if the pfc voltage booster is ok or not, you will be working in the primary deadly side of the circuit so do not touch anything with your hands, you need to check the dcv between the two legs for the main filter cap (100uf 450vdc) to see if it has >360vdc when power switch is activated, it should be quite steady voltage.
You can also try heating the whole board with hair dryer for 2~3 minutes to see if the 12v/24v will become steady.

394vdc

[budm]

Re: Dynex DX-LCD26-09 ---- NO 12V

That is fine, so the SMPS for the 12v/24v may not be getting steady VCC to run the SMPS IC.
So did you try hair dryer yet?

[saintlouis74]

Re: Dynex DX-LCD26-09 ---- NO 12V

That is fine, so the SMPS for the 12v/24v may not be getting steady VCC to run the SMPS IC.
So did you try hair dryer yet?

hell yea your the best... heating up the board did the trick... i got a 24v and 12v back.. the TV even powered up.. so what do i need repair for this to be fixed?

[budm]

Re: Dynex DX-LCD26-09 ---- NO 12V

OK, just try heating the suspected cap (the one I marked with 'SUSPECTED' by itself or replace it, I would replace the whole set of caps any way.

[saintlouis74]

Re: Dynex DX-LCD26-09 ---- NO 12V

OK, just try heating the suspected cap (the one I marked with 'SUSPECTED' by itself or replace it, I would replace the whole set of caps any way.

replaced them all.. its back up and running thanx a ton

[budm]

Re: Dynex DX-LCD26-09 ---- NO 12V

That is fast. Thanks, glad it was just bad caps.