Sharp LC52D62U

[rviani]

After many years of service this unit now refuses to turn on and gives a once per second continuous blinking power indicator. Service manual indicates this is a "lamp failure".

If I force the power on with Channel down and volume up buttons I measure correct power supply voltages at the main board. The Power supply to the inverters (connector LA) measure 10V and 47.3V which I don't have a value for from the manual but appears should be 24V. LB connector which I guess are control voltages to inverter measure 3.3V, 3.1V, 0V, and 0V at contacts 1, 2, 3, and 4 respectivly.

I looked for open circuits at the inverter output transformers but all seem normal.

At this point I am stumped as to where to look next and any help from members of this forum would be greatly appreciated.

Thanks in advance
Ron

[rviani]

Re: Sharp LC52D62U

Update: all CCFL test ok. Why is power to inverters @48V -bad power supply ? Help appreciated.

[nomoresonys]

Re: Sharp LC52D62U

can you post a good clear straight on picture of each board and one of the whole back, as to see how everything is connected.

[R_J]

Re: Sharp LC52D62U

I don't have the exact power supply schematic but on a similar one, the inverter is supplied by unregulated 12v and 50v
What did you use to check the ccfls? I suspect you have a bad transformer on one of the inverter boards, check the secondary winding resistance and compare them to each other and see if one is different.
Also check the fuses on the inverter boards

[nomoresonys]

Re: Sharp LC52D62U

did you also try holding vol down and input while plugging in?

[R_J]

Re: Sharp LC52D62U

To bypass the lamp error, press and hold CH_DOWN and VOL_UP then plug in the tv This should light the backlight for a few minutes then shut down.

[nomoresonys]

Re: Sharp LC52D62U

if you haven't already, unhook the cables from powerboard to inverter board/s and retest the voltages of the connector pins on powerboard, another easy test, heat up the capacitors of the inverter board with a hairdryer for a couple minutes, heat the electrolytics first, then try it, don't wait til they cool down try it while its still hot, see if it comes on or theres any change, no joy, heat the blue ceramic caps and try it.

[rviani]

Re: Sharp LC52D62U

Thanks for all suggestions - will try all these and post results tomorrow.

REALLY APPRECIATE THE HELP

[rviani]

Re: Sharp LC52D62U

Update: Heating the electrolytic capacitors on the inverter boards worked ! This resulted in all the CCFLs flashing rapidly - the first time I have gotten any light at all. Assume the flashing may be due to having the LCD paned disconnected at this time? Assume I should change all the electrolytics on all four boards ? Input voltage from power supply board to inverters still reading 48V whether connected to inverters or not - service manual seems to indicate this should be 24V so not sure what is going on.

Once again suggestions appreciated.

[nomoresonys]

Re: Sharp LC52D62U

sure, change out those caps, might be all you need to do.

[rviani]

Re: Sharp LC52D62U

Will give it a try and post results .

THANKS MUCH !!!

[rviani]

Re: Sharp LC52D62U

Changed all 16 electrolytics on all 4 inverter boards. Result is that I now get rapidly flashing CCFLs when power on.
Doing reset procedures with channel and volume buttons does not cause any change. LCD display panel is currently removed but I don't think this causes the problem. Assume if inverters were working I would get CCFLs on constantly. Is the next step to change the blue ceramic caps?

Once again all help appreciated.

[rviani]

Re: Sharp LC52D62U

Additional info. Heating ceramics ( a bit more difficult due to location on the board) did not seem to make a difference. Also ceramics seem to be unmarked - any idea what rating they are?

[diif]

Re: Sharp LC52D62U

Don't waste you time trying to heat the ceramic capacitors it will have no effect.

[rviani]

Re: Sharp LC52D62U

Correct it had no effect - but is it useful to change these? - any idea what the rating is ?

[rviani]

Re: Sharp LC52D62U

Update: Still stumped as to what the is the problem. Does anyone have a schematic for the RDENCA184WJQZ power supply board or know where to get one? The only problem I can find is the output voltage to the inverters is 47.3 volts (even with the inverters disconnected) where the service manual calls for 24V. Am considering to buy a new power supply board. Any help appreciated.

[rviani]

Re: Sharp LC52D62U

Sharp power supply RDERNCA184WJQZ
Anyone know the correct output voltage of this board to the inverters? This board is used in many 42" to 62" Sharp Aquos (2005 - 2010 era) TVs. Also known as ZEBRALC605-4001CC.

SOMEONE must have this data - help gratefully appreciated.

Thanks in advance.
Ron

[nomoresonys]

Re: Sharp LC52D62U

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