sharp LC40ELE 600E standby only faulty backlight

[jimbofz]

Hi this sharp was stuck in sby 5v sby volts present.
after the usual checks i jumped the psu with 470ohm to panel on and 5v sby to power on .
all supplies came up 12v etc ,
so after trying many times to get it to start in s/mode vol_ and source, then powering on no luck
the sby led remains red and not even a flicker from remote control
i decided to open up to inspect the leds
i found two s/c and 3 would light fine
but had lower resistance when checked
as my meter on diode test mode would not provide enough voltage for them to light i decided they must be 6v types as used on many lg models
once replaced each strip would light fine with my led tester
i was very suprised to find 10v across each of the original leds!
i assumed the leds were either 3v or 6v with psu forced on leds would only flicker
there are 9 strips with 17 leds on each all strips are individually fed from psu
with my led tester each strip has 170v across it
as youve guessed it
once re assembled without lcd panel and removed 470 ohm and link
symptoms remain the same refitted lcd panel still the same
now im at the head scratching stage

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

the s maual is full of info
except the cct diagram is not readable
i wanted to check the components around the led driver ic
but simply cant read them

[diif]

Re: sharp LC40ELE 600E standby only faulty backlight

I don't know what PDF viewer you're using but in Foxit, pressing Ctrl and then the + key will zoom in making everything readable.

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

thanks will give it a try

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

well foxit is great thanks
now i realise this is not the correct cct
my board has two plugs feeding the strips one with 10 connections one with 8 connections

i found d7519 s/c across it
its a zener .
lifted one end and diode is good
my psu is RUNTKA 609WJQZ

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

d7519 has a low ohm resistor across it ,so my mistake.
any ideas why the original leds have 10v across them?
also tried many times to enter s/m no joy vol_ and source
simply dont work for me

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

any idea where i can buy leds for this model?
the working strips have 10 volts across each led
its model LC40LE 600E not as in title of post LC40ELE 600E
i know bl leds rely on constant current source,but the volts across each working led seems very high to me .any thaughts please
they dont have a built in zener

[R_J]

Re: sharp LC40ELE 600E standby only faulty backlight

I suspect your meter is not reading the voltage across the led's correctly, The drive for the leds has a high frequency component and your meter is reading that as well as the dc value.

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

I suspect your meter is not reading the voltage across the led's correctly, The drive for the leds has a high frequency component and your meter is reading that as well as the dc value.

thats something i would never have thaught of.
i replaced the faulty ones with 6 volt types used in LG models
and with my meter i read 6 v across the replacements
as it wont allow service mode ,is there any way to desensitise the protect cct just to allow s/m access
then according to manual i can reset the error codes
(more than 5 errors and tv locks up with just s/b lit)
ive tried many times to enter s/m no joy

[R_J]

Re: sharp LC40ELE 600E standby only faulty backlight

The circuit monitors the current for each led line, If the led's you installed are wrong then the current will be wrong. They might be 3v led's I don't know.

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

6 out of 9 strips are perfect complete with original leds when connected separately each strip measures 172v ,from this i assume that each strip is drawing the same current
now the 3 remaining strips ,
just as an experiment
i added an extra led to each strip because they had 167v across them
they now have 173v across them .within tollerance i think?
after trawling the net i found a supply of 9v leds as used in sharp ,
so there ordered from china so will take some time to arrive.
from reading the s manual i found that when in service mode it should be able to
clear the error detection and reset standby cause
but it refuses to enter s mode so its catch 22
thanks for your help
i will try measuring the current drawn by each strip when fed with b/l tester to see if theres any variation

[R_J]

Re: sharp LC40ELE 600E standby only faulty backlight

It does look like the VLED voltage is around 170v. The power supply raw supply voltage is likely around 150V (C7528) then gets boosted by Q7506 to a higher voltage (C7525)
So if there are 17 leds per string, 9v led's would make sense.

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

It does look like the VLED voltage is around 170v. The power supply raw supply voltage is likely around 150V (C7528) then gets boosted by Q7506 to a higher voltage (C7525)
So if there are 17 leds per string, 9v led's would make sense.

ive just tested the current drawn by each strip,
when fed externally via b/l tester
on the 2amp range its ,042amp
and to my surprise its the same on all strips including the ones i have fitted the replacement 6v type leds
so now im thinking there must be a fault in the lamp error detection cct .im going to have a closer look at the supplies around this
i do know about the "5 strikes and your out "
but to clear you need first to be able to enter s/mode

[jimbofz]

Re: sharp LC40ELE 600E standby only faulty backlight

It does look like the VLED voltage is around 170v. The power supply raw supply voltage is likely around 150V (C7528) then gets boosted by Q7506 to a higher voltage (C7525)
So if there are 17 leds per string, 9v led's would make sense.

with psu forced on and p on fed with 5v
theres no bl-on from cn7603 pin 2 .
so q7509 and q7511 (b/l switch ) off.
so no boosted vled volts from q7506
the v led volts across c7528 is the same as across c7625.
the 13v supply to ic 7506 pin6 is present
any thaughts please
i keep trying to enter s mode with no luck
im wondering if i should try a f/w update this may then allow s/mode entry
do you think that may work?

[Yanleb]

Re: sharp LC40ELE 600E standby only faulty backlight

When you power on the TV set, do you see at least an attempt to power on the backlight? If yes, there's still something the LED driver doesn't like.

If you plug in the TV set and it immediately starts to blink the lamp error code, then it likely reached the 5 tries and it is now locked indefinitely in the lamp error mode.

You already found my thread about another Sharp TV set stuck in the lamp error mode:
https://www.badcaps.net/forum/showthread.php?t=98411

On my TV set a sub processor was handling the lamp error, and this error can be cleared by erasing the small eeprom attached to it (IC2004). The difference is that your TV set seems to have the lamp error detection in the main processor, not in a sub processor. This means that erasing the eeprom will clear a lot more data than it did for me.

As you said in my thread it seems that the eeprom to erase in your case is IC8455. I would suggest that you backup its content before erasing it. In the case it doesn't solve your problem just restore its content. The BR24S64F is available here: https://www.mouser.co.uk/c/?q=BR24S64F

Or you can probably substitute it by another 24C64 compatible eeprom if you don't want to erase yours (after backing it up).

Another option is to look around for an eeprom dump of IC8455. You can also make a request for it in the eeprom dump section of this site.

As a last resort (I did it a few times), just buy a replacement board from eBay, backup the content of IC8455 and sell back the board on eBay. Just confirm with the seller that the board is indeed working and was not removed from a TV set with a backlight issue.

You will lose the shipping fees but it is not that bad. Just be kind and upload the dump file to help people in the future.

[lotas]

Re: sharp LC40ELE 600E standby only faulty backlight

Reset "error lamp" can be done through the service menu.

[Yanleb]

Re: sharp LC40ELE 600E standby only faulty backlight

Some of you don't understand that you cannot access the service menu if the TV set refuses to power on due to the lamp error. After getting the lamp error 5 times it locks down indefinitely. In that case all the key combinations you can read in the service manuals will just not work.

In my case the LED strips were repaired but it has been impossible to bring the service menu to reset the lamp error. An oscilloscope in single trigger mode on the LED driver circuit proved that.

The TV doesn't have a crystal ball. It has to power on the backlight to detect if it is working or not. After 5 tries with bad LED strips the TV will just abandon and will never try again.

[nomoresonys]

Re: sharp LC40ELE 600E standby only faulty backlight

Good question, might have to reprogram a chip or something.

[nomoresonys]

Re: sharp LC40ELE 600E standby only faulty backlight

This should work, make sure there's no status light on, on front of tv. Hold volume down and source button both keep holding hit power button, keep holding the volume- and source button til it comes on, then press volume down and channel down, screen should come on, look for lamp errors, there will probably be 5 of them.

[lotas]

Re: sharp LC40ELE 600E standby only faulty backlight

Lamp error detection
1. Function description
This LCD colour television has a function (lamp error detection) to be turned OFF automatically for safety when the lamp or lamp circuit is abnormal.
If the lamp or lamp circuit is abnormal, or some other errors happen, and the lamp error detection is executed, the following occur.
1) The main unit of television is turned OFF about 5 seconds after it is turned ON.
(The power LED on the front side of TV turns from green to red.)
2) If the situation “1” happens 5 times sequentially, the power is turned on (relay is turned ON).
However, the backlight is not turned on, and then the relay is turned OFF after 5 to 6 seconds. (The power LED remains red.)
2. Countermeasures
When television is turned OFF by the lamp error detection mentioned above, it enters the adjustment process with the power LED red.
Entering the adjustment process, turns OFF the error detection and turns ON TV.
This enables the operation check to detect errors in the lamp or lamp circuit.
Check whether “STANDBY CAUSE” on line 7, page 1/8 of the adjustment process is “1B”. it indicates the lamp error detection was executed.
After confirming that the lamp or lamp circuit is normal, reset the lamp error counter pushing “OK” in the R/C.
After resetting counter the green bar appears on Screen.
3. Reset standby cause error list
After confirming that the lamp error counter has been erased, select “ERROR RESET”, page 1/8 of the adjustment process and select YES using
the right cursor. For execute press “OK” in the R/C and the label “***OK***” appears on Screen.