sony KDL 40R483B 6 blinks

[jimbofz]

Hi need some help with this one, tv has external psu 19.5volts .
powers up backlight comes on ,
front led goes green ,sony welcome logo appears
then backlight goes off and 6 blinks .
ive tried various reset procedures with no luck
the internet advice is that 6 blinks is due to backlight problem
and like most led tvs backlight should be reduced as much as possible in the settings menu.
but cant adjust backlight until tv will stay on " catch 22"
cant find any service procedures specific to this model for reset
this is the first "one board" model ive seen ,
the main board seems to contain t con, psu regs ,and i/p interface
ive looked at the sony website but theres nothing specific to this model

[diif]

Re: sony KDL 40R483B 6 blinks

A software reset won't do anything if any LEDs have failed.
You need to either test the voltages at CN9000 at switch on, strip the panel down and check visually or use a decent (300mA) LED tester to confirm.

[jimbofz]

Re: sony KDL 40R483B 6 blinks

A software reset won't do anything if any LEDs have failed.
You need to either test the voltages at CN9000 at switch on, strip the panel down and check visually or use a decent (300mA) LED tester to confirm.

thanks for info .
the voltages in cn9000
rise up to 20v then fall away to around 3v
for the brief moment when backlight is on its around 20v
except for the last pin on right ,this rises to around 40v then falls away
what confused me was that the backlight does come on ,
i thaught they either work , go o/c, or s/c,
in which case i wouldnt expect them to come on at all

[neilc6]

Re: sony KDL 40R483B 6 blinks

TV is going into protection shutdown because shorted LEDs are detected which cause undervoltage. I have seen posts were the error signal is bypassed to keep the backlights on but shorted leds can damage the power supply or causes a fire. Proper repair is to replace all the strips with new and turn down the backlight level.

[jimbofz]

Re: sony KDL 40R483B 6 blinks

TV is going into protection shutdown because shorted LEDs are detected which cause undervoltage. I have seen posts were the error signal is bypassed to keep the backlights on but shorted leds can damage the power supply or causes a fire. Proper repair is to replace all the strips with new and turn down the backlight level.

thanks ill crack it open and test all led strips

[jimbofz]

Re: sony KDL 40R483B 6 blinks

ok stripped down to find one led s/c .
there are two strings of 5 strips each with 5 leds.
i assume that there is a comparator type cct that compares the current drawn between both sets of led strings, and as one string has a s/c diode the current drawn will be different .
these leds are 3v but have built in zener for foreward current .
i have a selection of leds but none have the built in zener
(meter on diode test one way led lights then, reverse leads reads 950.)
for some reason the strips all look the same
but some are marked A and some B
any ideas where i can buy these leds with zener ,as i can remove and solder in replacements

[diif]

Re: sony KDL 40R483B 6 blinks

A standard two pad LED ? I think it's measuring like that as it's in circuit.

[jimbofz]

Re: sony KDL 40R483B 6 blinks

A standard two pad LED ? I think it's measuring like that as it's in circuit.

all the working leds have a reverse reading on diode test mode of my meter .
i have found a suitable led and fitted it ,
all strips now light with external supply
also tested on 200meg ohm range all leds read 4.9meg one way and 1.2meg the other
all plugs and skts checked for dry joints . chain is not o/c ,
reassembled
and true to my luck fault still exactly the same .
so now i suspect the cct that feeds the leds
not producing enough volts to drive the leds
any ideas please?

[neilc6]

Re: sony KDL 40R483B 6 blinks

You either have another bad LED or your substitute LED has the wrong voltage. The TV should turn on with the panel disconnected. I always power up the TV and check that all the LEDs come on before reassembling the TV. You should also check with the diffuser panels replaced as well for bright spots and dirt.

[jimbofz]

Re: sony KDL 40R483B 6 blinks

You either have another bad LED or your substitute LED has the wrong voltage. The TV should turn on with the panel disconnected. I always power up the TV and check that all the LEDs come on before reassembling the TV. You should also check with the diffuser panels replaced as well for bright spots and dirt.

i agree but with this sony it
will revert to 5 blinks if turned on with panel removed ,
but it will stay on long enough to visually check leds for even brill levels ,
surely if led i fitted was wrong volts it would light differently from all the rest ie dimmer or brighter?
thanks for your tip

[diif]

Re: sony KDL 40R483B 6 blinks

so now i suspect the cct that feeds the leds
not producing enough volts to drive the leds
any ideas please?

Measure the voltages at CN9000.

[jimbofz]

Re: sony KDL 40R483B 6 blinks

still same as post 3

[jimbofz]

Re: sony KDL 40R483B 6 blinks

good news fault traced to poor connection on one of the plug in led strips,
sounds simple but it was a pig to trace ,
as when i used meter to check
i was putting slight pressure on the connection making it good
with panel removed you only have a few seconds before the set trips out ,
after a lot of head scratching i found i could cause a strip to flicker on and off which was enough to cause the sensitive control cct to activate
there was no sign of overheating ,
but a quick resolder of the plugs and skts ,and also cleaned and tinned the copper connections to ensure a good tight fit on each strip
thanks for all people who tried to help