LG 42PG1000 Stuck In Standby

[rebel-mc]

Hi, Got one of these in for repair and just can't establish where the fault is.  Power up tv the standby light goes from red to green then after 5 seconds back to red.

So far ive tested all voltages from power supply and everything is there (or at least for 5 seconds).  +5v standby allways there.  Power supply comes on for 5 seconds (relay click) and all voltages there, after 5 seconds all I have is the +5v standby.  On the power supply there are only two power outs (ysus and Mainboard). If I disconnect the Ysus the same thing happens.  If I disconnect the mainboard the same.  If I disconnect both the power supply stays on.  Anyone had any experience with this fault.  I believe the same fault can occur on the 42PG2000 and 42PG3000.  I was thinking the ysus but just can't prove it. 

Again any help would be appriciated.

Thanks

[jordan]

Chassis PD83A
On PSU change capacitors and check (with hot air) IC U701(MC80F0604B P)

[rebel-mc]

Hi Jordan, thanks for the advice.  I've tested most of the caps and all seem to be ok.  How would I go about testing u701?

Thanks 

[jordan]

Warm up him with hair dryer

[rebel-mc]

Right tried the hairdryer on IC U701 and this is what I get.

After the ic has been heated for 5 mins, I switched the tv on and the only difference was on the LVDS board the two right leds come on for 5 seconds  (there are three in a row).  When the ic has been left to cool the two leds on the left come on for 5 seconds.  Tv' still just shuts down after 5 seconds.  Front standby light green to red.

Still as clear as mud.

Any advice.

[rebel-mc]

Hi Think I have found it.  On the ysus there are three transistors all reading short.  Part Num 45f123. sgs thompson part.

Anyone know where I could get them from?