Lg TV Repair: Common Faults and Solutions.

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Lg Repair Guide: Common Issues and Fixes

Brand	Model	Fault	Detailed Problem
LG	CF25A50F	Reverts to st/by aft 2-3 secs, ht drops to 60v	Ic351 fop chip tda8350q & fr350 10r fusible
LG	CF25A50F	Field mod when foptr has blown	Fit tda8350q & use heatsink compound as well as the grey thermal transfer pad between the chip & the heatsink. change c352 to 22mfd (was 47mfd) 50 volts change c708 to 22mfd (was 47mfd) 100volts . this is located to the left of the lopt on the 45 volts rail. change fr359 to 22Ω half watt fuse resistor (was 10Ω) this is also located to the left of the lopt on the 45 volts. rail. add a 0.01 mfd cap on pins 8 & 9 of the frame chip & 0.1mfd between pins 7 & 8 (both 100volts)
LG	STUDIOWORKS SW57I / CS590	With the horizontal width greater than the screen view, even with width control at minimum	Obs ca-46 check the width transistor, it may be shorted, remove it from the board and see if the image shrinks, if it shrinks, replace it, if not, check associated components!!!
LG	STUDIOWORKS SW563A	Does not turn on, power supply voltages ok	I've already touched fly, micro, oscillator and it didn't solve the problem, the LED is very weak in orange. If the power supply of this monitor is ok, micro ok, oscillator ok, memory ok, changing the micro oscillator crystal. solved the problem.
LG	STUDIOWORKS SW563A	It arrived at my bench with the flyback swollen...it turned on and there was no video	I changed the fly, now the same as in the video, but the image has high contrast, even the adjustment is insufficient, and more or less in the middle of the screen there is a belly to the right so that you can look straight ahead... leaving the screen a little crooked, the same as the adjustment for this... but it's not enough... solved the problem... flyback that I bought came without the wire that goes through the fly's ferrite... then the contrast is horrible and crooked screen...I put one from a used fly and solved it.....
LG	STUDIOWORKS SW485 -CHASSIS CA-51	Dead	I went straight to the q704 (irf 640) showing a short in allΩic measurements. replaced the monitor worked normally. Note: this LG chassis is widely used by Unisys and Digital companies.
LG	STUDIOWORKS 77I 17"	Comet tail defect	This defect has basically two causes. Of course it could be problems with the cathode voltage filter capacitors but it's a little more unlikely. You said you've already tested these capacitors, "don't test" replace them. the two reasons are: coupling capacitors, and weak image tube. replace mainly c340, c341, c342, c347, c348, c349. I changed the TRC plate but it still gives the same defect. I discovered the problem... it was the damn tube itself, I changed it, it solved it.
LG	STUDIOWORKS 77I 17"	With frame increasing and decreasing	After several replacements of suspicious parts and no success, I found that when I increased the screen the frame also increased. I found that below the screen control there are 3 pins and 1 of these pins the voltage also varied. I verified that the voltage came from a c.i. which is behind the fly (lm358) I changed the c.i. and everything was normalized.
LG	STUDIOWORKS 77I 17"	Gun power supply but it doesn't have high voltage I'm in doubt is it the fly...or is it something else	Also check the +b fet, it also causes this defect!!! ok!!!thanks a lot for the tip it really was the fly
LG	STUDIOWORKS 775N- CA80	Does not adjust width and pin cushion	Check q 709 (2sd1413 you can use tip122 but insulate the collector with mica) and if it is good check leak or short in d 704 there is no substitute for it and you can ONLY use dmv32 or dmv56.
LG	STUDIOWORKS 775N	The monitor arrived at my assistance with the tsh burnt out (2sc5803), I replaced it with a bu2508af, then the monitor worked for about 3 minutes then the output burned out again.	You have to put the original transistor, with the bu2508 it really burns!!!
LG	STUDIOWORKS 775N	A resistor burned out where its resistance value is very low, I believe, because on the board it is located at (j169) close to the fly-back.	Take a look to see if it's not a 0.33Ω / 2w one, it looks like that's the value. Check the double diode, it's probably also leaking. This resistor is just a current limiter. Thank you, it worked.
LG	STUDIOWORKS 775N	It is not saving settings, it does the same ones, when it turns off it returns without the new settings made. could be the processor	The processor was actually replaced and it started working again.
LG	STUDIOWORKS 775N	Horizontal width does not work reduced frame.screen reduced horizontally.no adjustment	Changed r736 (100k, 0.25w which was open. studioworks 775n does not turn on, led blinking. when turning on the power the led blinks alternately (green and orange). I got one of these, with the same defect, the front led kept blinking, red and green, and it was the video amplifier IC that is on the crt board....
LG	STUDIOWORKS 775N	I can't increase the brightness of the monitor, I heard that increasing the value of a resistor solves the problem, I ask what the resistor is, as I don't have a diagram of this monitor???	It has two 380k resistors, r778 and r799, in series. increasing this resistance, you increase the value of voltage g2.
LG	STUDIOWORKS 76I	Video pre amp ic(0imo132820a ic,motorola mc13282ap) is no longer supplied	Corrective action. change ic301(0imo132820a ic,motorola mc13282ap ndip 24 bk pre amp) to ic301(0imo132820c ic,motorola,mc13282ep ndip 24 bk pre amp). when changing mc1328ap(ic301)to mc1328ep(ic301) additional work is required. (applied model: s/w 76i, 76m, 76t, 76w) - additional work. You need to add a jumper between pin #9 and pin #17 of ic301 on the back of the video pcb.
LG	STUDIOWORKS 575N	I have this monitor on the bench for maintenance and I found q719 shorted, but it's a strange number, I think it's a fet, but I'm not sure, could anyone tell me which component is used for this place???	2sj306, see the diode connected to it. I already checked and it's ok, what I want to know is which transistor should I put in place of the 2sj306 as a replacement. This is not a common fet, it's a p_channel fet and it's 250v by 3a, You can use any fet with these characteristics, remember that it is a 250v p-channel fet. note: see 2sj307 which is 250v for 6a.. friends I have several pumps like these on the bench what is their 719 and the irf 630 if there is another one it is good to know
LG	STUDIOWORKS 575N	With normal but weak image (low brightness and low contrast)	The filament voltage was low 4.5v the cause was the c926 1000mf/16v
LG	STUDIOWORKS 575N	When I turn it on, the power LED comes on and for about 3 to 4 seconds you hear a clicking sound coming from the power supply (I think it comes from the power supply relay) and the LED goes off and on continuously and the clicking continues each time the LED flashes	I have already disconnected the fly-back and the problem continues, I measured the voltage at pin 2 +b of the fly-back and it varies from 115v and rises to 195v then drops to 115v and rises again to 195v. check q706, if ok, check if there is 194v on the +b line power supply, if ok check pin 2 of t701 if there is a signal with a frequency of 31khz 60 to 69khz 160v, if not ok, check q717, q718, q719 and d707, If ok, see the waveform (signal) on the q705 collector, if ok, the flyback remains, replace it.
LG	STUDIOWORKS 563A	Def. a little crazy, he calls whenever he wants	I tested all the secondary components of the power supply plus the tsh, the vertical output, fly-back and I didn't find anything abnormal. Have you taken a look under the plastic grille of this monitor, I don't know if the defect is the same as the one I had, but what I had was that the image disappeared or didn't even appear, it was a jammer through which the tube filament feed passes, the solder was It's broken and it's right under the plastic grille, without dismantling it, you can't see it.