Samsung LA40A650A1F no 5.3v standby

[budm]

Re: Samsung LA40A650A1F no 5.3v standby

You can use through hole resistor in place just for testing.

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

OK I found a 10k resistor and bridged feed resistors 2 and 3 so dropping voltage thru 14k rather than 12k and we now have a red standby light. But when on is selected the light goes out the single fan gives a kick the light gives a blink and comes back on so something else yet to be found. Have some 1000uf 25v caps coming so will put those in and then see what happens
Voltages measured cold side 22v main 5.1v standby.

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

To bring up to date: after replacing caps must have moved resistor I had soldered onto bottom side of board - it shorted out after about 5min and blew fuse plus what else - red standby gone! But I had meanwhile got onto another power board (from Poland no less!!) and now have standby again. Activation gives red light blinks slowly about 4times then quickly - one time only did see very briefly screen light only a split second. Main board problem now ???

[budm]

Re: Samsung LA40A650A1F no 5.3v standby

So what DCV do you have on the connector pins of the power supply board that goes to the main board, all ZERO VDC except the STBY 5V?

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

That's right.and when power on is activated get the 13v up plus 5.1v the fan runs but no start otherwise.

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

Later to above can now get backlight to stay on with red light continuing fast blink.

[budm]

Re: Samsung LA40A650A1F no 5.3v standby

Hmmm.

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

Have connected AV2 input playing VCR and the remote causes screen to blink when using buttons such as menu and source but nothing shows up and red light continues rapid blinking
Almost there just the last step does not complete due to ???? I note again standby blinks 4 times before then rapid blinking which doesn't want to stop despite many inputs including power off but does eventually stop. Also no clicking sound ever - should there be??

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

Not being au-fait with these sets I do note that the touch sensitive buttons on front of set appear to work but do not light up at all. Of course the set has not fully turned on but....??? Took the tcon board out all looks OK and 13v seen on that board. Tried heating all boards no go.

[maxvalutech]

Re: Samsung LA40A650A1F no 5.3v standby

This saga continues. From the owner I have determined that 4 red light blinks before start is normal. Also that the set was a factory second. In this regard I noted that one of the power boards 1000uf caps had been replaced, a fan fitted above that area of usual trouble and a screw missing from main board all of which indicates work done to try rectify the badcaps problem before sale. I have fitted all new caps to the power board and confirmed all voltages ok. Redlight continues fast blinking so i have now tried to identify eeprom to do a reset - no luck!!! And cant find a schematic for bn41-01022d. Do have same board from 32" model but different stick on tag number and a number of circuit differences. Will try get reasonable pics of board - do note one ic has lcd printed after its number And another is numbered ic1111 which doesn't seem to relate to any others - can't read anything printed on the ics.