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Old 05-15-2019, 07:16 PM   #41
R_J
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

Quote:
so if i have 5vsb, then this IC7102 and the area around it should be fine?
yes.
Quote:
why are all 4 of the source pins showing 0v?
they are connected to HOT GROUND
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Old 05-15-2019, 07:27 PM   #42
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

great we're on page 3 now.
thank you RJ. that makes sense why i would be getting 0v there then. and makes my mind just a little more clear...possibly can understand what the datasheet is saying now about this IC. which is fine anyway so moving on...
my question is about where the PSON signal is going, and where it is not going, what it is not getting to, what is not getting the message to turn on!

specifically i dont understand why the side of the octocoupler i traced it to is the side with the phototransistor and not the side with the LED as i was expecting to find.
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Old 05-15-2019, 07:49 PM   #43
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

I think you traced the AC_DET line and not the PS_ON line, that would explain why the opto's output connects to that pin.

I had one of these one time and I had poor connections on the standby transformer, so it might be an idea to resolder it.
On the one I repaired, the standby 5 volts was there but it was more of a phantom voltage, it had no current, as soon as it was loaded down it would drop to almost nothing.
when I measured the resistance of the feedback winding it checked open, I removed the transformer and rechecked it and it was ok, I reinstalled it and it worked fine.
I marked the feedback winding in red
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File Type: jpg sharp_ps_stby.JPG (20.4 KB, 0 views)

Last edited by R_J; 05-15-2019 at 07:59 PM..
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Old 05-15-2019, 07:59 PM   #44
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

i triple checked my tracings. did you see the image i posted with the trace in red? also i can trace the voltage along the capacitors and jumper wires all the way to where it is present on the pin of the octocoupler which if i read the datasheet right, is pin 3 which is the emitter. (again makes no sense to me)
this voltage is not present if i disconnect 5v from pson, so it must be coming from there.
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Old 05-15-2019, 08:05 PM   #45
R_J
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

Your tracing is wrong, before you get to the opto your trace is connected to ground, R7552 connects to the base of Q7504, the collector goes to the opto PC7102

Make sure your 5 volt standby stays up when you try to turn on the tv.
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File Type: jpg PC7101-back.jpg (107.6 KB, 5 views)

Last edited by R_J; 05-15-2019 at 08:22 PM..
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Old 05-15-2019, 08:11 PM   #46
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

im not seeing what you're talking about. can you give more details? i trace pin 14 PSON to the SMD resistor labeled 1002 which measures 10k as it should. from there it goes thru C7520 then thru J7572 and thru C7524 to pin 3 of the optocoupler. also i see this voltage with my meter the whole way there. how can i be wrong?

where is ground in this area?

<<EDIT: I THOUGHT I WAS SEEING VOLTAGE ALL THE WAY THERE BUT I MUST HAVE IMAGINED IT>>>

Last edited by triplefour; 05-15-2019 at 09:16 PM..
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Old 05-15-2019, 08:27 PM   #47
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

ok thank you for your edit. i see now that it would go to ground there. and learned again another thing to look for to help understand where things are going. i still dont understand why i see that same voltage on that pin tho. i better do some more poking around.
i thank you for your patience
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Old 05-15-2019, 08:52 PM   #48
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

I don't understand "that pin" what voltage?

Last edited by R_J; 05-15-2019 at 08:54 PM..
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Old 05-15-2019, 09:12 PM   #49
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

i thought i was tracing the voltage going from pin 14 to pin 3 of the octocoupler all the way to the left. but i was wrong about that. thanks for your help in seeing that. so disregard that.

so now i see that the true path from the PSON is to pin 2 of octocoupler PC7102
which is the cathode of the internal LED and i am reading 0v to that pin. also 1.13v on the anode would not be enough to light a LED, right?

im still confused though...why does PSON go to the cathode of the LED? if its purpose is to light that LED, shouldnt it go to the anode? and where am i getting that 1.13v from? and what is Q7504 and how do i test it? maybe thats bad and why im not getting any voltage to pin 2 of the octocoupler?

see picture for voltages in the area
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File Type: jpg voltages-near-optocouplers.jpg (402.9 KB, 3 views)

Last edited by triplefour; 05-15-2019 at 09:14 PM..
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Old 05-15-2019, 09:39 PM   #50
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

I think pin 1 of pc7102 should be connected to 5 volts standby via R7538 1k (1001) and Q7504 collector connects to pin 2, the base of Q7504 gets switched by the PSON voltage and Q7504 emitter is ground.
I see 5 volts on J7573 so re check the voltage on R7538 and pin 1 of the opto
Attached Images
File Type: jpg PC7101-back2.jpg (106.8 KB, 5 views)

Last edited by R_J; 05-15-2019 at 09:55 PM..
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Old 05-15-2019, 10:57 PM   #51
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

ok i just checked again and those voltages in the picture are correct. i get 5v on that jumper J7573 , and it only goes thru that 1k resistor R7538 (which checks out fine at 1k btw) and then it ends up being only 1v when it hits pin1 of the octocoupler PC7102?? who stole my 4 volts??? also, tracing pin1 back to the line that you did, and following it, it does indeed go to the 5vsb pin.

i am sort of getting the picture of what is going on here... the base should get the signal from PSON and then switch on the path between collector and emitter, allowing the voltage coming in on the anode to pass through the cathode, and through Q7504 emitter to ground?


how do i look at Q7504 and know which is base, collector and emitter? and what should i call it? a NPN transistor? or is it a PNP transistor?

do i think like this? :
knowing thats a LED in the optocoupler, and the cathode needs a path to ground to work, i should assume the transistor handles (collects) that, and then seeing which pin of it goes to ground, tells me the identity of the base pin?

Last edited by triplefour; 05-15-2019 at 11:17 PM..
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Old 05-16-2019, 04:31 AM   #52
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

I don't know which meter is a LED tester, i think you don't have to measure that diode, since you have a 5vsb output only sometimes, there's a component that makes defect only at certain moments, since that diode is in the path of destruction already seen and it's with a discolored leg, you must change it.. i'm not following your "optocoupler story" since for me is not relevant for now, the damage we seen was surely on the primary, other things are following eventually..
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Old 05-16-2019, 08:40 AM   #53
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

Quote:
ok i just checked again and those voltages in the picture are correct. i get 5v on that jumper J7573 , and it only goes thru that 1k resistor R7538 (which checks out fine at 1k btw) and then it ends up being only 1v when it hits pin1 of the octocoupler PC7102?? who stole my 4 volts???
What is between pin #1 of the optocoupler 7102 and the resistor R7538? it's a piece of copper. Did you ever remove that optocouler? are you getting the pins for the opto confused and checking pin 2 instead?
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File Type: jpg PC7101-back2000345.JPG (113.1 KB, 7 views)

Last edited by R_J; 05-16-2019 at 08:51 AM..
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Old 05-16-2019, 01:09 PM   #54
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

DAVI.P thank you for your input but i have moved on from checking that area because i have steady 5vsb all the time now. after i resoldered the IC a second time, i have had no problems there.

whats the best way to read voltages on the underside of the board?
soldering test wires is a pain.
can i safely run the board upside down, on a piece of cardboard, without any screws connecting it to a chassis?
<edit> i went ahead and used a piece of cardboard, turned the board upside down and used a wire to connect a cold ground to chassis. seems to work fine.

so what i found out:
im getting 4.6v coming in from the PSON line, but it gets cut to .6v by the 1002 resistor right before it hits (the base of the transistor?)
and im getting 5V coming from the 5VSB line but it gets cut to 1.1v by the 1001 resistor right before it reaches the optocoupler.
im not mixing up the pins.

so in your picture where you show i should have 5v after the resistor, thats not what is happening.

i checked with ohm meter and found only 7ohm resistance between the opto side of the resistor and the optocoupler pin so there is no broken trace or bad connection. but it wouldnt matter anyway because im already at 1.1 volts there. also there is low ohm resistance before the resistor. i have 5v on one side of the resistor and 1.1v on the other. what is the minimum volts the LED in the optocoupler should need to activate the phototransistor on the other side?
and no i never removed the optocoupler.

really not seeing what is happening here. how can a 1k resistor that checks out fine at 1k rob me of 3.9 volts? the 1k resistor i use to take 5vsb to the PSON only drops half a volt. stumped! ....for now?

Last edited by triplefour; 05-16-2019 at 01:52 PM..
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Old 05-16-2019, 02:01 PM   #55
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

voltage drop due to current draw by the looks of it
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Old 05-16-2019, 03:02 PM   #56
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

is this some ohms law math stuff? where if the current increases over a resistor, the voltage drop increases as well? i may need some schooling here.

but if so, what could be drawing so much current? i have 5v right before the resistor, and all there is after it is the optocoupler. current would go through the LED and out through the cathode and thru the collector and out the emitter of the transistor to ground. i dont see any component after that 5v that would draw a lot of current...unless the optocoupler or transistor is damaged in some way? how would something be damaged in a way that would cause it to draw a lot more current? more practically, how can i check these components?
i think i have to take these optos out of circuit to test them properly. just check them like a normal LED? they should read a voltage drop one way, and OL the other way, right? what voltage drop should i expect?

in circuit i am getting 0.73 voltage drop on all of them except the third one (if looking at the previous picture and counting from RIGHT TO LEFT. backwards counting i know)
on the third one i read 0.53 voltage drop. but this could be due to other components in that area affecting it.
reversing the probes (red on cathode, black on anode), and ordering the optos RIGHT TO LEFT according to the picture i get:
1---OL (and yes i remembered this opto is the one that faces different from the other 3, so yes i checked the LED not the phototransistor)
2---1.5v (this is the one we've been looking at)
3---0.53 (same both ways)
4---OL

the led in opto 3 has the same voltage drop both ways surely means its the other components being measured, right?

the 1.5v voltage drop could mean a bad LED? or it could be a path through the other components in the area. should i remove the optocoupler to test it?

testing the LED seems easy enough, but how would i test the full operation of the LED and the phototransistor?
no point in taking it out if i dont even know how to test it :/

Last edited by triplefour; 05-16-2019 at 03:32 PM..
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Old 05-16-2019, 03:53 PM   #57
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

That circuit that turns on the opto should look like this.
Now I want you to trace the pins of the optocoupler back to the nearest components on your picture
Quote:
checked with ohm meter and found only 7ohm resistance between the opto side of the resistor and the optocoupler pin
There should be 0 zero ohms, nada, zip. That should be a copper trace.

Also you can work on the board outside the tv, on the bench, you need a couple 1k resistors, you connect one 1k from 5 volt standby to PSON, that turns on most of the power supply, To turn on the PNL12v (panel power) you need another ik between 5volt standby and PNL_POW
Attached Images
File Type: jpg pc7102.JPG (45.2 KB, 7 views)
File Type: jpg PC7101-back.jpg (148.6 KB, 2 views)

Last edited by R_J; 05-16-2019 at 04:18 PM..
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Old 05-16-2019, 08:04 PM   #58
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

If you still have the board in, hit those optos with a hairdryer, see if tv will turn on or anything changes.
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Old 05-16-2019, 08:38 PM   #59
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

RJ i know about using 1k resistors to trick a power supply on. i believe i mentioned i was doing that in this thread. thank you though, in case i didnt know that. its critical knowledge for sure, and among the first things i learned when coming to this forum years ago. still got a lot to learn as is obvious, so i appreciate the help.

i dont know what you mean about tracing though...havent we already traced everything in that area? and that picture you posted was an old picture i made when i wasnt noticing that i was following a path that went to ground, so that trace is totally wrong, remember?

so when working on the board itself on a bench, do i have to attach anything to the board to simulate a chassis ground?

and as for the 7 ohms, my meter shows about 4ohm when just touching the probes together, so i guess i should write that as 3 ohms which is really nothing, isnt it?

is that a schematic for this power supply? can i have a link to it please?

nomoresonys i will try that when i get back to it. what is the theory there?

Last edited by triplefour; 05-16-2019 at 09:02 PM..
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Old 05-16-2019, 08:57 PM   #60
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Default Re: SHARP LC-80LE633U has open resistor r7133 on PSU

Sometimes heating them will make them work, I don't fully understand it myself, lol.
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