Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

I'm not sure how to measure this IC chip, but before I had to send it back to the garage for the night I took the following readings of of IC7102:

In this configuration, with the three pins on the top side and the four on the bottom:

1 x 2 3
4 5 6 7

AC Voltage (set to 200 on the DMM) on each pin was as follows:
1 = 12.4
2 = 13.4
3 = 13.4
4 = 13.4
5 = 13.4
6 = 13.4
7 = 13.4

DC Voltage (with the setting on 200m) simply fluctuated quickly and rather wildly between a + 5.0 and a - 5.0. It would change about 4 or 5 times per second, up and down that plus 5 to minus 5 spectrum, back and forth and back and forth on all 7 of the pins.

Does that help in any way? Please let me know if there is a better way to measure the functionality of this chip. Thanks.

~ kca

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

I'm not sure how to measure this IC chip, but before I had to send it back to the garage for the night I took the following readings of of IC7102:

In this configuration, with the three pins on the top side and the four on the bottom:

1 x 2 3
4 5 6 7

AC Voltage (set to 200 on the DMM) on each pin was as follows:
1 = 12.4
2 = 13.4
3 = 13.4
4 = 13.4
5 = 13.4
6 = 13.4
7 = 13.4

DC Voltage (with the setting on 200m) simply fluctuated quickly and rather wildly between a + 5.0 and a - 5.0. It would change about 4 or 5 times per second, up and down that plus 5 to minus 5 spectrum, back and forth and back and forth on all 7 of the pins.

Does that help in any way? Please let me know if there is a better way to measure the functionality of this chip. Thanks.

~ kca

1) First of all, you need to read the meter user manual. Setting to 200m = 200mV scale.

2) Read the meter user manual about what the meter will show when the reading is over scale, this is important for step #3.

3) You will be testing the Voltage in the HOT DEADLY SIDE of the circuit, you need to plug your TV into the GFCI outlet at the least to protect yourself. To check the DCV of the IC7102 you will put black meter probe on the negative leg of the main filter cap, that leg is the HOT side circuit ground, the red will be use to check the Voltage for each pin, you will set the meter to 600VDC scale first, then you will go down to lower scale on what is shown on the meter.

4) Do not touch anything on the board with your hands or body unless you know what the cold side and hot side are.

5) Tell you the truth, I am not sure you should be trying to troubleshoot the complex board, especially in the HOT DEADLY side of the board.

6) Do you have proper tools to do surface mount component repair?

[budwich]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

this thread certainly seems very "scary" and "tough to believe" that there is sufficient understanding / testing capability including equipment with the OP.

I am wondering if this is just a broken neutral connection. IF I understand most of the testing, it appears that it has been done with regards to either a chassis ground (for DC stuff) and the neutral plug point but I don't think that all connectivity of the power has been verified.... maybe.

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Morning ~
I'll try to address your points, budm:

1+2) I only used the 200m scale because there were no readings on the other DC settings. I always start with the 600 VDC setting first and work my way down.

3) I am using a GFCI outlet. I understand now from your post that to test the IC I will have to use the negative leg of the main filter cap as the ground. Just to be sure, you are referring to any one of the three main 47uf 450V caps we were dealing with before, right?

4+5) I never touch anything with hand or body. Very careful about this.

6) I have done SM component repair in the past and have the tools to do so.

I'm hoping to isolate this problem before going down the new PSU road. The cost is fairly reasonable for a replacment PSU (about $100), but at this point I don't know if it's the power supply that's at fault or if the LED array itself is broken or defective or if it's some other problem. I'll slow down. I do understand the inherent dangers with these voltages and will follow directions in a more exacting manner from here on in.

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Morning ~
I'll try to address your points, budm:

1+2) I only used the 200m scale because there were no readings on the other DC settings. I always start with the 600 VDC setting first and work my way down.

3) I am using a GFCI outlet. I understand now from your post that to test the IC I will have to use the negative leg of the main filter cap as the ground. Just to be sure, you are referring to any one of the three main 47uf 450V caps we were dealing with before, right?

4+5) I never touch anything with hand or body. Very careful about this.

6) I have done SM component repair in the past and have the tools to do so.

I'm hoping to isolate this problem before going down the new PSU road. The cost is fairly reasonable for a replacment PSU (about $100), but at this point I don't know if it's the power supply that's at fault or if the LED array itself is broken or defective or if it's some other problem. I'll slow down. I do understand the inherent dangers with these voltages and will follow directions in a more exacting manner from here on in.

Thanks for clarification.

#3 Yes, any one of those 3 main filter caps since they all connected in parallel.

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Will be back at this Sharp Aquos 80" tv just a little later on today. One quick quesiton:

Should I attempt to measure the AC voltage on this IC Chip (IC7102) as well, after getting the DC voltage readings off of those 7 pins?

[RJARRRPCGP]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

RJ ~

Q: Were you speculating in your earlier post that someone might have replaced the original power supply board with this one, wherein this one is designed more for CCFL and does not provide an "engineering fit" for this tv that has the LED backlit system?

When I looked up possible power supply board replacements the other day, in the event I cannot repair it, this same PSU board # came up as one of the logical choices. But, maybe this board and this tv don't play well together??

Well, I saw what look like inverter caps, IIRC. (Those blue ones, which if they are caps, can be confused with MOVs)

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Will be back at this Sharp Aquos 80" tv just a little later on today. One quick quesiton:

Should I attempt to measure the AC voltage on this IC Chip (IC7102) as well, after getting the DC voltage readings off of those 7 pins?

No AC reading.

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Okay.

DC Voltage Readings off of the IC7102:

Well, when I used the negative leg of one of the three main filter caps, I was not able to get anyting to register on either the 600 VDC scale, nor the 200 VDC scale. Went down to the 20 VDC scale next and it did barely register a 0.01 on Pin #1 but all of the other 6 pins read 000.

Kept going, and did get some measurements but they were generally fluctuating and inconsistent.

At 2000m, I got the following:

Pin Configuration (same as before):
1 x 2 3
4 5 6 7

Pin 1 = 12 (stable)
Pin x = No pin available here
Pin 3 = 000
Pin 4 = 000
Pin 5 = 000
Pin 6 = 000
Pin 7 = 000

Then, for good measure, I went to the 200m VDC scale and got the following:

Pin 1 = Fluctuating between 7 and 8.5, and then every time I would lift the red probe and place it back down on this pin the range would jump up another point or two. For example, upon the 2nd placement of the red probe the flucutaiting range then became 9.0 to 10.8. It continued to follow this same pattern
Pin x = No pin available here
Pin 3 = 00.7 (stable)
Pin 4 = 00.0
Pin 5 = 00.0
Pin 6 = 00.0
and
Pin 7 = 00.0

Does the lack of readings at the 600 VDC and 200 VDC settings indicate that this IC is defective, or maybe it's some other component yet?

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

If the reading is true then the IC is not getting the Voltage to run.
Are you still getting 160VDC between the two legs of the main filter caps?

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Yes, the 160 VDC exists on all three of the main filter caps.

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

https://www.badcaps.net/forum/attach...1&d=1598919712
Can you get focused pictures of the whole top side of the board? I cannot read any printing on the top side of the board at all.

Never mind, I got pictures from shopjimmy instead.

Pictures provided by shopjimmy.
Sharp RUNTKA903WJN1 Power Supply.

[budm]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Check the resistance of the resistor R7133, it is between the heatsink and the main filter cap C7223.

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Okay. Found it. No resistance reading changes on 200, 2000, or 20K. Meter just read 1 the whole time.

Odd results when I put it on the 200K setting it started off at about 12 and steadily climbed upward into the 20's before I stopped. Tried it again just now and it started off at 120 and climbed upward into the 130's.

When the meter was set at 2000K I was able to get a steady and stable reading of - 276.

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Got a good close up pic just now and it looks like it might have suffered some damage:

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Here is R7133 up close:

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Looks like Brown Brown Red Red, yes?

[R_J]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

I believe R7133 should be 2.2Ω (red,red,gold,gold)

[kca]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

Yes, I see now that you are right, RJ. Should I pull that out now? Seems like there is enough damage there to make is suspect and replace it with one with the exact same value.

[R_J]

Re: Sharp Aquos 80" TV ~ Model # LC-80LE844U ~ Not operational

The resistor is acting like a fuse, if it is open, there is something shorted. likely IC7102.
This is the circuit that provides the standby voltage for the BU5V CN7501, pin 15