Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I remove it to check it out, and it's ok, no short or open on any of both diods...
rabitbay
Member
Last Activity: 02-02-2021, 05:23 PM
Joined: 08-24-2019
Location: Mexicali
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
After trying to make a small simulation of the OpAmp IC7202, the simulator gave me the same values on pin 3 and 2, but on reality I have very difrent values,
PD: I didn't find the TO220...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I'm thinking to make a video, so I can show you better, because I'm starting to think that I'm misunderstanding some points or maybe or maybe I am misjudging some testings.
So some points I'm gonna cover is:
Voltage tests on LED pins
Voltage peak on LED pins when tv is turned on
Returned voltage on each strip
PMW effect of multimeter probe when testing pin 5/6 on LED driver...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I agree with you, I appreciate your answer, do you know some technique to check if it has the right values?, for Rs just by reading the number, but in the other components...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
It reads 45v AC from HOT to COLD just to verify, is that normal?...Last edited by rabitbay; 09-25-2019, 09:20 AM.Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Yes I understand that
Just in case...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Well, this is not going good, I did changed the MOSFETs and still is in black.
Still have 0v on DIMOUT not even a peak when I plug to AC, now I'm really lost.
Ok but now something weird happened, when I connect my positive probe to
PWM1 or PWM2 the LED's turned ON, well that's a progress I guess, but I thought that the driver DIMOUT was controlled by ADIMM, and Why is this happening, I've attached some pictures, you can see the backlight through the holes
Can I hook up everything to test it o...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Yeah!! After trying to test it on ON state, both of the MOSFET was not Closing, so Both MOSFET are OPEN ??
I will replace them an tell you what happend...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Between DIMOUT and GND got 12.5k
The resistor to the gate R7231 labeled as 2.49k seem ok, with 2.47k
I couldn't find the R7299 I'm assuming you are talking of the jumper resistance R7229, have 0 as labeled
Some days ago I removed the MOSFET to test it out, and couldn't find any faults, but just to double check I removed it again, I've attached the readings. Also no continuity between gate and S on any direction...Last edited by rabitbay; 09-24-2019, 12:42 PM.Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Not even a flick
Correct, BTW when I did the test for the first time this morning (for double check) I got around 300v reading, then over 200v
Just to avoid any bad reading, I just changed my multimeter batteries for new ones this morning and double checked, I did had the same readings....Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
After seeing the chip Led driver specs and comparing with my voltages reading, I realised I haven't voltage on the DIMOUT pin, and the UVLO (Under voltage lock out detection pin) It's receiving 4.26v so LED booster is called but it seems to not respond because has no voltage on DIMOUT pin.
As long as I reed and understood the datasheet, this driver has the condition of LED Open Protection Function if ISENSE < 0.1v (that's true I have 0v, look at attached images on old post) for about 4 cycles,will cause an abnormal state,...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
The max value I could catch (In digital multimeter it's harder) was 268v, I did the test once the board was uncharged (seen ~.5v on LED+), otherwise I couldn't catch a peak.
That's interesting, what could be limiting the voltage to rise up?...Last edited by rabitbay; 09-23-2019, 06:54 PM.Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
1) 418V on each of the three
2) I've attached a diagram as the voltages are different, but I have ~34.27v of return, and it's not more than 200v.
3) That's bad, sorry my ignorance, I suppose that, as the 7030 was on the serial number of the stripe (2012SSP70_64_7030_REVO_12012) what a shame, but it's 6v LED, if you need more LED spec info let me know to ask to the seller...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I tested every PIN after circuit test was plug in, I've attach voltages, including of the LED driver and the OPAMP, there I was doubting (I'm not electrician expert) but I have different voltages proporcions from one of the internal OPAMP1 and the OPAMP2 so what do you think, the chip seems ok?
The LED I used to replace was 7030
And just to clarify, as you said, I make the mistake once plugin in every harness and forcing on CHDown and Vol+, but now I'm just with the led stripes plugged and the test...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
Hi, thanks for the advice, so I made a test circuit, and yes, like budm said, I'm testing now with the unhooked main plug, and just LED plug connected
this is the circuit I made, just bypass every pin to a pot, just to be able to play with it, by default I set every pot to ~600 then tested with LED stipes conected but nothing...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I did just cut and bridge 5v BUS to STB and Dimmer, and nothing happend while CHDown and Vol+ combination was used. Start to suspect on the OPAMP (LM258A) or the LED Driver (BD9488F)...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
That's correct, I did bridge from 5V Bus to STB pin and led strip connected and nothing happend, i't 3v mandatory?...Leave a comment:
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Re: Sharp LC-70SQ15 PWB DPS-206EP problem
I've attached the readings, in this model the Cathodes are connected to a common point, to a MOSFET that I checked worked properly, but something curios happens when I was checking this MOSFET... I accidentally touch the drain pin with the sink (grounded) and then the backlight was turned on!!
What's going on here?...Leave a comment:
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Sharp LC-70SQ15 PWB DPS-206EP problem
Hi everyone
I have this problem with the PWB, it all begins with shade areas on the screen done by bad led strip, it worked for about 4 months until the tv goes off for it self, when try to power on again it just stay on for about 3 second and go off again, then throws a 1-1 blinking code, at that moment I thought "the strips just burn off" so I fully disassembled the tv and find out most of the led strips was burn. So I replaced de bad leds (almost 90) then I tested by groups of 4 by for leds for (I just have a 24v power supply) and every LED was tested and was OK.... -
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