Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
not sure but OFL seems low, could it be a voltage regulator on mainboard?
not sure but OFL seems low, could it be a voltage regulator on mainboard?
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
my bad, I missed that it wasn't connected to anything in post 13.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
T7701 and T7702 have been known to be a problem on these models, maybe check them closely.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
maybe try heating those looks like 6 electrolytic caps there by the connector on powerboard with a hairdryer, turn on and see if it does anything different, can you trace the ofl from connector to one of those caps, maybe one of them isn't up to par, what voltages are you getting on them with powerboard jumped?Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
I am not sure how accurately I checked. With DMM in Ohm mode, both input and output side measures 1-2 ohms only. Both T7701 & T7702 the same.
When powered-up with jumped PD cable, the reads 0V on input pin-pair, and 0V on output pin-pairs.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
I have earlier measures the capacitance of these caps, and all are on-par with the stated values. But I dont have the meter for ESR values.
On powered-up with jumped pins, all these caps measured between 5-13+V, looks quite normal to me.
What might not be normal is the T7901 - similar to T7701 & T7702, it measures mostly 0V on the input and output pin-pairs.
What is the correct way to measure transformer in put and output voltages?Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
you should be getting voltage on some of those, on hot side you use the negative of one of the big filter caps as ground, so neg. probe on that and pos. probe on what you're checking.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
if you still have no voltage when powered, maybe trace it to where it stops, which seems to be right after the big caps somewhere in that area.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
power boards are fine...
yours problem at MB, didn't send PS_ON... could be the MB tosted / dead or the SW or too the SPI flash.
the front LED when it blink its the first boot sequences of the SPI which it didn't complete... try freeze the SPIComment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
I am not getting any voltages on those 2 transformers. And you're right, after tracing the 400Vdc from the big caps to the component Q7700, and 0v output to the transformer.
I tested this transistor:
1) Red probe on middle pin:
Black probe on either pin - Open
2) Black probe on middle pin:
Red probe on left pin: 528
Red probe on right pin: 732
Does it sounds bad or OK?Attached FilesComment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
I am very convinced MB is completed toasted, since there is any shorts that causing fluctuating voltages like it was initially.
But I also curious about whether the BL is working since it has no power to he BL section of the PS.
From my precedent replying post - does it looks like BL is not working?
Question: What's a SPI ?Last edited by beetle1303; 04-20-2022, 08:31 AM.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
wondering why the backlights didn't come on when powerboard is jumped, sure seems like they should.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
test q7700 again, put black probe on neg. of big cap and red probe on each leg of that fet.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
make sure your meter is set to at least 200 if it isn't an auto range meter.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
what happened? beer break?
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
Black probe on big cap negative, red on middle pin of Q7700 - 402VDC
Black probe on big cap negative, red on either pin of Q7700 - 0VDC
Repeated a few times..
How does this Q7700 works?Last edited by beetle1303; 04-20-2022, 09:11 AM.Comment
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Re: Sharp LED TV flashing green 2x per second - LC-70LE735X, DPS-222BP, RUNTKA857WJQZ
men... you are really funny... who care on BL if they come on or not when the MB dead.
did you know which pin BL_ON ?? we tested panel 12V. and main 13V are good mean PCB 100% working
what the diffrent if man his legs brocken and you insist to teach him dancing !!!!Comment
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Hello everyone,
I'm currently diagnosing a MacBook Pro A1707 motherboard that does not power on. I've gathered some data but am stuck and need expert advice.
Note that i'm a beginner in electronics and i'm trying to learn while trying to repair this macbook that my work gave me. I'm really curious and love understanding how thing works and i already learned so much.
Only one usb c port is taking 20v and have 12.5v on PPBUS_G3H. when trying other ports, 2 are not going to 20v and one is going to 20v but the CD3215 is getting really hot.
Observations... -
Hello all
got another TV here im puzzled by. why cant they all be easy fixes that just need a little love and some tape???
anyway i go to this guys house to look at an ONN 100012588
this is my first time looking at one of these brand of TV's.
TBH i have low expectations because i see ONN as the cheap walmart brand that suddenly popped up selling the cheapest version of all kinds of tech things. and someone sent me a ONN flash drive with some data on it with some recordings they wanted me to check out and it immediately broke and corrupted the data and i was unable to... -
My wine chiller, TECNO SW-126LCD, is semi-functional - it powers up, can set temperature, and chilled to the set temperature, and cuts off compressor, etc. It however runs very hot.
Upon taken out the PSU and did some basic check - 5V output to LCD panel buttons and display is stable, but there is no 12V output to LED lights, and fans.
Further checks found the secondary side voltage is fluctuating around 8-15V range, but the 7805 regulator seems ok and producing the stable 5V output.
Checking further on the primary side: Incoming line input to bridge... -
Hi
board model: NM-D992
type c remains on 5v. when i connect it the 3.3VALW and 5VALW fluctuating. can someone please help understand why?
main power rail voltage 13v
till now i have tried:
measured all coils resistance looks ok
replaced RT6585CGQW to a brand new one
replaced all mosfets for 3.3v regulator and the dual mosfet for 5v regulator
happen both on DC power and on battery
issue remains
video
schematic attached... -
Good day everyone.
I have on the bench an amp board from DALI SUB E-12F. It is class D amp with a smps on the same board.
The issue is that it powers off way before the rated power is reached (the protection circuit kicks in). It has an independent standby power supply, which stays on after the main power supply is turned off via a relay on the primary side (thus there is no reason to believe that the protection is triggered from the smps IC on the primary side).
The normal value of the positive and negative power rails is +/- 43V.
The positive rail stays...Today, 10:33 AM
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