Re: samsung LN-T3253H no picture red standby light
Thanks for the reply. Here's some pics of my poor removal of glue. But I think I managed to get it away from all leads. I'm concerned that zener ZDTM851 (left of conn CM803 in the pic, had glue over all legs. I will try to test it.
I had a 5W 0.22R in my drawer so I used that instead. Should be Ok to replace the 1kW RM801....
inline79
Member
Last Activity: 07-24-2019, 03:11 PM
Joined: 05-28-2012
Location: BC
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Re: samsung LN-T3253H no picture red standby light
Sorry to bring up dead threads but I thought it useful as this is a top search thread for this TV model so we keep things in one place.
I had this TV given to me with the blinking red standby light.
The glue looked bad and there was some corrosion on the legs of RM801 RM810 so I went ahead and replaced them and scraped the glue away - no change.
Then I went ahead and replaced the 7 cold side caps as they are over 10yrs old. Still no luck.
The board is making a zzzt-zzzt-zzzt,...Leave a comment:
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SyncMaster 2043BW fixes
I've fixed two Samsung SyncMaster 2043BWs now for the same issue so I'm posting this here as a solution others can search for.
In both cases the symptom is no LEDs, no turn on at all. Power is connected but there is no blue power LED even when the stupid touch-button is "touched".
Culprit in these two cases are the SamWha GF 2 x 1000uF 16V. I can't believe these blow even on a 5.1V bus. They must really suck! So I replaced all Sam-Wha? caps but the two 2043 I had some different values on the tiny caps - it's like they just drop in what they happen to have... -
Re: HPvs19
I agree best place to start is the ribbon/cable going to the lcd panel. i think i had a vs17 with the same problem.Leave a comment:
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Re: Samsung 710N constant flicker
Update:
Still poking away at this once in a while. I got another 710N but it had the same issue though the flicker is at a slower rate. Swapped the power boards and the problem sticks with the power boards not the signal. I suspect the BIT3102A output but will have to borrow a scope to figure this out.Leave a comment:
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Re: Samsung 710N constant flicker
tom66: ripple checked with True RMS DVM on AC across the big cap. I'm not concerned about the supply voltage anymore.
- Tuning caps removed and checked out at exactly .15uF per spec. Reinstalled.
- Blue HV caps show no shorts, not sure how else to check them?
- Also tried to use the inverter board from a 940, but the unit wouldn't turn on.
Next thing I'm going to do is try to pull pin4 of U2 low to get max duty cycle out of the PWM controller (I think). If that makes the screen go solid...Leave a comment:
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Re: Samsung 710N constant flicker
Big cap checked out. ripple was about 4VAC or 2.5% of 160VDC.
Replaced that 330uF cap with 470uF, but the 330uF was still good.
Officially stumped.
Any ideas on what VR1 does?
I dug up someone's schematic and am trying to figure out the BIT3102A circuit which is the CCFL PWM Controller. It seems like this sort of flickering could come from here, especially if it shuts off when i reduce the brightness.
I appreciate everyone's time on this. I'm sticking with this to learn about these circuits, otherwise...Leave a comment:
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Re: Samsung 710N constant flicker
Hmm... can't seem to edit my old post to replace the pictures.
Anyways, I think it was much too late at night in my original post. Here is some updated information:
- 13V bus does flicker a bit. On my DVM it is 13.10-13.25, but I'm sure it is more than this on a scope.
- when the backlight is off this bus is up to 15.7-15.8VDC which seems odd.
- 5V bus is stable.
- checked the output diodes but there are no shorts
To do:
1. There is 2 x 470uF and 1x330uF on the 13V bus. I failed...Leave a comment:
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Re: Samsung 710N constant flicker
I forgot to turn macro on. I'll reshoot the photos.
I didn't see any voltages flicker on the DVM (it has a little bar that sometimes works for low frequency flickers).
15VDC, 5VDC, 3.3VDC all looked steady except the 15VDC dips to about 14V when the backlight is on.
I think I'm going to look for the inverter driver spec sheet.Leave a comment:
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Samsung 710N constant flicker
Need expert advice once again.
Been staring at this 710N whose backlight flickers about 10 times per second. Pretty annoying. It seems like setting brightness to 100 sets the duty cycle to 90% or so and at about brightness 20 the monitor just shuts off. It's like the inverter is getting a low PWM signal somewhere, can't figure out where.
- Tested with different backlight panel -> same issue
- installed new(ish) caps on the 15V and 5V bus
- 15V and 5V bus look good. 15V dips to 13V-14V when the CCFLs come on
- transformers check out - ~950ohm... -
Re: New Members - please post your introductions here
Hi, I'm an Electrical Engineer in Vancouver Canada. I have made the bold transition from systems design to Sales but recently two things happened that resulted in my participation her.
First, I've always repaired my own electronics since high school, but recently my townhouse complex has had "spring cleanings" where i have been rescuing electronics from the dump. But that left 9-10 months out of the year where i had no projects but still wanted to help keep good electronics out of the landfill.
...Leave a comment:
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Re: Lg 1953t smps pwm
This is what I wanted to hear - that it is not an invincible NEV-R-Fail IC. Thanks!...Leave a comment:
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Lg 1953t smps pwm
There's no switching happening on the main transformer on this LG 1953T. no 12V out, no 5V out.
I put a scope on U101 which is a FAN7601 PWM controller:
pin 1 -Start up- getting 160VDC off the bus (bus reads fine at 167VDC)
pin 2 - Current Sense/Feedback - is 0.13V so it is not being shut down here (>1V will shut it down)
pin 3 - Latch/SS - comes up to 1.5V as expected during start-up then goes to 0V (over 75ms)
pin 4 - RT/CT - is clocking
pin 5 - ground
pin 6 - Out - nothing...... -
Re: My SamQ/LGSung Project
So I tried a second panel, this time also a Hanstar one like the original. The image (1280x1024) shows up but is doubled. Sometimes I can get it to work if I reconnect, sometimes not.
So I suspect the new panel works with this unit, but perhaps something got messed up on the 5V bus when the 1000uF 10V Samxon GF caps blew up. Time for a new scaler board!Leave a comment:
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Re: My SamQ/LGSung Project
I should have been more specific - it is like a v.sync flicker, not a CCFL flicker. Anyways, my solution has been to track down another broken Dell/BENQ and swap things around to see if it is in the LCD panel circuit or the signal processing circuits.Leave a comment:
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My SamQ/LGSung Project
Hey hobbyists, great forum!
Sorry for the crappy pictures, but it's better than nothing.
I got a Samsung 940N which had blown caps, but then once I got the backlight on i saw that the LCD panel was cracked as in image 1. So I thought "Hey, I have the 19" panel out of the BENQ/LG Philips i can try to shoehorn in there". So I managed to do that and get it all put together to create my SamQ/LGSung monster!
But there's a problem - there is a very annoying flicker in the image. It happens with DVI or VGA images, but not with the internal monitor images (ie.... -
Re: Benq T903 and FP937s lower inverter xfmr
I know, the 450k measurement is a head scratcher. I can't find any info about this transformer and I've never seen one xfmr run two lamps before so all I can say is it WORKS and I'm not going to ask any more questions until something else blows up!Leave a comment:
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Re: Benq T903 and FP937s lower inverter xfmr [FIXED]
I also want to add that I think this is an inherent design flaw in this inverter. The transformers seem to be way undersized as they are driving two 19" monitor CCFLs with no heat sinking. Then again, if the transformers were OK sized, the C5707s would probably have blown!Leave a comment:
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Re: Benq T903 and FP937s lower inverter xfmr
SUCCESS!
I pulled the suspect transformer and checked the resistances. It was very high resistance across the secondary (ground is on the primary side??), and there was leakage into the primary windings... this was probably the "POP". The attached image shows the transformer, a 19.26043.001 with 7 pins on one side and 4 pins on the other side, though 3 of those 4 pins are not connected to anything!
Then off the parts monitor I pulled the "good" transformer and it was ~450k on the secondary....Leave a comment:
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Re: Benq T903 and FP937s lower inverter xfmr
Thanks for the tips so far.
Sorry, I should clarify that the FP937s PS/Inverter board is PN 48.L0G02.A00 and the T903 is 48.L0G02.A02. They're identical and have the same symptoms and I did all the same tests on both boards.
I'm going to pull the suspect transformers and test them next, maybe do some xfmr swapping around using the .A00 as the donor.
The main difference between the 2004 FP937S and the 2005 T903 is that the T903 has a totally different graphics board which has one big micro (probably...Leave a comment:
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