My friend has this EVGA GTX770 GPU that, after 7 long years of use, is now starting to act up with artifacting and causing random black screens requiring a hard power down.
I decide to check the caps, since I've revived other GPUs by replacing bad ones. Physically they all look fine. These are all very low ESR caps, like aluminmum polymer <=10 mhom and tantalum polymer in the range of 20-30 mohm. They all test fine ESR wise.
They're grouped as follows:
4x 270u 16V Al-polymer
3x 100u 16V? tant-polymer
9x 330u 2.5V tant-polymer
4x 470u...
itachi
Member
Last Activity: 05-22-2023, 11:43 PM
Joined: 03-10-2018
Location: SK
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Re: Toshiba 46RV535U 46" LCD Issue
So I went around the power board checking the "Protect" signals to see if something was triggering a shutdown, but it just seems to be coming from the mainboard itself. All voltages on the power supply boards test good.
I replaced the T-Con but it didn't change anything at all....is it possible this is a bad panel? For the most part I'm unsure how LCDs fail without physical damage and if the photo I attached could indicate such a failure. -
Toshiba 46RV535U 46" LCD Issue
Hello all, I have this Toshiba LCD giving me some troubles. Initially, upon pressing the power button it would refuse to turn on and instead blinked its little yellow light at me 3 times in succession. The service manual refers to this as "Seine Booting" where Seine seems to be the name of the main custom processor on the mainboard. Apparently this blink code means it is unable to boot for some reason.
I found a used replacement mainboard which was pulled from a working TV with a dead panel, or so they say, and with the new board the TV powers up, the backlight comes on,...Last edited by itachi; 05-25-2021, 09:01 PM. -
Re: Panasonic TC-50AS630 No Image - Blinking LED
It's high on both sides. 10k on the input and 20k downstream.
The issue seems to stem from the 1.1V rail. I was measuring the resistance on that rail and by heating up the main BGA I was able to make the resistance drop from ~50ohms to less than 5....Leave a comment:
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Re: Panasonic TC-50AS630 No Image - Blinking LED
Thanks for that! I only had the technical manual which was a bit limited. So as it turns out that PA2002 fuse is in fact blown. It's unlabeled on the board but it's marked with an 'X' on the back of the board near the top middle.
I'm assuming it blew for a reason and should just replace the entire A board at this point.
Edit: I can't seem to find the mainboard in stock online new or used. But I can find the Pansonic branded BGA which is powered by the SUB 1.1V and 1.5V rails. I'll see if I...Last edited by itachi; 01-07-2021, 06:26 AM.Leave a comment:
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Panasonic TC-50AS630 No Image - Blinking LED
Hello good people, I have another unit here which is giving me problems. Upon plugging the unit it, after a few seconds the front LED will start blinking 3 times in a row and repeating indefinitely. No image or sound.
The first thing I checked was the backlight. It's a single vertical strip on one side of the panel which has 8 groups of 7 LEDs. (Part #V500D2-LS1-TREM3) I used a backlight tester and each group lit up without issue.
The standby 5.3V is good, the 16V and 24V from the PSU board both come up for a few seconds while the TV_SUB_ON signal is high. Both 16V and...Last edited by itachi; 01-05-2021, 12:20 AM. -
Re: Samsung LN55C630 LCD - Not powering up properly
As it turns out one end the LVDS cable going to the TCON board was not making good contact. I reseated both ends and it works perfectly now.Leave a comment:
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Re: Samsung LN55C630 LCD - Not powering up properly
I swapped the mainboard out and the TV now starts up with its little startup sound, and it stays powered on but the picture is as shown below. The displayed image is jumping around erratically and it's not looking so good.
I also just realized the mainboard I just ordered is model BN41-01436C but the one from the TV is BN41-01436B and the new one is dated about a year and a half newer.
...Last edited by itachi; 12-20-2020, 03:52 AM.Leave a comment:
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Re: Samsung LN55C630 LCD - Not powering up properly
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Re: Samsung LN55C630 LCD - Not powering up properly
Thanks for the feedback! I thought maybe there was hope for the mainboard since it's still sending out an HSYNC signal and seems to be responding in some way to user input but it is a fairly complex board with many failure points....Leave a comment:
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Samsung LN55C630 LCD - Not powering up properly
Hello everyone, I have this Samsung LN55C630 TV which upon being plugged in attempts to power up but fails. The backlight turns on for about 3 seconds during which the screen is usually black but once in a while it shows some glitched imagery with widely spaced vertical lines, and then turns off for about 8 seconds before repeating. The red LED on the front of the panel is blinking, but it also responds to inputs from the front touch buttons like say pressing Vol+ will make the LED blink rapidly.
I found that disconnecting the mainboard connector (C201) to power board connector... -
Re: RCA RLDED3955 39" LCD - Backlight Flashing
Thanks for the input, you must be right because its acting pretty weird no matter what I do. The screen appears evenly lit for the most part but there's probably an LED out in there somewhere.Leave a comment:
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RCA RLDED3955 39" LCD - Backlight Flashing
I have a TV here that when powered up, the backlight blinks between dim and normal brightness over and over.
I started troubleshooting and found that the main processor on the board was sending a signal to turn the LED driver OB3350 on over and over, like it was trying to start it up but failing. On the schematic that's coming from ASIC_PINx.
I bypassed this signal and forced the LED driver IC high which still resulted in the backlight flashing brighter. I spent some time probing things and found that there was a constant 3.2V being applied to the PWM pin of the LED driver,... -
Re: Samsung UN55FH6030F - Confirming dead panel?
Unplugging the left side only results in the left side going white and the right side working. Unplugging the right side only results in everything going black. The left seems to pull all the rails down to unusable levels. 3.3V goes to 0.75V, 1.8 and 17.5 go closer to 0V.
It makes sense that would happen with the low impedances I'm reading on the left edge PCB, but as I mentioned removing the suspect caps resulted in no change. There are more caps on the board, but resistance measurements indicate...Leave a comment:
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Re: Samsung UN55FH6030F - Confirming dead panel?
That makes sense. Also unplugging that half of the panel makes it go from all black to all white. I went back and checked all the caps from one end to the other and recorded their values but once again it all pointed to the same three. CA44 (4.28 ohms), CA48 (10.36) and CH42 (11.68).
Removing them did not change the measured values and to be sure I just went and pulled the rest of them from this area. There are two more "groups" of capacitors and resistors off screen to the left, mostly identical in layout...Last edited by itachi; 08-03-2019, 07:49 PM.Leave a comment:
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Re: Samsung UN55FH6030F - Confirming dead panel?
Thanks for the reply. I measured the caps to where I found the lowest resistance and removed several to be sure but no luck. The lowest resistance reading is directly under one of those chip on flex connectors so I assume its something in there.Leave a comment:
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Samsung UN55FH6030F - Confirming dead panel?
Backlight works on this TV but no video or OSD showing. I started poking around the TCON board and found one of the large ASICs was cold to the touch so I started checking voltages. Found a regulator getting 0.75V in and nothing out, and eventually traced the voltage rail back to one of the two ribbon cables going to the LCD panel.
Unplugging this cable brings the picture back to the other half of the panel, so am I correct in thinking the panel is toast? The ribbon cables go to those small PCBs that run along the width of the panel and have some surface mount components on them.... -
Re: LG 50" 50PK550 - Sound, no image
That was indeed the fault. Replaced the mainboard and its good to go. Thank you good people.Leave a comment:
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Re: LG 50" 50PK550 - Sound, no image
Hey it works, test patterns look good. Thank you both. So mainboard it is then. It has serial port on it...I want to connect to it and see if its spitting out any info. Also might see if I can possibly troubleshoot it. Would you know of anything to look for on these boards or is it better to just replace it?Leave a comment:
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Re: LG 50" 50PK550 - Sound, no image
Oh wait it's not labeled but based on other variants of this board I'm assuming its the vias coming off R51 and R52 in the lower right, top side.Leave a comment:
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