Re: APPLE A1425 820-3642-A Schematic
Replace the U9200 IC, maybe it's causing a short to ground.
Just measure/find the pins that connect to ground, and find out which shouldn't connect
to ground, that's the simplest way to find out if it's toasted.
Removing that R6920 just prevents the current to reach U9200 so it don't get hot anymore.
Resistor can be blown too, it often measures too high resistance.
It still measures around 47 ohm?
Porto
Senior Member
Last Activity: 01-26-2017, 07:53 AM
Joined: 05-11-2015
Location: Ede
-
Last edited by Porto; 05-21-2016, 09:16 AM. -
Re: Commodore 1084s p1 monitor went black
Nice monitor, own one too, together with an Amiga 2000.
Leave a comment:
-
Re: Benq FP241W DVI-D input not working correctly
I had a similar case once with an Apple Cinema display.
In my case pin 6 (DDC Clock) on the DVI socket was shorted to ground because of a blown 'NL27WZ17-D' Schmitt-trigger IC; the 5v detection voltage didn't make it to the monitor.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Hi Budm,
A little follow-up.
Because I couldn't resist it, I desoldered the main inverter transformer (TI801S) and measured the two secundary windings and they both gave an OL, so 'open' winding. So I guess the transformer is definately toasted... pity.Leave a comment:
-
Re: Samsung LE40M86BD Transformer
Well, I managed to fry the connector to the inverter balancer board and after that every time the HV was passing through, that connector was instantly set on fire. I don't know if this was due to high current going to it or due to the black of the carbon all over the plug conducting but I'm not comfortable now to test that transformer with a spare CFL lamp.
I also get 11 ohm from both HV outputs to ground.
[URL="https://www.badcaps.net/forum/showthread.php?t=52130"]https://www.badcaps.net/forum/showthread.php?t=52130[/URL]...Last edited by Porto; 02-16-2016, 10:15 AM.Leave a comment:
-
Re: Samsung LE40M86BD Transformer
Not wanting to hijack this thread but I'm also looking for this same transformer, because I shorted mine.
Nothing to find on this specific p/n, only complete boards.
Anyone know of a replacement of this HV inverter transformer?
Thanks.
@ReeceyBurger123:
Will you be so kind to check the resistance between the two HV output pins on that board you have?
Mine measures 22 ohm so I guess it's blown but I'm curious of how much it should be measuring.Last edited by Porto; 02-16-2016, 09:18 AM.Leave a comment:
-
Re: Samsung Plasma problem PN60F5350AFXZA
I have a Samsung 50" plasma from 2007 (HD-Ready) which is going strong as if it was still new. It has burned through lot of hours already but I -never- had an issue with it so maybe I'm blessed.
I also have a modern Samsung Full HD Smart LED TV and I can say, without any doubt, the plasma wins it for better colors and deeper blacks; IMO, it's a beast! Plasma for the win and it's still my primary TV.
I'm quite disappointed they ditch Plasma and going to LCD/LED instead... maybe only OLED can convince me ditching...Last edited by Porto; 02-13-2016, 07:42 PM.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
It's not worth it. This was already an old TV which already had that pesky on/off switching, maybe also due to already bad/arcing CCFL's. Would be nice if the BL worked but now it's even more worse than it already was and brand new, and also better, TV's are sold for peanuts these days. Stupid mistake of me but maybe it's not a good idea to mess with these kind of things in the middle of the night.
But thanks for all the help, I'm much wiser and confident now.
...
Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Nope, none of them is open, they all measure in the range of 270~285Ohm.
But I think I screwed up and toasted the inverter transformer.
I had unplugged that HV connector to take a look at the back of that inverter board but forgot to replug it; it managed to 'hide' between the housing and the inverter board and I didn't saw that. I turned on the TV and as soon the HV was getting through, the transformer began to hiss loud and that plug was half fried and black; I guess it was arcing because it...Last edited by Porto; 02-12-2016, 09:16 PM.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Nope, no flash at all. It is like the voltage doesn't reach the balancer board and/or CCFL's or the lamps themselves are dead. Do you know how many lamps there are in this model? I see 20 output sockets, is one socket also one lamp?...Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
The HV is working, I got this CFL hooked up and it was going lit very bright on both of those HV outputs. I couldn't even hold it for more than 2 seconds because the glass was becoming very hot very quickly; I even burned my arm in the process due to leaning (stupidly) to the housing with it when the lamp activated.
DOH!
But that means the HV is present and there must be something wrong with either the inverter balancer board or the CCFL's themselves. I guess this balancer board can be...Last edited by Porto; 02-12-2016, 03:18 PM.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Can I use this lamp, it's a working one but that doesn't matter I guess?!
OFFtopic: I even found the schematic of it:
...Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
The BL in the screen isn't flashing at all and ATM I don't have a CFL to test the inverter outputs. What kind of lightbulbs can I use also?...Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Yes, BL-ON signal is there but maybe something else is causing this on that logic board.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Can the logic board cause the BL not to turn on and/or switching the TV on and off automatically?
I ask this because that shielding on it is becoming quite hot when the TV has been turned on for a while.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Ah, ok, I keep learning!
...
Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
I did a continuity test to ground on that FAN7382 IC and this came out of it:
TV off / standby:
only pins 4 (COM) and 6 (Vs: high voltage floating supply return) connect directly to ground (my DMM 'beeps').
TV on:
pins 1 and 4~8 all connect to ground (my DMM 'beeps'), with resistances varying from 0.0 to 5ohm. Pins 2 and 3 have a resistance of 380ohm and I hear some hissing coming from the inverter transformer when touched with the probe.
Does this mean...Last edited by Porto; 02-11-2016, 10:47 AM.Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
I have a few working CCFL's lying around which came out of a another screen. I tried one on one of the CCFL outputs but the lamp rapidly burned out; it did light up for a second though so I guess there is a high voltage present but I don't know if it's still outputting enough to lit the original lamps. Also, those onboard connections have both pins connected to eachother while my testlamp has a pink and a black wire... I guess that could be the cause of burning out the lamp. I only saw they were tied together when I flipped...Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Yes, I have a 5v output on the EN pin 9.
It also could be the inverter transformer TI801S, but I don't know exactly how to measure a transformer without a ringtester....Leave a comment:
-
Re: Samsung LE40m87BD ... no backlight
Well, I don't know exactly what happened to this screen in the meantime.
The screen was first brought to a repairshop (some guy in garage) but they said the 'board was damaged' and a new one costing about $250 so that was a clear no-go for such an old screen; they wouldn't say which board was broken, just to make things difficult for hobbyists like me (and they losing money over it ofcourse).
I said the screen suddenly turned off but the owner (my uncle) said the BL did work till the last moment and after...Leave a comment:
No activity results to display
Leave a comment: