The shorthand version:
TV was broken when I found it. No backlight, sound, or picture. BL_ON stays low regardless of power state. Disconnecting CN303 (the cable that includes BL_ON) shows 5.3V for BL_ON on the power board and BL_ON never changes state on the "A" board. BL_ON is 150 ohms to ground on the A board, which I'm assuming is not a short. All 15V, 12V, 6.5V, and 3.3V secondary voltages are present. The replacement board ordered from a business online does basically the same thing (difference explained in the questions below). Arrived in a heat-sealed plastic bag but the board was pretty dirty.
Do I need to factory reset the TV after installing a replacement board?
Is there a way to jumper somewhere to do so? I only have a universal remote (which didn't seem to do anything when I tried to reset per the manual), no picture for menu navigation, and would rather avoid the time it would take to set an arduino up to send the proper remote buttons.
What constitutes "no sound"? With the original board, there was 1) a faint "TV snow" sound coming from the speakers when power was toggled ON. I think I had to turn the volume all the way up to even hear it faintly and it only started after changing source via the top buttons. 2) Using a flashlight (it might have been barely visible even without one), There also seemed to be video of some sort, possibly the menu or a "no video" banner? It certainly was not showing the HDMI video I was sending. I've never seen this TV operational so I don't know what it was but it was definitely changing from time to time. The replacement board does neither of these things. Since the troubleshooting flowchart in the training manual doesn't have a "no backlight, video ok, no sound" state, I assume I was hearing "unamplified" sound and it falls under "sound ok".
Is there a logic flowchart or graph online somewhere that shows a typical startup sequence for test points on TVs? I would be interested in other models as well.
The whole thing:
Hello BadCaps! This is my first real TV repair so I thought I would ask the experts before returning a replacement A board I just bought. It seems to hang at the same step as the original A board, which makes me think I might have dropped the ball somewhere while diagnosing. The troubleshooting flowchart in the training manual (see attachments) points to only one culprit though (namely the A board), and looking at the test voltages I can see that the BL_ON signal at the "A" board is the hold-up. I assume it has to start HIGH on power-up and then be pulled LOW. The G board is supplying 5.3V to BL_ON but the A board is pulling it low no matter what. If there is any change in voltage when toggling states with the power button, it's too fast for my multimeter. As a last resort today I followed advice I found somewhere online and toggled the TV to ON, waited a bit, unplugged CN303, and then jumpered BL_ON (from the G board) to SYSGND on the same connector (CN303) to see if I could get the backlight to come on but no dice. I assume SYSGND is what they meant by "ground", though I doubt it matters.
I managed to find a post by someone on another repair site
with what seemed to be exactly my issue and the model was either the same one or extremely close. He was advised to replace the A board and given a link to the right one (minding the break in serial numbers) being sold online but the new one wouldn't turn the backlight on either. Our experiences diverge at this point. He got his to come on by pulling the CN303 plug while the unit is on. At that point, with the new board it was doing some sort of RGB cycle but no menu or video. His old board wasn't displaying anything after unplugging CN303 to force the backlight on. Late in the thread he mentions noticing what he thinks is evidence of water leaking onto it from the ceiling, so I'm entertaining the possibility that the issue with my set is multiple component failure from a surge or condensation. Or voodoo.
The particulars:
Sony Bravia 40S4100
48.71H01.031
1-857-092-11
Serial No. 1272986
Voltages:
LOW means well under a Volt. Less than .1 Volt I think. I didn't start recording voltage for LOWs until partway through. My apologies for the formatting (YOU SHALL NOT PARSE!!!). I have spaces and tabs and it looks orderly until I hit the preview button. Then all the characters huddle together for a picture.
Test Point With TV OFF (V) With TV ON (V) Notes
AC_OFF_DET LOW LOW UNPLUG, 2.34V FOR 30 SEC
PS_ON HIGH LOW
3VSB 3.3 3.3
3.3V LOW 3.46
6.5V LOW 7.16
12V LOW 11.68
15V LOW 15.54
BL_DIM LOW LOW
BL_ON LOW .16
BL_DET HIGH LOW
LD 0 10.51
FB 0 11.56
CN303 disconnected, tested at A board:
BL_DET 3.28 3.28
BL_ON .05 .05
BL_DIM .04 .05
GND 0 0
CN303 disconnected, tested at G board:
BL_DET 0 0
BL_ON 0 5.34
BL_DIM 0 0
GND 0 0
The sequence:
1) TV is plugged in, nothing apparent happens. I assume I should be seeing a standby light. See the attached picture "front indicators"
2) I toggle to ON using the buttons on the top of the TV. The green power indicator lights up immediately, not in ~30 seconds (as a number of sources and perhaps the manual suggest) and the relay clicks/pulls in. Nothing else seems to happen even if I leave the unit on for an hour. This model does not have blink codes.
3) I toggle the power state to OFF using the power button on the set. The green power indicator on the TV turns off immediately. No other lights come on. I hear a relay click.
4) I unplug the power. 30 seconds later I hear a relay on the G board click. I start to feel uneasy, as this is an odd number of relay clicks in a full power cycle
. If I plug in, wait a few minutes and touch nothing, and then unplug, one relay click. There was no warning sticker regarding voodoo (lawsuit waiting to happen, Sony) but I've come too far to turn back now. Maybe voodoo was making it work in the first place and some got out? Probably one of those "cheaper to just buy a new TV" repairs. Anyway...
At this point, the sequence becomes inconsistent:
5a) Usually I mutter loudly in broken sentences to myself for an hour solid about some ambiguity or blatantly false assertation in the manual before realizing I just plain read it wrong, which doesn't help the anger, but as the terminator says, anger is more useful than despair so I really lean into it.
5b) Sometimes I become despondent and weep and then retreat to the world of online gaming, which never quite seems to fill the void but at least isn't littered with pricey electronics giving me the old "come hither" look, one replacement part away from being a free upgrade for friends or family.
TL;DR
I get that a lot.
TV was broken when I found it. No backlight, sound, or picture. BL_ON stays low regardless of power state. Disconnecting CN303 (the cable that includes BL_ON) shows 5.3V for BL_ON on the power board and BL_ON never changes state on the "A" board. BL_ON is 150 ohms to ground on the A board, which I'm assuming is not a short. All 15V, 12V, 6.5V, and 3.3V secondary voltages are present. The replacement board ordered from a business online does basically the same thing (difference explained in the questions below). Arrived in a heat-sealed plastic bag but the board was pretty dirty.
Do I need to factory reset the TV after installing a replacement board?
Is there a way to jumper somewhere to do so? I only have a universal remote (which didn't seem to do anything when I tried to reset per the manual), no picture for menu navigation, and would rather avoid the time it would take to set an arduino up to send the proper remote buttons.
What constitutes "no sound"? With the original board, there was 1) a faint "TV snow" sound coming from the speakers when power was toggled ON. I think I had to turn the volume all the way up to even hear it faintly and it only started after changing source via the top buttons. 2) Using a flashlight (it might have been barely visible even without one), There also seemed to be video of some sort, possibly the menu or a "no video" banner? It certainly was not showing the HDMI video I was sending. I've never seen this TV operational so I don't know what it was but it was definitely changing from time to time. The replacement board does neither of these things. Since the troubleshooting flowchart in the training manual doesn't have a "no backlight, video ok, no sound" state, I assume I was hearing "unamplified" sound and it falls under "sound ok".
Is there a logic flowchart or graph online somewhere that shows a typical startup sequence for test points on TVs? I would be interested in other models as well.
The whole thing:
Hello BadCaps! This is my first real TV repair so I thought I would ask the experts before returning a replacement A board I just bought. It seems to hang at the same step as the original A board, which makes me think I might have dropped the ball somewhere while diagnosing. The troubleshooting flowchart in the training manual (see attachments) points to only one culprit though (namely the A board), and looking at the test voltages I can see that the BL_ON signal at the "A" board is the hold-up. I assume it has to start HIGH on power-up and then be pulled LOW. The G board is supplying 5.3V to BL_ON but the A board is pulling it low no matter what. If there is any change in voltage when toggling states with the power button, it's too fast for my multimeter. As a last resort today I followed advice I found somewhere online and toggled the TV to ON, waited a bit, unplugged CN303, and then jumpered BL_ON (from the G board) to SYSGND on the same connector (CN303) to see if I could get the backlight to come on but no dice. I assume SYSGND is what they meant by "ground", though I doubt it matters.
I managed to find a post by someone on another repair site
with what seemed to be exactly my issue and the model was either the same one or extremely close. He was advised to replace the A board and given a link to the right one (minding the break in serial numbers) being sold online but the new one wouldn't turn the backlight on either. Our experiences diverge at this point. He got his to come on by pulling the CN303 plug while the unit is on. At that point, with the new board it was doing some sort of RGB cycle but no menu or video. His old board wasn't displaying anything after unplugging CN303 to force the backlight on. Late in the thread he mentions noticing what he thinks is evidence of water leaking onto it from the ceiling, so I'm entertaining the possibility that the issue with my set is multiple component failure from a surge or condensation. Or voodoo.The particulars:
Sony Bravia 40S4100
48.71H01.031
1-857-092-11
Serial No. 1272986
Voltages:
LOW means well under a Volt. Less than .1 Volt I think. I didn't start recording voltage for LOWs until partway through. My apologies for the formatting (YOU SHALL NOT PARSE!!!). I have spaces and tabs and it looks orderly until I hit the preview button. Then all the characters huddle together for a picture.
Test Point With TV OFF (V) With TV ON (V) Notes
AC_OFF_DET LOW LOW UNPLUG, 2.34V FOR 30 SEC
PS_ON HIGH LOW
3VSB 3.3 3.3
3.3V LOW 3.46
6.5V LOW 7.16
12V LOW 11.68
15V LOW 15.54
BL_DIM LOW LOW
BL_ON LOW .16
BL_DET HIGH LOW
LD 0 10.51
FB 0 11.56
CN303 disconnected, tested at A board:
BL_DET 3.28 3.28
BL_ON .05 .05
BL_DIM .04 .05
GND 0 0
CN303 disconnected, tested at G board:
BL_DET 0 0
BL_ON 0 5.34
BL_DIM 0 0
GND 0 0
The sequence:
1) TV is plugged in, nothing apparent happens. I assume I should be seeing a standby light. See the attached picture "front indicators"
2) I toggle to ON using the buttons on the top of the TV. The green power indicator lights up immediately, not in ~30 seconds (as a number of sources and perhaps the manual suggest) and the relay clicks/pulls in. Nothing else seems to happen even if I leave the unit on for an hour. This model does not have blink codes.
3) I toggle the power state to OFF using the power button on the set. The green power indicator on the TV turns off immediately. No other lights come on. I hear a relay click.
4) I unplug the power. 30 seconds later I hear a relay on the G board click. I start to feel uneasy, as this is an odd number of relay clicks in a full power cycle
. If I plug in, wait a few minutes and touch nothing, and then unplug, one relay click. There was no warning sticker regarding voodoo (lawsuit waiting to happen, Sony) but I've come too far to turn back now. Maybe voodoo was making it work in the first place and some got out? Probably one of those "cheaper to just buy a new TV" repairs. Anyway...At this point, the sequence becomes inconsistent:
5a) Usually I mutter loudly in broken sentences to myself for an hour solid about some ambiguity or blatantly false assertation in the manual before realizing I just plain read it wrong, which doesn't help the anger, but as the terminator says, anger is more useful than despair so I really lean into it.
5b) Sometimes I become despondent and weep and then retreat to the world of online gaming, which never quite seems to fill the void but at least isn't littered with pricey electronics giving me the old "come hither" look, one replacement part away from being a free upgrade for friends or family.
TL;DR
I get that a lot.
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