Hello everyone,
I'm trying to repair this TV which has stopped turning on and everytime you try to do so, I get two red blinks. I'm fairly experienced in electronics as well as troubleshooting, TV isn't what I normally repair (although I do have some past experience) so I could use a bit of your help.
I looked up the error code online and I got a few mixed results. Some tell me that this means some type of power supply issue unless the relay/power on signal never shows up, in which case it could be the main board. Others tell me that it's a b+ over current protection code which would be on the power supply. Others tell me its an overcurrent external to the PS.
This TV uses an MA2 chassis, I noticed it must be an edition only available for latin america as I can't find results for it in english, however it seems to be the same as 32L4000 for the most part. If you would like me to post the service manual let me know but it can be easily found by googling MA2 Sony service manual.
Back to the diagnosing. I disconnected all peripherals that feed off the power supply and main board, leaving only the main board, PS, and control buttons attached together. I still got the same result. I disconnected the PS and isolated it, then I fed the power on pin 3.3V from the standby PS output. The PS clicks on and produces all voltages as follows
Power_ON 3.3V (only when fed manually)
AC_DET_OFF 3.3V
13V UNREG 15.7V
12V REG 11.9V
24V UNREG 24.1V
The only thing that struck me as odd is the 13V unreg voltage which is a bit elevated but considering it's unregulated, it seems normal without load. At the same time the 24V rail is also unregulated and stays close to its written value.
When you try powering the set on, the Power_ON signal doesn't appear at all. I also read that if there is a power supply AC input issue AC_DET_OFF will go low, which doesn't occur.
The power supply seems to work fine when i power it on while isolated and also works pretty good when I put a dummy load on it's 24, 13, and 12V power rails. The 13V unreg does go down a bit with a dummy load, settles at around 14V.
One of my search results, as mentioned earlier, told me that if the relay never clicks on, the issue is on the main board. Out of curiosity i disconnected the 12V reg and 13v unreg lines to see if the issue might be on the main board and related to these two lines. Tried again but nothing, still two blinks even when only 3.3 standby and AC_DET_OFF signals are being fed into the board.
So it seems like the main board is the issue. I would preferably like to repair this main board if possible. I searched around and checked for obvious shorts but found nothing. Checked all the fuses scattered around this board but also found nothing wrong.
Can you guys confirm that the issue is probably the main board? Could you also offer any insight as to the possibility of repairing this main board?
I'm trying to repair this TV which has stopped turning on and everytime you try to do so, I get two red blinks. I'm fairly experienced in electronics as well as troubleshooting, TV isn't what I normally repair (although I do have some past experience) so I could use a bit of your help.
I looked up the error code online and I got a few mixed results. Some tell me that this means some type of power supply issue unless the relay/power on signal never shows up, in which case it could be the main board. Others tell me that it's a b+ over current protection code which would be on the power supply. Others tell me its an overcurrent external to the PS.
This TV uses an MA2 chassis, I noticed it must be an edition only available for latin america as I can't find results for it in english, however it seems to be the same as 32L4000 for the most part. If you would like me to post the service manual let me know but it can be easily found by googling MA2 Sony service manual.
Back to the diagnosing. I disconnected all peripherals that feed off the power supply and main board, leaving only the main board, PS, and control buttons attached together. I still got the same result. I disconnected the PS and isolated it, then I fed the power on pin 3.3V from the standby PS output. The PS clicks on and produces all voltages as follows
Power_ON 3.3V (only when fed manually)
AC_DET_OFF 3.3V
13V UNREG 15.7V
12V REG 11.9V
24V UNREG 24.1V
The only thing that struck me as odd is the 13V unreg voltage which is a bit elevated but considering it's unregulated, it seems normal without load. At the same time the 24V rail is also unregulated and stays close to its written value.
When you try powering the set on, the Power_ON signal doesn't appear at all. I also read that if there is a power supply AC input issue AC_DET_OFF will go low, which doesn't occur.
The power supply seems to work fine when i power it on while isolated and also works pretty good when I put a dummy load on it's 24, 13, and 12V power rails. The 13V unreg does go down a bit with a dummy load, settles at around 14V.
One of my search results, as mentioned earlier, told me that if the relay never clicks on, the issue is on the main board. Out of curiosity i disconnected the 12V reg and 13v unreg lines to see if the issue might be on the main board and related to these two lines. Tried again but nothing, still two blinks even when only 3.3 standby and AC_DET_OFF signals are being fed into the board.
So it seems like the main board is the issue. I would preferably like to repair this main board if possible. I searched around and checked for obvious shorts but found nothing. Checked all the fuses scattered around this board but also found nothing wrong.
Can you guys confirm that the issue is probably the main board? Could you also offer any insight as to the possibility of repairing this main board?
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