G
Gobzo
Guest
Hi All:
Here are all the symptoms of the problem:
- The unit may start normal and work for days or may not start at all.
- Once on it may go off any time.
- While off the TV supplies power to the U3101 and buttons/IR sensor PCB.
I will try my best to describe what I diagnosed, but without schematics
my description will not be worth much, anyway this is what I did before
reading the FAQ:
- Traced the power button connection to the pin 5 of the U3101 and
checked that the signal reaches there.
- Checked all pins of that chip and figured that pin 6 and some others
will have two states consistent with pressing of the power button. I
came to a conclusion that the microcontroller was Okay.
- Checked that secondary AC on the power source transformer is rectified
and filtered to +147V at C107
I tried to figure if EEPROM was cooked, but it is not like in the FAQ,
which says that if there is permanent signal then it is cooked and if it
only sends a few pulses than it is Okay. In my case if TV was plugged in
after being left in the ON state, then there will be constant exchange
of information between EEPROM and uP, otherwise there will be a few
pulses sent.
Now I am at the point where I have no idea where the DC power goes, what
stabilizes it and what actually turns the power on and off. If I new
what pin of the microcontroller is used for switching the power, I would
be able to find what happens when the TV refuses to turn on.
I read the FAQ and found that I my problem is only briefly mentioned.
This unit seems to have no tuner problems whatsoever: the picture is
crisp and geometry is good on all channels, sound quality is also fine.
After inspecting the soldering with a magnifying glass I could not find
any problems at all. It looks like the soldering problem has been fixed.
The manufacture date is 1997, which seems to be more recent than all
horror stories in the FAQ.
If I decided to resolder everything, then how do I need to resolder the
tuner: do I need to take out that PCB that is sitting on the
motherboard? Or do I only resolder all that is accessible to me on that
little PCB inside the tuner screen? And do I need to take out the top
portion of the screen, or bottom or both?
So does anyone here have schematics for this model that they could share?
Any ideas and help appreciated.
Gobzo
Here are all the symptoms of the problem:
- The unit may start normal and work for days or may not start at all.
- Once on it may go off any time.
- While off the TV supplies power to the U3101 and buttons/IR sensor PCB.
I will try my best to describe what I diagnosed, but without schematics
my description will not be worth much, anyway this is what I did before
reading the FAQ:
- Traced the power button connection to the pin 5 of the U3101 and
checked that the signal reaches there.
- Checked all pins of that chip and figured that pin 6 and some others
will have two states consistent with pressing of the power button. I
came to a conclusion that the microcontroller was Okay.
- Checked that secondary AC on the power source transformer is rectified
and filtered to +147V at C107
I tried to figure if EEPROM was cooked, but it is not like in the FAQ,
which says that if there is permanent signal then it is cooked and if it
only sends a few pulses than it is Okay. In my case if TV was plugged in
after being left in the ON state, then there will be constant exchange
of information between EEPROM and uP, otherwise there will be a few
pulses sent.
Now I am at the point where I have no idea where the DC power goes, what
stabilizes it and what actually turns the power on and off. If I new
what pin of the microcontroller is used for switching the power, I would
be able to find what happens when the TV refuses to turn on.
I read the FAQ and found that I my problem is only briefly mentioned.
This unit seems to have no tuner problems whatsoever: the picture is
crisp and geometry is good on all channels, sound quality is also fine.
After inspecting the soldering with a magnifying glass I could not find
any problems at all. It looks like the soldering problem has been fixed.
The manufacture date is 1997, which seems to be more recent than all
horror stories in the FAQ.
If I decided to resolder everything, then how do I need to resolder the
tuner: do I need to take out that PCB that is sitting on the
motherboard? Or do I only resolder all that is accessible to me on that
little PCB inside the tuner screen? And do I need to take out the top
portion of the screen, or bottom or both?
So does anyone here have schematics for this model that they could share?
Any ideas and help appreciated.
Gobzo