I have been repairing TV SETS A long time, but occasionally I GET ONE IN THAT beats me, this is that one, this set came to me from a chap that said he was watching it, went to kitchen, came back and it had no picture again, my immediate thoughts are Ysus panel, however this is doing such strange things I am confussed, i am better on lcd sets but when i get a plasma it always causes me a headache, this is also now doing so.
Samsung Plasma.
Problems I have so far, I have checked all the ICs on the buffer boards and can't find any shorts, i presume my method of setting my meter to beep test, putting one probe to a buffer ground and running along the output nodes is pretty standard test, no beeps, no sign heat ups on ICs, so next I check all mosfets, diodes and capacitors on Ysus main, stiull nothing that stands out, next I check the output from the main PSU VS and VA, the issue is now that on switch on the VS volts rise to 206 V but then just drop and drop until it settles around 10 volts, the VA which is usually around 60 volts seems to do the same dance, but is in millivolts by the end of the sequence, my next thought is a bad capacitor or short on the output, but again after 2 hours testing i find nothing, i then disconnect the output from the psu to the xmain which is then connected to the ysus main so ive now got nothing connected but a main board, as before there is sound, but not much else, the psu va and vs dont do anything now, no start up, I am guessing because there is nothing connected to the psu output ?? OK, so now im connecting it all back up and it does the same again, the VS VA ramps up to voltage for a second or two then drops like a stone again, voltage to the Ysus input is also sitting at 10 volts so i know its getting through, just far too low to fire up the panel, I have read as much as I can but as this is a 2012 TV there isnt any fault info I can find online.
Adding more information now, I need to find out if the fault is on the psu itself as this is where the volts are just not coming out of, or if its just a PWM chip detecting a fault and clamping down the switching rate to the transformer, thus lowering volts on output, ok, so I have 3 vs 2 va, couple grounds, a 15 volt and a 4.8 volt pin, the 15 volts stable as is the 4.8 volt outputs, the other pins are vs_on VA_on I think, and another one which is possibly VSN_on not sure im not with the tv now so from memory. I need to tell this psu to switch on with no panels conected so i can eliminate if the psu is fully functioning or at fault, does anyone have any ideas, or ask me anything and I will reply as I am getting desperate now having spent nearly 8hrs on this set and got nowhere, thank you, Tim Bilbo.
Samsung Plasma.
Problems I have so far, I have checked all the ICs on the buffer boards and can't find any shorts, i presume my method of setting my meter to beep test, putting one probe to a buffer ground and running along the output nodes is pretty standard test, no beeps, no sign heat ups on ICs, so next I check all mosfets, diodes and capacitors on Ysus main, stiull nothing that stands out, next I check the output from the main PSU VS and VA, the issue is now that on switch on the VS volts rise to 206 V but then just drop and drop until it settles around 10 volts, the VA which is usually around 60 volts seems to do the same dance, but is in millivolts by the end of the sequence, my next thought is a bad capacitor or short on the output, but again after 2 hours testing i find nothing, i then disconnect the output from the psu to the xmain which is then connected to the ysus main so ive now got nothing connected but a main board, as before there is sound, but not much else, the psu va and vs dont do anything now, no start up, I am guessing because there is nothing connected to the psu output ?? OK, so now im connecting it all back up and it does the same again, the VS VA ramps up to voltage for a second or two then drops like a stone again, voltage to the Ysus input is also sitting at 10 volts so i know its getting through, just far too low to fire up the panel, I have read as much as I can but as this is a 2012 TV there isnt any fault info I can find online.
Adding more information now, I need to find out if the fault is on the psu itself as this is where the volts are just not coming out of, or if its just a PWM chip detecting a fault and clamping down the switching rate to the transformer, thus lowering volts on output, ok, so I have 3 vs 2 va, couple grounds, a 15 volt and a 4.8 volt pin, the 15 volts stable as is the 4.8 volt outputs, the other pins are vs_on VA_on I think, and another one which is possibly VSN_on not sure im not with the tv now so from memory. I need to tell this psu to switch on with no panels conected so i can eliminate if the psu is fully functioning or at fault, does anyone have any ideas, or ask me anything and I will reply as I am getting desperate now having spent nearly 8hrs on this set and got nowhere, thank you, Tim Bilbo.
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