I give up.
Almost Everything I try to fix has a faulty switchmode powersupply
And for the life of me, I cannot seem to grasp properly how to sort them out. With SeanB's help, I have managed to get a CRT tv working again (5Vsb was not stable due to an open resistor).
Now I managed to get my hands on an HDMI LCD Television to try get working for myself.
When you press the soft power button, the SMPS ticks three times, then starts giving output voltage, but as soon as it tries to turn on the Inverters, the CCFL tubes all flash on and off the whole time (about 3 times a second) You can hear the Inverters ticking during that time. There is also a Tick-Tick-Tick from the SMPS. When this is happening, the sound is fine, and you can see the menu when the backlights flash.
I have replaced the main filter cap on the SMPS, as well as all the output caps.
I then disconnected the inverters from the control board, and put some resistance on the 18v and ground lines from the SMPS to the controller, and the PSU does tick-tick-tick.
I disconnected all the CCFL tubes. Ticking from SMPS is very soft, but it is still there.
If i test with my Voltmeter on the 18v and Ground lines from the PSU, it is about 16v and fluctuates the whole time. If I try the 5v Rail, it is solid as a rock.
I have been through repairfaq small switchmode supply repair, but still am drawing a blank. If somebody knows about another resource for SMPS repair Ideas, Please let me know
Attached is the schematic of the powersupply.
Thanks for any assistance.
P