Protect LED

[KS]

My Hitachi 50FX30B had been dead for quite a while, but this weekend I took some time to go over it and it now it works, FOR NOW.

(see previous thread: http://forum.eserviceinfo.com/viewtopic.php?t=3923)

In summary: before I started the set would go immediately into protect (no green LEDs). based on info. from this forum I checked the 4 fuses (2 cartridge and 2 pico - F902, F903, F905 and F906 I believe) all were fine. The two small blue caps next to the protection cct appear to be fine (physically).

Hence I figured there was no short on the power section and decided to try to isolate the power board from the other (audio?) board so I pulled the 5 or 6 flat connectors that connect the two boards and got no lights at all. After reconnecting these incrementally from the front of the set to the back I found with P505 (audio, I believe) disconnected all 5 green LEDs are lit, but so is the (red) Protect LED (D975) and the set does not power on, it does click when the power button is pressed, but there is no video or audio at all. When the power button is pressed D951 (Audio) & D952 (+11V) are the only LEDs lit, but then they gradually fade.

Finally with all of the connectors reconnected, all of the Green LEDs (5 in total) light fully, but the Protect LED is also lit (perhaps a little dimmer than it had been) and now the set plays and has done for about 10 hours since without a problem (hope I’m not jinxing it), but I suspect the underlying issue is still there and would like to head this problem off, since the following formula applies.

XMAS + Kids + Family - TV = DOGHOUSE

I’d like to know if the Protect LED should be on at all when the set is operating normally and if it is reasonable to think that the Protect IC itself may have been falsely triggering the fault condition and shutting the set down and is now falsely lighting the Protect LED.

I'm in Tampa, FL and since I was getting estimates of $450-$900 to fix this, if it is just replacing the IC (STRM-6511) or something similarly straightforward which is how it seems, I'd really rather take care of it myself, with a little help, though the board does seem a little tricky to remove, I guess with patience it's feasible.

Thanks for your feedback.

[Guest]

Set is now dead again as I suspected it would be (almost made it to XMAS ), anyone have any clues about the Protection LED: If it should be on and do the symptoms below indicate the possible issue.

I'd like to try to resolder cold joints but it looks a little tricky to get the board out to do this, any tips are welcome.