After reflow of the neck board everything started up just fine. It was very promising.
To confirm I did a little bit of gentle non-conductive tapping on the C-Board. No flicker.
After a minute or two of letting things burn in I started to notice "video 1" drifting upward toward the top of the screen, then, Black screen.
No picture, no nothing except for the status light: four quick flashes and then one long one. At least it wasn't 5 flashes anymore!
According to the service manual this could mean: +13V is not supplied. (A board) or IC 541 is faulty (A board)
Effectively I think I'm in a permanent standby state.
for the remaining post I'm referencing this schematic -
https://imgur.com/q0Poaqp
I want to point out exactly what happens now. The tv effectively never shuts "off". I power down and the relays click like it power cycles but it never goes off. As long as its plugged in the 4-blink state persists.
If I unplug/plug back in there's a relay click and then 5-7 seconds later a second relay click.
All further voltage/continuity tests are relative to chassis ground (tuner-can).
The first thing I did was test TP 502. This is the +13v test point going to IC541 pin 2. Sure enough I'm getting basically 0v.
I continued with other test points. TP 504 (180V). At first relay click it goes to about 8v. At second relay click it goes down to 0v.
+9v (TP601) - ~ .7v
+5v (TP602) - ~.2v
+B (TP600) - should be 135v. I get ~3v peak.
Most of these show a rise at first relay click and a drop at second relay click.
It may rise to expected voltage but my meter isn't fast enough to capture that.
The only thing that is consistently powered is standby +5v which stays at a steady 4.92v.
At this point I'm unsure where to proceed. I'm definitely not getting power but I can't figure out if its a faulty part or somethings tripping the protection circuit to bring voltages low.
This is literally the first time I've seen this happen. It seems awful coincidental that it happened after the neck board reflow. I can't fully rule it out but I'm at a loss as to how it would cause such a catastrophic power failure.
I don't want to make assumptions here. (its the flyback, its the power supply board, etc). I've checked and re-checked for cracked joints around the a-board power areas. I've rechecked my solder job on the c-board. I'm honestly not sure where to go from here.