Hello, I am a new member.
Sorry to dig this thread, but I have exactly the same problem with my Mac Classic.
My analog board is 630-0525.
I received it with leaky capacitors, which I have replaced.
Also, voltage regulator LM339 had cold solders, so I fixed that.
After powering on, with the yoke connected, K get a bright horizontal line on the screen, and general power drop.
Resistor RL1 (220ohm) goes up in smoke.
I temporarily fitted a 270ohm replacement, which goes red hot when powered on.
When yoke is disconnected, I get normal voltages and computer boots normally (I can hear the chime, hdd spins).
I replaced the vertical deflection IC TEA2037A, with no chanhe to the behavior.
It gets the power, I can measure around 15V on the IC.
I have no other yoke to test, but it looks ok (horizontal coil 0.3ohm, vertical 8ohm).
Took it out and checked, no signs of burning.
Flyback seems to be ok, I reckon there would be no high voltage if it would be shorted.
I am really puzzled about this one.
Analog board is very clean, there are no obvious shorts, or any sign of damage.
Did anyone solve this problem before?