Mac Plus seems to power cycle, short beep — #5

Post #5 by unity

Source Forum	Mac Plus seems to power cycle, short beep — #5
Category	Troubleshooting
Post Date	Sun, 5 Jan 2014 - 01:56
Original URL	https://68kmla.org/bb/threads/mac-plus-seems-to-power-cycle-short-beep.29564/

Post

Who cares about the yoke at this point, but that diode definitely need replaced.
But before you go and fry another diode, You need to check Q3 for shorts. CR1 is the supply feed for your horizontal output transistor. Without that, you will have no raster, or no B supply for your CRT gun.

if Q3 is shorted, its possible your flyback is wasted.

I will pull Q3 and test. Not sure if I have to, but its not testing good while on the board. To be certain my testing was in order, I benched tested a good Bu406. But the one on the analog is showing different results.