My trusty Apple // monitor has given up (A2M2010P European/PAL model). The root issue seems to be a dead short between the #1 and #7 pins of the flyback transformer. That's a short between a primary and secondary winding. Not good.
What a bummer. It's still got a bright green phosphor CRT, decent, unscuffed case - and not too much yellowing. And having my original green CRT with the machine is somehow part of the whole experience of running the machine.
Finding a replacement for a flyback seems to be generally very tricky. Was this an Apple-specific part or are there any known matching replacements?
And do the US/NTSC monitors use the same flyback as the European/PAL types or where there differences?
Ok, thanks, same part used for the US version, that at least increases the options for finding a parts donor.
I haven't removed the flyback yet, but I'm still convinced (unfortunately). I can measure the dead short directly between the pins (1+7), but not behind the diodes (D403 or D502 respectively) - and that's the only connections those pins actually have. And none of the other flyback pins are shorted to anything. So, there really is no other way for this short, except to exist within the flyback directly between those two pins.
Since you haven't removed the flyback are you sure the short is only between pins 1 and 7? How about pins 4 and 7? Or 2 and 7?
There are some caps that might be shorted that would give you a very low resistance between these pins.
Ok, I went ahead and removed the flyback. I have little to loose, suspecting that it's broken anyway.
Still shows a dead short between 1 and 7. The resistance between each pair of 1, 2, 3 and 4 is below 1 ohm - though there also seems to be some inductivity (and a low resistance could be normal between those). But a short from a primary- to a secondary-side pin certainly can't be normal. Also, I measure infinite resistance between pins 6 and 7 - which also isn't correct: pins 5-8 should all be tapping into the windings of the same secondary coil.
So, this flyback seems pretty much roasted to me - unfortunately...
apple_ii_monitor_flyback3.jpg
Just want to point out that my good flyback shows 0.2 here.
Screen Shot 2022-06-16 at 1.33.42 AM.png
If you have a LCR meter that may be a better test. A dead short should have a low inductance, while an intact primary should have a significant inductance, probably in the microhenry to tens of microhenry range.