Requiem for this Mac SE
Requiem for this Mac SE
Ok, just to close this thread off...
The new transistor arrived yesterday. First thing I did was to measure the resistance across the various pins. Hmm...strange, quite similar to the one I removed. Maybe that one wasn’t broken after all?
Anyway, soldered it in, assembled, and plugged it in. Still nothing on the screen. Measured the voltages around the transistor on the board. Same as the measurements with the old transistor. Hmm..
Suddenly the hum of the fan changes tone. It starts to slow down. Uh oh...now we have magic smoke...coming from where though? Hard to see...maybe the power supply. Or perhaps further up the analogue board. Fan grinds to a near halt. I switch off.
Ok, so that didn’t go so well (-:
Checking the unit I discover a few things.
I’d forgotten to plug the flyback lead, back onto the side of the screen (duh!). There are just too many damn connectors on an SE..lol
The transistor had a crack in it? This was either from it burning out (maybe this is where the smoke came from), or from me over-tightening the screw which secures it to the Flyback cage.
So, time to take stock. The transistor has cracked and the power supply has failed. The former could have been because I over tightened it. Then again, perhaps it was because I didn’t plug the flyback into the screen? Maybe this is also why the power supply has failed. A cap could have blown in the latter?
It could be that the transistor wasn’t even faulty in the first place and that some undiagnosed issue still lurks (the fly transformer?) along with a few other problems now.
Anyway, I’ve decided to end my Mac misadventure with this machine. I have four other classic Macs (including an SE/30) so there is just not enough motivation to persist with this one, despite the fact I don’t like being beaten by it.
It’s good to write about successes, but more of the learning actually comes from the failures. I’ve learnt to...
- Always check all leads carefully to make sure they are plugged in. It’s easy to miss one where there are a few
- Large transistors with a screw hole at the top shouldn’t be screwed in too tightly (although this might not have been the cause of failure in this case)
- Check components when out of circuit or readings can mislead you
As to the SE, the tube is a useful spare part, as it’s swappable with the other Macs. Cases can be used for aquariums of course (but I'm not really into fish). The SE logic board would
make a good wall hanging! Now this is a distinct possibility.
Thanks for all the comments and help. They are appreciated.
Tez