I found a "Mac SE" at a local electronics recycling shop which seems to have been a project of someones. There was a home made expansion card in the PDS slot and appears to have been powered by the analog board for power. However, the analog board was not an SE board, it's a Mac 128k/512k/Plus analog board.
I also obtained a gutted Mac Plus case with floppy drive, as well as two gutted Mac 128k cases with only their 400k floppy drive's remaining.
I pulled the CRT assembly as well as the analog board from the SE case and transplanted it into the Mac Plus case, and was able to get a good Mac Plus logic board.
After swapping everything over and installing the logic board, I have yet to get it to power on successfully. I have no power the CRT, completely black. I have got the unit to "bong" a couple times without re-caping the analog board, but it would restart and loop, eventually leading me back to square one without any bong, and no "whup whup whup" sound, just the sound of the high voltage circuit high pitch squealing.
I have re-caped the analog board, as well as replaced the common diodes and resistors, however I still have no power, no luck with any adjustments to the voltage POT either. I have, at times, been able to get some very short (like half a second) activity from the floppy drive, sounding like a groan, if I tinker with the brightness POT and the voltage POT.
I have checked voltages and for 5V I am only getting 3.06, and on the 12V I am sitting around 7.46. Occasionally, if I adjust the brightness and voltage POTs just right, it will raise up to 11.9V then drop back down to 7.46 for a few seconds, then climb up to 11.9V and loop again. You can hear this raise in voltage in the frequency of the high pitch squeal.
I do have SOME power to the CRT guns, as there is a dim amber light from the back of the tube, and when the 12V line starts to go up to 11.9V you can see it getting slightly brighter and then dim again, at the same time the voltage raises and drops.
I have gone through the ENTIRE analog board, removed original solder from every component and applied new solder, and still nothing.
Q3 transistor heat sink shows signs of overheating and the metal is dark around the transistor, which leads me to believe the flyback transformer is bad, which caused Q3 to fail.
Any other tips or advice before I go about replacing the flyback transformer, should I be able to locate one?
I also obtained a gutted Mac Plus case with floppy drive, as well as two gutted Mac 128k cases with only their 400k floppy drive's remaining.
I pulled the CRT assembly as well as the analog board from the SE case and transplanted it into the Mac Plus case, and was able to get a good Mac Plus logic board.
After swapping everything over and installing the logic board, I have yet to get it to power on successfully. I have no power the CRT, completely black. I have got the unit to "bong" a couple times without re-caping the analog board, but it would restart and loop, eventually leading me back to square one without any bong, and no "whup whup whup" sound, just the sound of the high voltage circuit high pitch squealing.
I have re-caped the analog board, as well as replaced the common diodes and resistors, however I still have no power, no luck with any adjustments to the voltage POT either. I have, at times, been able to get some very short (like half a second) activity from the floppy drive, sounding like a groan, if I tinker with the brightness POT and the voltage POT.
I have checked voltages and for 5V I am only getting 3.06, and on the 12V I am sitting around 7.46. Occasionally, if I adjust the brightness and voltage POTs just right, it will raise up to 11.9V then drop back down to 7.46 for a few seconds, then climb up to 11.9V and loop again. You can hear this raise in voltage in the frequency of the high pitch squeal.
I do have SOME power to the CRT guns, as there is a dim amber light from the back of the tube, and when the 12V line starts to go up to 11.9V you can see it getting slightly brighter and then dim again, at the same time the voltage raises and drops.
I have gone through the ENTIRE analog board, removed original solder from every component and applied new solder, and still nothing.
Q3 transistor heat sink shows signs of overheating and the metal is dark around the transistor, which leads me to believe the flyback transformer is bad, which caused Q3 to fail.
Any other tips or advice before I go about replacing the flyback transformer, should I be able to locate one?
