Thread
Macintosh Classic II Analog Board repair Help!
Hello everybody
I have a problem with my Macintosh Classic II.
the computer would not start more '.
I made the first tests with hot air to the analog board and give satisfactory results booting.
The image was moved and the hard disk intermittently started and stopped.
At this point, I replaced all capacitors (thanks to Uni for capacitors references )(many were gone)
1 - 1000μf - 10v - radial
1 - 1000μf - 16v - radial
1 - 1000μf - 35v - radial
2 - 2200μf - 10v - radial
1 - 2200μf - 35v - radial
2 - 470μf 25v
Now the computer starts, but still has the problem that the hard disk spin intermittently.
I tested the gates of the floppy: pin 6 measuring 4.8 v
pin 7 measuring 12.3
although it is not recommended I tried to modify the voltage from the analog board, but did not give any improvement.
The problem is in the 2 diodes in pictures displayed in red?
Unfortunately i can not read 'code and model cause are discolored , someone can tell me the specs model and possibly replacement part?.
They may be the cause of my failure?
Or the problem is to be found from something else?
Thanks for your help
I have a problem with my Macintosh Classic II.
the computer would not start more '.
I made the first tests with hot air to the analog board and give satisfactory results booting.
The image was moved and the hard disk intermittently started and stopped.
At this point, I replaced all capacitors (thanks to Uni for capacitors references )(many were gone)
1 - 1000μf - 10v - radial
1 - 1000μf - 16v - radial
1 - 1000μf - 35v - radial
2 - 2200μf - 10v - radial
1 - 2200μf - 35v - radial
2 - 470μf 25v
Now the computer starts, but still has the problem that the hard disk spin intermittently.
I tested the gates of the floppy: pin 6 measuring 4.8 v
pin 7 measuring 12.3
although it is not recommended I tried to modify the voltage from the analog board, but did not give any improvement.
The problem is in the 2 diodes in pictures displayed in red?
Unfortunately i can not read 'code and model cause are discolored , someone can tell me the specs model and possibly replacement part?.
They may be the cause of my failure?
Or the problem is to be found from something else?
Thanks for your help
Have you considered that the hard drive spinning intermittently could be a hard drive problem? I seem to have nothing but back luck with quantum drives...
Hi there
HD is perfect i have tried also with another hard drive , external SCSI HD and tested it on another Macintosh , when i wrote hard drive spin intermittently mean that it seems that low voltage is powering hard drive, and computer intermittently boots and hard drive spin, then stop than spin again
HD is perfect i have tried also with another hard drive , external SCSI HD and tested it on another Macintosh , when i wrote hard drive spin intermittently mean that it seems that low voltage is powering hard drive, and computer intermittently boots and hard drive spin, then stop than spin again
Hi there
HD is perfect i have tried also with another hard drive , external SCSI HD and tested it on another Macintosh , when i wrote hard drive spin intermittently mean that it seems that low voltage is powering hard drive, and computer intermittently boots and hard drive spin, then stop than spin again
Replace QP1
Another Possibility is the potentiometer itself, it is a 220 ohm 6mm potentiometer... It's a pattern failure... but try reflowing it first...
original is CNY75GB 245 A TK4 0884 , i found on eBay CNY75B 023 A TFK4 0883 can replace original?
https://68kmla.org/forums/index.php?/topic/21414-classic-analog-board-voltage-problem/
here is a similar thread, and he had some good success!
here is a similar thread, and he had some good success!
Send it to Uni, he'll get it straightened out (that's my stock answer for complex issues like this that aren't getting sorted out). I wouldn't let anyone else touch my Macs. But I guess I'm kinda spoiled, I can just drive them over to him.
Problem Solved : thank you Guys , replaced QP1 with CNY75B 023 A TFK4 0883 now Classic II is back to life !
thank techkinght, Techknight also was the one that solved this one too!
https://68kmla.org/forums/index.php?/topic/21414-classic-analog-board-voltage-problem/
https://68kmla.org/forums/index.php?/topic/21414-classic-analog-board-voltage-problem/
techknight
- 68LC040
Posted 04 January 2014 - 07:55 PM
check the optoisolator in the feedback circuit, it may need replaced.
Main PC: Intel core I7 920, MSI x58 platinum, Radeon4850
PB: tibook G4, ibook G4, ibook g3x2, Lombard, 160, 165, 180, 180c Duo 2300x2, Duo 270c x2, 520cPPC, 3400c, 1400c
Desktop: G3AIO, SE, SE/30, 512k, plus, LCIII, iMac G4, iMac intel, 6400/225
Glad it all worked out.