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Macintosh Plus burnt analog board.
Posted by: dragonpunchu on 2022-11-28 01:36:44 I've recapped (240v analog board) a Macintosh Plus a year ago and everything was fine. Recently when I tried to boot it it blew its fuse. On further inspection I can see burned off pcb in C33. I've attached photos of the carnage. Can I recover this? or is this analog board now dead?
Posted by: bibilit on 2022-11-28 02:14:05 Can you have a look at the bridge rectifier set (CR22 to CR25) for any shorted diode ? can see anything else that can blow the fuse and burn that capacitor on the neighborhood.
Posted by: dragonpunchu on 2022-11-28 02:20:16 Can you have a look at the bridge rectifier set (CR22 to CR25) for any shorted diode ? can see anything else that can blow the fuse and burn that capacitor on the neighborhood. CR24 is shorted, the other ones are fine. Good call! What diode do I need to replace this one? Kind hard to read them.
Posted by: bibilit on 2022-11-28 02:34:26 AFAIK probably a standard unit 1N4001 or 1N4007, but the best way is to remove the bad one a have a look at the reference.
Posted by: dragonpunchu on 2022-11-28 05:30:37 AFAIK probably a standard unit 1N4001 or 1N4007, but the best way is to remove the bad one a have a look at the reference. I've removed it and it is a 1N4007, ordered some and will be replacing and checking if that fixes it. Thanks
Posted by: techknight on 2022-12-01 07:03:04 I've recapped (240v analog board) a Macintosh Plus a year ago and everything was fine. Recently when I tried to boot it it blew its fuse. On further inspection I can see burned off pcb in C33. I've attached photos of the carnage. Can I recover this? or is this analog board now dead? View attachment 49441 View attachment 49440 You should grab a dremel tool and clean out that carbon tracking below the capacitor. This will always remain conductive to some degree and start causing you problems.
Posted by: dragonpunchu on 2022-12-02 04:31:13 You should grab a dremel tool and clean out that carbon tracking below the capacitor. This will always remain conductive to some degree and start causing you problems. Well spotted!
Posted by: dragonpunchu on 2022-12-02 04:45:10 I've replaced the CR24 and the mac cameback to life with no problems! Thanks for the tips
Posted by: marcelv on 2022-12-02 10:57:29 You could possibly also replace CR22,CR23 and CR25 as they are the same age and wear.
Posted by: dragonpunchu on 2022-12-02 10:59:41 You could possibly also replace CR22,CR23 and CR25 as they are the same age and wear. It's on my todo list! 👍
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