To amplify II2II's comments a little: Start at the beginning.
The most humble compact Mac is an incredibly complex device in comparison with the Z80 or 6502 based machines on which many of the *ld f*rts here crafted their skills. Most of us learn to diagnose Mac hardware faults by swapping major assemblies, such as RAM SIMMs, graphics cards, analogue boards etc. And most of us mark the component as "bad" and leave it in the cupboard for eight years, enough time for us to forget the original symptoms. There is nothing wrong about swapping out major assemblies, but it becomes painful when replacements become rare. At that point in time, you do need a few electronics skills.
Check the multitude of past threads here about leaky capacitors or dodgy compact Mac analogue boards. Typically the repair is a simple component swap, but it is where we all start.
Unacknowledged previously in this thread is that most "broken vintage Macs" have a software problem or a trivial hardware problem (dead hard disk).
The most humble compact Mac is an incredibly complex device in comparison with the Z80 or 6502 based machines on which many of the *ld f*rts here crafted their skills. Most of us learn to diagnose Mac hardware faults by swapping major assemblies, such as RAM SIMMs, graphics cards, analogue boards etc. And most of us mark the component as "bad" and leave it in the cupboard for eight years, enough time for us to forget the original symptoms. There is nothing wrong about swapping out major assemblies, but it becomes painful when replacements become rare. At that point in time, you do need a few electronics skills.
Check the multitude of past threads here about leaky capacitors or dodgy compact Mac analogue boards. Typically the repair is a simple component swap, but it is where we all start.
Unacknowledged previously in this thread is that most "broken vintage Macs" have a software problem or a trivial hardware problem (dead hard disk).