I'll start this thread with a very short prologue... (feel free to jump to the second paragraph)
I'm totally new to electronics and only have a vague understanding of the various components inside a circuit (I know what each does on it's own, but get quickly confused by circuits such as this one - can't follow the "logic of the current" yet), but I would really like to learn. So I thought that the best way to learn is to just dive in, make some black magic smoke
, ask stupid questions and experiment. I'll just call it 'applied electronics' so I can feel better.
So, I searched the ads for a defective amp and this little Kenwood looked like a good place to start (not that complex, good looking, fairly good reviews when working).
The previous owner said it had one totally dead channel and the other with low volume and heavy distortions. I didn't plug it in and started looking for bad parts. So far I found one burnt resistor and one burnt fuse. I checked all transistors in-circuit and removed those that read 'funny'. Out of them 4 proved to be dead (various shorts plus one open base-collector junction).
I marked all identified components in red on the schematic.
Next step is to make a parts list on mouser (including a full recap for the electrolytics) but I have a real hard time picking equivalents for the transistors and I'm also not sure whether I should only replace the faulty transistors, replace them in pairs (as per schematic - both in a darlington pair even if only one is bad), replace them in pairs across the two channels (ie. also replace the inverted darlington pair in the left channel even if both read ok). I tried to find replacements filtering by specifications but I would feel a lot safer to get suggestions from people who actually know what they're talking about
All suggestions will help a lot
Thank you!
I'm totally new to electronics and only have a vague understanding of the various components inside a circuit (I know what each does on it's own, but get quickly confused by circuits such as this one - can't follow the "logic of the current" yet), but I would really like to learn. So I thought that the best way to learn is to just dive in, make some black magic smoke
, ask stupid questions and experiment. I'll just call it 'applied electronics' so I can feel better.So, I searched the ads for a defective amp and this little Kenwood looked like a good place to start (not that complex, good looking, fairly good reviews when working).
The previous owner said it had one totally dead channel and the other with low volume and heavy distortions. I didn't plug it in and started looking for bad parts. So far I found one burnt resistor and one burnt fuse. I checked all transistors in-circuit and removed those that read 'funny'. Out of them 4 proved to be dead (various shorts plus one open base-collector junction).
I marked all identified components in red on the schematic.
Next step is to make a parts list on mouser (including a full recap for the electrolytics) but I have a real hard time picking equivalents for the transistors and I'm also not sure whether I should only replace the faulty transistors, replace them in pairs (as per schematic - both in a darlington pair even if only one is bad), replace them in pairs across the two channels (ie. also replace the inverted darlington pair in the left channel even if both read ok). I tried to find replacements filtering by specifications but I would feel a lot safer to get suggestions from people who actually know what they're talking about
All suggestions will help a lot
Thank you!
