Had a perfectly working f5m playing music then just stooped .blowing ac fuses, Found it was
left channell issue,.
Removed mosfets and jfets , found mosfets faulty , jfets tested as fine.
So replaced mosfets re installed the jefets new r6 and r7.
connected power and was slowly ajusting bias, going well then all of a sudden
smoke started coming from R5 which is the 22w 2watt resister included in the kit,
should i just replace R5 or do i have a problem with the jfets ,
thanks
Glenn Kaspar
left channell issue,.
Removed mosfets and jfets , found mosfets faulty , jfets tested as fine.
So replaced mosfets re installed the jefets new r6 and r7.
connected power and was slowly ajusting bias, going well then all of a sudden
smoke started coming from R5 which is the 22w 2watt resister included in the kit,
should i just replace R5 or do i have a problem with the jfets ,
thanks
Glenn Kaspar
Zen Mod's thought above would be my guess. Post a pics of the amplifier from different angles and also show the boards close up.
Also, the below should guarantee that the mosfet will not conduct to the heatsink through the insulator. If you are making an order from Mouser, then maybe they are worth a shot.
https://www.mouser.com/ProductDetail/Aavid/4180G?qs=2v7q0MSBcBMwt5GBytMENg==
Install them with thermal grease. The cheap white stuff will do. If enough current was flowing through the JFETs to smoke the 22R resistor, then the JFETs and the trimmer pot would likely visually be fried. So I suspect it is an issue with the mosfet again.
Also, the below should guarantee that the mosfet will not conduct to the heatsink through the insulator. If you are making an order from Mouser, then maybe they are worth a shot.
https://www.mouser.com/ProductDetail/Aavid/4180G?qs=2v7q0MSBcBMwt5GBytMENg==
Install them with thermal grease. The cheap white stuff will do. If enough current was flowing through the JFETs to smoke the 22R resistor, then the JFETs and the trimmer pot would likely visually be fried. So I suspect it is an issue with the mosfet again.
Problem solved i think, still had meter attached to outputs and found that the speaker out where a
dead short, removed mosfets and found both no good,
dead short, removed mosfets and found both no good,