I am trying to test an amplifier board that keep blowing fuses. I thought I got the bad components out which was a bad mosfet. Resistance across the DC side was 0 ohms, now with the mosfet removed, it is up in the mohms. I figured I would power up the board to make sure nothing was going to blow, I was wrong.
The circuit uses a 2A slow blow glass fuse. I figured it was a shot to try a 1A fast act fuse just to power the front stage. Blew instantly. So I did not have a 2A slow blow so I tested with a 5A ATC automotive fuse (going for broke here). Still blew that! Took a couple seconds though and that is what concerns me that inrush is not the cause, but rather a possible STILL existing short somehow. I just do not get it. I test for resistance at the bridge rectifier and have very high resistance yet blowing a 5A fuse at 120V.
My question is would the 5A fuse give this problem if it is not rated for 120V? I realize that would not be a proper permanent solution but just for a minute unloaded, I figured it would work. I am still wondering if the inrush is an issue but I would sure think a 5A fast act would be similar to a 2A slow blow in terms of peak current/time.
The circuit uses a 2A slow blow glass fuse. I figured it was a shot to try a 1A fast act fuse just to power the front stage. Blew instantly. So I did not have a 2A slow blow so I tested with a 5A ATC automotive fuse (going for broke here). Still blew that! Took a couple seconds though and that is what concerns me that inrush is not the cause, but rather a possible STILL existing short somehow. I just do not get it. I test for resistance at the bridge rectifier and have very high resistance yet blowing a 5A fuse at 120V.
My question is would the 5A fuse give this problem if it is not rated for 120V? I realize that would not be a proper permanent solution but just for a minute unloaded, I figured it would work. I am still wondering if the inrush is an issue but I would sure think a 5A fast act would be similar to a 2A slow blow in terms of peak current/time.