fistman said:
Hey all -
So I’ve got two units. One I just finished and the other just needs the mains hooked up to the transformer. Couldn’t wait to try out the completed build... and... the fuse blows. Immediately. No light no power to the test points.
I took the heat sink off in stage 3 to check that the lock washers hadn’t come off the pad. All was good there. Took the bottom of the case off and tried a new fuse to be sure I wasn’t grounding out somewhere there. No dice.
Anyone have any recommendations where to look next? I blew 3 fuses in a row so I’m doubtful of a bad fuse. I’m assuming some sort of grounding issue, but if anyone has any advice I’d greatly appreciate the help.
Feeling pretty bummed as I’ve built a few other diy kits previously with no issues and I’m generally very meticulous when putting these things together.
Thanks,
JF
Hey man ~ I'm sure you've been over it several times but I think you've just gotta keep checking for solder problems. I was sure I didn't have any on mine until I unhooked it from the case and looked really, really close. I caught 2 solder joint problems. In the end I'm not sure exactly what fixed my phantom power, but after I removed a solder bridge and redid some questionable joints, I reflowed solder on most of the joints on the board just to see if that would make a difference. Something I did fixed it.
So I would encourage you to do that too.
If you built two units, compare the two and see if you've got any misplaced parts anywhere. It's pretty easy to do this visually since the resistors are color coded.
There's always the chance you misplaced something on both units though. If it's a misplaced resistor, it's going to be pretty time consuming to find it. You are basically gonna have to go through the whole build again and measure resistors from step 1.
Look for shorts. Try a different power cable. Check your power transformer wiring, did you wire for the correct voltage? Look at the teeth on your input transformer pins. Anything bridged? Electrolytics placed the correct polarity? Transistors facing the right direction?
Could be a bunch of different things.
Check that your LED is orientated the correct way if it's not lighting up. If you're viewing the unit from the front, the positive leg goes to the right. It's the opposite of the Electrolytics polarity, if memory serves. That's not marked anywhere, I found it in this thread buried deep somewhere when I was trying to figure out which way it went, too.
Good luck. When you finally get it working, you will love the way it sounds.
Best,
Matt