Is this a safe/reliable solution for fuse holder?

Hogwild

Member
2010-10-08 4:46 am
Hi everyone:

In my efforts to build two Gainclone amps, I purchased some inrush boards from eBay. A trusted friend who is fairly knowledgeable said the schematic looked good and the parts good enough.

I populated and soldered two of the boards. On the second board, one leg of each fuse holder terminal does not go extrude far through the board like the other leg does. If I had to guess, the "good" foot extrudes about 1 mm or so. The other foot (on each holder), maybe half a mm.

I've included a picture, but it's hard to see well. What I'm talking about is in the rear left corner.
https://drive.google.com/open?id=0BwhuqW4sXCHtRGRLZ0JPQTlsS2c

You can see the 4 unsoldered terminals, with the two "inner" terminals not fully extruded.


I know I can get solder to adhere to these joints. The question is, will this be a safe, reliable solution? If the fuseholder terminals (and therefore, possibly the fuse) were to fall out, it might cause some chaos, right?

Do you all think it will be secure enough with one leg properly soldered and the other leg soldered but not fully extruding from board?



EDIT: Why can I never get the insert image function to work?


Thanks
 
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infinia

Member
2005-05-15 9:51 am
SoCal
When soldered down look for any movement when fuse is removed and reinserted, hard to say how stable it is by looking at the bottom only.
id worry more about the basic design and primary safety spacings than mechanics.
if its a chip amp id go with a IEC entry fuse / switch all in one combo, knowing smaller transformers <400VA limit inrush all by themselves. or solving non existent problems may create others.
 
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The biggest problem you will have with that is heating the shorter pins well enough to wick a fillet through the plated holes to the top side. If you get such a fillet, you've done everything needed. If possible you might try heat and solder from the top side, but there might be trouble with that in that you don't want to solder up the spring/clamp area of the holder, at all.
 

infinia

Member
2005-05-15 9:51 am
SoCal
how to solder short pin/s is a different answer to using a cheaper PCB fuse holder.
if you cant reach the pin with your soldering iron > use a lot of heat applied quickly to the top side and feed solder from the bottom. In my mind "safe and reliable" are unanswered.
 
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Hogwild

Member
2010-10-08 4:46 am
That's some great info everybody. Thanks!

Might there be similar versions of the same fuse terminals I could buy but that have longer legs and/or narrower legs to fit better into those holes?

Acc. to the eBay seller, the holes on the red version of the PCBs were drilled too small. He and other sellers are selling green PCBs which apparently do not have this flaw.

BTW, there already will be a fuseholder built into the AC inlet for the amp. I was told this inrush circuit would be good as "extra insurance". At some point, I think my friend figured out inrush, and it was pretty large. This was with a 300VA toroid.

I will have same friend help me test these before I implement them, of course.
 
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Hogwild

Member
2010-10-08 4:46 am
No one? No one has any idea if there might be an alternative fuseholder terminals I could just drop in that might fit better?

Any idea for some kind of hack/mod that might be safer (that still sits on the PCBs)? I'm really reluctant to add another external fuseholder other than the inlet one.
 

Hogwild

Member
2010-10-08 4:46 am
Okay, as a followup, the eBay seller told me that the red boards do not have the proper distance between the holes and proper diameter holes. He sent me 4 new green-coloured boards and 2 new packages of components.

I can confirm that with the new version (green) boards, the fuse holder legs fit perfectly.

Thanks to eBay seller jims_audio for doing the right thing (though it would've been nicer had he not sold defective product in the first place).
 

Hogwild

Member
2010-10-08 4:46 am
Bare:

I don't know, I think this circuit is more sophisticated in its functioning, not just its parts count. I'm a newbie, so can't really say without help.

For anyone who is following this thread, I ended up pushing the pins from the fuse terminals just a little further through the PCB, and then soldering them. I figured I had nothing to lose by trying.

I tried yanking with some good force to get the thing to come out. There's no way it's coming out without desoldering. It's in very firmly.

I'm fairly happy with my outcome.