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Blown fuse and its soldering to a PCB

I need competent advice:

I purchased a new amplifier (Dared MP-60, made in China). It is cheap and rather good sounding, but its left side got dead (left-side tubes stopped glowing) when I replaced the stock 5881 tubes with RFT EL-34 (everything was OK for 30 min. but next morning, when I was switching it on, the problem appeared), though it was permitted by the user manual and was authorized by the seller.

When I opened the cover, I saw four 125V 8A fuses covered with opaque plastic cases. The fuses have leads soldered to the PCB. We measured them and indeed one was blown.

What is strange that the seller says "you can use unsoldered fuse, but there is no place to place a unsoldered fuse on the PCB". I asked for explanations ("Does it mean that the whole PCB must be changed or that the unsoldered fuse should be replaced by another fuse which should be soldered to the PCB?, and she said "Yes, there is no place to place the unsoldered fuse on the PCB, it means the whole PCB must be changed".

Is this PCB a single-use dummy (if it is possible in principle)? How can it be that the blown fuse must be unsoldered but the new fuse cannot be soldered to the same place in the PCB?
transl
transl OP
156 posts
 
Stonedeaf:

I don't believe the RFT EL-34 tube was a suspect - this set worked properly with Cary SLI-80 and another manually biased integrated amp. My technician insists that an auto-bias function may create problems when installing vintage tubes...
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stonedeaf
101 posts
 
Final note: Most service depts. will stock what are commonly referred to as "pigtail" fuses - these come from the factory with the wire already soldered to the end caps - much easier to use than trying to solder to the fuse without overheating it and blowing it before you ever get it installed.
transl OP
156 posts
 
Thanks a lot!

I will contact Partsconnexion or Parts Express for that.
rodman99999
6,110 posts
 
If you can't locate a pigtail type fuse: Find a plastic inline fuse holder, ie:(http://cgi.ebay.com/FUSEHOLDER-INLINE-FUSE-HOLDER-WITH-14Ga-WIRE_W0QQitemZ270366963842QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item270366963842&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A1%7C294%3A50) and solder the leads to the PCB. I can't understand what the problem would be with de-soldering and re-soldering to a PCB. We've been doing it for decades, in the electronics repair business. That's what solder suckers and solder-wick are for. Here's an inexpensive kit: (http://cgi.ebay.com/SOLDER-SUCKER-DESOLDERING-PUMP-HIGH-POWER-WICK-SOLDER_W0QQitemZ220376267737QQihZ012QQcategoryZ46413QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)
markd51
763 posts
 
Here's a real stupid, but simple fix, and might work for you? I did this once to a Sansui Reciever, that had a similar type blown fuse on the power supply board, and did this to sidestep mucho headaches.

Go to Radio Shack, get yourself some Fuse Clips. Solder two pairs of Fuse Clips back to back. You can then clip one side of the Fuse Clips to the Blown Fuse, and then clip in the new fuse on top "piggyback" style.

The paired clips, will look like two "U's" back to back when soldered together.

As long as it's the same value fuse, all will work just fine, and this will permit you to do a quick fix, without ripping out boards, or the worry of damage to the board from heat. Hope this helps, Mark
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