2. amps-preamps
  3. 1057837334

Amp blowing fuses

I have a BAT VK-200 amp(purchased used 8 mos ago) and a BAT VK-31se(recently purchased new). 2 weeks ago I came home, put on an album-no sound. I pulled the amp and inserted my old b&K ST-140 mono blocks. When I turned them on one was OK but the other had a loud hum through the speakers, I switched interconnects and it went away. I called BAT and talked to Steve and he told me how to check and replace the fuses in the VK-200 amp. I did this and I was up and running in a few minutes. Could it be the bad interconnect that caused the fuses to blow? By the way these are 10 amp fast blow fuses. I just got the VK-31Se new a few weeks. This is my first piece of tubed equipment, is there something that I should be worried about with that unit? I will be calling BAT agian, but I would like to hear some of your thoughts and experiences.
jdodmead
marakanetz's avatar
marakanetz
5,473 posts
 
Sidssp,
does it?
bigtee
803 posts
 
The reason the fuses are there is to protect the unit from stuff like you just experienced. If the fuses do not continue to blow with a different set of interconnects, you have your solution. If something is wrong with the unit, it would blow the fuse everytime you turned it on. Otherwise, it's an external problem. When an interconnect grounds as yours did, it will pop fuses because of the high input surge to the amp and the subsequent peak out.
sean
6,231 posts
 
Just because you've got a cap in series with the circuit does not mean that you are guaranteed to be "DC free". Sean
>
s23chang
620 posts
 
Sometimes a bad tube can also blow a fuse. I had an amp that was working fine until it blow the fuse one day. I replaced the fuse and I saw the rectifier tube was very unstable and it blow the fuse again. I replaced the retifier tube and problem still exist. I then trace the circuit until I found out that one of the output tubes had a short. You never know...
gpdavis1
50 posts
 
BAT told me that the VK-200 needs an upgrade to the bias circuit, at $500, which might be your problem. I know that S/N 274 and earlier need the upgrade and S/N 371 and later do not. I am not sure where between these two S/Ns BAT made the modification to the bias circuit, but yours may be one of the older models which needs the work.
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