VHF blowing fuses

[Kernow Buoy]

Went out for a quick blast today and as usual ran all the electrics before leaving home, all seemed fine.
As I left harbour I tried to turn up the volume of the VHF but with no response, all the lcd digits were working but could get no response, tried to transmit and the unit died, found the fuse in the fusebox blown, replaced it and it came to life but then promptly died again as I tried to transmit, another fuse gone, Fuse changed again and unit seemed fine afterwards although no response to radio check request (not that unusual down here I was very close inshore) At some point during this my Fish finder also blew a fuse, admittedly the fuse is right alongside the VHF one and I may well have moved/dislodged it whilst the unit was switched on. Can't think that blowing 2 fuses is a coincidence its never blown 1 before so thought I'd better investigate
Any thoughts?

[Erin]

Sounds like a suspect radio. Can't think of much else that would cause two fuses to blow when trying to transmit. Drawing too much power. Was it on 25W or 1W?

[Kernow Buoy]

Originally Posted by Erin

Sounds like a suspect radio. Can't think of much else that would cause two fuses to blow when trying to transmit. Drawing too much power. Was it on 25W or 1W?

Erin it's usually on 1W but with all the faffing about may well have gone onto 25W.

So if I stick a multimeter on it tomorrow and try to transmit what would I expect the reading to be?

[ashbypower]

Could also be an antenna problem, perhap a High VSWR .. cause by a short in the Antenna feeder.. but for an adjacent fuse to pop on a totally different circuit is a wierd one .. coincedence ? mmmm

[jyasaki]

Possibly a low voltage condition?

Low input voltage causes the unit to pull more current to generate the required operational power, which may blow "just enough" rated fuses.

jky

[Kernow Buoy]

It's the fuses themselves
I rewired the boat myself and used good quality marine wire, shrinkwrap, nice 12 way fusebox etc, in my toolbox however were a selection of fuses that probably cost me a quid for 50! The fuses just don't sit in the holders correctly, if you put a multimeter on the box at the VHF terminal and just touch the fuse gently the readings go all over the place, pick a number between 0 and 12V and you'll see it by wiggling the fuse, you can feel that only 1 of the prongs of the fuse is held, given a roughish ride on a Rib I'm sure the fuse was disconnecting itself and then re-connecting and/or blowing, I mentioned the fishfinder in the original post and lo and behold that had a gash fuse in it too but my chartplotter which always stays on and is nice and steady had a decent looking fuse which is firmly sat in it's holder. Think I've cracked it

[Mollers]

Originally Posted by Kernow Buoy

I rewired the boat myself

[Kernow Buoy]

Originally Posted by Mollers

Yea yea OK, I rewired the boat myself but followed DHD's instructions to the letter, true he didn't mention a box of poundlands marine grade lifetime warranty fuses though

[Mollers]

Originally Posted by Kernow Buoy

.. true he didn't mention a box of poundlands marine grade lifetime warranty fuses though

Poundland-DHD

[BumbleAbout]

I replaced my fuses with these circuit breakers Auto-Reset Circuit Breakers : Circuit Breakers : Maplin Electronics - soldered and shrink wrapped, in a waterproof box in the console. I hate messing around with fuses at sea !

If you want a warning that circuits are tripping the circuit breaker then you just wire an LED and resistor across the breaker (so it lights when tripped).

[Nightfisher]

Originally Posted by BumbleAbout

I replaced my fuses with these circuit breakers Auto-Reset Circuit Breakers : Circuit Breakers : Maplin Electronics - soldered and shrink wrapped, in a waterproof box in the console. I hate messing around with fuses at sea !

If you want a warning that circuits are tripping the circuit breaker then you just wire an LED and resistor across the breaker (so it lights when tripped).

Always the best way ie: Soldering the connectors. Never had a failed connection/splice after doing it.

[jyasaki]

Originally Posted by Nightfisher

Always the best way ie: Soldering the connectors. Never had a failed connection/splice after doing it.

Well, maybe. The American Boating and Yachting Council (which comes up with a lot of the marine standrads in the US) disagrees:

paraphrased from the ABYC standards, from Sailangle.com :
Another common misconception dictates that the best of all connections is a soldered connection. However with stranded wire, the solder bonds the individual strands together, making a solid, inflexible wire. ABYC standards prohibit soldering as the sole means of making a connection because the newly solid wire is subject to cracking or breaking through vibration and flexing. A more practical solution is to use a crimp connector described above. Wires should never be joined simply by soldering and taping (or heat shrink); however, if solder is used, use only 60%/40% rosin core or solid solder, soldering after the butt connector is crimped. Acid core solder as used in plumbing may never be used in any electrical wiring.


Probably more relevant on RIBs which subject wiring to more vibration than sailboats.

That said, I solder and heat shrink as well, depending on the application.

jky

[BumbleAbout]

Agreed - it is best to join mechanically (twist wires together or crimp) before you solder and then cover in waterproof heat shrink insulation.