Jump to content

Electric Gremlin!


Recommended Posts

We went to the boat today with the intention of replacing two Duff switches, first one took me 30 seconds onto No2 the toilet pump switch, change the switch, try it and nothing, get the tester out and plenty of power, head scratch and a swear, I start tracing the cable back find the pump test and find power at the pump, big swear as I start think pumps caput need new one, Pump looks new and it worked the day before, I re-test the switch this time no power, Same at the pump connections, the connections look at bit corroded so I decided to change them making a note of the connections re-cut the cables and test, got power, check switch, no power, by now I'm making up swearwords and if your confused reading this imagine how I felt trying to work it out, Ok ruled most things out by now but gained a few new swearwords, I decide there must be a break in the cable somewhere or a dodgy connection, just done the pump and the switch so I know they are good, re-check pump and power again, Ok Frank! time to walk away have a cuppa and re-group, Right one last check, this time power at the switch and pump, but pump not working so pump must be busted,, I stick the tester on the pump connections to make sure the power is off even though I turned the isolator off, take the pump of stick the leads on the battery, pump works fine, thats it the nothing for it but to re-wire the whole thing, Into the bow cupboard find the fuse for the pump take it out, weird fuses using fuse wire and not glass or car fuses, Now I have no idea why but I decide to test the fuse, put circuit tester on and no circuit meaning fuse has blown, Oh great I just spent four hours trying to find the problem and it's the fuse, as I didn't have any fuse wire I put another fuse from a different pump after testing it, go to test switch,nothing, nothing at the pump either, if swearing was an event at the Olympics I'd win Gold, put the borrowed fuse back and the blown one, Right only thing left is rewire from the fuse box to the Pump, off to Stalham for some cable and fusewire, I get back to the boat and think I'll put the switch faceplate back first, as I'm doing it I caught the switch and the Bloody pump burst into life, impossible as the fuse is blown, I take the fuse out and I get a circuit, check the borrowed one in case I put the wrong one back, nope it's fine, I check everything again 10 times and everything works fine, I spent 5 hours trying to find a problem that the Electric Gremlin sent to test me, Everything worked after I played with the fuses so I can only think it was a dirty contact, but why I was getting power intermitantly I don't know, the whole thing is a mystery to me,,,

Regards Frank,,,

Link to comment
Share on other sites

Resistance from corrosion is almost always the culprit in such cases Frank, whether feed or return, auto cable instead of tinned, poor quality auto Blue, Red, yellow insulated terminals, untinned distribution boards and fuse holders all cotribute to the mix and they are present on huge numbers of inland and seagoing boats too. I recently had to chop the stern light cable on a good quality TSDY at 1m intervals trying to find bright conductor and was almost at the switch panel (about 9 metres ) before I found some, I might just as well re cabled it all and not bothered looking for some bright copper. :o

What you experienced is not unusual, using a multimeter will show 12v DC, but 12v is only part of the equasion,lt is also important to check you still have 12v under load as the corrosion resistance is preventing current, so, always use a load rather than a multimeter or a combination of both to check circuits, a fairly high wattage bulb will usualy give a good indication as most people don't have acces to an instrument that can apply a load.

Link to comment
Share on other sites

I use a Uni-T UT58A Digital Multimeter but this problem had me baffled, I tested continutity, voltage, resistance you name it I checked, one minute I had power and the pump wouldn't work then it would show no power, I split the circuits down and tested each one, it showed power going into the chocolate box for the pump but none coming out to the pump, so I did away with the connector and used heat shrink crimp fittings, even when it was showing power going in and out the pump wouldn't work so I'd re-check everything and then it would show no power going into the pump or at the switch, then when I checked the fuse it didn't give me a circuit, I changed it for a good fuse and it still showed no power, on the verge of giving up I put the good fuse back because it was the bilge pump one, put the broken fuse back and the pump suddenly started working, next time I'm at the boat I'm going to take a look at the fuseboard and check the cables and re-wire the fuses, I think there may be a loose, corroded or broken cable, my guess is that the cable has a break in where it goes to the fuseboard because thinking about it the problem didn't start untill the day warmed up, making me think that as the warmth expanded the cable the break opened and broke the circuit then as it cooled it gave a circuit, the part I can't work out is how the fuse tested as blown but was ok when I put it back, and why even when it showed power the pump didn't work, I've completely re-wired 4 boats now so I'm no novice, I even use tinned cables of the right sizes for the job, and put everything on it's own fuse but I've come across this problem before,, all very odd, I'll put the hairdryer on the cables at the fusebox to warm them up, and if my break theory is right i'll find a break in the cable near the fuseboard,,

Regards Frank,,,,

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Sponsors

    Norfolk Broads Network is run by volunteers - You can help us run it by making a donation

  • Create New...

Important Information

For details of our Guidelines, please take a look at the Terms of Use here.