Weird fuse problem

Hi all. I’m currently away in the motorhome (2007 Nuevo) which has the PDU4M charging unit. The panel says fuse 5 is blown. In the book it says fuse 5 is for the awning light/ internal locker lights. Not the end of the world, at least it’s not the beer fridge. The fuses are in a sealed plastic box cover on the front but when you ‘wiggle’ the offending fuse a bit the lights come on. That makes me think it’s not the fuse at all, but the fuse housing has somehow deteriorated? Anyone had experience of iffy fuse housing on the PDU4M. I’ll get some new fuses when I get home, but if it is the fuse housing it looks like I have to take the unit apart?

Not specific to the PDU4M (which I've never used) but there are several things that can cause this.

The simplest is a cheap fuse - the Chinese are masters at chopping tiny fractions off their manufacturing costs, and one thing they do is to make fuses with very thin blades. These don't always make good contact with the fuse socket - especially if a properly made fuse has been used in it before.

Another is that if a fuse overheats,  it can weaken the fuse sockets, making them lose their springiness, so that they open out and don't grip the fuse well.

The third is that you can get a failure of the connection behind the socket - either a break in the circuit board link or a loosening of the wire clamp, depending on how it's fixed.

I would guess at the latter if you only manage to get very intermittent connection, but you'll probably only know for sure by taking the unit apart. However, one thing you can do is view the "socket" part by removing the fuse and using a torch. This should let you see whether the contacts that connect to the fuse are physically damaged.

Cheers Roopert. That’s all makes sense. Thanks for responding

Hi Mr A,

If you are just 'wiggling' the fuse and things work then if it was me I would;

Switch everything off so the fuse panel is dead.

Pull the offending fuse out/check its ok and replace it a couple of times to clean the blades and the housing.

I would do the same to all the fuses.

Sometimes due to age the fuse blades and holders 'corrode' in a way that shows its self by being 'dull' taking them in/out will clean the main contacting bits.

This will show its self by being scraped/polished brighter clean metal.

In similar situations I often swap the same type of fuses arround different fittings putting what is thought to be the 'iffy' one somewhere less important (not the beer fridge!)


Cheers



Boots

Boots wrote:
Sometimes due to age the fuse blades and holders 'corrode' in a way that shows its self by being 'dull' taking them in/out will clean the main contacting bits.

That's a good point - I bought some LED "glowblow" fuses a few years ago and they became corroded very quickly (in fact I'm fairly sure they were corroded from brand new) with a crystalline coating which was quite hard to clean off.

Hi Mr R,

I will remember those words 'crystalline coating' for future reference !



Cheers


Boots

I had a problem with the charging on our ride on mower. After a lot of puzzling I realised that the fuse was covered in a grey deposit. Cleaned it off and all was well.