Electronics help

We might, of course, wonder why it has failed so catastrophically.

Before spending a lot of time sourcing a fuse and doing a repair, I would be inclined to pop an ammeter with a reasonably high range across the location. Even cheap DVMs normally have an internal fuse which should protect them if (say) there is now mains across the two sides.

Is it just me, or does that look like it's been bodged and there should be a fuseholder on that board with a cartridge fuse?

Any letters such as F, T or S on the remnants of the end cap?

Fairly academic really.

The state of the fuse suggests that someone needing advice on how to identify an antisurge fuse, would not be in a good position to find the fault that caused that problem.

The only hope is that the event was caused by a spike initiating a crowbar, or a "self healing" suppression cap, tranzorb etc.

A slim chance methinks!

AB

it's a 3A fuse. Whether it'll then work or the replacement blow who knows. I suspect the latter is more likely.

NT

The replacement almost certainly wont work.

Trying to solder directly to the end caps of a 20mm glass fuse is difficult, unless the mp of solder has changed a lot.

The current taking the thing out would be quite impressive.

AB

for testing just clip it in place. But like you said. I was wondering if there might be a chance it got connected to the battery the wrong way round, but it seems unlikely.

NT

I cannot see the picture, but is it a switch mode device or a good old analogue supply? If the latter the most common fault is the bridge rectifiers which are commonly under specified for spikes in current etc.

If its swwitch mode then it might be possible to get a new module, but I've seenin the past that companies have cut costs by fitting a soldered in fuse as of course they never blow do they? :-)

Is the company that made the device still around? Brian

Yes if its directly onto the mains wire a 100 watt light bulb across it first and look for smoke....:-)

Brian

So much easier to use a "leaded fuse", also "Fuses with Leads (Through Hole)"...

Thomas Prufer

You can get wire ended fuses though. Brian

It would be interesting to look at the print side of the pcb to see if any track is left. This is what did for the pcb on my old washing machine in the end, fried track syndrome. Brian

On the end of the matal cap for the one with remnants of what appears to be a glass fuse it has TAP I cant see any other writing.

Without going in to the detail as I covered in a previous post the scooter was FILs and he had an uncanny knack of just looking at something and it broke,,,mobiles,computers, hearing aids, TV, set the microwave on fire, he would pull plugs out of sockets by the cable, he was a nightmare.

Anyhow his scooter has 2 chargers, 1 he lost the fuse (ordered ebay) and the other (this one) who knows what he done. I have replaced the batteries in the scooter and it works good and I will be selling it locally for just above what it costs to get it all going, if I need to buy another charger so be it but if I can keep the cost down its a better buy for some old buddy.

So if I replace a fuse and it blows the charger I aint too bothered, I just need to know what I am looking to replace.

So do you think the fuse could have been physically damaged, rather than blowing?

Possibly the charger output was shorted?

Thomas Prufer

I dont think by accessing it, but more than likely dropped it a few times or ran over it in his scooter.

... and the photo shows a NTC. Those are sometimes used as an inrush current limiter. Switching the charger on and off frequently in a short time can defeat the NTC, causing the fuse to blow.

Replace the fuse, and see!

Thomas Prufer

By the looks of the picture the fuse detonated with considerable force. I expect an insane current flowed briefly. It may do so again if the fault was permanent as opposed to a transient dead short of the output.

A lash up with a 3A mains fuse is worth a try but be prepared for the magic smoke coming out or worse. You don't want it starting a fire.

I'd conduct any tests outdoors and wear eye protection. YMMV