VHF radio blowing fuses

[Mei Mac]

You could have brought the alternator to a firm that repairs and reconditions automotive starters and alternators. There's generally at least one in any decent-sized town. e.g. Auto Parts UK is one search result that crops up. There a firm that does similar for "marine" starters and alternators, but these will be the same items at twice the price.i

Thanks for the advice. I attended to the battery (bought new new house and starter, cables etc) along with a new alternator in June. Just can't believe it would take so long to repair the radio. But as Paul Rainbow mentions above there appears to be a shortage of parts around.

 

[Refueler]

Just based on the thread title .....

My Cobra DSC radio suffered after a particularly cold few days winter 20-21 ...... when spring came along - blew fuses .... Kept returning to it often ... still blowing fuses.

No-one over here is interested in repairing VHFs ... so I dipped hand in pocket and replaced it with next model up with inbuilt GPS. Deciding that I would remove from boat during such winter days !

The 'old' fuse blowing VHF sat on the shelf in my workshop all last year ... and through to Aug this year when I thought .. lets power up and see what happens ... Switched on fine ... works a treat !!

Funny thing is - my old Lowrance 3500 Plotter had screen failure same time as the VHF ... that ALSO is working again after beding in workshop !!

Just posting based on thread title ....

 

[Spirit (of Glenans)]

Just based on the thread title .....

My Cobra DSC radio suffered after a particularly cold few days winter 20-21 ...... when spring came along - blew fuses .... Kept returning to it often ... still blowing fuses.

No-one over here is interested in repairing VHFs ... so I dipped hand in pocket and replaced it with next model up with inbuilt GPS. Deciding that I would remove from boat during such winter days !

The 'old' fuse blowing VHF sat on the shelf in my workshop all last year ... and through to Aug this year when I thought .. lets power up and see what happens ... Switched on fine ... works a treat !!

Funny thing is - my old Lowrance 3500 Plotter had screen failure same time as the VHF ... that ALSO is working again after beding in workshop !!

Just posting based on thread title ....

Could have been the effects of dampness/condensation on the boat, drying out in the workshop.
Apart from a dehumidifier over winter, the solution might be to demount the instruments and store them in an airtight container or bag with some of those dehumidifying sacs that arrive in the packaging of many products. (Tape plastic bags around the ends of the cables).

 

[Bilgediver]

I bought a new Standard HorizonGX2400E a few months ago. Wired it up, new antennae and cable, and it powered up and worked a treat.

A few days ago I noticed my alternator had started kicking out 17v. A few days later my lovely new radio wouldn't come on. Before I can even turn it on It blows the 6A glass inline fuse (supplied with the unit) . As soon as power is sent to the radio from my fuse panel, the glass fuse blows. I took the radio home and hooked it directly to a leisure battery and the same thing happens. Therefore no problem with the boat's electrics. No dodgy connections, no shorts.

I know for a fact that the polarity hasn't been reverse since it was working a week ago and now it doesn't, the wiring hasn't been changed.

I have read that inside these radios there is a reverse polarity diode, that can cause blown fuses.

Since the radio is still in warranty, my next step is to call Standard Horizon for advice but I thought I would also ask you guys for any advice/experience you may have.

Call Standard Horizon and be honest and tell them the reason for the fault is possibly overvoltage and they might take pity. If you send it in making a claim there may not be the outcome you wish! The chances are it is a simple matter to just change a burnt out component. This might be visible if you look but then there will be evidence of tinkering

Yes some equipment has a protection diode which conducts the reverse current as a short circuit and blows the supply fuse. This should not be damaged under normal circumstances so long as the correct fuse is fitted.

 

[savageseadog]

SH might be aware of a "stock" vulnerability, a specific component that blows regularly in those circumstances.
A protection device called a TVS diode might be fitted and they can short circuit under sustained overvolage/current. A cheap diode but ease of fitting depends on how easy it is to open the radio and access the diode. It will probably be surface mounted and the right equipment and skills will be required.

 

[Refueler]

Could have been the effects of dampness/condensation on the boat, drying out in the workshop.
Apart from a dehumidifier over winter, the solution might be to demount the instruments and store them in an airtight container or bag with some of those dehumidifying sacs that arrive in the packaging of many products. (Tape plastic bags around the ends of the cables).

That is what it appears to be. Because of the internal construction - unlike radios of old ... when case is opened - the internals are contained within a metal box making it hard to get at boards. That may have something to do with it ...

 

[PaulRainbow]

If the circuit in #2 is correct the diode is only for reverse polarity protection. Even the cheapest diode would probably have a 100v rating. It would be better to use a power zener diode such as a Tranzorb TVS which would also provide voltage protection and be robust enough for the fuse to blow before damaging the diode. I always fitted 1500W ones on any PCB that might be subjected to voltage spikes.

All well and good, but how you do/did things obviously does not apply to every electronic device out there. Just a few weeks ago i had to deal with a very expensive black box VHF that had been connected to 24v. Blew the fuse repeatedly. Manufacturer said they could not repair it. It's now working just fine, but no longer has the over voltage protection.