Any electronics whizzes?

[nev]

Long shot, but thought I'd ask anyhoo.

Short version - If a capacitor is getting very hot is it likely to be that at fault or something further down the line causing it to get hot?
long version-
Makita site radio stopped working.
Put battery in, display goes to --/- .
press power button - It powers up, beeps once, briefly displays all lcd 'icons', and then settles on the default 87.? preset 1.
Thats it.
no buttons work, nothing, nada, zilch. not even the on off. need to remove battery to power off.

Its not the common fault of dodgy battery cable cos its the same on mains.

I noticed by accident :evil: after returning to it after a cuppa that the capacitor (biggest one on the board) was extremely hot.
I imagine that a cap is only quid or two so will have a go at replacement if its likely.

Cheers in advance
nev

 

[Dee J]

Capacitors should not run hot. It might have gone leaky and not behave like a capacitor any more. No harm in replacing it.

 

[novocaine]

is it bulging on the top? (they should be flat as a pancake, any raise and it's dead).

as said, a cap shouldn't get hot, replace it (assuming it's an electrolytic one it'll cost from a few pence for a cheapy from ebay to a few quid for a cheapy from maplin). while your at it, turn the board over and look for **** stains and loose joints, it could be that something is shorting out and the reason the cap is getting hot is excessive current.

 

[Racers]

It could be that the cap is leaky and getting hot or it could have too much voltage across it or a leaky rectifier.
Its a smoothing cap so it is across the supply its not going to be affected by excessive current draw.
I would replace it, its not going to cost you much to do, Farnell or RS are good.

Pete

 

[woodenstx]

odds on the voltage regulator chip has failed hence the odd behaviour of the radio, and subsequently the hot cap.

I've never experienced a hot cap without something else (more important) at fault.

 

[nev]

Cheers gents, I'll take a punt - 49p in Maplins. although not quite an exact match, the voltage is different. Would i be correct in assuming that the V figure is what the component can tolerate? i.e. if I go up in V I'll be ok?

e.g. http://www.maplin.co.uk/p/2200f-50v-105 ... itor-dt73q


If the voltage regulator is up the swanny, I imagine I could determine this with a (volt)meter by trying to trace the input?

 

[Gerry]

Yes you can go up as high as you like with the voltage.

Gerry

 

[Skeety]

That cap does look slightly bulged. Also look at the top to see if there is any brown stuff leaking out.

The replacement will be absolutely fine. Just be aware that as it's an electrolytic cap that you get the polarity + - correct as they go off like a bomb if reverse polarised.

Worth checking the rear of the board over for dry joints too.

Cheers,

Jon.

 

[LancsRick]

Not sure I agree with skeety that it looks bulged but there's no harm in replacing it. Have you got a voltmeter to check test points?

 

[Skeety]

Not sure I agree with skeety that it looks bulged but there's no harm in replacing it. Have you got a voltmeter to check test points?

Agree,

Was looking at the pic on my phone when I replied, having seen the bigger pic it doesn't look bulged but it could still be bad.