Kogan Internet radio KGNDRVCA

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Hello All,

I have a Kogan internet radio which worked fine for years and then
conked out.

It seemed to me the power supply had failed, so I pulled it apart to
have a  look-see. It has a 100VAC-240VAC to DC voltage converter as
one unit, and then follwed by a voltage regulator card which develops
and sends various voltages off to different sections of the radio.

It turns out the initial 100VAC-240VAC to DC voltage converter has
failed. 240AC in and nothing out!

I've proved this by sticking metal pins into the DC output wires and
connecting an external variable DC power supply to these pins. The
radio then plays again. Currently I'm feeding it 12Volts DC, and the
radio stops working if I wind the voltage down to about 8 volts.

I'm not planning to try to repair the faulty module. My intent is to
feed it with an external plug-pack. I have no circuit description or
repair manual for this radio.

Mu question is this:

Does anyone know what the DC voltage output is from this particular
100VAC-250VAC module? Or what they typically are?

I'd like to feed the correct voltage from a plug-pack into the
subsequent multi-voltage regulator.

Ross  

Re: Kogan Internet radio KGNDRVCA
On Wed, 01 May 2019 05:44:52 +0000, RMD wrote:

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Nope, but does it matter. You've found a common voltage that it works at,  
why not just go with that? Any extra is just heat production.
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Do none of the components give you a clue? E.g output side.

Re: Kogan Internet radio KGNDRVCA
On 1/05/2019 3:44 pm, RMD wrote:
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Determine the highest regulated output voltage, and then wind down the  
input voltage until the regulated output voltage starts to sag. Add back  
a couple of volts to the input, and you're good to go.

Sylvia.

Re: Kogan Internet radio KGNDRVCA
RMD wrote:
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From my experience the ratings on the capacitors around power circuitry
indicates the operating voltage.

E.g if Capacitors are marked 16v then operating voltage is below this say
12v.

If you use higher voltage say 18v , you may end up burning components not
rated to operate at that voltage.



Re: Kogan Internet radio KGNDRVCA
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Except that if the device is designed to last (probably not in this
case), the electrolytic capacitors may be specified to be over
double, or triple, the normal operating voltage in order to reduce
the likelihood of early failure due to aging.

The capacitor voltage rating is no guarantee of the voltage ratings
for other components and the circuit as a whole.

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Re: Kogan Internet radio KGNDRVCA
On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

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Has anything mass produced since Henry Ford been designed to last?

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Well, they are unlikely to be higher.


Re: Kogan Internet radio KGNDRVCA
news18 wrote:
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And if 16 definitely lower.

Re: Kogan Internet radio KGNDRVCA
On Fri, 03 May 2019 12:45:50 +1000, FMurtz wrote:

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Which, on the above proposition, they were designed for long life.


Re: Kogan Internet radio KGNDRVCA
Computer Nerd Kev wrote:
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they're usually rated *higher* than 'operating voltage' to accommodate for
sudden voltage surges.
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its just a rough guide but you can be *sure* about  the electrolytic
capacitors ratings around the 'power circuitry' (i.e. around where the 240v
step down transformer connects to circuit board) will indicate the
"operating voltage" of circuit.

You will also see electrolytic capacitors ratings *change* at different
parts of board,
but you should only concerned with the ones around the 'power
circuitry'.

 it requires a bit of cautious 'trial and error' tinkering (i.e. starting at
low voltage & going higher) in
getting something to work without burning it.  



Re: Kogan Internet radio KGNDRVCA
On Wednesday, 1 May 2019 15:44:53 UTC+10, RMD  wrote:
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Are there no markings on the AC module that you can google?

--
Chris.

Re: Kogan Internet radio KGNDRVCA
On Wed, 01 May 2019 05:44:52 GMT, snipped-for-privacy@invalid.invalid (RMD) wrote:

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Thank you all for your comments.

This radio, like so many consumer goods these days, isn't really
designed for repair. It is hard to get it apart enough to actually
look for component or module identification numbers, leaving aside old
person dodgy close-up vision!

The AC module is essentially covered with a metal shield and is
basically un-identified. It possibly needs to be dis-assembled to see
any identification numbers. Also, actually seeing where to check
voltages elswhere  etc is not that obvious or easy to do.

I've soak tested the radio at 12V for 24 hours with no obvious signs
of distress occuring. The radio draws 300-400mA while playing and
about 70mA on standby.

Anyway, I then looked through all my e-waste plug-packs. (Things die,
but not usually the plug-pack!) Many of these plugpacks are
unregulated, so allegedly 12V plugpacks put out about 19V un;oaded. I
thought  that particular 12V plugpack is not desirable for my planned
application!

I found a 7.5V/500mA  plugpack, once used to power a defunct 6-way LAN
switch. This plug-pack put out 11.5V unloaded.  

So I tried it temporarily hooked up to the radio. It falls to 10.5V
when the radio is on and is at 11.2V when the radio is on standby.

So, seems good to me! :)

Anyway, I'll leave it soaking for a week or so with this temporary
hook-up to see if it keeps working without letting the smoke out.

Ross




Re: Kogan Internet radio KGNDRVCA
RMD wrote:
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dead right about that, if it breaks - it's all designed to be thrown away.
Its impossible to fix most things even if you wanted to

The surface mount components are too tiny to handle,
without proper equipment you can't solder the little black
speck of a resistor/capacitor/transistor?

Sometimes You can even see them to distinguish what they are.

you can't pick the damn things up with tweezers, you're more than likely
squeeze it too tight where component just flies out of your grasp & its lost
forever!

if you managed to get the component on the board to solder, more than likely
it'll stick to the wet solder & burn up without sticking to circuit board.

the counter argument of course is that electronic devices haven't been this
plentiful & cheep .

You can afford to buy replacement (E.g TV's, phones, computers etc.) with
probably more features and at a cheaper price.

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Re: Kogan Internet radio KGNDRVCA
On Sat, 4 May 2019 10:19:10 +1000, "#BoycottEurovision2019"

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I fix these things because I'm of an age (73 years old) where we fixed
things as a matter of course. But I must confess I've already bought
the replacement internet radio with more features etc.

It amuses me to try to fix these things, but minus any service
information, just to make it more interesting technically. (Some
things I've tinkered with on and off for months before finally fixing
it.) Btw some of the stuff is glued together, so no easy dis-assembly
is really possible any more with these items.

I don't deal with any surface mount stuff. But many faults are still
not complicated things. Dry joints etc still happen. :)

Btw I wound the voltage to this radio up to 15 Volts or so without
anything obviously awful  happening.

Interestingly it draws more current if I lower the voltage to 9 Volts,
and less current at a higher voltages. The regulator card following is
a switching regulator type producing the various voltages the radio
requires. Anyway, it means it doesn't look like a resistor as it puts
out the same power output over a range of input voltages.


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Re: Kogan Internet radio KGNDRVCA
RMD wrote:
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Same here.
I can't believe the amount of stuff people throw out, & most of it
serviceable/repairable.
Some stuff left on the kerb that I've come across have been in working
condition.

Does anybody know how to replace the fuse in a microwave these days?
Why bother for $99 you can buy a 20L oven brand new .

what about all those bubble jet printers that are used once,
the next time you need to use it,
 the heads are clogged, you leave it out on the kerb & head
on down to officeworks for a replacement.

The politicians & others keep saying *we need coal energy* for our
lifestyle,
yet 'our lifestyle' is wasting energy, throwing out working/reparable items.

what happens in my neighborhood, you multiply that all over Australia  &
there is insane amount of wasted energy
 ( energy consumed to make stuff & ship it here )
going straight into land fill.

Yet all that CO2 created in manufacture still in the atmosphere , and the
bubble jet printer in land fill somewhere.

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just as rewarding as solving a puzzle or finishing a crossword .
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I've repaired an early iphone 3 which had swollen battery that
deformed/curved the circuit board, yet managed to power on once I got an
equivalent sized battery for it.

Irony is even though 'hardware works', I'd be lucky to find an app. from the
app. store that'll work on it.

in my experience most of the manufactured surface mount computer boards etc.
are bullet proof , if they're not physically damaged can be made to work.

however repairing Iphones damages Apples business model,
 i.e. trying to get you to buy new phone every 18months,
 they're trying to make it *illegal to repair your own phone*!.

"Apple Is Telling Lawmakers People Will Hurt Themselves if They Try to Fix
iPhones"
https://motherboard.vice.com/en_us/article/wjvdb4/apple-is-telling-lawmakers-people-will-hurt-themselves-if-they-try-to-fix-iphones

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Re: Kogan Internet radio KGNDRVCA
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What they mean is that their lifestyle is financially supported by the coal
mining industry.

Those throw-away items were probably not produced using Australian Coal power

--  
  When I tried casting out nines I made a hash of it.

Re: Kogan Internet radio KGNDRVCA
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I wish you could tell that to some laptop motherboards that I have.
It always annoys me that if it gets to the point where the
motherboard's the problem, that's the end of any attempt at repair
(short of a new motherboard, which doesn't count in my book).

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Re: Kogan Internet radio KGNDRVCA
Computer Nerd Kev wrote:
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I'm going by my experiences with mobile phones, they seem to be made well .
I guess they have to take abuse like being bent, & dropped etc. weak point
being the screen.
IMO Laptops vary in quality in manufacture, I've seen some that have had the
soldered add-ons like SD card /USB slot, tear away from the board over use.

There are other issues like the ribbon cable foil separating off plastic
ribbon, or the latch
that secures it breaks off, because it's cheap & flimsy.

Some manufactures cut corners, others do thorough job
 but you pay more for it.  



Re: Kogan Internet radio KGNDRVCA
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Yeah, that's what I pull them apart looking for, and it seems to
often turn out to be the motherboard that's the problem in the
end. However by the time I've concluded that, the laptop is
completely disassembled (probably except for the screen) and I've
done countless tests on the individual parts. So the failures are
probably a lot more memorable than "swap the HDD... ah, it works
fine", "change the RAM... ah, it works fine", "new BIOS battery...
ah, it works fine" etc. successes.

In fact I recently bought a "broken" laptop very cheaply from Ebay,
which turned out to boot normally simply after I'd mounted the
Windows partition in Linux after booting to a Live CD. The Linux
ntfs-3g driver fixed the file system problem without me even
telling it to do so, and the hardware passed all the tests that I
threw at it.

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Perhaps, though I think there's a fair bit of luck involved these
days. Especially with laptops and phones where everything is being
crammed in to as tight a space as possible. It would be nice if
someone still made thick, heavy, but reliable laptops like the old
IBM (pre-Lenovo) Thinkpads, for example.

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Re: Kogan Internet radio KGNDRVCA
Computer Nerd Kev wrote:
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I don't think you can do more than look for the obvious faults, if the
problem is at chip level , just toss it out.

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Had something similar happen, I had a laptop that I thought the camera  
didn't
work in windows (after trying different drivers ) , when I booted it up in
linux live CD , the camera was detected & working!

I presume the general 'vanilla' drivers in linux are better written or less
'buggy' than window drivers .

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I get the feeling electronics devices will have most of the 'superfluous
components' removed and have them integrated into a handful of chips,
& that's it!

Totally impossible to repair.  



Re: Kogan Internet radio KGNDRVCA
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That's been happening for half a century at least, and while in the
past it was still possible to buy most of the chips replacing
individual parts, now custom chips and BGA chip packages have become
so common that most consumer goods are either impractical or
impossible to repair if one of their main chips dies.

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