Kogan Internet radio KGNDRVCA

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

Reply to
RMD
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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.

Do none of the components give you a clue? E.g output side.

Reply to
news18

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.

Reply to
Sylvia Else

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.

Reply to
#BoycottEurovision2019

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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Reply to
Computer Nerd Kev

Are there no markings on the AC module that you can google?

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Chris.
Reply to
Chris

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

Well, they are unlikely to be higher.

Reply to
news18

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

Reply to
RMD

And if 16 definitely lower.

Reply to
FMurtz

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

Reply to
news18

they're usually rated *higher* than 'operating voltage' to accommodate for sudden voltage surges.

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.

Reply to
#BoycottEurovision2019

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.

Reply to
#BoycottEurovision2019

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.

Reply to
RMD

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.

just as rewarding as solving a puzzle or finishing a crossword .

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"

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Reply to
#BoycottEurovision2019

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

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  When I tried casting out nines I made a hash of it.
Reply to
Jasen Betts

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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Reply to
Computer Nerd Kev

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.

Reply to
#BoycottEurovision2019

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.

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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Reply to
Computer Nerd Kev

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.

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 .

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.

Reply to
#BoycottEurovision2019

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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Reply to
Computer Nerd Kev

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