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RMD
Guest

Wed May 01, 2019 6:45 am   



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

news18
Guest

Wed May 01, 2019 9:45 am   



On Wed, 01 May 2019 05:44:52 +0000, RMD wrote:

Quote:

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


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.
Quote:

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


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

Sylvia Else
Guest

Wed May 01, 2019 3:45 pm   



On 1/05/2019 3:44 pm, RMD wrote:
Quote:
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


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.

#BoycottEurovision2019
Guest

Thu May 02, 2019 5:45 am   



RMD wrote:
Quote:
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


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.

Computer Nerd Kev
Guest

Thu May 02, 2019 11:45 pm   



#BoycottEurovision2019 <jonahreal_at_yopmail.com> wrote:
Quote:

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.


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.

--
__ __
#_ < |\| |< _#

Chris
Guest

Fri May 03, 2019 1:45 am   



On Wednesday, 1 May 2019 15:44:53 UTC+10, RMD wrote:
Quote:
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


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

--
Chris.

news18
Guest

Fri May 03, 2019 2:45 am   



On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

Quote:
#BoycottEurovision2019 <jonahreal_at_yopmail.com> wrote:

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.

Except that if the device is designed to last (probably not in this
case),


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

Quote:
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.


Well, they are unlikely to be higher.

RMD
Guest

Fri May 03, 2019 2:45 am   



On Wed, 01 May 2019 05:44:52 GMT, rmd_at_invalid.invalid (RMD) wrote:

Quote:
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


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

FMurtz
Guest

Fri May 03, 2019 4:45 am   



news18 wrote:
Quote:
On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

#BoycottEurovision2019 <jonahreal_at_yopmail.com> wrote:

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.

Except that if the device is designed to last (probably not in this
case),

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

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.

Well, they are unlikely to be higher.

And if 16 definitely lower.


news18
Guest

Fri May 03, 2019 5:57 am   



On Fri, 03 May 2019 12:45:50 +1000, FMurtz wrote:

Quote:
news18 wrote:
On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

#BoycottEurovision2019 <jonahreal_at_yopmail.com> wrote:

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.

Except that if the device is designed to last (probably not in this
case),

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

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.

Well, they are unlikely to be higher.

And if 16 definitely lower.


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

Computer Nerd Kev
Guest

Fri May 03, 2019 11:45 pm   



news18 <news18_at_woa.com.au> wrote:
Quote:
On Fri, 03 May 2019 12:45:50 +1000, FMurtz wrote:
news18 wrote:
On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

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

Well, they are unlikely to be higher.

And if 16 definitely lower.

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


In which case the intended operating voltage of the circuit may be
6V, and connecting 12V may cause the voltage regulator to heat up
much more than its heatsinking was designed to handle. Hence even
if the regulator itself is rated for, say, 30V, it will be exposed
to excessive heat and fail early (though probably not immediately).

The cost between electrolytic capacitors of different voltage ratings
often isn't very great, so overspecifying them may be worth the small
extra cost for higher priced devices, given that they are a common
point of failure. Deciding to connect a voltage to a circuit just on
the basis that it's a little bit lower than the capacitor rating
strikes me as an approach that's likely to cause as much harm as
good.

Sure, it's a bad idea to connect a higher voltage than the capacitor
rating. But as far as determining what voltage you _will_ connect to
it, I don't see how that gets you anywhere.

--
__ __
#_ < |\| |< _#

#BoycottEurovision2019
Guest

Sat May 04, 2019 1:45 am   



Computer Nerd Kev wrote:
Quote:
#BoycottEurovision2019 <jonahreal_at_yopmail.com> wrote:

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.

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.


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

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


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.

#BoycottEurovision2019
Guest

Sat May 04, 2019 1:45 am   



RMD wrote:
Quote:
On Wed, 01 May 2019 05:44:52 GMT, rmd_at_invalid.invalid (RMD) wrote:

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

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!


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.

Quote:

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


RMD
Guest

Sat May 04, 2019 3:45 am   



On Sat, 4 May 2019 10:19:10 +1000, "#BoycottEurovision2019"
<jonahreal_at_yopmail.com> wrote:

Quote:
RMD wrote:
On Wed, 01 May 2019 05:44:52 GMT, rmd_at_invalid.invalid (RMD) wrote:

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

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!

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 .


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.


Quote:

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


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





news18
Guest

Sat May 04, 2019 8:45 am   



On Fri, 03 May 2019 22:15:56 +0000, Computer Nerd Kev wrote:

Quote:
news18 <news18_at_woa.com.au> wrote:
On Fri, 03 May 2019 12:45:50 +1000, FMurtz wrote:
news18 wrote:
On Thu, 02 May 2019 22:39:49 +0000, Computer Nerd Kev wrote:

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

Well, they are unlikely to be higher.

And if 16 definitely lower.

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

In which case the intended operating voltage of the circuit may be 6V,
and connecting 12V may cause the voltage regulator to heat up much more
than its heatsinking was designed to handle. Hence even if the regulator
itself is rated for, say, 30V, it will be exposed to excessive heat and
fail early (though probably not immediately).

The cost between electrolytic capacitors of different voltage ratings
often isn't very great, so overspecifying them may be worth the small
extra cost for higher priced devices, given that they are a common point
of failure. Deciding to connect a voltage to a circuit just on the basis
that it's a little bit lower than the capacitor rating strikes me as an
approach that's likely to cause as much harm as good.

Sure, it's a bad idea to connect a higher voltage than the capacitor
rating. But as far as determining what voltage you _will_ connect to it,
I don't see how that gets you anywhere.


Ther Op was discussing a hack, not circuitry design.

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