Phil Allison
Guest
Mon Aug 29, 2011 2:54 am
** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor ( ie
in a speaker crossover network ) or transformer winding in parallel - as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple voltage
test, it tells you a lot about the condition and state of charge of such
cells.
One more use is when servicing SMPS - often a MOSFET or high speed diode
will have a switching transformer winding in parallel making it test *dead
short* with an ohm meter.
Instead cutting leads to isolate the part so you can test it, just use Bob's
meter.
You will soon see if it really is shorted or not.
.... Phil
Tom
Guest
Mon Aug 29, 2011 6:08 am
On 29/08/2011 12:54 PM, Phil Allison wrote:
Quote:
** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor ( ie
in a speaker crossover network ) or transformer winding in parallel - as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple voltage
test, it tells you a lot about the condition and state of charge of such
cells.
How much DC voltage can you apply to Bob's meter?
Quote:
One more use is when servicing SMPS - often a MOSFET or high speed diode
will have a switching transformer winding in parallel making it test *dead
short* with an ohm meter.
Instead cutting leads to isolate the part so you can test it, just use Bob's
meter.
You will soon see if it really is shorted or not.
... Phil
Clifford Heath
Guest
Mon Aug 29, 2011 7:52 am
Phil,
That's excellent - thanks so much for reporting.
I've had one of these kits unbuilt on the shelf
for over a year now - musty put it together!
Clifford Heath.
Phil Allison
Guest
Mon Aug 29, 2011 8:34 am
"Tom"
Phil Allison wrote:
Quote:
How much DC voltage can you apply to Bob's meter?
** See schem of Mk 2 version:
http://electronichobby.info/wp-content/uploads/2011/05/digital-esr-meter-mk2-circuit-board.jpg
In theory - up to 50 volts DC, providing C6 is rated for that.
In practice - any DC voltage you like IF you use an electro cap of about
100uF to isolate DC to the meter.
Step 1.
Zero the ESR meter with the electro in series.
Step 2.
Charge the electro across the DC voltage source.
Step 3.
Connect the electro and ESR meter across the DC source in series.
NB
Don't let the voltage source or the electro BITE you !!
..... Phil
Ian Field
Guest
Mon Aug 29, 2011 1:45 pm
"Tom" <tom_at_no.spam.invalid> wrote in message
news:j3facc$m6k$1_at_dont-email.me...
Quote:
On 29/08/2011 12:54 PM, Phil Allison wrote:
** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's
famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor
( ie
in a speaker crossover network ) or transformer winding in parallel -
as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the
tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple
voltage
test, it tells you a lot about the condition and state of charge of such
cells.
How much DC voltage can you apply to Bob's meter?
IIRC there's a 47uF non-polar electrolytic in series with the input.
If you borrow someone else's meter, bear in mind that some people who
regularly check electrolytics in TV PSUs put an inverse parallel pair of
diodes across the input as a safeguard against forgetting to discharge HV
electros before testing.
Such a mishap can blow the micro, and I imagine there must be only a finite
remaining stock of spares anywhere, silicon rectifiers on the other
hand..........
David
Guest
Tue Aug 30, 2011 1:15 am
In article <9c0da0F6dkU1_at_mid.individual.net>,
"Phil Allison" <phil_a_at_tpg.com.au> wrote:
Quote:
** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor ( ie
in a speaker crossover network ) or transformer winding in parallel - as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple voltage
test, it tells you a lot about the condition and state of charge of such
cells.
One more use is when servicing SMPS - often a MOSFET or high speed diode
will have a switching transformer winding in parallel making it test *dead
short* with an ohm meter.
Instead cutting leads to isolate the part so you can test it, just use Bob's
meter.
You will soon see if it really is shorted or not.
... Phil
....and I have an unbuilt kit I want to sell - any interest here? any
offers?
David
Joseph Webster
Guest
Tue Mar 06, 2012 5:22 am
On 30/8/11 10:45 AM, David wrote:
Quote:
In article<9c0da0F6dkU1_at_mid.individual.net>,
"Phil Allison"<phil_a_at_tpg.com.au> wrote:
** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor ( ie
in a speaker crossover network ) or transformer winding in parallel - as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple voltage
test, it tells you a lot about the condition and state of charge of such
cells.
One more use is when servicing SMPS - often a MOSFET or high speed diode
will have a switching transformer winding in parallel making it test *dead
short* with an ohm meter.
Instead cutting leads to isolate the part so you can test it, just use Bob's
meter.
You will soon see if it really is shorted or not.
... Phil
...and I have an unbuilt kit I want to sell - any interest here? any
offers?
David
Do you still have it?
How much?
Joseph
