Testing small Transformer questions

I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff.
Im trying to learn how to test Transformers. This transformer says on it AM=
S10405 RG 1320F. I provide this to give all information, however Im not sur=
e it matters much to my question.

I have so far removed from what I can gather are the Primary wires from the=
 board. I assume they are because they are white and black and are literal =
wires going into transformer, as oppose to all the other connections which =
appear to be pins in the circuit board.  I believe to properly test transfo=
rmer you need to remove it fully eventually.

Here are my results with digital tester, When set to continuity, which appe=
ars to be (2) ohms setting.  I get Beep and .002 Ohms.
This seems to be very low ohms.
I do find it difficult when any information on testing transformers says ch=
eck with the data sheet. I'm sure someone will say sure here is the informa=
tion its easy to find.
Does .002 Ohms seem right for the primary.

Regards

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Hash: SHA512

On 2023-02-22, StevWolf wrote:
> I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff.
> Im trying to learn how to test Transformers. This transformer says on
> it AMS10405 RG 1320F. I provide this to give all information, however
> Im not sure it matters much to my question.

Can't find the part with a quick google.  I'm going to assume it's not
generally for sale (e.g. only sold in the Chinese market for making
other stuff with; or old).

>
> I have so far removed from what I can gather are the Primary wires
> from the board. I assume they are because they are white and black and
> are literal wires going into transformer, as oppose to all the other
> connections which appear to be pins in the circuit board.  I believe
> to properly test transformer you need to remove it fully eventually.
>
> Here are my results with digital tester, When set to continuity, which
> appears to be (2) ohms setting.  I get Beep and .002 Ohms.
> This seems to be very low ohms.

Might be that you're misinterpreting the meter.  Mine here _always_
shows the decimal point when in continuity mode. If yours is like mine
in that regard, it's not supposed to be read as  "2 milliohms", but
rather "2 ohms" (which might be a concerningly high value, depending on
how large this transformer happens to be).

Quick sanity check for yourself -- grab something you know the
resistance of (or can check easily), such as a 100 ohm resistor.  You'll
probably see it displayed in the range of " .105" to " .095" (under the
assumption of a standard 5% tolerance resistor).  

My meter here does have some error between resistance and continuity,
generally with continuity mode showing an ohm or two less than
resistance mode; at least across the 10 resistors I tested with just
now.

HTH :)



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-- 
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1  E067 6D65 70E5 4CE7 2860

> On 2023-02-22, StevWolf wrote:=20
> > I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff.=20
> > Im trying to learn how to test Transformers. This transformer says on=
=20
> > it AMS10405 RG 1320F. I provide this to give all information, however=
=20
> > Im not sure it matters much to my question.
> Can't find the part with a quick google. I'm going to assume it's not=20
> generally for sale (e.g. only sold in the Chinese market for making=20
> other stuff with; or old).
> >=20
> > I have so far removed from what I can gather are the Primary wires=20
> > from the board. I assume they are because they are white and black and=
=20
> > are literal wires going into transformer, as oppose to all the other=20
> > connections which appear to be pins in the circuit board. I believe=20
> > to properly test transformer you need to remove it fully eventually.=20
> >=20
> > Here are my results with digital tester, When set to continuity, which=
=20
> > appears to be (2) ohms setting. I get Beep and .002 Ohms.=20
> > This seems to be very low ohms.
> Might be that you're misinterpreting the meter. Mine here _always_=20
> shows the decimal point when in continuity mode. If yours is like mine=20
> in that regard, it's not supposed to be read as "2 milliohms", but=20
> rather "2 ohms" (which might be a concerningly high value, depending on=
=20
> how large this transformer happens to be).=20
>=20
> Quick sanity check for yourself -- grab something you know the=20
> resistance of (or can check easily), such as a 100 ohm resistor. You'll=
=20
> probably see it displayed in the range of " .105" to " .095" (under the=
=20
> assumption of a standard 5% tolerance resistor).=20
>=20
> My meter here does have some error between resistance and continuity,=20
> generally with continuity mode showing an ohm or two less than=20
> resistance mode; at least across the 10 resistors I tested with just=20
> now.=20
>=20
> HTH :)=20
>=20

Well thanks for your comments. You have encouraged me to dig into my meter =
a bit.
 Here are some results of my meter using some resistors I have.

100R set to 200  is 107 Ohms - Ok I guess
1 R set to Continuity says .974 Ohms - Yes seems OK.
.39 R set to Continuity says .002  - thats close
.39 set to 200 says  3.6 (which seems odd to me)

Importantly The manual for the for the meter seems to say that it will show=
 continuity for anything less than 50ohms.
Also while the meter has no information about the following, in the manual,=
 when I set it to Continuity there is a little 2 under the decimal point, i=
n the same way that it shows up when set to 200 for example with the respec=
tive 200 under the decimal. I asume that means 2  Ohms,=20

Sooo Im still trying to figure out if this transformer primary is bad?
Maybe transformers which are basically two sets of winding in simple transf=
ormers dont have much resistance.=20
I mean wire has loss but not a lot. ??=20
Again Im just trying to learn and understand.

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Hash: SHA512

On 2023-02-22, StevWolf wrote:
> [on 2023-02-22, I wrote]
>> [...]
>> Quick sanity check for yourself -- grab something you know the 
>> resistance of (or can check easily), such as a 100 ohm resistor. You'll 
>> probably see it displayed in the range of " .105" to " .095" (under the 
>> assumption of a standard 5% tolerance resistor). 
>> 
>> My meter here does have some error between resistance and continuity, 
>> generally with continuity mode showing an ohm or two less than 
>> resistance mode; at least across the 10 resistors I tested with just 
>> now. 
>> 
>> HTH :) 
>> 
>
> Well thanks for your comments. You have encouraged me to dig into my
> meter a bit.
>  Here are some results of my meter using some resistors I have.
>
> 100R set to 200  is 107 Ohms - Ok I guess

107 ohms is within 10% tolerance; so it's fine assuming it's got a
silver (or no) tolerance band. What did this show in continuity mode?

The range doesn't "really" come into play here (it just means you can
accurately measure from 0 Ohms to 199 Ohms; usually to the nearest
tenth)

> 1 R set to Continuity says .974 Ohms - Yes seems OK.

What did this resistor show in Resistance mode?  I mean if your display
works the same as mine, it's showing just shy of 1k ohms.

> .39 R set to Continuity says .002  - thats close
> .39 set to 200 says  3.6 (which seems odd to me

With the assumption your display operates the same as mine, 2 ohms is
nowhere near 0.39 Ohms. Likewise if it really is showing milliohms; 2
milliohms is nowhere near 390 milliohms.

3.6 ohms reading on a 3.9 ohm resistor is within 10% tolerance.  Color
marking would be Orange, White, Gold; with a Silver (or no) tolerance
band.

(0.39 ohms would be Orange|White|Silver).

>
> Importantly The manual for the for the meter seems to say that it will
> show continuity for anything less than 50ohms.

Means it'll beep if the circuit total resistance is 50 Ohm or less -- so
a 100 Ohm resistor will never beep, but a 47 Ohm resistor most likely
will (noting, of course that 10% tolerance can get you as high as 51
Ohms).

> Also while the meter has no information about the following, in the
> manual, when I set it to Continuity there is a little 2 under the
> decimal point, in the same way that it shows up when set to 200 for
> example with the respective 200 under the decimal. I asume that means
> 2  Ohms, 

What's the meter make/model?

>
> Sooo Im still trying to figure out if this transformer primary is bad?

You get continuity, chances are "no", unless it's supposed to have more
resistance than it does.  But we'd need a datasheet or technical manual
to know for sure (I mean I have a couple of old rail locomotive
maintenance manuals that're like "if you need to rewrap the solenoid,
use 28AWG magnet wire until you get 75 ohms in the coil")

> Maybe transformers which are basically two sets of winding in simple
> transformers dont have much resistance. 

Depends on the wire gauge.  For example, 30 AWG magnet wire is something
like 100 Ohms / 1000 feet.  


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-- 
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1  E067 6D65 70E5 4CE7 2860

On Thursday, February 23, 2023 at 6:43:16=E2=80=AFAM UTC-5, Dan Purgert wro=
te:
> -----BEGIN PGP SIGNED MESSAGE-----=20
> Hash: SHA512=20
>=20
> On 2023-02-22, StevWolf wrote:
> > [on 2023-02-22, I wrote]=20
> >> [...]
> >> Quick sanity check for yourself -- grab something you know the=20
> >> resistance of (or can check easily), such as a 100 ohm resistor. You'l=
l=20
> >> probably see it displayed in the range of " .105" to " .095" (under th=
e=20
> >> assumption of a standard 5% tolerance resistor).=20
> >>=20
> >> My meter here does have some error between resistance and continuity,=
=20
> >> generally with continuity mode showing an ohm or two less than=20
> >> resistance mode; at least across the 10 resistors I tested with just=
=20
> >> now.=20
> >>=20
> >> HTH :)=20
> >>=20
> >=20
> > Well thanks for your comments. You have encouraged me to dig into my=20
> > meter a bit.=20
> > Here are some results of my meter using some resistors I have.=20
> >=20
> > 100R set to 200 is 107 Ohms - Ok I guess
> 107 ohms is within 10% tolerance; so it's fine assuming it's got a=20
> silver (or no) tolerance band. What did this show in continuity mode?=20
>=20
> The range doesn't "really" come into play here (it just means you can=20
> accurately measure from 0 Ohms to 199 Ohms; usually to the nearest=20
> tenth)
> > 1 R set to Continuity says .974 Ohms - Yes seems OK.
> What did this resistor show in Resistance mode? I mean if your display=20
> works the same as mine, it's showing just shy of 1k ohms.
> > .39 R set to Continuity says .002 - thats close=20
> > .39 set to 200 says 3.6 (which seems odd to me
> With the assumption your display operates the same as mine, 2 ohms is=20
> nowhere near 0.39 Ohms. Likewise if it really is showing milliohms; 2=20
> milliohms is nowhere near 390 milliohms.=20
>=20
> 3.6 ohms reading on a 3.9 ohm resistor is within 10% tolerance. Color=20
> marking would be Orange, White, Gold; with a Silver (or no) tolerance=20
> band.=20
>=20
> (0.39 ohms would be Orange|White|Silver).
> >=20
> > Importantly The manual for the for the meter seems to say that it will=
=20
> > show continuity for anything less than 50ohms.
> Means it'll beep if the circuit total resistance is 50 Ohm or less -- so=
=20
> a 100 Ohm resistor will never beep, but a 47 Ohm resistor most likely=20
> will (noting, of course that 10% tolerance can get you as high as 51=20
> Ohms).
> > Also while the meter has no information about the following, in the=20
> > manual, when I set it to Continuity there is a little 2 under the=20
> > decimal point, in the same way that it shows up when set to 200 for=20
> > example with the respective 200 under the decimal. I asume that means=
=20
> > 2 Ohms,
> What's the meter make/model?
> >=20
> > Sooo Im still trying to figure out if this transformer primary is bad?
> You get continuity, chances are "no", unless it's supposed to have more=
=20
> resistance than it does. But we'd need a datasheet or technical manual=20
> to know for sure (I mean I have a couple of old rail locomotive=20
> maintenance manuals that're like "if you need to rewrap the solenoid,=20
> use 28AWG magnet wire until you get 75 ohms in the coil")
> > Maybe transformers which are basically two sets of winding in simple=20
> > transformers dont have much resistance.
> Depends on the wire gauge. For example, 30 AWG magnet wire is something=
=20
> like 100 Ohms / 1000 feet.=20
>=20
>=20
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>=20
> --=20
> |_|O|_|=20
> |_|_|O| Github: https://github.com/dpurgert=20
> |O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

Well to try to answer questions,
100 ohm Resistor on continuity is .145 oddly
.39 ohm Resistor on 200 scale is 7.6 again oddly=20
Model of meter is MTP model 2322

The thing is its dashes ones Hope's when every website on testing says chec=
k data sheet, when they are so scarce if at all. And the numbers on the tra=
nsformer so cryptic.  I get that you need it but, they seem hard to come by=
 so i assume you there must be charts to guestemate .
I dunno.
Regards.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

On 2023-02-23, StevWolf wrote:
> On Thursday, February 23, 2023 at 6:43:16 AM UTC-5, Dan Purgert wrote:
>> > 100R set to 200 is 107 Ohms - Ok I guess
>> 107 ohms is within 10% tolerance; so it's fine assuming it's got a 
>> silver (or no) tolerance band. What did this show in continuity mode? 
>> 
>> The range doesn't "really" come into play here (it just means you can 
>> accurately measure from 0 Ohms to 199 Ohms; usually to the nearest 
>> tenth)
>> [...]
>
> Well to try to answer questions,
> 100 ohm Resistor on continuity is .145 oddly

Okay, and it shows 100 (+/- 10%) on the Resistance scale?

> .39 ohm Resistor on 200 scale is 7.6 again oddly 

What's the banding on this resistor? Also; have you checked the leads
themselves?

> Model of meter is MTP model 2322

I can't find a single thing about this online.  Must be old?

>
> The thing is its dashes ones Hope's when every website on testing says
> check data sheet, when they are so scarce if at all. And the numbers
> on the transformer so cryptic.  I get that you need it but, they seem
> hard to come by so i assume you there must be charts to guestemate .

No, there are datasheets... but old stuff might not have them (or
they're limited to china markets )


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-- 
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1  E067 6D65 70E5 4CE7 2860

On Thursday, February 23, 2023 at 6:26:45 PM UTC-5, Dan Purgert wrote:
> -----BEGIN PGP SIGNED MESSAGE----- 
> Hash: SHA512
> On 2023-02-23, StevWolf wrote: 
> > On Thursday, February 23, 2023 at 6:43:16 AM UTC-5, Dan Purgert wrote: 
> >> > 100R set to 200 is 107 Ohms - Ok I guess 
> >> 107 ohms is within 10% tolerance; so it's fine assuming it's got a 
> >> silver (or no) tolerance band. What did this show in continuity mode? 
> >> 
> >> The range doesn't "really" come into play here (it just means you can 
> >> accurately measure from 0 Ohms to 199 Ohms; usually to the nearest 
> >> tenth)
> >> [...]
> > 
> > Well to try to answer questions, 
> > 100 ohm Resistor on continuity is .145 oddly
> Okay, and it shows 100 (+/- 10%) on the Resistance scale?
> > .39 ohm Resistor on 200 scale is 7.6 again oddly
> What's the banding on this resistor? Also; have you checked the leads 
> themselves?
> > Model of meter is MTP model 2322
> I can't find a single thing about this online. Must be old?
> > 
> > The thing is its dashes ones Hope's when every website on testing says 
> > check data sheet, when they are so scarce if at all. And the numbers 
> > on the transformer so cryptic. I get that you need it but, they seem 
> > hard to come by so i assume you there must be charts to guestemate .
> No, there are datasheets... but old stuff might not have them (or 
> they're limited to china markets ) 

Yes the 100 ohm resistor  shows 100 ohms on the 200 scale.

The .39 ohm resistor is a 2 watt  orange, white, silver, gold.

The leads are in good condition. 

Actually I have found several links for this meter. Here is one.

https://www.directindustry.com/prod/mtp-instruments-inc/product-131921-1932654.html

Well as far as data sheets for transformers I find for me anyway,  I do not find them as easy to find as common as other small parts, I mean you can find a data sheet on almost any old transistor, triac diac or component etc. But l find transformers less available. And if Chinese transformers are less likely then we are really out of luck as almost everything is made there. 

Regards.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

On 2023-02-25, StevWolf wrote:
> On Thursday, February 23, 2023 at 6:26:45 PM UTC-5, Dan Purgert wrote:
>> On 2023-02-23, StevWolf wrote: 
>>> [...]
>> > 100 ohm Resistor on continuity is .145 oddly
>> Okay, and it shows 100 (+/- 10%) on the Resistance scale?
>> > .39 ohm Resistor on 200 scale is 7.6 again oddly
>> What's the banding on this resistor? Also; have you checked the leads 
>> themselves?
>> > Model of meter is MTP model 2322
>> I can't find a single thing about this online. Must be old?
>> [...]
>> No, there are datasheets... but old stuff might not have them (or 
>> they're limited to china markets ) 
>
> Yes the 100 ohm resistor  shows 100 ohms on the 200 scale.

Perfect.  Sounds like the continuity scale is off by a considerable
amount then.

>
> The .39 ohm resistor is a 2 watt  orange, white, silver, gold.

Perfect.  That might simply be too low if the LOWEST range your meter
does is 200 ohms. You'd likely want a 20 or 2 ohm range.

>
> The leads are in good condition. 

More that they can impart resistance / capacitance / etc into a circuit;
also selection of the terminals on the meter can matter.

>
> Actually I have found several links for this meter. Here is one.
>
> https://www.directindustry.com/prod/mtp-instruments-inc/product-131921-1932654.html

Yeah, I found that too; but no real information to be had.  They only
have a defunct link to the manufacturer's website for more details.

>
> Well as far as data sheets for transformers I find for me anyway,  I
> do not find them as easy to find as common as other small parts, I
> mean you can find a data sheet on almost any old transistor, triac
> diac or component etc. But l find transformers less available. And if
> Chinese transformers are less likely then we are really out of luck as
> almost everything is made there. 

There's a difference between "made for chinese markets" (such as what
one finds inside a cheapo USB hub / power supply / etc), and "made for
export markets" (such as what one finds everywhere).


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|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1  E067 6D65 70E5 4CE7 2860

On Friday, February 24, 2023 at 8:11:10 PM UTC-6, StevWolf wrote:
> On Thursday, February 23, 2023 at 6:26:45 PM UTC-5, Dan Purgert wrote: 
> > -----BEGIN PGP SIGNED MESSAGE----- 
> > Hash: SHA512 
> > On 2023-02-23, StevWolf wrote: 
> > > On Thursday, February 23, 2023 at 6:43:16 AM UTC-5, Dan Purgert wrote: 
> > >> > 100R set to 200 is 107 Ohms - Ok I guess 
> > >> 107 ohms is within 10% tolerance; so it's fine assuming it's got a 
> > >> silver (or no) tolerance band. What did this show in continuity mode? 
> > >> 
> > >> The range doesn't "really" come into play here (it just means you can 
> > >> accurately measure from 0 Ohms to 199 Ohms; usually to the nearest 
> > >> tenth) 
> > >> [...] 
> > > 
> > > Well to try to answer questions, 
> > > 100 ohm Resistor on continuity is .145 oddly 
> > Okay, and it shows 100 (+/- 10%) on the Resistance scale? 
> > > .39 ohm Resistor on 200 scale is 7.6 again oddly 
> > What's the banding on this resistor? Also; have you checked the leads 
> > themselves? 
> > > Model of meter is MTP model 2322 
> > I can't find a single thing about this online. Must be old? 
> > > 
> > > The thing is its dashes ones Hope's when every website on testing says 
> > > check data sheet, when they are so scarce if at all. And the numbers 
> > > on the transformer so cryptic. I get that you need it but, they seem 
> > > hard to come by so i assume you there must be charts to guestemate . 
> > No, there are datasheets... but old stuff might not have them (or 
> > they're limited to china markets )
> Yes the 100 ohm resistor shows 100 ohms on the 200 scale. 
> 
> The .39 ohm resistor is a 2 watt orange, white, silver, gold. 
> 
> The leads are in good condition. 
> 
> Actually I have found several links for this meter. Here is one. 
> 
> https://www.directindustry.com/prod/mtp-instruments-inc/product-131921-1932654.html 
> 
> Well as far as data sheets for transformers I find for me anyway, I do not find them as easy to find as common as other small parts, I mean you can find a data sheet on almost any old transistor, triac diac or component etc. But l find transformers less available. And if Chinese transformers are less likely then we are really out of luck as almost everything is made there. 
> 
> Regards.
 Put that 100Ω resistor in series with the transformer primary and measure the resistance of both of them together.
It should read 190Ω to 500Ω.
I just pulled 4 random old style wallwarts and measured 90Ωs to 359Ωs.
Is this an old style transformer and diode style or a lightweight switching type wallwart?
Old style will only have a few parts maybe 6 or less. Is there a fuse that you can see?
Old style you won't see it, new style it may or may not be covered with heat shrink tubing.
                                        Mikek