Unknown device "3B" on motor drive boards.

[Robbie Hatley]

Greeetings, group. Lately I've been repairing motor drive boards
for variable-frequency 3-phase AC motors. (These typically use
a diode bridge to rectify 120VAC to 160VDC, then feed the 160VDC
into a network of 6 IGBTs to generate the variable-frequency AC
to power the motor.)

At least 2 of these motor drive boards (one from Advanced Drive
Technology, one from Hyundai) also have switching power supply
circuits for generating low voltages needed (+5V, +12V, -8V, etc),
and these circuits all use a transistor switching a transformer,
with a feedback circuit using a P181 optocoupler and an unknown
device (dual zener?) labeled just "3B". The "3B" device is
designated "ZD3", so I'm assuming it's a dual zener diode, but
I haven't been able to identify it. It looks like this:

http://www.well.com/~lonewolf/3B.jpg

It's surface-mount, with the tab and all 3 pins soldered to the board.
Pin 2 and the tab are connected together internally, and connect to
ground externally.

With my meter set to "Diode", i'm seeing a diode from p1 to p3
and a diode from p2 to p3. The reading between p1 and p2 is
indeterminant.

Anyone have an idea of what this part is?

--
Puzzled,
Robbie Hatley
hatley [dot] software [at] gmail [dot] com

 

[Arfa Daily]

"Robbie Hatley" <see.my.sig@for.my.contact.info> wrote in message
news:UtCdnXRSfbO-4-_TRVn_vwA@giganews.com...

Greeetings, group. Lately I've been repairing motor drive boards
for variable-frequency 3-phase AC motors. (These typically use
a diode bridge to rectify 120VAC to 160VDC, then feed the 160VDC
into a network of 6 IGBTs to generate the variable-frequency AC
to power the motor.)

At least 2 of these motor drive boards (one from Advanced Drive
Technology, one from Hyundai) also have switching power supply
circuits for generating low voltages needed (+5V, +12V, -8V, etc),
and these circuits all use a transistor switching a transformer,
with a feedback circuit using a P181 optocoupler and an unknown
device (dual zener?) labeled just "3B". The "3B" device is
designated "ZD3", so I'm assuming it's a dual zener diode, but
I haven't been able to identify it. It looks like this:

http://www.well.com/~lonewolf/3B.jpg

It's surface-mount, with the tab and all 3 pins soldered to the board.
Pin 2 and the tab are connected together internally, and connect to
ground externally.

With my meter set to "Diode", i'm seeing a diode from p1 to p3
and a diode from p2 to p3. The reading between p1 and p2 is
indeterminant.

Anyone have an idea of what this part is?

--
Puzzled,
Robbie Hatley
hatley [dot] software [at] gmail [dot] com

This any use, maybe ?

http://www.marsport.org.uk/smd/mainframe.htm

The section on "HP Diode Coding" looks as though it might contain some
relevant numbering to what you have ??

Arfa

 

[Franc Zabkar]

On Thu, 15 Sep 2011 15:37:23 -0700, "Robbie Hatley"
<see.my.sig@for.my.contact.info> put finger to keyboard and composed:

At least 2 of these motor drive boards (one from Advanced Drive
Technology, one from Hyundai) also have switching power supply
circuits for generating low voltages needed (+5V, +12V, -8V, etc),
and these circuits all use a transistor switching a transformer,
with a feedback circuit using a P181 optocoupler and an unknown
device (dual zener?) labeled just "3B". The "3B" device is
designated "ZD3", so I'm assuming it's a dual zener diode, but
I haven't been able to identify it. It looks like this:

http://www.well.com/~lonewolf/3B.jpg

It's surface-mount, with the tab and all 3 pins soldered to the board.
Pin 2 and the tab are connected together internally, and connect to
ground externally.

With my meter set to "Diode", i'm seeing a diode from p1 to p3
and a diode from p2 to p3. The reading between p1 and p2 is
indeterminant.

Anyone have an idea of what this part is?

If you hadn't identified the component as a dual zener, I would have
guessed that it was a PNP transistor with an ECB (123) pinout.

In fact I can't recall seeing a dual diode package where the tab
wasn't either the common anode or common cathode. But then my memory
isn't the best anymore ...

Can you help us out with a little circuit tracing? The circuitry in
that area is typically very simple. In fact, we may be able to work
out the zener voltage(s) by knowing the output voltage of the supply
plus the values of any feedback resistors in potential dividers, etc.

Could we see a close-up photo?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[spamtrap1888]

On Sep 15, 6:11 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:

"Robbie Hatley" <see.my....@for.my.contact.info> wrote in message

news:UtCdnXRSfbO-4-_TRVn_vwA@giganews.com...









Greeetings, group.  Lately I've been repairing motor drive boards
for variable-frequency 3-phase AC motors.  (These typically use
a diode bridge to rectify 120VAC to 160VDC, then feed the 160VDC
into a network of 6 IGBTs to generate the variable-frequency AC
to power the motor.)

At least 2 of these motor drive boards (one from Advanced Drive
Technology, one from Hyundai) also have switching power supply
circuits for generating low voltages needed (+5V, +12V, -8V, etc),
and these circuits all use a transistor switching a transformer,
with a feedback circuit using a P181 optocoupler and an unknown
device (dual zener?) labeled just "3B".  The "3B" device is
designated "ZD3", so I'm assuming it's a dual zener diode, but
I haven't been able to identify it.  It looks like this:

http://www.well.com/~lonewolf/3B.jpg

It's surface-mount, with the tab and all 3 pins soldered to the board.
Pin 2 and the tab are connected together internally, and connect to
ground externally.

With my meter set to "Diode", i'm seeing a diode from p1 to p3
and a diode from p2 to p3.  The reading between p1 and p2 is
indeterminant.

Anyone have an idea of what this part is?

--
Puzzled,
Robbie Hatley
hatley [dot] software [at] gmail [dot] com

This any use, maybe ?

http://www.marsport.org.uk/smd/mainframe.htm

The section on "HP Diode Coding" looks as though it might contain some
relevant numbering to what you have ??

HP microwave diodes did not include zeners, as far as I know. Intended
for receiver applications, mixers, etc., they don't seem right for
160Vpk applications.

This manual indicates that "3B" could be either a pnp or npn
transistor:

http://elektronik.googlecode.com/files/SMD_Catalog222.pdf
http://elektronik.googlecode.com/files/SMD_Catalog222.pdf

 

[Robbie Hatley]

Franc Zabkar writes:

If you hadn't identified the component as a dual zener, I would have
guessed that it was a PNP transistor with an ECB (123) pinout.

Yah, it does look sort of like a transistor, both visually and on meter.
However, I have reasons to believe its actually some kind of multiple-
zener-diode contraption. More on this below....

In fact I can't recall seeing a dual diode package where the tab
wasn't either the common anode or common cathode. But then my memory
isn't the best anymore ...

I'm guessing pin 2 is common anode, but the two zeners are very different
breakdown voltages (like 1V and 5V or something like that), so that the
zener from pin 2 to pin 1 conducts both ways on a diode meter, but the
zener from pin 2 to pin 3 doesn't.

Can you help us out with a little circuit tracing? The circuitry in
that area is typically very simple. In fact, we may be able to work
out the zener voltage(s) by knowing the output voltage of the supply
plus the values of any feedback resistors in potential dividers, etc.

Many of today's switching power supplies use a transformer
switched by a transistor or even directly by a PWM controller IC.
The transistor or controller gets feedback from the transformer via
an optocoupler (P181 is almost invariably used), with the LED
cathode of the optocoupler fed to ground through a back-biased
zener diode. Sort of like this appnote for the 2A265 PWM controller:
http://www.well.com/~lonewolf/appnote.gif

The zener diode, in practice, is typically pins 2,3 of the mystery
"3B" device I'm trying to identify.

For example, one of the circuits this part appears in is the Hyundai N100
motor controller. The power supply board on that looks like this:
http://www.well.com/~lonewolf/schematic.gif

Note that if you envision a zener diode in the "3B" device with
cathode on pin 3 and anode on pin 2, it becomes much like the
appnote I link-to above. (As to what pin 1 is connected to
internally, I have no idea yet.)

Could we see a close-up photo?

My camera, even set to "macro", can't give a good image of an SMD.
The diagram I linked to in my OP gives a good idea of what it looks like,
though: http://www.well.com/~lonewolf/3B.jpg

Oh, and I did find the package name for that shape: its "SO- 89".
Here's what the SO-89 package looks like:
http://cdn.sigma.octopart.com/8898728/image/Rohm-2SB1132T100Q.jpg
(Turns out, the tab and pin 2 are all one piece. Can't see that from top side,
but on removing the part, I can see that it's so.)

So now its a matter of finding a SO-89 device with a zener diode from
pin 2 to pin 3, and (????) from pin 2 to pin 1.

I've seen this "3B" gizmo on boards from 2 different manufacturers, so
I'm assuming its actually a common part in switching power supplies.
So I'm surprised I haven't been able to track it down yet.

--
Still puzzled,
Robbie Hatley
Hatley [dot] Software [at] gmail [dot] com

 

[whit3rd]

The most common item that one sees in a switching supply
next to an optoisolator is a TL431 programmable zener
(actually a voltage reference/error amplifier combination).
Possibly that's what you have, they're multiple-sourced
in LOTS of package styles.

 

[Franc Zabkar]

On Fri, 16 Sep 2011 15:49:49 -0700, "Robbie Hatley"
<see.my.sig@for.my.contact.info> put finger to keyboard and composed:

For example, one of the circuits this part appears in is the Hyundai N100
motor controller. The power supply board on that looks like this:
http://www.well.com/~lonewolf/schematic.gif

Note that if you envision a zener diode in the "3B" device with
cathode on pin 3 and anode on pin 2, it becomes much like the
appnote I link-to above. (As to what pin 1 is connected to
internally, I have no idea yet.)

ZD3 in that schematic looks exactly like the TL431 whit3rd alluded to.

A TL431 is effectively a programmable precision zener diode. It has an
internal 2.5V reference. The potential divider consisting of R13 and
R11 sets the output voltage to ...

Vo = 2.5 x [1K / (1K + 1K)] = +5V

http://www.fairchildsemi.com/ds/TL/TL431A.pdf
http://www.ti.com/lit/ds/symlink/tl431a.pdf

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Franc Zabkar]

On Sat, 17 Sep 2011 09:57:33 +1000, Franc Zabkar
<fzabkar@iinternode.on.net> put finger to keyboard and composed:

The potential divider consisting of R13 and
R11 sets the output voltage to ...

Vo = 2.5 x [1K / (1K + 1K)] = +5V

Sorry, that should have been ...

Vo = 2.5 x [ (1K + 1K) / 1K ] = +5V

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Jamie]

Robbie Hatley wrote:

Franc Zabkar writes:


If you hadn't identified the component as a dual zener, I would have
guessed that it was a PNP transistor with an ECB (123) pinout.


Yah, it does look sort of like a transistor, both visually and on meter.
However, I have reasons to believe its actually some kind of multiple-
zener-diode contraption. More on this below....


In fact I can't recall seeing a dual diode package where the tab
wasn't either the common anode or common cathode. But then my memory
isn't the best anymore ...



I'm guessing pin 2 is common anode, but the two zeners are very different
breakdown voltages (like 1V and 5V or something like that), so that the
zener from pin 2 to pin 1 conducts both ways on a diode meter, but the
zener from pin 2 to pin 3 doesn't.

The legs that conduct both ways and the other one not at all, may
indicate it being an Thyristor. SCR/TRIAC etc..

If the value of this two way conduction in down around 100 ohms or
less, I would say that is what you have, which would be the
Gate-cathode(K) you're seeing.
If so, here is some resource you can use on testing thyristors with a DMM.

http://www.ab.com/support/abdrives/documentation/fb/1012.pdf

Just a thought.

Jamie

 

[N_Cook]

Robbie Hatley <see.my.sig@for.my.contact.info> wrote in message
news:97SdnRr-IssNT-7T4p2dnAA@giganews.com...

Franc Zabkar writes:

My camera, even set to "macro", can't give a good image of an SMD.
The diagram I linked to in my OP gives a good idea of what it looks like,
though: http://www.well.com/~lonewolf/3B.jpg

Hold a hand magnifying lens over the camera lens for an impromptu macro
set-up. Take shots at different by 1/4 inch measured spacings for future
reference of the exact focus distance.

 

[Michael A. Terrell]

N_Cook wrote:

Robbie Hatley <see.my.sig@for.my.contact.info> wrote in message
news:97SdnRr-IssNT-7T4p2dnAA@giganews.com...
Franc Zabkar writes:

My camera, even set to "macro", can't give a good image of an SMD.
The diagram I linked to in my OP gives a good idea of what it looks like,
though: http://www.well.com/~lonewolf/3B.jpg


Hold a hand magnifying lens over the camera lens for an impromptu macro
set-up. Take shots at different by 1/4 inch measured spacings for future
reference of the exact focus distance.

I lay a circuit board on an old flatbed scanner to get good images,
if there are no tall components. If they do, I use my Fuji Finepix
S5200 in macro mode.


--
You can't have a sense of humor, if you have no sense.

 

[Arfa Daily]

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:17o777dq4n9ks5nb8jurlvqe1mdehomk24@4ax.com...

On Fri, 16 Sep 2011 15:49:49 -0700, "Robbie Hatley"
see.my.sig@for.my.contact.info> put finger to keyboard and composed:

For example, one of the circuits this part appears in is the Hyundai N100
motor controller. The power supply board on that looks like this:
http://www.well.com/~lonewolf/schematic.gif

Note that if you envision a zener diode in the "3B" device with
cathode on pin 3 and anode on pin 2, it becomes much like the
appnote I link-to above. (As to what pin 1 is connected to
internally, I have no idea yet.)

ZD3 in that schematic looks exactly like the TL431 whit3rd alluded to.

A TL431 is effectively a programmable precision zener diode. It has an
internal 2.5V reference. The potential divider consisting of R13 and
R11 sets the output voltage to ...

Vo = 2.5 x [1K / (1K + 1K)] = +5V

http://www.fairchildsemi.com/ds/TL/TL431A.pdf
http://www.ti.com/lit/ds/symlink/tl431a.pdf

- Franc Zabkar
--

I'm with you on that one Franc. They are very common on the TV LCD switchers
that I repair quite often. The reason that I had hesitated on this, is that
I don't think I have seen one before in that package, with the solder-down
tab at the top. However, if there is a version in that package, then I agree
that it does seem to be in the right position in the schematic, and the
resistors wrapped around it work out very neatly. I have also found that
just because it says something like "ZD" as a component identifier, these
days, you can't necessarily trust that as being a zener diode. Likewise, you
can't always trust symbols on schematics. The designers use CAD packages for
preparing PCBs and documentation (when they even bother with that!) and they
have a tendency to just use the libraries of parts that come with their
package. This means that every now and then, they use a device in their
design that has no symbol in the library. Rather than do the proper thing,
and either update the library or make a custom symbol, they just use a 'best
fit' symbol that's got the right amount of pins and roughly the same
function. In this case, "zener" is probably close enough, as the '431 is
known as both a programmable zener, and a precision variable voltage source.
I have seen this device shown on schematics as both a three pinned
rectangle - like a 78xx regulator - and a conventional zener, but with a
third connection sticking out of the side at right angles.

Just the other day, I had a case of a mis-drawn device on a schematic. It
was in the ignitor circuit for a short-arc discharge lamp. It was shown on
the schematic as a thyristor with the gate left unconnected. This made no
sense at all in figuring how the circuit worked. When I looked up what the
device actually was, it turned out to be a SIDAC - yes, I know, I'd never
heard of one either. It is actually a two terminal device, that comes in a
variety of packages, including a tabbed thru'-hole three pin version
(TO-202), where two pins are joined together. It's correct (manufacturer's)
schematic symbol, is a "Z" with a horizontal line through it. Quite similar
to a diac. Once this was known, the operation of the circuit became much
clearer.

Arfa

 

[N_Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:UAZcq.249$2F.208@newsfe23.ams2...

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:17o777dq4n9ks5nb8jurlvqe1mdehomk24@4ax.com...
On Fri, 16 Sep 2011 15:49:49 -0700, "Robbie Hatley"
see.my.sig@for.my.contact.info> put finger to keyboard and composed:

Just the other day, I had a case of a mis-drawn device on a schematic. It
was in the ignitor circuit for a short-arc discharge lamp. It was shown on
the schematic as a thyristor with the gate left unconnected.

Is that schematic out there in wwwland? I was recently trying to find any
schematic of the ballast part of such a supply but could only find patent
references or nulled-out block diagrams. I was trying to get an idea of the
post-trigger start up regime while the lamp is warming up.

 

[Ron D.]

Could it be any of these?:

3B- BC856BW Phi SOT323
3B BC856B ITT SOT23
3B BC856BT Phi SOT416
3B FMMT918 Zet SOT23
3B MMBT918 Mot SOT23

 

[Franc Zabkar]

On Thu, 15 Sep 2011 15:37:23 -0700, "Robbie Hatley"
<see.my.sig@for.my.contact.info> put finger to keyboard and composed:

At least 2 of these motor drive boards (one from Advanced Drive
Technology, one from Hyundai) also have switching power supply
circuits for generating low voltages needed (+5V, +12V, -8V, etc),
and these circuits all use a transistor switching a transformer,
with a feedback circuit using a P181 optocoupler and an unknown
device (dual zener?) labeled just "3B". The "3B" device is
designated "ZD3" ...

FWIW, Hitachi has a HA17432VLTP device with a "3B" marking code in an
MPAKV package:
http://www.datasheetarchive.com/dl/Datasheets-13/DSA-247658.pdf

It is designated for "industrial use".

Its pinout is K-A-Ref whereas the pinout of the HA17431VLTP device
(marking 3A) is Ref-A-K.

Specifications:
http://www.renesas.com/_full_product_info_/products/standard_ic/general_purpose_linear/power_management_linear/shunt_regulators/shunt_regulators_root.jsp

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Arfa Daily]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:j520bp$svb$1@dont-email.me...

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:UAZcq.249$2F.208@newsfe23.ams2...


"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:17o777dq4n9ks5nb8jurlvqe1mdehomk24@4ax.com...
On Fri, 16 Sep 2011 15:49:49 -0700, "Robbie Hatley"
see.my.sig@for.my.contact.info> put finger to keyboard and composed:




Just the other day, I had a case of a mis-drawn device on a schematic. It
was in the ignitor circuit for a short-arc discharge lamp. It was shown
on
the schematic as a thyristor with the gate left unconnected.


Is that schematic out there in wwwland? I was recently trying to find any
schematic of the ballast part of such a supply but could only find patent
references or nulled-out block diagrams. I was trying to get an idea of
the
post-trigger start up regime while the lamp is warming up.

The manuals are on the manufacturer's website, but that doesn't actually
help, as the schematic for the version of ballast that shows the ignitor, is
not included in any of the models' manuals. We had to get that one direct
from them. I have it printed out, but for some reason, I don't seem to have
it saved away anywhere. I have been through the rest of my manual versions
that I have got saved, and have found another schematic that has the same
ignitor on it, but with the SIDAC (almost) correctly shown as a diac. If you
care to mail me direct off-group with a current valid address that you
receive and read mail on, I'll send it to you.

I have discovered by being involved in repairing them, that there is
actually no great mystery to how the lamp starts up. I too initially thought
that it was a carefully controlled start-up procedure, but it's actually
not, and seems to rely totally on the characteristics of the lamp itself.
Basically, a current-limited AC voltage of something in excess of 100v RMS
is applied across the lamp, and at the same time, a series of striking
pulses of several kV are superimposed on top of that. This causes the basic
arc to strike, and the AC voltage drops to around 25 volts, which seems to
be enough to maintain the arc through the gas in the discharge tube. By
whatever means - in the case of this particular one by use of a thermal
switch heated by a power resistor in the RC network of the pulse generator -
the ignition pulses are stopped, leaving just the AC across the lamp. As the
lamp starts to warm up, the full plasma discharge starts to form in the arc
tube, and as this builds, the impedance of the lamp increases, resulting in
the AC voltage across the lamp increasing, until it settles at around 90 to
100 V with the lamp at full operating temperature. This appears to be purely
down to the lamp, and nothing to do with the ballast, whose sole job appears
to be to limit / control the current in the lamp so that it burns within
its rating. The max hot running voltage does tend to drop as the lamp ages,
and does vary a little between manufacturers. I have seen voltages ranging
between about 80 and 100 volts. I guess it's a bit like a neon bulb where
you get a fixed voltage across it of around 90 volts, irrespective of the
applied voltage on the back side of the current limiting resistor.

A couple of weeks ago, I had a similar lighting fixture from a different
manufacturer on the bench. It used exactly the same short-arc discharge
lamp, but had no electronic ballast. Instead, it had a simple passive series
inductive ballast, fed directly from the mains. The ignitor for this one was
a sealed unit that 'floated' on the lamp side of the choke, so this further
reinforced my belief that the electronic ballasts do nothing 'magic' and
it's just a case of arcing up the lamp initially, and then limiting the
current through it, leaving it to otherwise just 'do its own thing'.

I have a very good pdf on metal halide discharge lamps and how they work,
which I could also send you, if you are interested.

Arfa

 

[Robbie Hatley]

On 2011-09-17 4:52 PM, Franc Zabkar wrote:

FWIW, Hitachi has a HA17432VLTP device with a "3B"
marking code in an MPAKV package:
http://www.datasheetarchive.com/dl/Datasheets-13/DSA-247658.pdf

It is designated for "industrial use".

Its pinout is K-A-Ref whereas the pinout of the HA17431VLTP device
(marking 3A) is Ref-A-K.

Specifications:
http://www.renesas.com/_full_product_info_/products/standard_ic/general_purpose_linear/power_management_linear/shunt_regulators/shunt_regulators_root.jsp

AH, I think that's it or something very close! Hitachi even
specifies that the part is intended to be used in switching
power supplies, in conjunction with an optocoupler in the
feedback circuit, so it's a very probable match.

The device on the boards I've been working on is SO-89, which
Hitachi is calling "UPAK". Any of their "U" versions of the
431 & 432 have this package, with marking codes 4A, 4B, etc.
So this is probably the same basic kind of part, but a different
manufacturer, using 3B as marking code for the SO-89 version.

Thanks for the tip!

--
Cheers,
Robbie Hatley
Stanton, CA, USA
lonewolf (at) well (dot) com
http://www.well.com/user/lonewolf/

 

[Robbie Hatley]

On 2011-09-16 2:48 PM, whit3rd wrote:

The most common item that one sees in a switching supply
next to an optoisolator is a TL431 programmable zener
(actually a voltage reference/error amplifier combination).
Possibly that's what you have, they're multiple-sourced
in LOTS of package styles.

Yep, I think that's probably it! Thanks! (Also see my
reply to "Franc Zabkar". I saw his reply first. He
mentioned the Hitachi version of 431, 432.)

--
Cheers,
Robbie Hatley
Stanton, CA, USA
lonewolf (at) well (dot) com
http://www.well.com/user/lonewolf/