SMD marking

O9in SOD-123F

Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables.

Not sure which one you have?

Answer up to 4 quick questions and these 4 parts are ranked, with a meter test that settles it. It works on a dead part too.

The only part printed O9 in this package in our tables

BZD27C22P-M

What it is: Zener diode
Maker: Vishay
Package: SOD-123F
Pins: 2
Details: 22 V Zener diode
Source: From the manufacturer's datasheet

Is it dead?

Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.

Working, it reads

About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.

Dead, it reads

The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
Open both ways, forward too: failed open.
Holds well off its rated voltage on the supply test: drifted.
A soft knee, or a voltage that creeps on the supply test: leaky.

On the board:: On the board this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:: If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:: A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.

A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.

Datasheet

Printed with a code easy to misread

These parts are printed with a character that is easy to misread as what you typed. The odd one out is marked on each.

Zener diode. What differs:

BZD27C8V2Pprinted D9SOD-123FVishayVishay
Printed D9 on the part. Easy to misread as O9. Check that character with a loupe before you order anything.
What it is
Zener diode
Maker
Vishay
Package
SOD-123F
Pins
2
Details
8.2 V Zener diode
Source
From the manufacturer's datasheet
Is it dead?
Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
Working, it reads
About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
Dead, it reads
The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
Open both ways, forward too: failed open.
Holds well off its rated voltage on the supply test: drifted.
A soft knee, or a voltage that creeps on the supply test: leaky.
On the board:
On the board this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor BZD27C8V2P, opens in a new tab
BZD27C150P-Mprinted Q9SOD-123FVishayVishay
Printed Q9 on the part. Easy to misread as O9. Check that character with a loupe before you order anything.
What it is
Zener diode
Maker
Vishay
Package
SOD-123F
Pins
2
Details
150 V Zener diode
Source
From the manufacturer's datasheet
Is it dead?
Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
Working, it reads
About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
Dead, it reads
The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
Open both ways, forward too: failed open.
Holds well off its rated voltage on the supply test: drifted.
A soft knee, or a voltage that creeps on the supply test: leaky.
On the board:
On the board this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor BZD27C150P-M, opens in a new tab
1 more part has no package on record. Nothing rules them out, so they stay.
- BZT52C43Kprinted D9Taiwan SemiconductorTaiwan Semiconductor
  Printed D9 on the part. Easy to misread as O9. Check that character with a loupe before you order anything.
  What it is
  Zener diode
  Maker
  Taiwan Semiconductor
  Package
  Not recorded
  Pins
  Not recorded
  Source
  From the manufacturer's datasheet
  Is it dead?
  Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
  Working, it reads
  About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
  Dead, it reads
  The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
  Open both ways, forward too: failed open.
  Holds well off its rated voltage on the supply test: drifted.
  A soft knee, or a voltage that creeps on the supply test: leaky.
  On the board:
  On the board this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
  Compare:
  If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
  Watch for:
  A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
  A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
  Datasheetfor BZT52C43K, opens in a new tab

5 more parts have codes that begin with O9

Codes that begin with O9

For a marking with its end worn or burnt off. Each one shows its full printed code.

MOSFET, all Panjit.

PSMQC094N10NS2printed 094N10NS
Printed 094N10NS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
MOSFET
Maker
Panjit
Package
Not recorded
Pins
Not recorded
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
The gate reads low to source or drain: gate shorted.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor PSMQC094N10NS2, opens in a new tab
PSMQC098N10LS2printed 098N10LS
Printed 098N10LS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
MOSFET
Maker
Panjit
Package
Not recorded
Pins
Not recorded
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
The gate reads low to source or drain: gate shorted.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor PSMQC098N10LS2, opens in a new tab
PSMQE090N08LS2printed 090N08LS
Printed 090N08LS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
MOSFET
Maker
Panjit
Package
Not recorded
Pins
Not recorded
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
The gate reads low to source or drain: gate shorted.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor PSMQE090N08LS2, opens in a new tab
PSMQE093N10NS2printed 093N10NS
Printed 093N10NS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
MOSFET
Maker
Panjit
Package
Not recorded
Pins
Not recorded
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
The gate reads low to source or drain: gate shorted.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor PSMQE093N10NS2, opens in a new tab
PSMQE096N10LS2printed 096N10LS
Printed 096N10LS. Only the start matches what you typed, so this fits only if the rest of the marking is worn off.
What it is
MOSFET
Maker
Panjit
Package
Not recorded
Pins
Not recorded
Source
From the manufacturer's datasheet
Is it dead?
Diode range, part lifted. Test drain to source first, then short gate to source and test again.
Working, it reads
One way between drain and source reads about 0.4 to 0.9 V, the body diode, and the other way open. The gate reads open to both other pins.
Dead, it reads
Drain to source the same both ways, near 0 V with a continuous beep, and still so after shorting gate to source: shorted. The classic failure.
The gate reads low to source or drain: gate shorted.
No body diode at all: failed open.
On the board:
On the board the gate usually has a resistor to the source, which reads as that resistor and is not a fault. Lift a leg to be sure.
Compare:
If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
Watch for:
The diode range can charge the gate enough to turn the part on, and then drain to source reads near 0 both ways on a good part. Short gate to source and test again before you condemn it.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Datasheetfor PSMQE096N10LS2, opens in a new tab

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