SMD code EH
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.
5 parts are printed EH
Not sure which one you have?
Answer up to 4 quick questions and these 5 parts are ranked, with a meter test that settles it. It works on a dead part too.
BZX84B30SOT-23Zener diode, 3 pins, DiotecZener diodeSOT-233 pinsDiotec
- What it is
- Zener diode
- Maker
- Diotec
- Package
- SOT-23
- Pins
- 3
- Details
- SMD Planar Zener Diodes
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Zener diode.
BZX585-B33SOD-523Zener diode, 2 pins, NexperiaZener diodeSOD-5232 pinsNexperia
- What it is
- Zener diode
- Maker
- Nexperia
- Package
- SOD-523
- Pins
- 2
- Pinout
- 1 cathode
- 2 anode
- Details
- 33 V ±2% voltage regulator (Zener) diode
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Zener diode.
MM3Z7B5SOD-323Zener diode, 2 pins, DiotecZener diodeSOD-3232 pinsDiotec
- What it is
- Zener diode
- Maker
- Diotec
- Package
- SOD-323
- Pins
- 2
- Details
- SMD Planar Zener Diodes
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Zener diode.
MMSZ4716SOD-123Zener diode, 2 pins, Taiwan SemiconductorZener diodeSOD-1232 pinsTaiwan Semiconductor
- What it is
- Zener diode
- Maker
- Taiwan Semiconductor
- Package
- SOD-123
- Pins
- 2
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Zener diode.
1 more part has no package on record
BCW66HTransistor, InfineonTransistorNot recordedNot recordedInfineon
- What it is
- Transistor
- Maker
- Infineon
- Package
- Not recorded
- Pins
- Not recorded
- Source
- From the manufacturer's datasheet
Is it dead? The meter test is below: Bipolar transistor.
Is it dead? One meter test per kind
Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.
Bipolar transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
From the base, one probe colour reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- 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 pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Zener diode
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
- 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.
Codes that begin with EH
For a marking with its end worn or burnt off. Each code has a page of its own.
Open this in the search to correct a character or try another package.