SMD code 78R
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 and published code lists.
78R on a chip resistor
78 Ω
78 Ω resistor
A trailing R marks the value in ohms, with nothing after the decimal point. The same marking also reads as 6.34 Ω, and nothing in the code says which; the body of the part does.
Other readings of the same characters, most likely first
- 6.34 Ω resistor, 1%
Check it with a meter
Lift one end and measure across it. A good one reads 78 Ω. Measuring it in circuit reads the parallel combination of everything around it, which is almost always lower, never higher: well above 78 Ω on the board is a fault. Open, or well above 78 Ω, means it has failed: burnt, cracked or corroded. That does not change what to fit: the marking still says 78 Ω. A burnt resistor usually means the part it feeds drew too much, so find that before fitting a new one.
On a transistor or diode body (SOT-23-5, DFN, SOT-23), 78R is a part code instead. Those parts are listed below.
3 parts are printed 78R
Not sure which one you have?
Answer up to 4 quick questions and these 3 parts are ranked, with a meter test that settles it. It works on a dead part too.
APW7178-33DFNDC-DC converter, AnpecDC-DC converterDFNNot recordedAnpec
- What it is
- DC-DC converter
- Maker
- Anpec
- Package
- DFN
- Pins
- Not recorded
- Details
- 1.5MHz, 1A Synchronous Buck Regulator
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Integrated circuit.
ELM7326CAB1ASOT-23-5Voltage supervisor, 5 pins, ELM TechnologyVoltage supervisorSOT-23-55 pinsELM Technology
- What it is
- Voltage supervisor
- Maker
- ELM Technology
- Package
- SOT-23-5
- Pins
- 5
- Details
- Voltage detector IC: 2.6V±1.2%, -Reset PPO
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
XC6111B423MRSOT-23-5Voltage supervisor, 5 pins, TorexVoltage supervisorSOT-23-55 pinsTorex
- What it is
- Voltage supervisor
- Maker
- Torex
- Package
- SOT-23-5
- Pins
- 5
- Details
- CMOS-IC: VDet 2.3V, -MR, -Reset PPO, Wt=200ms, Rt=25ms
- Source
- Published code list
Is it dead? The meter test is below: Integrated circuit.
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.
Integrated circuit
Voltage with the board powered; ohms from each pin to ground with it off.
Working, it reads
Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.
Dead, it reads
- A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
- Supply present, output stuck: failed, or its load has.
- On the board:
- A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
- Compare:
- The surest reference is the same IC on a working board, measured pin by pin.
- Watch for:
- Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Printed with a code easy to misread as 78R
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Did you find your part?
Open this in the search to correct a character or try another package.