SMD code 124S
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.
124S on a chip capacitor
120 nF, 75 V
120 nF, 75 V tantalum capacitor
A moulded tantalum capacitor: 124 is the capacitance in picofarads (120 nF) and S is the rated-voltage code (75 V). S for 75 V is Vishay's code; other makers' ranges stop at 50 V.
Check it with a meter
Lift one end and measure it on a capacitance range. A good one reads close to 120 nF. In circuit the meter also sees everything connected across it, so the reading means little until it is out. It is polarised: the band on the body marks the positive end, and a tantalum fitted backwards fails short, sometimes with a flame. A failed tantalum usually reads near 0 Ω both ways, often with a burnt or cracked body. A failed reading does not change what to fit: the marking still says 120 nF, 75 V. Fit the same capacitance at the same or a higher voltage.
On a transistor or diode body (SOIC-8, USP-6B), 124S is a part code instead. Those parts are listed below.
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.
The only part printed 124S in our tables
SS12P4S
- What it is
- Schottky diode
- Maker
- Vishay
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Diode: SBR, 40V, 12A, Vf<0.60V(10A)
- Source
- Published code list
Is it dead?
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- 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 large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Was it this one?
Printed with a code easy to misread as 124S
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes that begin with 124S
For a marking with its end worn or burnt off. Each code has a page of its own.
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