Product Overview
Glass-Passivated 4A 100V Bridge Rectifier - GBU Through-Hole Package, AC to DC
Condition
Unused NOS. Leads show moderate tarnish from age, consistent with long-term storage - cleans up nicely with a mild citric acid solution. Fairchild logo, part number GBU4B, date/lot code AB18, and polarity indicators (+, AC, AC, -) are legible on the body. Sourced from an electronics distributor consolidating inventory.
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Product Overview
Fairchild Semiconductor GBU4B - glass-passivated single-phase bridge rectifier in the GBU through-hole 4-pin SIP package. Rated 4A forward output current and 100V maximum repetitive peak reverse voltage, it converts single-phase AC to DC in a compact molded body with integral mounting hole and stamped polarity symbols. A workhorse component for power supply design, repair, and retrofitting.
Key Features
- Maximum repetitive peak reverse voltage (VRRM): 100V
- Average rectified forward output current (IO): 4.0A (with heatsink at TC = 100°C)
- Peak forward surge current (IFSM): 150A (8.3ms single half sine-wave)
- Maximum instantaneous forward voltage drop (VF): 1.0V per diode at 4.0A
- Operating temperature range: -55°C to +150°C
- Package: GBU / Through-Hole 4-Pin SIP with integral mounting hole
- Glass-passivated junction for reliability and stability
- Polarity symbols stamped on body casing for correct installation
Applications
- Swapping a failed bridge rectifier in a vintage amplifier or receiver power supply - desolder the old GBU, drop in the GBU4B, confirm polarity from the stamped body markings, resolder, and restore clean DC rails
- Replacing the rectifier in a consumer electronics power adapter or monitor that has lost output or developed excessive AC ripple
- Integrating into a custom bench power supply or variable DC supply build where a compact through-hole 4A bridge is the right fit for the PCB footprint
- Prototyping small-batch OEM power supply boards where the standard GBU footprint simplifies layout and the 4A/100V ratings cover a broad range of low-voltage AC inputs
- Maker and hobbyist DC power projects - charging circuits, motor driver supplies, LED driver rails, or any project that needs a straightforward AC-to-DC stage without a switcher
Frequently Asked Questions
Does this fit the standard GBU PCB footprint?
Yes. The GBU4B is in the GBU / Through-Hole 4-Pin SIP package with an integral mounting hole. It is a direct fit for any board laid out for the GBU footprint.
What is the difference between GBU4B and other GBU4 variants?
The GBU4 series shares the 4A current rating across variants. The letter suffix identifies the voltage rating: GBU4A is 50V, GBU4B is 100V, GBU4D is 200V, GBU4G is 400V, GBU4J is 600V. Confirm your circuit's reverse voltage requirement before substituting.
Will this work without a heatsink?
The 4.0A IO rating is specified with a heatsink at TC = 100°C. For low-current applications well below the rated maximum, a heatsink may not be required, but thermal management should be assessed for the specific load and enclosure conditions of your design.
Is this the Fairchild or ON Semiconductor version?
ON Semiconductor acquired Fairchild Semiconductor. This unit carries the Fairchild logo and markings. Electrically, Fairchild and ON Semi GBU4B parts share the same specifications.
Tarnished leads on a brand-new part tell a simple story - this one sat in a distributor's bin instead of going into a board, and now it gets a second chance. Clean the legs, solder it in, and it does exactly what a GBU4B is supposed to do.
