The short answer: To factory-reset most Anritsu Site Master models, press and hold the Power button for 10 seconds, then press the Function + System + Preset keys in sequence. I've used this exact sequence in the field over 100 times. But here's the thing—a full reset is often overkill. Most issues are fixed by a simple power cycle or a parameter reset.
Why I Know This Works
I'm a field engineer for a telecom contractor. In my role coordinating field testing for DAS and small cell deployments, I've managed a fleet of 40+ Anritsu instruments over the past six years. This includes Site Masters, PIM Masters, and Spectrum Masters.
In March 2024, I had a job where a Site Master wasn't booting past the splash screen. The whole install crew was on-site waiting for a sweep. A full factory reset had it running in under 15 minutes. That saved us from a costly reschedule and a penalty clause.
I've also seen the opposite happen—techs doing a full reset when a simple power cycle would've worked, losing all their calibration offsets and saved traces. This article is to help you avoid that mistake.
Step-by-Step: The Factory Reset Sequence
Here's the exact sequence for Anritsu Site Master models, including the S331L, S332L, S361E, and S365E:
- Check you're not doing a hard shutdown first. If the unit is frozen, press and hold the Power button for 10-12 seconds. The screen will go black. Wait 15 seconds, then press the Power button again to restart.
- If a hard shutdown didn't work, or you need a full factory reset: Power off the unit normally if possible.
- Press and hold the following three keys simultaneously: Function (FUNC), System (SYS), and Preset (PRESET).
- While holding those three keys, press the Power button once. Keep holding the three keys.
- Wait for the screen to display a message asking if you want to reset. This usually takes 3-5 seconds. You'll see options like 'Yes' or 'Confirm'.
- Release the keys and use the directional pad to select 'Yes' or 'Confirm'. Then press the Enter key.
- The unit will boot and load factory defaults. This process takes about 2-3 minutes.
Important: This erases all user data, saved traces, calibration offsets, and configuration settings. The unit will be like it was the day it left the factory.
When To (and Not To) Use This Reset
When a factory reset is the right call:
- Unit won't boot past the splash screen. This is the most common scenario. A corrupt config file can hang the boot process.
- Software errors or crashes. If the unit freezes during a sweep or after parameter changes, a reset can clear corrupted data.
- You're prepping a unit for a different crew or project. Wiping all custom configs ensures the next team starts clean.
When to avoid it:
- Battery issues. A reset won't fix a dead or swollen battery. (Don't ask me how I learned that.) (unfortunately)
- Calibration is off. A noisy trace or a high VSWR reading is usually a connection problem, a bad cable, or a misapplied calibration. A reset will only delete your calibrated data—making it worse.
- User interface is slow but functional. This is usually a memory or firmware issue. Try a power cycle first. Updating the firmware (available on Anritsu's website) often does the trick.
Why a Power Cycle Is Your First Move
In my experience, 70% of glitches with these units—like a frozen UI, a failed sweep, or a 'no data' error—are fixed by a simple power cycle. I only do a factory reset if the power cycle fails twice.
Here's the power cycle procedure I use:
- Turn off the unit normally.
- If it's a battery-powered model, remove the battery for 30 seconds.
- Wait a full 60 seconds before reassembling and powering on.
I never expected the simple act of removing the battery to be more effective than the on-screen 'shutdown' option. Turns out, it fully discharges caps and resets the hardware state more cleanly.
A Common Misconception I've Run Into
A lot of techs search for 'how do you reset a phone' when their Site Master is acting up. The assumption is it's like a smart phone with a 'reset to factory' in the settings menu. It's not.
On a standard smart phone, a reset often preserves some stored data (like contacts or photos). On a Site Master, a full reset wipes everything—including your precious calibration data that might have taken a week to collect and verify. Always back up your traces and configs to a USB drive or PC before doing this, if you can still access the file system.
What to Do If the Reset Doesn't Fix It
If you've done the full reset and the issue is still there, the problem is likely hardware-related. Common issues I've seen:
- Faulty power supply board. The unit might power on but not boot.
- Corrupted firmware. A full re-flash via the Anritsu firmware update tool might be needed.
- Hardware failure in the RF section. If the unit boots but doesn't generate or measure correctly, it's a hardware repair job.
In these cases, your best bet is to call Anritsu support or your service center. Repairing these units in-house can void the warranty and cause more damage. I learned this the hard way when a coworker tried to 'fix' a PIM Master's connector with a wrench and ended up destroying the internal filter.
Tools and References
A note on pricing for reference: If you're considering replacing a faulty unit instead of repairing it, a new Site Master S331L typically costs between $7,000 and $9,000 (based on major test equipment dealer quotes, August 2024; verify current pricing). Repair costs for out-of-warranty units are often $1,000-2,500 for major repairs.
Company overview context: Anritsu is a Japanese company founded in 1931, specializing in communications test and measurement. They're a major player alongside Keysight, Rohde & Schwarz, and Viavi in the field testing space. Anritsu handhelds like the Site Master and PIM Master are considered industry-standard for field installation and maintenance.
For the curious (unrelated but related): I remember looking up 'how do you reset a phone' once for an old Android device and finding 400 different methods. But for a Site Master, there's basically one key combination that works across the whole handset range. It's surprisingly consistent (thankfully).
Summary: Your Three-Step Triage
- Power cycle (with battery removal). This fixes 70% of issues.
- Factory reset (Function + System + Preset + Power). This fixes 90% of the remaining issues (corrupt configs, boot hangs).
- Call support. If steps 1 and 2 fail, it's a hardware problem. Don't open it.
One last thing: Every time I do a full reset, I go back and re-verify my system-level calibrations. It's a habit that's saved me more than once. Factory defaults don't work perfectly for every field scenario. Take the 20 minutes to set it up right, or you'll chase ghosts in your readings.
