You're on the right track thinking about the response time of your meter. A digital multimeter (DMM) often averages readings, masking rapid fluctuations. A solenoid voltage tester (wiggy) might be better, but it depends on the chatter frequency. Here's a breakdown and some suggestions

Why a Wiggy Might Work, But Has Limitations:
Faster Response

A wiggy reacts much faster than a DMM. It's essentially an inductive device that visually deflects a plunger based on the presence of voltage. The analog movement can show very fast changes.

Load

Wiggies intentionally place a small load on the circuit. This can help show if the voltage is collapsing under load even if your DMM sees voltage momentarily.

Limitations



Frequency Response

The wiggy has inertia. If the chatter is extremely fast (think several times a second or more), the plunger might just vibrate without a clear indication of on/off states. It would likely just hum or vibrate weakly.

Indication

You're relying on visual interpretation of the plunger movement. It's not precise.

Ideal Vol-Con Specifics (and Alternatives)

The Ideal Vol-Con is a common and reasonably good wiggy. It's likely to be better than your DMM at detecting this, but not guaranteed to be definitive.

Consider the Test Points

Make sure the Vol-Con you are using is rated for the proper voltage range and is properly calibrated.

Better Options for Diagnosing a Chattering Relay

Here are some tools/methods that will be much more reliable:1.

Analog Multimeter

An analog multimeter with a needle-type display will show fluctuations much more clearly than a digital one. Watch the needle. If it's jumping rapidly between 0 and 120V (or whatever the control voltage is), that's your confirmation.2.

Oscilloscope (Best Choice)

If you have access to one, an oscilloscope is the ideal tool. Connect the probe to the control voltage circuit and you'll see the voltage waveform in real-time. You'll clearly see the "on" and "off" periods, the frequency of the chatter, and even the shape of the voltage transitions. This gives you the most information.3.

Relay Analysis Tools

These aren't cheap, but if you work on relay-based systems frequently, they are invaluable. These specialized tools can often diagnose relay problems without dismantling the system.4.

Audio Monitoring

Sometimes, simply listening can help. If the relay is chattering mechanically, you might hear a distinct buzzing or rattling sound. You can also use a stethoscope (like doctors use) to amplify the sound from the relay.

Troubleshooting Steps (Regardless of Tester)


Isolate the Problem

Disconnect the load powered by the contactor. Does the chattering still occur? If not, the problem is likely in the load circuit (short circuit, excessive current draw).2.

Check the Voltage Source

Verify that the 120VAC supply to the chattering relay is stable. Measure the voltage at the relay's terminals while the problem is happening. Is the supply voltage fluctuating before it gets to the relay? If so, the problem is upstream (a loose connection, a failing transformer, a low-voltage condition).3.

Examine the Relay



Visual Inspection

Look for signs of damage, corrosion, or loose connections.*

Mechanical Binding

Manually operate the relay (if possible with power off) and check for smooth movement. Sometimes a relay can get gummed up or have a sticking armature.4.

Test the Relay Coil

Use a multimeter to measure the resistance of the relay coil. A significantly higher or lower resistance than expected indicates a problem.5.

Consider a Transient Voltage Suppressor (TVS)

Sometimes, inductive kickback from the contactor coil can cause voltage spikes that upset the control circuit. Adding a TVS diode (or MOV) across the contactor coil can help suppress these transients.6.

Check the Wiring

Be sure that the conductors are properly rated and sized. A loose connection or a wire that is under-sized for the application could potentially cause issues.7.

Consider a Time-Delay Relay

If the contactor dropping out for only a split second is causing issues, a time-delay relay may be able to solve the problem.

Important Safety Note: Always work on electrical systems with the power OFF whenever possible. If you must troubleshoot live circuits, use extreme caution and follow all applicable safety procedures (PPE, insulated tools, etc.). If you are not comfortable working with electricity, consult a qualified electrician. Flag for review