How to Fix Fluctuating Meters for Telegraph Fire Alarms

By Andrew Erickson

June 13, 2024

Maintaining the integrity of your telegraph fire alarm systems is important for the safety and security of your municipal facilities. Recently, John (a Digitize engineer) had in an interesting email exchange with a client experiencing issues with their systems. The two worked to reestablish this stability.

Today, let's look at their conversation to learn the possible causes of the issues and how to solve them. Doing so will indicate the extent to which Digitize will work to help you find the right solution.

Identifying the Problem

The client's initial email outlined a persistent issue with a fluctuating meter on one of their Form Four regulators. The meter readings were inconsistent. This raised concerns about the accuracy of the alarm system:

"When I throw the toggle switch to mA or Volt, the meter constantly jumps between -00.1 and 00.1. When I start taking circuit readings, the numbers jump around all over the place. Every other Digitize Form Four I use, the numbers are solid. Could this be a problem with the common card or a bad ground in the electrical outlet in which it is plugged?"

John used this information to create a detailed response that addresses several potential causes for the fluctuating meter readings. He was able to take a methodical approach to diagnosing the problem because of the helpful diagnostic details provided by the client.

Form Four
Form Four Control Center

Common Causes of Fluctuating Meters

John provided a list of potential issues that could cause the meter to fluctuate. This offered a clear path for troubleshooting:

"There are a few things that can cause the Form Four meter to fluctuate. Overheating Q1 regulator with 16 VAC transformer meter supply, missing Q1 regulator heat sink, old rechargeable 9-volt battery, Q1 regulator is bad, or a bad meter."

As you can see, John also provided this list of variables that can cause the meter to fluctuate:

  1. Overheating Q1 regulator with 16 VAC transformer meter supply.
  2. Missing Q1 regulator heat sink. Overheating regulator with 16 VAC or 10 VAC transformer meter supply.
  3. Old rechargeable 9-volt battery.
  4. Q1 regulator is bad.
  5. Bad meter.

John's response highlights the importance of understanding the various components and their functions within the fire alarm system. The Q1 regulator, for instance, plays a crucial role in maintaining a stable voltage supply. Overheating or the absence of a heat sink can significantly impact its performance. This will lead to erratic meter readings.

Detailed Diagnostics and Solutions

John's follow-up email provided additional insights into the specific locations and potential remedies for the fluctuating meter issue:

"Older Form Four (FF) card cage AC panels had two 110 VAC x 16 VAC transformers. One 16 VAC for Supervision on the Common card if 24 VDC is lost. The other is for the 9-volt rechargeable battery charging circuit. The 9-volt rechargeable battery is back up power for the meter in case of an AC loss. Try pulling the 9V battery and check the meter."

This level of detail from a technical support rep like John is essential for technicians working on-site. It guides them through the physical inspection and troubleshooting process.

John emphasized the need to check the battery and the Q1 regulator's condition. These are practical steps to isolate and identify the issue.

Collaborating for Effective Solutions

John's commitment to resolving the issue was evident in his willingness to seek additional expertise and collaborate with other knowledgeable individuals:

"I reached out to a guy in NE. He's sharp on FF old and new. He and I collaborate on FF issues all the time. He said the same on the usual suspects for a fluctuating meter. He said he's seen pretty wild readings when Q1 gets hot or is bad."

John’s proactive approach in seeking advice from other experts in the field reinforces the importance of collaboration in addressing complex technical issues. This collaborative effort ensures that all potential causes are considered and the most effective solutions are identified:

"I haven't heard of any other things causing a fluctuating meter. However, I learn new things all the time."

This openness to new information and collaboration with others promotes the importance of staying updated with the latest knowledge and techniques in fire alarm system maintenance. Engaging with a network of professionals allows for the sharing of best practices and enhances the overall effectiveness of troubleshooting efforts.

System 3505 Prism LNX
Telegraph monitoring gives you abilities that modern technology can't.

Practical Tips for Safe Battery Removal and Replacement

When the client encountered difficulties removing the 9V battery, John provided practical advice to prevent damage to the system:

"You might be able to sneak a flat blade screwdriver between the battery and the terminal and give it a slight assist. A little on each post. A flat plastic screwdriver or other plastic tool vs. metal screwdriver might be best."

John's advice shows his commitment to remedying the client's issues, no matter the type of problem. John is expected to know the technical specs of the device. However, being able to provide niche advice regarding the device's physical composition and assembly shows just how well-rounded and experienced the support team is at Digitize.

Additionally, John addressed the client's query about battery specifications, ensuring they understood the importance of using the correct type and rating for optimal performance:

"We currently use a Powerone P7/8H Ni-MH rechargeable. I believe it's rated 200mAh."

Addressing Meter Stability Through Power Supply Inspection

An important aspect of troubleshooting fluctuating meters involves examining the power supply stability. John emphasized the need to assess the power supply components and their configuration within the system:

"Older units with a 16 VAC for the battery charge ran the regulator pretty hot. Q1 transistor is on the back of the FF card cage. Q1 should have a heat sink on it. Even with the heat sink, the transistors would run pretty warm. If the transistor runs too hot, the meter can fluctuate."

This highlights the significance of proper heat dissipation in maintaining system stability. Ensuring that components like the Q1 regulator are not overheating is critical for accurate meter readings.

You and/or your technicians should verify the presence and functionality of heat sinks and check for any signs of thermal stress on the regulators.

Importance of Regular Battery Maintenance

Regular maintenance of the battery backup system is needed for a reliable fire alarm system. In one of his emails, John provided detailed instructions on checking and maintaining the rechargeable 9V battery:

"An old 9-volt rechargeable battery whether used with 16VAC or 10 VAC can cause enough noise on the transistor regulator that the meter will fluctuate. Try pulling the 9V battery and check the meter."

Regularly replacing old batteries and verifying proper connections can prevent fluctuations and ensure the reliability of the meter readings. This proactive approach helps maintain the overall health of the fire alarm system.

Detailed Troubleshooting Steps for Field Technicians

John's emails also included practical, step-by-step troubleshooting procedures tailored for field technicians. These instructions were designed to help technicians strategically identify and resolve issues with the meter:

"Pull the 110VAC power to the FF AC panel and remove the 9V rechargeable battery from the FF card cage. Install a regular 9V battery then take some readings. If the readings are okay, the rechargeable 9V battery is probably bad."

These detailed steps are invaluable for you. They provide a clear and actionable plan to isolate the cause of the problem.

By methodically testing different components, you can accurately diagnose the issue and implement the appropriate solutions.

How You Can Ensure System Reliability

Ensuring the reliability of telegraph fire alarm systems requires a comprehensive understanding of the systems' components and potential issues. John’s detailed guidance and collaborative approach exemplify the expertise needed to maintain these systems effectively.

For those facing similar challenges with their fire alarm systems, consulting with experienced professionals like John can significantly enhance your system's reliability and safety.

Whether you're experiencing issues, you'd like to upgrade your fire alarm system, or you just have a few questions, contact our technical support team for expert assistance.

Call 1-800-693-0351 or email today.

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and...Read More