Topcon GC-35 User Manual (English)

Questions and Answers:

S
Sarah BaxterAug 3, 2025
What to do if my Topcon GC-35 Control Unit sonic tracker picks up the ground but not a stringline?
- O
  onielsenAug 3, 2025
  If your Topcon Control Unit's sonic tracker detects the ground but not a stringline, consider these steps: 1. To verify the tracker's stringline detection, position the tracker at least 16 inches above the stringline. Gently pull up on the stringline and check for an immediate change in the sensor reading on the Control Box’s Control Screen. 2. Make sure the tracker is at least 14 inches above the stringline. 3. Avoid using smooth, steel wire; instead, use a minimum 1/16 inch diameter string for elevated stringlines or averaging skis, or 1/8 inch string for surface stringlines. 4. If using an ST-3, ensure it is set to Stringline in the Control Box’s Performance Menu and is properly aligned with the stringline.
B
Brian LawsonAug 13, 2025
What to do if sensor readings on my Topcon Control Unit fluctuate rapidly?
- J
  James LongAug 13, 2025
  If you observe rapid fluctuations in sensor readings on the control screen, and the grade lights flash high and low without staying on-grade, verify that the stringline is not bouncing if you are using one.
A
Amy LeeAug 25, 2025
How to troubleshoot slow tow point cylinder response in Slope Control on a Topcon Control Unit?
- S
  Shannon GrahamAug 25, 2025
  To address slow tow point cylinder response in one direction (raise or lower) within Slope Control on your Topcon Control Unit: * Decrease the Valve Offset value of the direction (either Raise or Lower) in which the tow point cylinder moves faster from the Performance Menu. * If necessary, adjust both the Slope and Elevation Gains in the Performance Menu to increase overall responsiveness of the valve.

Topcon GC-35 Specifications

General

Model	GC-35
Manufacturer	Topcon
Type	Control Unit
External Memory	SD card slot
Wireless Communication	Bluetooth, Wi-Fi
Ports	USB
Power	Rechargeable battery
Communication Interface	Bluetooth, Wi-Fi, USB, Cellular (optional)
Operating Temperature	-20°C to 60°C (-4°F to 140°F)
Storage Temperature	-40 to 70 °C

Summary

Terms and Conditions

Usage and Safety

Guidelines for safe and professional operation of Topcon products.

Copyrights and Trademarks

Information on Topcon's copyright and trademarks for the GC-35.

Disclaimer of Warranty and License Agreement

Details on product warranty, license agreement, and liability.

Website

Official Topcon website for product support and information.

Features

GC-35 Control Box Overview

Identifies physical components and ports of the GC-35 Control Box.

First Time Setup

Mounting and Connecting

Steps for mounting the Control Box and connecting sensors and power cables.

Powering the Control Box On/Off

Instructions on turning the GC-35 Control Box on and off.

Control Screen

Understanding the Control Screen Display

Details elements and information displayed on the GC-35 Control Box screen.

Performance Menu

Accessing and Navigating the Performance Menu

Steps to access the Performance Menu and select items using controls.

Adjusting Elevation Gains (Raise and Lower)

Procedure to highlight and change Raise and Lower values for Elevation Gains.

Performance Menu Settings Overview

Table listing Performance Menu items, their ranges, and default values.

Paving Applications

Setting Valve Offsets for Paver

Procedure to set Raise and Lower valve offsets for paver applications.

Paving with Elevation Control

Steps to start paving using elevation control with the GC-35.

Paving with Slope Control

Steps to start paving using slope control and calibrate the slope sensor.

Profiler Applications

Setting Valve Offsets for Profiler

Procedure to set Raise and Lower valve offsets for profiler applications.

Milling with Elevation Control

Steps to start milling using elevation control with the GC-35.

Milling with Slope Control

Steps to start milling using slope control and calibrate the slope sensor.

General Features

Adjusting Setpoint Value Before Operation

How to adjust the setpoint value on the GC-35 before starting a job.

Adjusting Setpoint Value During Automatic Control

Procedure for adjusting setpoint value while GC-35 is in automatic control.

Cross Communication

Remote Control of Secondary Box

Enables remote control of a secondary Control Box via Cross Communication.

ST-3 Mode Settings

Selecting Surface or Stringline Mode

How to select Surface or Stringline mode for the ST-3 Sonic Tracker.

Machine Configuration Files

Loading Configuration Files

Steps to load machine configuration files from a USB drive to the GC-35.

Saving Configuration Files

Procedure to save machine configuration files from the GC-35 to a USB drive.

System Settings

Selecting Language Type

How to change the user interface language on the GC-35 Control Box.

Troubleshooting

Slow Cylinder Response in Slope Control

Solutions for slow tow point cylinder response in one direction during slope control.

Fluctuating Sensor Readings and Grade Lights

Troubleshooting sensor readings and grade lights that are erratic or off-grade.

Sonic Tracker Not Picking Up Stringline

Troubleshooting steps when sonic tracker detects ground but not stringline.

Strange Valve Response (Cylinder Speed)

Diagnosing issues with tow point cylinders moving too fast or too slow.

Safety Warnings

General Usage Precautions

Important warnings on product usage, tampering, and environmental conditions.

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94 pages

Topcon GC-35 User Manual

Table of Contents