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What improvements does the ESTechnical Controller provide

We are often asked what improvements we have made to the T962 / T962A reflow oven. The following article answers most of these questions.

Electrical Safety

The original T962 / T962A controller that is fitted to the T962, T962A and T962C reflow ovens are poorly designed in several ways. The most important of these shortcomings is the separation between mains/line voltage and low voltage parts of the circuit.

The ESTechnical controller upgrade packages provide greater electrical safety by increasing the separation between mains/line voltage and low voltage circuitry. Opto-isolation is built into the SSRs used in the upgrade.

The original manufacturer powder coats the case components and does not leave proper contact for case earthing connections.

The ESTechnical controller upgrade kit provides components and instructions to fix the shortcomings in case earthing connections.

Improved Safety

The original manufacturer of the T962 / T962A uses masking tape in the assembly of the oven. When heated the adhesive produces a bad smell and the paper tape may be a fire hazard.

The ESTechnical reflow controller upgrade package includes kapton tape to replace the paper tape. This reduces the smell produced during reflow.

Better Temperature Measurement

The original T962 / T962A controller uses a basic op-amp based thermocouple input circuit. This circuit provides poor accuracy and poor temperature stability. The measurements from these input stages are affected by the temperature of the controller PCB as well as the thermocouple input.

The ESTechnical reflow controller upgrade uses precision thermocouple measurement ICs for minimal error in temperature measurement. These ICs have built in temperature compensation (cold-junction compensation) which effectively eliminates any measurement error introduced by the temperature changing at the controller PCB.

Better Reflow Cycle Settings/Control

The original T962 / T962A reflow oven controller relies on “taught” profile settings, requiring the user to turn on and off the fan and heater multiple times to teach a new profile. This is an awful way to “describe” a reflow cycle to the controller. Making a mistake in this process means starting from the beginning.

The ESTechnical controller has a control loop which includes a PID temperature controller. To produce the desired temperature profile, the controller generates the changing setpoint for the PID controller. The PID controller ensures close tracking of the desired temperature within the oven.

The parametric reflow profile adjustment of the ESTechnical reflow controller means that it takes seconds to change settings and save them. Up to 30 profiles can be stored on the ESTechnical Reflow Controller. 

Fan Speed Adjustment

The original T962 / T962A oven controller doesn’t make any use of the main fan, except during cooling. This means the middle of the oven heats faster than the edges and the difference between hotter and cooler areas within the reflow oven can be large.

The ESTechnical reflow controller has a “fan idle speed” setting which provides airflow during the whole reflow cycle. During the heating stages, the fan runs constantly at low speed to move air around the oven, dramatically reducing the difference between the hottest and coolest areas of the drawer. The fan speed can be adjusted to get the best results.

USB Connection & Software

The original reflow oven controller does not provide any way to monitor the reflow cycle. If careful profile adjustment is required, additional tools such as a thermocouple meter, or a thermocouple datalogger are required for measuring the PCB temperature.

The ESTechnical Complete Upgrade Packages include the needed parts to fit a USB socket to the oven and free software to view reflow cycle temperatures in real time.

An extra thermocouple input is provided on the controller for a PCB mounted thermocouple to be used. This provides real time feedback of the PCB temperature during reflow cycle testing. Adjusting the profile settings to get the desired profile temperatures at the surface of the PCB has never been easier.

Accurate Timer

The original T962 / T962A controller doesn't have an accurate timer, it seems like the timer is running too slowly. The crystal fitted to the controller may be the wrong frequency, or there may be some mistake in the firmware that causes this effect.

The ESTechnical reflow oven controller has an accurate 20MHz crystal for timing and is stable over a wide temperature range. This accurate timing combined with accurate temperature measurement gives much better repeatability than the original controller.

For a review of the ESTechnical Controller Upgrade see petrockblock blog review