A Drop-In Controller Replacement For Commercial Reflow Ovens

If you need a reflow oven, you can very easily head down to Walmart or Target and pick up a toaster oven for fifteen bucks or so. Even without any control electronics, a bone-stock toaster oven works well enough for reflow soldering, but if you want to do it right you’ll also want to add a themocouple, a microcontroller, and maybe a fancy display. That’s option one.

If you value your time more than your money, you’ll probably just plonk down a few hundred bucks for a T-962A reflow oven, the standard infrared oven that’s meant for reflowing solder. It’s a good oven, but as with all bargain basement tools from China, the user interface isn’t great. [PhillyFlyers] is working on a drop-in controller for what is probably the most popular reflow oven on the planet, and this thing looks good.

This is a controller for the T-962A oven that includes all the connectors as the stock control board. We’ve seen a few of these projects to improve cheap tools, from 3D printer controllers to a replacement board for the ubiquitous K40 laser cutter. Now the most popular reflow oven is getting the same treatment.

The specs for this replacement board include a five-inch, 800 x 480 display, powered by an STM32H7 microcontroller. All of the usual functionality of the oven is retained, but it adds the ability to hand-draw reflow profiles, save reflow profiles to an SD card, and support for four K-type thermocouples. Basically, it’s what you would expect from an upgraded version of the T-962 oven.

Most importantly, this is a direct drop-in replacement for the stock electronics. Grab one of these boards, and all you have to do for installation is break out a screwdriver. It makes a great tool even better, which is exactly what this very popular reflow oven needs.

Improving The T-962 Reflow Oven

The T-962A is a very popular reflow oven available through the usual kinda-shady retail channels. It’s pretty cheap, and therefore popular, and the construction actually isn’t abysmal. The controller for this oven is downright terrible, and [wj] has been working on a replacement firmware for the horribly broken one provided with this oven. It’s open source, and the only thing you need to update your oven is a TTL/UART interface.

[WJ] bought his T-962A even after seeing some of the negative reviews that suggested replacing the existing controller and display. This is not in true hacker fashion – there’s already a microcontroller and display on the board.

The new firmware uses the existing hardware and adds a very necessary modification: stock, the oven makes the assumption that the cold-junction of the thermocouples is at 20°C. The controller sits on top of an oven with two TRIACs nearby, so this isn’t the case, making the temperature calibration of the oven slightly terrible.

After poking around the board, [WJ] found an LPC2000-series microcontroller and a spare GPIO pin for a 1-wire temperature sensor. The temperature sensor is placed right next to the terminal block for the thermocouples for proper temperature sensing.

All the details of updating the firmware appear on a wiki, and the only thing required to update the firmware is a serial/USB/UART converter. A much better solution than ripping out the controller and replacing it with a custom one.