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.

17 thoughts on “A Drop-In Controller Replacement For Commercial Reflow Ovens

  1. For the T-962 there is an alternative firmware with a much better menu on github by some swedish guy. Costs nothi g and even sports alternative temperature readings with cold junction compensation.
    works much better than stock firmware but heat distribution is still uneven in mine so that the effective solderable area is just 14×10 cm on mine. (Keep in mind these ovens are rubbish. Good enough rubbish)
    for the hobbyist the ovens are fine. I use mine weekly.
    never got it working reliably with lead free though

    1. I don’t think it makes sense to use lead free solder otherwise than in a series production environment. The good stuff (Sn/Pb) just is easier to work with and works better. I do not eat my solder.

    2. Same here. I was not able to get good results with standard lead free solder paste. I’ve switched to using low temperature lead free. I know it can be problematic on some boards to have low melting point solder, but it’s fine on most of my projects. It’s a good compromise.

  2. I’m a bit floored. He has a STM32 in a QFP-176 package, a 64 MB SDR SDRAM footprint, 4 ADCs and ZERO by-pass decoupling ANYWHERE on the board. And it’s auto-routed to boot. I guess it probably works most of the time. But I wouldn’t use one. Oddly there is series termination going to the RAM and LCD.

    1. And the main resonator is 3 cm away from the STM with auto-routed traces. And there is no main ground pour. All the ground returns for much of the board are badly-auto-routed 6 mil traces. I’m really surprise the board works.

    2. This is a fair, but not entirely correct, criticism. Most of the ICs on the board (MAX31855, 74HC138, AS4C32M16SB) and the 24MHz clock are properly provided with their own local decoupling.

      But the STM32H743 does not have 100nF at each VDD pin, as advised in the datasheet:

      “Caution: Each power supply pair (VDD/VSS, VDDA/VSSA …) must be decoupled with filtering ceramic capacitors as shown above [Figure 15 depicts N x 100nF, where N corresponds to the number of VDD pins available on the package]. These capacitors must be placed as close as possible to, or below, the appropriate pins on the underside of the PCB to ensure good operation of the device. It is not recommended to remove filtering capacitors to reduce PCB size or cost. This might cause incorrect operation of the device.”

      Instead it gets 1x 10nF, 1x 100nF, and 2x 4.7uF decoupling caps, mysteriously situated several centimeters away from the chip.

      The routing and current return issues are indeed concerning.

      I would not be willing to endorse V3.3 of this board as a reliable upgrade from the stock T-962A controller.

  3. “but as with all bargain basement tools from China, the user interface isn’t great.”

    I haven’t used it but I will take your word for it. This kind of reminds me of all the K40 upgrade projects.

    So… that brings me back to a question that I have wondered ever since I first started reading about those. What’s up China?

    I mean seriously, these Chinese shops have all the ability to build a workable, functioning device and do it on a budget. Why can’t they build a decent UI? And in the case of the K40, one that accepts some sort of open format. What would it be to make the UI better, a couple of afternoons of very light programming? And is it really easier to hack some commercial CAD program and build everything around that than it is to use a pre-existing, freely available HPGL or G-Code library and get compatiblity with everything for free?

    Maybe it’s just because software is my day job but it seems like they are excelling at the hard stuff then totally dropping the ball on the easy things. It’s like a whole bunch of people are climbing mount Everest but forgetting to take any pictures. WTF!

    1. Same with your average PC motherboard from Taiwan – good hardware but horrible BIOS/junk utilities.
      Hardware tends to come with reference designs and a lot more modular. Hardware needs math, physic reading/understanding requirements and is very straight forward. Software requires a lot more abstraction thinking. It is a different skill set. They will get better. It is a matter of time.

  4. I have been using both the T-962 A and C ovens with the modified firmware from Unified Engineering. Successfully using the entire plate to run several thousand boards. Chipquik SMD291AX available on Amazon. Requires a custom temp profile to get consistent runs.

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