T-962 Reflow Oven Upgrades & Fixes | Voltlog #338

this is the famous t96 theory flow oven coming from china you might find it under a bunch of different brands it's available to order directly from china but also from a bunch of local distributors who are importing these ovens but in general they all have this list of problems which can be easily addressed for improving the performance as well as the safety aspects of operating one of these i got mine for about 180 shipped from germany so there was no tax involved and it got here pretty quickly via courier but you can probably find it for less if you're willing to wait a bit longer and get it from china i used to run my own reflow oven based on a toaster oven but trust me unless you invest in a really expensive toaster oven with ir heating elements you're not going to get the same performance as with one of these dedicated ovens they're not perfect as i'm going to show next they still have a bunch of issues but once we address those it becomes a decent oven with superior performance when compared to a regular toaster oven so here is a list of problems that this oven has and i'm going to show you how to fix it in this video number one the paper tape insulation problem number two the earth connection problem number three a firmer problem number four missing cold junction compensation number five fan noise problem and you'll better understand these issues once we start talking about them but before we get started on fixing them i highly recommend you check out the sponsor of this video pcboa.com they offer high quality professional pcbs manufactured at affordable pricing with fast turnaround times they also offer complete turnkey solutions where they handle everything from sourcing the parts to assembling and testing your boards before shipping so you can get them fully assembled check out their website linked below so let's start with the paper tape insulation problem this oven uses glass wool for installation of the hot chamber and to seal that they've used the combination of aluminium tape and paper tape and it really looks like that cheap painters tape now obviously the insides of this oven are gonna get really hot and that paper tape is gonna start to burn and it will release fumes and a nasty smell if you buy this oven and start operating it right away without implementing this fix he will need to vent that room most certainly luckily this is an easy fix the only thing you need is some good captain tape the idea here is to start by equipping yourself with a pair of gloves and place the oven on a table that you can wipe clean when you're finished to avoid contamination with the fine particles released by the glass wool it's best if you have some genuine captain tape because it will stick better and you will have to remove all of the paper tape and replace it with captain tape you might also find some pieces of rigid cardboard paper like material which is used for installation i wrapped those in some captain tape as well for protection against the heat and inserted them back where they were located when you're finished replacing all of the tape your oven should look something like this next you might notice that the oven has a rather poor implementation for earthing the metal case there is an earth strap but it's connected over the painted metal and there is no serrated lock washer used luckily this is an easy fix as well i used my dremel tool to remove the paint from the metal chassis i added a serrated washer and i now have a solid earth connection to the metal case the top part of the case relies on the screws holding it together for earthing through the lower part but when the two halves are apart there is no earthing to the top part so this is also the time to add a second earth strap that goes to the top of the case uh i'm not really worried about that aspect so i didn't do it here but you can do it on your oven next there is the firmware topic and while i can't mention any specific problems with the stock firmware there are some advantages to flashing an alternative open source firmware by using the open source alternative you can create and compile your own reflow profiles you can make changes to the code and probably most importantly the open source firmware supports a cold junction compensation sensor which is our next topic so to flash the new firmware start by downloading the utility for flashing and the latest pre-compiled firmware bin links for both of these will be in the description of the video next you will need a serial to usb converter and a few jumper wires for connections connect the usb serial converter and check the serial port it's installed by your operating system open the newly installed flash utility app and configure it like this first input the crystal frequency 11.059 under settings then set the serial port which you've just connected earlier the mcu needs to be selected in my case this is the lpc2134 the baud rate is 57 600 and this is the maximum baud rate uh you might have trouble with this depending on the length of cables you use for me it worked okay with the maximum baud rate and you just have to load the hex file next you'll need to connect ground rx and tx you should follow the pin pin out on screen and you also need a way of grounding pin one from the isp header on the oven during power up to put the mcu into boot loader mode i'm using this small clip i power up the oven it goes into boot loader mode and then i release the small clips connected to pin one to disconnect it from ground now i can click flash and it will start loading the firmware just a quick warning there are mains live exposed connections right now so be careful what you touch inside the oven with the case open also during the flashing procedures the oven will likely turn the fan and the heating elements fully on this is normal and it's not a problem for the approximately 60 seconds it needs to complete flashing and once flashing is complete you need to cycle power and the oven will start into the new firmware which will continue to run the fan full on until the oven cools down now that we have the new firmware loaded we are ready to install the call junction compensation sensor and this mod is required to improve the accuracy of the thermocouple sensing circuit because by default the oven just assumes it will always run at an ambient of 25 degrees celsius but during operation this is not always true and it introduces errors in the measurement the new firmware supports the ds18b20 plus temperature sensor with a one wire interface so for this mode you will need one of these sensors and a 4.7 k resistor surface mount one 1206 package style works great and some k704 silicon adhesive for fixing everything in place the plan is to stick the temperature sensor to the uh wall of the connectors where the thermocouple inputs are so i scraped a bit of the solder mask to create the ground connection where pin one and three of the sensors will be attached then i will have the one wire data pin connected to the newly installed 4k 7 resistor through a wire so i installed my resistor according to this image and after the wiring and soldering was done i used some k704 silicon adhesive to mechanically secure the sensor to the connector and hide the wire behind this connector and this might also help with thermal conductivity you will also find the link for this product in the description below and i've done an entire video reviewing some of these ka footer adhesives you can check that out if you're interested to learn more about these products just a quick mention here because you might be wondering if there is only ground and data where does the sensor get its power well it turns out the ds18b20 plus is capable of parasitic power input via the uh 4.7 k pull up on the data line so it has this internal circuitry with a capacitor which it charges and it is able to run off that however if you got your ds18b20 from aliexpress and it's a fake one or it's an older dallas part instead of the newer maxim ones that might not be possible so i advise you get yourself a more recent ds18 b20 plus from a known good distributor like i don't know mouser dg key uh one of the big ones otherwise the older 18b20 is uh still usable but you're gonna have to run a uh second wire for powering the sensor with 3.3 volts now if you want to check if the newly installed call junction compensation sensor is working you need to go into the manual bake mode f3 key and it should show you a reading of the sensor confirming everything is working right and last in this series is the system cooling fan fix so first the issue is that the system cooling fan is pretty noisy it's always running full blast and it's screaming loud this is a small 40 by 40 20 millimeter server type fan that ensures enough airflow over the electronics some people might want to make this quieter personally i don't use the oven as often to consider that noise disturbing because to be honest if i use it for 10 minutes every few weeks which is my normal use case scenario i can accept 10 minutes of noise in my lab you have the possibility to have the newly installed open source firmware control this uh via pwm there is a spare i o pin you can use and add a mosfet and have it control the fan however i wouldn't recommend doing this fix on the t962 oven the one with just two heating elements because the heater control is done via this triad on the pcb which only has a rather modest heatsink which gets fairly hot during operation lowering the airflow might put it under a lot of stress so if you do any fan mode i would also suggest increasing the heatsink size or maybe moving it closer to the cooling fan but then you would have these long wires with the high currents uh controlling the heater elements i'm not sure that's such a good idea now a good alternative might be to install a silent fan and you can use one with a similar airflow in a size of 40 by 40 by 20 millimeters if you still decide to go ahead with the pwm fan mode use an n channel mosfet something like a 2n 7000 or a similar one the gate connects directly to the ad0 test point on the pcb source goes to ground drain goes to the ground wire going to the fan and that should help you implement the fan mode now by no means these upgrades will give you a perfect oven it will still suffer from uneven heating inside the oven but that's a limitation of the internal construction and the fact that this oven uses just two heating elements even with these limitations it should now be capable of providing decent reflow performance this video kind of showed the hardware upgrades you can do to bring the most obvious benefits but once you're finished with this you might think about putting in some custom reflow profiles in the firmware running some calibration just to make sure the readings from the internal thermocouples are accurate but that's a subject for another video so let me know in the comments below if you'd like me to make a video about that as usual i would appreciate your feedback let me know in the comments if you own the t962 if you've done these upgrades and how it's been working out for you if you found this video useful you can support the channel through patreon with as little as one dollar per month if not i would still be happy if you would hit that like button thank you for watching and i'll see you next time

Channel: VoltLog

Views: 39,698

Keywords: T-962 IR Reflow Oven, T-962 reflow oven hacking, T-962 IR Reflow Oven Upgrades, T962 Oven Fixes, T-962 bad smell, T-962 burning tape, T-962 paper tape, T-962 kapton tape, T-962 Cold Junction Compensation, T-962 DS18B20, T-962 Triac, T962 Open Source Firmware, T962 Unified Engineering, T962 Firmware PID Controller, T-962 PWM Fan Mod, T-962 earthing metal case, T-962 Problems, T-962 hobby reflow, LPC2134 firmware, Flashing Procedure T-962, reflow oven, reflow oven soldering

Id: bgVey2O3W2k

Length: 12min 31sec (751 seconds)

Published: Tue Nov 17 2020