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T962A SMD Reflow Oven Fix/Hack

Picture of T962A SMD Reflow Oven Fix/Hack
I've recently purchased a popular T962A SMD reflow oven. The reviews are split on this oven - some find it to be quite acceptable, while others find it completely useless. After much researching, I decided to give it a try.

(Feel free to skip this part if you already have the oven.)

T962A is an inexpensive IR (infrared) SMD reflow oven. It has a microcontroller to control temperature and timing (profile), so you can basically put populated PCBs in, push the button and simply wait for a few minutes. Then the PCBs are done.

There are some issues with this oven, but my experience is rather positive overall. For my purpose this oven works well.

However the problems are:

1. The oven produces horrendous smell.
I'm not taking about the smell of solder paste melting. The oven itself produces the smell even without anything in it.

2. The heat distribution is not very even.
This is not an issue with leaded solder, but becomes a major problem with lead-free solder. As lead-free solder requires much higher temperature to reflow, the extra temperature needed to ensure the solder reflow on all parts of PCBs can burn the parts in the hot spots. Even though I'm lucky enough to not fry any PCBs with this oven, some parts did come out looking burned.

I want to share what I did to improve on those issues.
 
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brettjones4 days ago

I have the T962 and like dzak, the arduino worked for the fan. However, the fan doesn't go on during cool down mode anymore. It works with the arduino controlling it but no longer with the stock controller. Any hints? Worst case I can always add a switch to the circuit to manually turn it on.

ledartist (author)  brettjones3 days ago

Do you have a 1k ohm resistor in series in the fan control line? You need one.

(see 5th photo under step 2)

colorado_rob made it!1 month ago

Very nice! I purchased a T-962 (the smaller sibling of the T-962A) and the Arduino hacks works there too. I ripped out the masking tape and replaced it with kapton tape. I used a tiny, cheap Digispark (which uses an ATTINY85) instead of an Arduino Uno for the fan control. A little shrink wrap to insulate the USB connector and a little more hot glue to hold it in place (who is going to notice a little more in there, eh?) and it works like a charm. I had to change the LED pin to "led = 1" for the Digispark. Everything else just worked.

Digispark_T-962.JPG

I was wondering Colorado_rob, How is that ATTINY85 working out for you in the system regarding the Main intake fan at the back regarding the even temperatures and temp profiles. I have the exact the same version of reflow oven and I find the temps seriously crazy. On Profile 1 with fluke DMM temp sensor I reach up to 277 degress (C) (LCD screen thinks it's doing a great temp job with false readings)

which is crazy, although it doesn't burn the boards, I am worried about the lifetime of the components attached to the PCB over the heat madness. There is another problem about hot, and cold spots, will this mod actually help it ?

Thanks for your reply Rob..

i need some information for t962a

We are a computer and mobile phone repair shop and we repair laptop and mobile phone motherboards, for example GPU on the laptop main-board we fix by applying certain heat by hot air gun and applying flux on it reflowing process, and liquid damaged mobile phone main-board we do ultrasonic cleaning and then heat the main-board to reflow.

My understanding of this machine is that while doing the reflow manually we can just put the laptop mother board in this oven set the right time and heat setting and it will reflow the soldering on the ic and chips? am i right? if this is correct i will buy the machine and is it compatible with voltage in new zealand?

hoping to hear from you soon?
As far as I know, this machine is someone in Australia using a consistent voltage Australia and Ireland, but the first machine 240V is influential, but you can adjust the temperature by modifying the curve, I have a machine model 962S, her clock is accurate , and the flue. My mailbox ds1236282126.com.
ledartist (author)  budgetcomputer6 months ago
There is a lot of information about this oven - just google T962. My experience is that if you limit the use to lead-tin solder and avoid large components like USB jacks, this oven works well.

I'd look for a better oven for what you are trying to do personally...

dcms45 months ago
I was wondering what width and approximately how much Kapton tape you needed for this modification?
ledartist (author)  dcms45 months ago
I used wide tape (about 6 inch wide), but narrow tape should work just fine. Not too much tape is needed. I'm guessing about a yard.
I think you'll have to buy a roll anyway right?
dcms4 ledartist5 months ago
Yeah, I was just trying to figure out how much of a roll, based on the width and length.

You posted in May, is it still working well for you? How often do you use it? What's the largest thing you've baked?

Thanks.
Don
ledartist (author)  dcms45 months ago
It's working pretty well. Once the temp profile is tuned in, this oven produces pretty reliable results.
I only use it once or twice a week on average. The largest PCB I've done is about 5 x 5 inches, two of them together.
You program the machine to modify, right?
frankav4 months ago
Nice article. Just received mine and sure enough, masking tape inside. Have Kapton tape already on order for another project, not arrived yet though. Anyway, need to add one very important thing: Safety. I checked mine and suspect all will be the same. The panels are coated with paint which acts as a good insulator. An earthing check showed the earth tag to not be connected to the back panel chassis. Having fixed that, there was also no continuity from the back panel to the rest of the case. This was fixed by grinding away the paint under a couple of screws each which go attach the back to the bottom and top chassis halves respectively.
Do you have friends need this machine? I have this one machine model 962S, my mailbox is ds123628@126.com, there are technical problems can be the mail exchange.
dzak23 months ago
thanks for the info; i have ordered a T962 ; which in fact is only 800W ; this model is NOT using the solid state relay to power the lamps, but is in fact using a BT139 triac to power on/off the heaters. the board is the same as your just that the empty spot on your board is filled with the BT139 and some resistors
ledartist (author)  dzak23 months ago
Good to know. Thanks!
I have a machine with a flue, other problems have improved, the operation is more simple. My mail is ds123628@126.com, my English is poor, which is translated by Google.
dzak2 ledartist3 months ago
I can confirm that the hack works fine also with the T962 version; there is just a little space problem to put the ardunio board ; i glued it to the top and protected top & back with some kaptop tape.

Mine also had masktape underneath the isolation instead of just on top; stripping that solved the horrible smell aswell!

thanks for the nice mod, and your code! it's simpel but effective!
How to use the machine, there are technical problems can exchange, my mailbox is ds123628@126.com.
petrockblog3 months ago
Thanks a lot for your instructions - helped me a lot!

Recently I also finished a review about the T-962a - maybe you are interested in it: http://blog.petrockblock.com/2014/01/10/reflow-oven-t-962a-a-review/
Hello, I am the structure and operation of the machine, as well as some understanding of performance, hoping to talk to you about the problem areas of the machine. My e-mail ds123628@126.com, my English is poor, which is translated by Google.
chinmay.das11 months ago
Hello Akimitsu Sadoi. good to know you have found a solution of that nasty smell. I bought the same model oven few months back. But during running this oven I found a serious defect in heating process. As per the profile configured for re-flow soldering the complete process should be completed in 7-8mins, but when I ran the process It took nearly 12 mins in actual .And a very strange thing is you can actually monitor that time delay error on its GLCD screen. I did some test running to monitor the re-flow graph , and I found this delay was happening through out the process.I hv more detail information regarding this issue n wud like to share . But you have also found way to improve heat distribution. I will try it on my system, hence will update you if dat solve that delay problem.
and All the best for your Maker Faire trip. :)
Hello chinmay.das, maybe you need a flue machines, then there is some error 962A clock on uneven temperature is almost impossible to change. My e-mail is ds123628@126.com, if you have questions about this machine, you can email me, and my English is poor, which is translated by Google.
ledartist (author)  chinmay.das11 months ago
Thanks for your comment.
The timer is indeed very off - takes about 1.5 times what the panel says. So I took that into account in creating my temp profile.

I think it's an usable enough machine to be worth the price, but could be a lot better.

Please let me know more about your experience.

Aki

Your question should be the clock, concrete or do not understand, my English is poor, which is translated by Google. There are questions regarding the reflow machine can send an email to ds123628@126.com, I am a little bit about the machine, hoping to talk to you about the problem SMT aspects.
962A upgraded version of the 962S, with exhaust function, simple curve to modify the internal insulation material is more environmentally friendly. My mail is ds123628@126.com
gbmhunter7 months ago
Thanks for this teardown of the T962A! I am looking at getting one, this is better than any review I have found!
chinmay.das11 months ago
Hey I just post my reply to this post, but It just got vanished somewhere, so I am reposting my comments.
I got you. But I can say the IR heating part is doing there work quite well, because I use an additional set up for Temperature Measurement using an Industrial Thermocouple+ Arduin+LCD display. What I found the heating element is actually working w.r.t Temperature increment resolution (Which is 1-3 degree C rise in temp per Sec) which is required for reflow process. All issue comes with Uneven heat distribution. Yah you are right , I will try out your Fan trick, n find if it solves the heating issue. Thanks for your support.

Oh yes I will ask her to leave comment or query on your blog , in fact your blog is the best resource to know about your work.. :)
chinmay.das11 months ago
Is it.. Did you set up your own temp profile? Have you tested it? I hope Customized profile does not show up That time difference. I tried to bake two WiFi board using this oven, but due to this time difference the whole process ran over time , as result WiFi modules pop out n module got dead :( . Then I learn for this reflow process timing is very imp factor, even if you bake little more just for 2-3 secs components get damage seriously. So please share your results on the customized temp profile. :) And yes I am A Fan of your Led Art work. I showed your work to one of my Friend , who is an Interior Designer, and she totally blown away. She asked me if you would like to share your art work process from your blog.
ledartist (author)  chinmay.das11 months ago
I did set up custom profile, but the preset one worked pretty well for lead-tin solder. I just wanted to see if I can improve it.

The built in timer is simply slow. It's the same when you use custom profile as well, so you can simply treat each 10 sec step as 15 sec step in creating your profile.

I also did not find the timing to be too critical. With lead-free solder, I tweaked the profile to keep the peak temperature time as short as possible, but temperature accuracy (which I don't have the tool to verify) and heat distribution are more important.

I'd attribute your problem of burning parts to uneven heat distribution (hot spots), and temperature error. This oven can be running much higher temp than what it's telling you.
Also taller parts get too much heat because they are closer to the heater. My fan trick might help a bit.

Thanks for showing my work to your friend! Please have her email me or leave comments on my website, and I will answer her questions.



kbaudio11 months ago
muy didactico muy buen trabajo te felicito!!!!!
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