Author Topic: puhui T-937M experience  (Read 9795 times)

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Offline lamabrewTopic starter

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puhui T-937M experience
« on: December 20, 2018, 06:00:54 pm »
There's been a couple of different threads about reflow ovens but mostly people asking if anyone owned one. Instead I'm writing this thread as a (long) summary of having recently purchased the T-937M. I'm still learning it and if there's anyone else with it that can offer up their experience that would be great.

The T-937M doesn't appear on their website, compared to the T-937 it has a bigger drawer 350x400mm with a usable area listed as 290x375 for lead free and 315x375 for regular solder. 3300 Watt heater.

I ordered it directly from them (via Dragon Group, the parent company). I had a couple of questions such as the information said 220V 50 Hz in one place and 50/60 Hz elsewhere. They got back to me within 24 hours on the requests. (60 Hz is fine)

I ordered and they sent me a Paypal invoice (around US $720 total with shipping to me in the Boston area) and the package arrived about 8 days later. The box was a bit dinged up and some the styrofoam paking had cracked but there was no signs of damage.  (for something of this weight (22 kg) probably a double box would hold up better)

(I cut the straps to remove the docs that came with it)

I  changed the plug to match US 220V 20A outlet style (they double checked with me to make sure I understood it wasn't a 120V machine and I would have to change it, though oddly enough they included a US 120V 15A plug in the box).  The yellow wire in the cord was the safety ground, here it's usually green.

They provided a metal exhaust hose, some foil tape (not sure exactly what for as the exhaust hose clamps on), a spare fuse, a serial to USB adapter, and a CD.

The CD wasn't readable and the files are not on their website, I emailed them and got an email back with the files the next day.  The manual (in English) is provided as a pdf but it doesn't give a lot of information.

The unit can run without a computer so I tried the built in profiles first with it empty. The light line is the profile temp, the heavy line is what it measures (I'm guessing the sensor is on the top side of the chamber but I didn't look for it)


No odd smells even with the exhaust vent not actually routed outside.  A slight "new paint" smell that faded. Only place that gets hot to touch is the drawer front, which isn't insulated.  The small fan that runs all the time for the controller has a bit of a whine, but the machine overall isn't loud.

The USB driver Puhui supplied wouldn't install but it uses the CH340 and I grabbed a recent driver for that and it installed fine (Windows 7).  The Puhui app installed OK though it seems like it needs to be run as administrator as otherwise it doesn't seem to save changes. I did not look to see where it's trying to keep files, etc.

I haven't total figured out the app, it has three databases it keeps for solder paste profiles (and comes with quite a lot, but I had to add my Chipquik paste), a recipe (which you create by drawing over the solder paste profile to adjust the time/temps to get the results on the board you want), and a manufacturing one which I haven't tried to figure out yet but seems like it lets you save away the setup and measured temps.

When it's running it replaces the setup screen with a run-time screen that shows what it's doing.

The green line is the target, the purple is what it measures.  You can see that the initial ramp I put in is too fast and it doesn't catch up until the soak period. OTOH this was the first run so the unit was cold, it does a little better on later runs but I'll probably extend the initial warmup time.  For cooldown it draws in room air and it can't really drop too quickly.  Opening the drawer a little helps. If you terminate the run the exhaust (cooling) fan stops.

I have 3 thermocouples so I attached them to some small leftover PCB blanks and ran the oven with them arranged across the middle and then centered front to back.  The outside sensors are somewhat over the edge of the area they define as usable and at some point I'll try one large board and measure across it.

(Left center right measurement locations)


Measured temps on PCB with peak setpoint of 235C.

The center measurement location typically shows it hits the desired temp, with the left and right about 10C less. The results seemed consistent but I didn't try and characterize beyond eyeballing the curves.

Front to back showed considerable variation.

(red middle, green front, blue back)

The front area stays around 25C cooler than the middle so I'm planning to not put anything in the front 1/4 until I figure out where the drop off is. Given the defined usable area in the datasheet I think this probably falls "in spec" but it would be nice if the manual gave some guidance as to *where* they think the usable area is.

I have a Sense power monitor and it shows 3600W used when the unit is running, but my "220" is actually 240 so that probably covers the higher than advertised number I measured.

I've run 3 different SMT board types through it (same sizes as used for the measurements) with regular solder and the results look really good compared to my previous IR hot plate/hot air method.  I've got a lot more things to try but so far for what I wanted (easy to use, consistent results for small prototype batches) it seems pretty good, and the whole purchase process/experience dealing with Puhui/Dragon was positive.

« Last Edit: December 20, 2018, 08:03:29 pm by lamabrew »
 
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Offline lamabrewTopic starter

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Re: puhui T-937M reflow oven experience
« Reply #1 on: January 17, 2019, 05:49:24 pm »
A self followup now that I've run some boards through it.  For a mid size desktop/drawer reflow oven the Puhui 837M seems like a good choice for me.  I've still got some work to do with temperature profiles - I leave the three small PCBs with thermocouples (see original post) in all the time and use them to monitor what's going on.  On the TODO list is to experiment with slower ramp times prior to the high temp phase to see if that gets things to be more uniform.

My most recent build included a QFN (sorry for the big image, I wanted to keep it full resolution to allowing zooming in but haven't mastered controlling the preview size). No clean solder so that's the random goop you see in the photos.  Chipquik SMD291AX50T3 67/37 paste.



I'm pretty happy with the results. One pin was maybe a bit off but I think there that was a paste problem that I didn't notice.




Unrelated the closeup does show the solder mask was just a tad off, but not in a way that affected results. Given the 0.5 mm pin to pin spacing I get amazed that it just doesn't come out as one big blob of mush.

If I find any issues I'll update this thread again but so far I'm happy with the unit as a solution to my particular needs.
 
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Offline istipb

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Re: puhui T-937M experience
« Reply #2 on: February 19, 2019, 01:43:08 am »
HI thanks for writing the detail experience.  Do you think 937 will work reasonably well? 937M is $100+ usd more.  There are 2 more models 961 and 960.
« Last Edit: February 19, 2019, 01:45:05 am by istipb »
 

Offline lamabrewTopic starter

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Re: puhui T-937M experience
« Reply #3 on: March 31, 2019, 11:14:36 pm »
Sorry for the slow reply to your question.  I went for the 937M because I have some larger size boards that I needed to handle and the 937 wasn't quite large enough after allowing for some room around the edges.  I also liked that the larger one has a higher power heater (2300W vs 3300W), though I had no actual experience to base that choice on.

(corrected a mistake about power, based on the sheet the 960 is Ok with 220V)  BTW even though they list 50Hz 'only' for the 937M  it works fine with 60 Hz (I checked with them before ordering). If it helps I attached a comparison chart they sent which I didn't find on their website.
« Last Edit: April 02, 2019, 02:07:08 am by lamabrew »
 

Offline IanJ

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Re: puhui T-937M experience
« Reply #4 on: October 17, 2019, 07:27:28 pm »
How are you getting on with the T-937.........I am looking at getting one so would be nice to hear an update.....

Ian
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Offline lamabrewTopic starter

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Re: puhui T-937M experience
« Reply #5 on: October 20, 2019, 03:49:52 am »
How are you getting on with the T-937.........I am looking at getting one so would be nice to hear an update.....
Ian
Still happy with my choice.  It's just a minor annoyance that the front part stays cooler; I stick to the 'center' half and really can't say I have issues with the oven.  I need to do some work to tweak the profiles for running a few small 2 layer board vs. larger oven filling 4 layer boards with lots of copper planes. I think the answer is to extend the ramp up time for the boards with more thermal mass but I'm not sure if/how that might affect the flux activation (and if I should try different pastes, etc).

Running a cycle to preheat from a cold oven before the first run is a good idea but I haven't created a cold start preheat profile to cut the time down vs. just using my normal default cycle to preheat.

There are times I wish for a better software experience/documentation but it's still "good enough".

Still on my to-do list is with some 0.4mm pitch QFNs finding the right paste and paste mask expansion values to get consistent results; with 0.5 mm pitch and up I really haven't had issues.  I don't know how much, if any, the oven plays in to my successes and non-successes there.

Between the presales support, the prompt shipping, and the experience I've had using it I would recommend it for my type of use case.  Of course I have no comparison to other ovens that might be better; in all honesty I think better here means a multizone oven and that's big jump in price.

Brewster
 

Offline IanJ

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Re: puhui T-937M experience
« Reply #6 on: October 25, 2019, 08:22:18 pm »
Thanks for the info, my 937 arrived today, got it all ducted up and gave it a run with a test pcb and using GC10 paste.........really good 1st time, perfect joints and nice and shiny.
Seems like a good upgrade to my 962 (modified).
Can't wait to try a full tray next production run.

Ian.
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Offline amiq

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Re: puhui T-937M experience
« Reply #7 on: February 15, 2020, 02:00:15 am »
Hello Ian, Now that you've had this oven for a while what are your thoughts?
 

Offline IanJ

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Re: puhui T-937M experience
« Reply #8 on: February 16, 2020, 12:34:03 pm »
Hello Ian, Now that you've had this oven for a while what are your thoughts?

Well, I am getting on great with it......I think. I have reflowed a lot of boards, some just one at a time, other with a largely full tray. The heat seems pretty even across the entire tray.

I noticed some issues though:-

I was experimenting with some double side and single sided boards and lead-free GC10 paste.
For single sided boards, no ground plane on Profile 1 it can burn the board, on Profile 2 it can show heat mark the pcb's, so Profile 3 is used.
For my normal double sided boards with ground planes on the profile 1 setting it can heat mark the boards so Profile 2 is used. Profile 3 doesn't quite reflow properly.

I think this is due to the fine line between incinirate and good reflow with lead free paste though.

So, I want to start using leaded paste again, and I want to use the software and serial connection to achieve more custom profiles. And just this morning I attempted this, but the software on the CD won't install. I get "LAUNCHER ERROR - Unable to open archive file" on all the EXE's supplied.

Anyone got a newer version of the software they can send me? PM if you have and I'll give you my email address.
Meanwhile I have emailed the manufacturer.

Ian.

UPDATE:
Got the software from one of the users here.......and yes, it's quirky.

You can remote control the reflow, or better still from my point of view create new reflow profiles based on paste profiles you can load up.
My first test was to load the profile for Multicore MP100 (183) and create a profile on top of that.......then save it to the reflow oven and thus the software no longer required except for future modification.

I am probably missing a lot of the functionality, but thats what I am getting so far.

UPDATE 2:
Some functions of the software don't work properly or crash the app.......you have to give FULL ACCESS to teh security permisions for the main folder C:\Program Files (x86)\T937 Series Reflow Soldering Control System

Ian.
« Last Edit: February 16, 2020, 07:12:28 pm by IanJ »
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Offline amiq

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Re: puhui T-937M experience
« Reply #9 on: February 17, 2020, 09:37:48 pm »
Thanks Ian, I'll keep this one on the shortlist.  The serial command protocol should be easy to figure out so poor control software isn't a show stopper.  Can't you input custom profiles using only the front panel with this machine?


Also looking at the 962C and the ZB series ovens.
 

Offline szymon019

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Re: puhui T-937M experience
« Reply #10 on: May 15, 2020, 08:07:31 am »
Hi Colleagues,
Could you describe how they make thermal circulation inside the oven? In modiffied software to T962 we had backside fan "vibrating" pumping room air on heaters. Could you describe behaviour of fume gasses fan work ?  What would happen in situation of connecting fume gasses pipe to chimney with natural convection flow? Would it grab heat from soldering chamber or they implemented some air shutter?
Best Regards
Simon
 

Offline lamabrewTopic starter

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Re: puhui T-937M experience
« Reply #11 on: May 15, 2020, 03:22:11 pm »
Could you describe how they make thermal circulation inside the oven?
I did not take the unit apart but there's a circulation fan of some sort mounted above the heaters.  I don't know which way it's pushing air.  That fan does not run continuously, if I had to guess its running is decided by the temp delta and desired ramp rate. 

Could you describe behaviour of fume gasses fan work ?  What would happen in situation of connecting fume gasses pipe to chimney with natural convection flow? Would it grab heat from soldering chamber or they implemented some air shutter?
There's no shutter, just the fan blades. Since the hot air in the chamber is going to expand and naturally want to find its way out I doubt there would be an issue hooking it up to a chimney unless it had a noticeable pressure difference.  There's 3000 watts of heating elements in the 937 and I would guess it could deal with some extra loss, though the question is the fast ramp at the reflow (peak) part of the cycle as you want to get hot quickly to avoid frying things.

 

Offline fschuetz

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Re: puhui T-937M experience
« Reply #12 on: June 17, 2022, 11:05:23 am »
Dear all

I hope it is ok to revive this older thread for my concern, as opening a new topic for my problem seems a bit overkill. After reading about the T937 I decided to buy one and after a first test drive it seems to work fine. Unfortunately the software delivered with it seems to be corrupted and does not install ("unable to open archive file" error). I wrote to the manufacturer, but no reply yet. I wanted to ask if anyone of you that possesses the software would be willing to send me a copy. Of course, if you like I can provide proof of purchase over pn. I was really hoping to start dialling in some profiles soon.

Best,
Florian
 

Offline lamabrewTopic starter

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Re: puhui T-937M experience
« Reply #13 on: June 17, 2022, 02:43:03 pm »
Send me a PM with your contact info, it's about 11MB.

The software has issues but works well enough to do what I want.  I run it from an old laptop disconnected from my networks is it requires admin privs to run (it won't save things if run as a normal user).

Though bug PuiHui again, maybe by now they have an update that solves some the annoyances.
 
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Offline fschuetz

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Re: puhui T-937M experience
« Reply #14 on: June 17, 2022, 03:24:53 pm »
Thank you for your support. I just found out how to execute the software provided. Instead of running the .exe from the provided memory stick or from a folder on the computer, copying the exe to the windows desktop and executing from there works. I guess they have some hard coded paths in the installer. Thanks anyway for the offer.

The software seems to be the same. Its buggy, crashes, does not safe the profiles if not admin (thanks for the hint, would not have found this otherwise) and does not display all characters correct, even if switched to english. But well, a profile needs to only be created once, so I guess it does the job....
 

Offline cncrthrzn

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Re: puhui T-937M experience
« Reply #15 on: February 03, 2023, 09:40:42 pm »
Hey all,

I am in a similar position as most users here; trying to get my hands on a readable copy of the software for the T937, if anyone would care to pass it along I would be very appreciative. Happy baking

best,
D
 

Offline lamabrewTopic starter

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Re: puhui T-937M experience
« Reply #16 on: February 10, 2023, 05:17:07 am »
Sorry, let this one scroll off the top.  If you still need it I put a copy of the .exe here temporarily: https://1drv.ms/u/s!AmAunFZtb8ZikMcoFJZmWhjKv34o2A?e=zANe0J

 
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Offline s-ol

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Re: puhui T-937M experience
« Reply #17 on: February 07, 2024, 05:06:54 pm »
If anyone else is looking for the official software, I'd recommend reaching out to the manufacturer (Puhui) via WeChat or perhaps email. We purchased a T-937M from them directly and they were very responsive.
On the USB key that came with the oven there was two versions, one that was labelled "Win 10" with a "portable" .exe install, and another version with a T937.exe installer. The "Win10" version seems to be more recent, as it has a few more features (e.g. "remove last control point" button in right sidebar). I've also found it to be a bit less crashy.

There's some reverse-engineering of the T-937M controller in this github issue thread:
https://github.com/UnifiedEngineering/T-962-improvements/issues/194#issuecomment-876803891
Getting a custom firmware with PID control would be great, but it doesn't seem anyone is pursuing that actively at the moment.

The PC software has some cute features like annotations and measurements in the main window with image export that would be really useful - except that applies only to the plot of the solderpaste specification and the programmed curve, and not to the graph of the measured cycle temperature!
Alas when you run a cycle, you only get the small preview window visible in OP that tracks actual vs programmed temp, but I haven't found a way to pull that data back into the programming window to do measurements or compare it with the paste specifications. (You can do a PNG export and import that as a background in the programming window, but the scale adjustment isn't enough because the exported scales add an offset). There's a "cycle history" feature that stores cycle curves in a local database that could be mined, but I can't imagine the serial protocol being very complex so that seems like an interesting way to put together a nicer interface, perhaps even using WebSerial.

I've only run a few boards so far but found that stock profile #4 worked great with Chipquik TS391 paste on both a larger (300x120mm) and a smaller board (100x100mm), each centered in the oven.
We went fort he 937M over the 937 for the same reasons as lamabrew. I'm quite happy with the 3kW version, 5min of cycletime including a decent amount of cooling is really neat.
 
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Offline s-ol

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Re: puhui T-937M experience
« Reply #18 on: February 19, 2024, 10:56:31 pm »
I've spent some time recording and analyzing the Serial traffic between the control software and the oven over the last two weeks and I think I've mapped pretty much all of it at this point (when sending/receiving profiles there's some acknowledgement messages that I haven't looked into yet in detail but it shouldn't be too complicated).

The oven uses a modbus-RTU inspired serial protocol with a 38400 baud. While connected, the oven reports three integer temperatures in ºC, the first two are usually similar and their average is what the GUI displays, so presumably those are two themocouples in the chamber. The third temperature is usually quite a bit lower so I'm guessing it's measured on the control board.

The commands for turning on and off the heater and cooling fan are actually not only on/off as the GUI impoements, but can be set to a range of PWM values. The PWM frequency is very low though (~2Hz) so it doesn't really add much value.

This got my hopes up for implementing a PID Controller in JS with the temperature readouts and fix the overshooting, but I can't find a way to turn on (or off) the circulation fan which is a real bummer. The command codes for the heater and cooling are 0x8 and 0xD respectively, so I tried 0x7 to 0x1f (all the nearby numbers that aren't other known commands) but alas nothing turns on that LED.

Reading and writing profiles is also very simple, a profile consists only of number of ºC temperatures, one every 3s.

There's WireShark analyzers and a JS implementation of the protocol using WebSerial here:
https://git.s-ol.nu/t937-serial/-/

There's no UI for the web version yet aside from reading the temperature values, but I've successfully used the console to control the heater and cooling fan.

I'm planning to expand this into a web-based tool that allows at a minimum reading and writing profiles, as well as running them and seeing the actual curve in the same chart as the paste spec. That feature and linux support should make the time spent worth something.
« Last Edit: February 19, 2024, 11:01:18 pm by s-ol »
 


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