MaxSTM v3 through-hole construction tips


johnwashington1978@...
 

Is there any recommendation for the RTC mounting, if I solder it straight into the PCB it looks like it will be awfully close to shorting R20 if it bends down a little bit on the end without a header.

Generally is it "done" that all of the daughterboards go into header sockets or is it better for reliability to solder them directly to the pcb through their header?  I think there maybe a requirement to remove the WemosD1 although I have already programmed that, is there a expectation to remove the blackpill, RTC or stepper drivers?

Just looking for some best practice pointers before I unleash the soldering iron!


Howard Dutton
 

The assembly instructions are a work in progress.

But yes standard 0.1" pin and socket headers there.  You want it lifted up.  And those cheap RTC modules occasionally have issues and being able to just plug another in is a good idea.


Howard Dutton
 

On Fri, May 21, 2021 at 05:39 AM, <johnwashington1978@...> wrote:
I think there maybe a requirement to remove the WemosD1 although I have already programmed that,
It's supposed to be socketed also.

is there a expectation to remove the blackpill, RTC or stepper drivers?
Yes.  It's best to make it modular so you can swap out these components that would otherwise be difficult or nearly impossible to repair, the pin/socket headers are very reliable in our experience.


Howard Dutton
 

The Wiki for the MaxSTM3.6 through-hole design PCB has been updated with more information.

Nearly complete build instructions now I think.

The MaxSTM


George Cushing
 

What I like: slotted vias for the power jack, adoption of the micro fuse holder and DE-25 eliminating jumper hell!


Howard Dutton
 
Edited

On Fri, May 21, 2021 at 05:39 AM, <johnwashington1978@...> wrote:
Just looking for some best practice pointers before I unleash the soldering iron!
The MaxSTM3 Wiki pages have been updated again.  Mainly this was to add instructions to guide users on how to order the required parts from LCSC and how to source the handful of other parts that LCSC doesn't stock.

I welcome feedback on the build process and any issues/shortcomings you notice with the Wiki/build.


Drew 🔭📷🚴‍♂️
 

I welcome feedback on the build process and any issues/shortcomings you notice with the Wiki/build.
Ok, I guess I'm just dense but I cannot find this? Where is this "Wiki/build"?


Howard Dutton
 

On Wed, May 26, 2021 at 06:30 AM, Drew 🔭📷🚴‍♂️ wrote:
I welcome feedback on the build process and any issues/shortcomings you notice with the Wiki/build.
Ok, I guess I'm just dense but I cannot find this? Where is this "Wiki/build"?
I guess I should call it "MaxSTM" not "MaxSTM3" or "MaxSTM3.6" as I don't label Wiki sections with the version as they tend to lead to all versions of a given series...

The MaxSTM and The MaxSTM (SMT)


Drew 🔭📷🚴‍♂️
 

My misunderstanding. I thought this was some Groups.Io option that I was missing.


johnwashington1978@...
 

Well, JLCPCB arrived in the post this morning and within 30 minutes or so I was up and running - I'm not too keen on the RTC dangling - I'll design up a small 3d printed block that screws between it and the pcb stand off hole - shall post it tomorrow.

Other than that I didn't have any build issues - I sourced the majority of my parts from digikey - I had the leds and diodes already, used an lm7805 vreg and some ebay headers.

If a wally like me can get it together and working, anyone can !!  Big thumbs up!


Howard Dutton
 

On Thu, May 27, 2021 at 02:10 PM, <johnwashington1978@...> wrote:
Well, JLCPCB arrived in the post this morning and within 30 minutes or so I was up and running - I'm not too keen on the RTC dangling - I'll design up a small 3d printed block that screws between it and the pcb stand off hole - shall post it tomorrow.
I'll put that in the files section.

Other than that I didn't have any build issues - I sourced the majority of my parts from digikey - I had the leds and diodes already, used an lm7805 vreg and some ebay headers.
Technically the board isn't designed for the lm7805, they usually need stabilization caps nearby.  There's a 0.1uF but usually they need a 0.33uF too and the board doesn't have that one.  Then it's not going to be good for much current without overheating, especially if powering from 24VDC.  Might be ok, but best to use the spec'd switching regulator though.

If a wally like me can get it together and working, anyone can !!  Big thumbs up!
Thanks, these are nice boards in my opinion too, another step up in the evolution of the Max series.  Better documented, easier to source parts for, easier to assemble, better TMC stepper driver support (allowing the most important settings for all axes at runtime,) and more easily extended for BME280 dew heaters, etc.


George Cushing
 

Similar problem on the MaxESP3. I just add the pins and glue a de-pinned length of female header to the pins.



George Cushing
 

BTW, any one have a spare MaxSTM PCB available? Let me know, thanks.

 


George Cushing
 

The OKI 78S can be a bit dear. Just ran a 12V and a 5V through Mouser and It's $18.30. Not sure I see a reason for the 12V. I understand that 24V may exceed the capacity of some driver somewhere, but nothing in my inventory!  At $9 for the regulator maybe better to just shop some drivers that stand up to the voltage. 

Most 7805s are rated 1A. OKI claims 1.5A, but Murata says their IC can deal with 3.5A, more than Howard designs the PCBs for. The same Murata IC is used on this regulator:

They come in at about $1.60 if I buy 30. So I can get you one for $5. If you want more it's a buck 60 plus the postage. I've started shipping these 7805-12 replacements in case anyone really needs them. They run a buck a piece. Basically a 100mH inductor, 3 caps and a SS34 Schottky diode. Probably do the job for a focuser.






Howard Dutton
 
Edited

The preferred regulators in the Wiki are low cost alternatives to the OKI78SR, I added mention of that other one too though, thanks.


Patrizio Boschi
 

Is the MaxSTM v3 through-hole PCB compatible with WeMos D1 Mini based on ESP32 (such as "TTGO T7 V1.3")? I think that they are a bit larger, and I don't see so much space on the left side of the Wemos footprint (where the buzzer is).

That would enable the use of the bluetooth joystick as explained in another section of the wiki.


Drew 🔭📷🚴‍♂️
 

It should be OK. On my MaxESP3 the spacing is similar. The buzzer top is actually lower (underneath) the Wemos ESP32.