Anyone have schematics of the Printrboard F5 Z-VSEL circuit?

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Anyone have schematics of the Printrboard F5 Z-VSEL circuit?

Postby CltFlyboy » 2017-Jan-Thu-14-Jan

I'm troubleshooting my Printrboard (was starting to convert the inductive Z probe to a capacitive) and, waht do ya know, accidentally shorted the dang connection.

I fried the pre-biased transistor, already replaced it, and thought I was good to go.

However - I now have zero volts on the HV side pin of the Z-VSEL jumpered connector. The +5V side is fine.

My ask: Does anyone have the actual schematic for this part of the Printrboard PCB? The Eagle files on github are *incomplete* and show the bus coming off the HV side terminating to nowhere (it's just a hanging trace). Additionally, what voltage should I expect to see on that pin (I thought it was +12VDC)? I'd really love to fix this, any help is greatly appreciated.

Thanks all!

--Henry
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Anyone have schematics of the Printrboard F5 Z-VSEL circuit?

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Re: Anyone have schematics of the Printrboard F5 Z-VSEL circ

Postby RetireeJay » 2017-Jan-Thu-16-Jan

Here's the Endstops portion of the F5 schematic that I downloaded from Github several months ago.
Printrboard Rev F Endstops.PNG
Printrboard Rev F Endstops.PNG (5.27 KiB) Viewed 132 times

The upward-pointing arrow labeled "12V" simply means that this node connects to all other nodes labeled "12V" - it's a convention in drawing the schematic to save space and cut down on clutter. On the board layout view, you can get this connection to become visible if you play around with the visibility of different layers.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: Anyone have schematics of the Printrboard F5 Z-VSEL circ

Postby CltFlyboy » 2017-Jan-Thu-17-Jan

Thanks Jay - appreciate the info. I've got the full github repo here already and have opened the schematics in Eagle. i understand schematic labeling conventions, i should have been more clear earlier - I get that the pin connects to the +12VDC bus per the schematics, but I'm trying to find the *exact* interconnect point on the PCB. Eagle is showing, in the BRD view, an unterminated trace for the pin (see the attached screen cap with the mystery termination circled in red).

Short story long (Freudian pun?), I think that I've actually cooked a trace on the board somewhere between the HV pin and it's source - thus why I'm trying to find the actual source. I may just say eff it all and run a new bus wire to the +12VDC pad at the PWR connector and be done with it.

That's what I get for going too fast and not paying attention to my meter lead - a short that caused more problems that I ever though would happen :-)

Thanks again,

--Henry
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Attachments
Printrboard_F5_HV_Pin.PNG
Printrboard F5 Z-VSEL HV Pin Termination
Printrboard_F5_HV_Pin.PNG (62.62 KiB) Viewed 121 times
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Re: Anyone have schematics of the Printrboard F5 Z-VSEL circ

Postby RetireeJay » 2017-Jan-Thu-17-Jan

AFIK, the "official" Printrboard is a multi-layer board, so I'm guessing that the dead-end trace actually just moves to another layer. After all, the boards do work!

So I agree 100% with you: you'll never be able to repair a trace that's internal to the board, so you might as well just run a jumper wire.

Your problem reminds me of a situation I ran into about 35 years ago. At work, I had designed a PCB and etched it using fairly crude "homebrew" equipment. It looked good, but before populating it, I wanted to check it out with an ohmmeter. All the places that were supposed to be connected were connected, but there was one undesired connection between two unrelated nodes. I searched and searched for the wayward hairline connection with a microscope but couldn't find it. I took a tool and scraped along the gap between the traces and still couldn't fix it. Finally, I figured that whatever was causing the undesired short circuit must be very tiny. So I connected the two traces to opposite sides of 110VAC. I never saw a flash or a puff of smoke, but the undesired short circuit magically disappeared! The board worked fine.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
User avatar
RetireeJay
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Re: Anyone have schematics of the Printrboard F5 Z-VSEL circ

Postby CltFlyboy » 2017-Jan-Thu-17-Jan

That's a great story and brings back memories from those days long ago... And it brings a whole new meaning to the term "HI-POT" :-) Your solution was elegant and shows just how much critical thinking we've "lost" over the past generation or two. I've tried to instill in my kids that they should always think not only outside of the box, but outside of any predisposed patterns. I remember taking them to Home Despot one day when they were young (maybe 8 or 10); I needed a custom bushing or collar (can't recall exactly what for now) for a DIY project - something that there wasn't a "ready made product" for. When we walked in i told them to look for a "round" for me - no more, no less. And wouldn't you know it, one of the kids found something that was absolutely perfect for my project in a place that I never would have looked. It's a lesson that they still talk about today :-)

Thanks again for all of your help, off to run a new +12VDC buss.

--Henry
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Re: Anyone have schematics of the Printrboard F5 Z-VSEL circ

Postby CltFlyboy » 2017-Jan-Thu-18-Jan

New buss wire installed, board installed, bingo, back in business.

:-)
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