This is the part of the schematic we are talking about
@Douglas_Pearless Iam not completely sure how to check with the meter (I tried). I do understand that when a pin is LOW it is connected to GND. Just not sure how to check that with a meter. I will research it though…I really appreciate your help!!! Big time!!!
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Measure the voltage between the bright green pin (P2.4) and the nearby pin (GND) and it should be close to 0V I have highlighted them on the picture
If not, then something is stuck “on” and we need to figure out what and why, can you post your entire config file as well as it may be something in there.
Okay yeah I figure out how to measure. It makes sense too. I have voltage on 2.4 and 2.6. I compared to 2.5 and 2.7 which are only .001
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Note - I don’t have the USB connected so the firmware is not booted. So something is stuck on…I will download the brd and sch files and review during lunch.
OK, sounds like it is most probably and issue with the soldering and something is shorted. Most likely candidate is the 22R resistor, of the MOSFET itself. If you carefully remove the 22R resistor and measure the voltage between the gate and GND is not really close to 0V, then it is most likely the MOSFET soldering that is the issue, you can confirm that by then also removing the 10k resistor so the MOSFET is isolated and re-run the measurement. If the issue goes away with the 22R resistor, then check the PIN at the header I showed (check the PIN against where the 22R resistor was) is also at GND, if it is not, then it is further up the circuit; let me know how you get one.
I am gonna remove the mosfet first. it looks like I have excess flux under the mosfet. May have used too much.
I removed the two mosfets. The 22R resistor would not lift. maybe its a different solder used. Anyway I tested with the mosfets off. 2.6 was .001 and 2.4 was .005. I am not sure what that means but they both should be consistent. Also the black silkscreen is starting to lift…I think I am going to install an old MKS board to get my printer going. Then work to install components and connection for X9 (bottom of picture). I wish I had thought of this early on… I can use 2.4 to power my cooling fans for the hot end and control board fan, they run all the time anyway. Then get X9 working to cool the print and enable bridging
…of course I need to review the wiki to find out what controls X9 but it should be possible. Big thanks to @Douglas_Pearless for his help…I couldn’t pull it off but I learned a lot! Thank you very much!
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OK it looks like the problem is the soldering around the GATE of the MOSFET as the copper around that pin is actually the 24V VBB which any solder bridge will have the MOSFET turned on (and may even destroy the MOSFET, but hopefully not), the first picture shows the PWM0 trace from the LPC1769:
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The next picture shows the trace going to the GATE of the MOSFET:
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The final picture shows the 24V “plane”:
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so you can see any excess solder can very easily create a bridge to 24V and I think that is exactly what happened when you replaced the dead MOSFET(s)
So, resolder CARFEULLY and use a desoldering braid to wick up any excess solder and check for shorts in this area, good luck!
Thanks @Douglas_Pearless ! That makes sense. I have some really good copper braid that soaks up well.
Great, let me know how you progress, would be good to get you running properly
Cleaned with contact cleaner. Getting ready to clean up pads. The Via under drain is not exposed although it looks that way in the picture. There is a spot by the gate but I cannot tell what it ismissing/deleted image from Google+
The drain via is exposed on q9. Loose the black silkscreen too. Gonna clean up the pads and reflow withmuch less solder. Fingers crossed. missing/deleted image from Google+
That may simply be some silk screen to mark the orientation of the part. Suggest your reduce the excess solder on the pads and hand solder the tab first, then continuity check looking for shorts and then proceed with each pin checking for shorts after eacd solder; user the finest solder you have (0.56mm diameter would be ideal).