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Hi,
I built the board ok and checked all solder joints. When i got to the point of powering up, the lcd lights up but there is no text. I went through the troubleshooting forum posts and saw the usb test. When i plugged in the usb and turn off the switch the board works perfectly. I can connect through a web browser and everything. If i switch the power on while still connected to the usb, the screen gets a little brighter but continues to work. If I then pull out the usb cable the board continues to work. I did the resistance test between VIN and GND and i got a high resistance so it does not seem like i have a short.
Do you have any ideas?
Thanks,
PEter.
If the circuit works with USB power, it means at least everything other than the power supply section is working. Now, did you follow the build instructions to test VIN to GND voltage, as well as VCC to GND voltage? Are they roughly 5V and 3.3V respectively (assuming the controller is powered by 24VAC only)?
Hi,
Yes I did those tests. The first was 5v. The second test was a little higher at about 3.8v. Though I have a crappy volt meter do it is a little hard to read.
Yes I have a 24vac supply 875mw. I tried it with a second power supply 24vac 700mW and the board behaved the same way.
I found that if I kick start the board with the USB I can then turn on the power and disconnect the USB and the 24v. Seems to maintain everything up and running.
Peter.
Hmm, that’s rather strange. I’ve never seen such a symptom before. 3.8V Vcc is definitely strange. It’s still within the mcu’s spec, so the mcu should be up running. But it’s certainly not normal (should be between 3.2V to 3.4V). I can’t think of any reason for the abnormal Vcc voltage. Assuming the MCP1702-33 is working (the chance of it being defective is very small), the only thing I could think of would be the capacitors C2 and C3. If these capacitors are not soldered reliably, or if you accidentally soldered the 10uF capacitor onto the position of 220uF, it may cause the voltage to be abnormal.
I double checked the capacitors. Top right is the 10uF capacitor and bottom left the 2 identical 220uf next to the large 100uF capacitor. Could it be they are bad capacitors?
For the heck of it, i connected it up to the sprinkers and tried. I didn’t work. When i did a manual override on any of the 3 zones, the animation for each zone worked but they were not powered. I tested each zone with the volt meter and they did nothing.
I am running out of ideas.
The areas of the PCB that look like a green checkerboard pattern are tied to ground. Looking at your pictures, I see several areas where solder dross appears like it could be bridging the solder pad to ground. I also see several places where the soldering appears to be insufficiently filling the pad.
I am reluctant to blame your solder, because a two dimensional picture often has shadows and other artifacts that make things appear to be an issue when they really are not. However, as Grandma always told me, “Cleanliness counts”. I would suggest touching up all the insufficient solder areas. Then get some rubbing alcohol and an old toothbrush and remove all the solder flux, solder dross, solder balls and other stuff from the bottom of the PCB. Give it a couple of good rinses with a squirt bottle. Q-Tips are also good to mop up between component pins. You can either air dry it or use compressed air to dry the board.
After the board is good and clean. The visually inspect your soldering with a magnifying glass. Look for cold solder joints, insufficient solder, and solder bridging pads. Once everything passes inspection. Power it up and see if your symptoms are still there.
Skeptics may wonder why this could possibly be a problem. The issue is that solder flux residue attracts moisture and can often be conductive. It is like sprinkling a ton of high value resistors all over the board.
When soldering it is important not to ball up your connections with solder, use just enough to make the connection. Make sure your soldering tip is clean and apply a bit of solder before hand, apply heat to one side and solder from the other. Always clean up dirty connections and use solder with flux. Never apply heat for too long, because you can remove the traces and cause issues with the components. This will minimize headaches. 😉
@talsprinkler wrote:
For the heck of it, i connected it up to the sprinkers and tried. I didn’t work. When i did a manual override on any of the 3 zones, the animation for each zone worked but they were not powered. I tested each zone with the volt meter and they did nothing.
I am running out of ideas.
Check your resistor arrays RN2 and RN3: make sure you’ve soldered the 220 ohm x 4 ones to them. If you accidentally soldered the 10K x 4 resistor arrays to RN2 and RN3, your valves will not be activated because the triac will not be able to turn on with such a large gate resistor.
Oh Man,
That was it. The resistor arrays were swapped around.
Ray, not your fault but I got confused by the text:
“For example, 10K array should read ‘L83S 103 xxxx’, “I think i read the first part of the label L83S and made the [wrong] assumption that the resistor i was holding was the10k and i labeled it as such while doing the parts check.
Because they are so similar, It would have been super hand if those were distingushed in the kit.
But then again i am the only numbskull that made that mistake. I broke one of the arrays desoldering so i am waiting on an order from digi-key.
I’ll let you know how it turns out.
Thanks for your help everyone.
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