OpenSprinkler › Forums › Hardware Questions › DIY Kit Assembly Questions › 1.42u Power Supply Problem › Re: Re: 1.42u Power Supply Problem
The part name difference should not be a problem: we buy parts in different batches. Usually even if you order from the same supplier a few days apart, the part number can be slightly different. ‘ST CHN 063AC 41E241’ is an MC34063 chip, so no worry about that.
You can use this thread as a reference to troubleshooting:
My suggested list in order:
1. test the resistance between VIN and GND. If it’s less than at least several kilo-ohms, some components must have been damaged and shorted. Start with zener diode D3, desolder it or simply clip it off, measure VIN-GND resistance again; if still too low, desolder or clip the MCP1703-33 linear regulator. Basically follow the components that have to do with the VIN line, and check them one after another, and replace if necessary.
2. If the VIN-GND resistance is above several kilo-ohms, the next thing you should try is to power the controller through USB. Plug in a USB cable, and measure VIN-GND voltage, which should be somewhere around 4.7V to 5V. Then measure VCC-GND voltage, which should be around 3.2 to 3.3V. At this point, you can plug in the other ICs and the controller should function normally (except since there is no 24VAC it can’t activate solenoids).
3. If your MC34063 is damaged, you should get it replaced. The final step is to go back to what you did before: test the power supply with 24VAC transformer. Just to be safe, you should take out all ICs except IC1. If it passes the voltage tests, you can then plug all ICs back.
To get replacement components, you can either follow the part list to buy them from Digikey, or you can send me an email and I will send you requested components at a nominal cost.