amontesano wrote:Hello everyone,
I've finished my AC/DC psu kit and I'm reading correct voltage on each rail (burnt it in for about 45 mins, measuring each rail). I then went to check continuity between the voltage regs and the psu chassis and noticed a short between the lM337 and the chassis...according to the information on the build, I shouldn't read continuity between any of the regs?
This is the second time I've powered up the psu, the first time, the 1W resistor burnt up, which was then replaced, and was never an issue after that.
Is this detrimental to the psu? Or can it operate normally like this? Like I mentioned before, the rails measured perfect, so I'm unclear as to how I should proceed. Any help would be greatly appreciated.
If you have the power supply fully wired in and out then you can often measure ohms to chassis etc. The main thing is to check you do not have a dead short between the metal tabs and chassis. Below is the best info to follow.
Make sure you deburr any holes before fitting the silicon insulators and white bush and bolt kit otherwise the silicon washer will be cut and short to the chassis. Once all regs are mounted tight to the chassis with there insulator kits check you have no short between the chassis and metal tab of each reg before you wire any wires to the power supply. If you have a short between the chassis and any of the metal tabs it will be bad. If the 48v reg is shorted to the chassis the 47R 1W resistor will burn up. The best way to save burning anything when first powering up is to fit a small 100mA or less fast blow fuse and have nothing connected to the output of the power supply. If there is a short to the chassis the fuse will blow.