Re: 13.8V HW1200R-20A repair

So really the controller circiutry will usually not fail when the two big transistors fail. The controller circuit is "protected by the transformer" yes? Also the secondary part usually will not fail because it is also isolated by transformers?

I have detailed and removed all components on the primary board area, cleaned the board and tested all the components, so far I have found the two 0.2 ohm 1W resistors were open circuit and all other components ok. I will replace the caps (electrolytic and ceramic. The big 470 uF caps seem...

Re: Mom got me a new laptop for xmas, it is infected with Windows 8

I like Windows 8, does everything I need and it runs faster than win 7 on a core 2 duo. It doesn't seem to crash as much as XP either.
Agent24, try using Ubuntu first up, I have spent quite a few years playing with Linux. My first install was RedHat 5.2 and I have just removed Ubuntu from my desktop. Don't seem to use it so much these days, noe that I am teaching!
Ubuntu is an easy install and set up but with all the good bits under the hood when you want to go looking for them. It is still very powerful...

Re: 13.8V HW1200R-20A repair

G'day All,
I know this is an old post, but I happen to have one of these HW1200 units as well with the same problem. So far I have found the transistors u/s, have replaced them with Fairchild 13009's and I have found the 2 ohm 1 w resistors open circuit. So far I have not replaced anything else. All the other components seem ok. Does anyone have any pointers? I am relatively inexperienced with this one and I need some help with understanding the diagram from kaboom. My issue is not understanding how the transformers work between the circuits. Any...

Re: New Members - please post your introductions here

G'day All,
My name is Dave and I come from Adelaide, Australia. I first found this forum when I was researching a blown powertech 12V 20A power supply from work. I have a healthy interest in electronics and have been playing with arduino a bit. This is really one of my first repair jobs I have tackled.
I hope to learn much from everyone here.