Bestec....the next generation

[everell]

Re: Bestec....the next generation

On the down side, capacitor C36 was bulging on this power supply. C36 is in the same location as in most of the Bestec models. C36 is the input filter for a pi filter on the 5vsb line. Therefore with time it gives the same 5vsb problems as earlier models. My solution is simple. Move C36. First remove capacitor C36 from its present location. Drill two new holes on the other side of the heat sink. See photo showing new location. Then solder a new capacitor in the new location for C36.

[everell]

To begin, this is the Bestec ATX-300-12EB3. In general appearance it looks much like the Bestec ATX-250 12Z, but is oriented toward the 12 volt processors. It has two 12 volt outputs each rated for 18 amps, and a 5 volt output rated for 25 amps. It uses the same 5vsb chip as the 12Z, the A6351 chip, therefore preventing the 5vsb overvoltage problem in the early 12E model. It also has four optoisolators, one of which is the crowbar circuit for added protection. When something causes the power supply to shut down, the crowbar circuit prevents you from turning the computer off then back on. You have to unplug it from the wall to release the crowbar. This prevents people from thinking the problem went away by using a simple restart.

From the pictures you can see two shunts used for the two 12 volt overcurrent protection circuits. Something new added since the 12Z.