One quiet summer evening I had a big trouble - absolutely unexpectedly dropped dead AC adapter of the laptop. Of course, it can be repaired (and in the future, I repaired a powerful replacement the chip pulse Converter and two diodes), but there was no the time nor the necessary details. But there was a set of boards from an old TV set USCT, including the power module MP-3-1.
In Fig. 1 shows a diagram of the output of the power module.
As can be seen, the available voltage 130 V, 28 V, 15 V, 12 V and 16 V, Nothing suitable for laptop power no, because it requires 18V.
Rewinding the transformer TPI-4-3 - worst case, the core is glued tightly, and when you try to split ferrite crack (I know about this from the practice of repair). Therefore, optimally, perhaps, to use exit 28 for powering personnel scan - power is more than sufficient. The only problem excessive the tension. But this problem was solved with the help of two powerful Zener DG (Fig.2). Each Zener diode has a voltage stabilization 10 V and a current of stabilization of from 20 to 800 mA. The current consumption of the laptop is 1.5 A. hence, the maximum current greater 800mA, so taken two Zener included in parallel (maximum current of 1.6 A).
They work on a current almost to the limit, so it is advisable to put them on some radiator. I just screwed them on a piece of metal area. When the flow return current Zener diode enters the stabilization mode and holding the voltage of 10V. Thus, this voltage is subtracted from the voltage of 28 V and the output remains 18 Q. If you need more voltage, for example, 20 To need to use Zener DV (8.2 In). Resistor 390 Ohm gives minimum current at idle the go.
Some MP-3-3 don't want to start if it is not loaded circuit 130 V. If so - load it in the usual incandescent lamp 220V capacity of 15 or 25 watts.
To set accurate voltage can trimming resistor R2 on the module Board power.
Author: S. Andreev