FACTORY SPECIFICATIONS
========================================
Input Voltage ...... 240V/AC
Input Current ......
Output Voltage ..... 13.8V/DC
Output Current ..... 28 Ampere (Maximum 30A)
Dimensions .........
Weight .............
Manufactory ........ MAAS

Fan replacement
2006.08.18 Replaced the noicy standard 80mm fan inside the 'MAAS' powersupply. Decided to trye a pc-grade 80mm low-noice fan. I been using this type of fan in my HTPC project - Noice is specified to 12dB from the factory


The Arctic Fan 3TC in place

FACTORY SPECIFICATIONS for the 3TC Fan
========================================
Input Voltage ...... 12V DC
Input Current ...... 0,12Amp
Dimensions ......... 80x80x45mm
Weight ............. 75g
Air Flow ........... 32 CFM (Max)
Fan Speed .......... 1900 RPM (Max)

Manufactory ........ Arctic cooling
                     Switzerland

Using LED instead of Lamp's
When the scale lamps on this one failed, i desided to trye to replace them with 2pcs of 5mm LED diodes, i found some white ones (Thay are actualy bright blue)


Replaced scale lamp's with white LED's

2007.09.16 Made some modifications to the LED installation today. There is always some differance in quality to any two LED-Diodes. Due to this fact, if hocked up in parallel one of them always carry more of the load,- and give therfore more light. The modification is made to eliminate this problem.

The LED's requires 3,5V 30mA, i use now also use two resistors in parallel, one to each LED, the current drain is 30mA per one LED, i hoocked them up to the output voltage 13,8v so i deeded to make a voltage devider using a 343ohm (350ohm) 1/2watt resistor. - The LED's is not warm so i 'mounted' them above the meters using a glue-gun.


Modified circuit drawing


Previous circuit drawing


LED Pinout

Calculation of voltage devider
========================================
Voltage drop over the diodes need to be 3,5 Volt
Supplied voltage is 13,8 Volt
Needed voltage drop over resistors: 13,8 - 3.5 = 10,3

Using 'ohm's law' R = U / I
========================================
Resistance(in Ohm) equals U(in Volt) devided by I(in Ampere) 
10,3 / 0,03 = 343 (I use standard resistor value 350 ohm)

LED SPECIFICATIONS
========================================
Drive Volt (Vf) ....... 3.5/4 (Typ/Max)
Current (If mA) ....... 30 mA
Emitted Light (lv) .... 7000 mcd

LED's data sheet

Voltage devider projection
This diagram / table show needed resistans for voltage supply from 5-30volt for a SINGLE 3,5V 30mA LED diode

If(A)   Vf(V)   Supply(V)   Drop(V)   R(Ohm)*
============================================
0,03    3,5     5           1,5       50
0,03    3,5     6           2,5       83
0,03    3,5     7           3,5       117
0,03    3,5     8           4,5       150
0,03    3,5     9           5,5       183
0,03    3,5     10          6,5       217
0,03    3,5     11          7,5       250
0,03    3,5     12          8,5       283
0,03    3,5     13          9,5       317
0,03    3,5     14          10,5      350
0,03    3,5     15          11,5      383
0,03    3,5     16          12,5      417
0,03    3,5     17          13,5      450
0,03    3,5     18          14,5      483
0,03    3,5     19          15,5      517
0,03    3,5     20          16,5      550
0,03    3,5     21          17,5      583
0,03    3,5     22          18,5      617
0,03    3,5     23          19,5      650
0,03    3,5     24          20,5      683
0,03    3,5     25          21,5      717
0,03    3,5     26          22,5      750
0,03    3,5     27          23,5      783
0,03    3,5     28          24,5      817
0,03    3,5     29          25,5      850
0,03    3,5     30          26,5      883

*Use a close standard resistor value

Reading resistors color code



Color code

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