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The very simple load test for MAX 4000 power supplies..

It is a really simple plug and run solution. It is made for the first test to see, if its running at all. Now we own a much better professional hightec electronic load. This new one is good for one voltage at a time.

What we did build to check the power supplies from a MAX 4000.

After some years with MAXen, service people get some experience, where to find bugs and mistakes. With the MAXen it is not so difficult. Mostly the power supply fails, next comes the mainboard. If the power supplies fail, there are no more lamps lightening on the MAX´s frontpanel.


Next we need to know, why the power is broken. If the mainboard has a shortage, the fuses break. But mainboads will fail rarely, as we found out. If a mainboard fails, there is little help and little hope. All critical components are soldered onto the board. You and we have almost no chance to fix it. And it is not worth to spend 500 dollars into a five years old unit.

We did build a test power source from a MAX4K unit with extremely light LED´s for all 5 secondary DC voltages. Inside are both MAX 4000 power units.


And we did build a simple load for all 5 voltages with simple 6V and 12V car bulbs. Each voltage has its own bulb.

We call this a simple load, because it is a stable resistance load and not a switching processor, which changes its power consumption extremely fast with 25 MHz or faster.


Because we know, that the MAXen are working well, we do not need to check the possibility of switching loads at all.

We need this simple load, to check the thermal reliability of the components under long term conditions with 75 Watts or more. This little display unit calculates the true power consumption regardles of phase and frequency. Our simple load takes 74.1 watts for hours.

Here we did connect the MAX 4000 motherboard without fans and without any modem card. If the mainboard has a failure or a shortage on any of the five voltages, the lamps (LEDs) will easily show, whats going or not. If the voltage is going up and down under a faulty load, we will easily see this at these LED lamps.

The standard MAX 4000 mainboard is taking 22 watts in a working standby modus with one E1 PRI connected. That means, with our 75 watts simple load we are checking a good average thermal load of the power supplies.

More and all the voltages is here:


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