Behringer Europort Epa300 fuse keeps blowing. Question is about Dim Bulb Tester.

[donkey]

Dear friends,

I have an on going topic in the repairs section but i wanted to try to send it here because my question is about a Dim Bulb Tester suggestion.
https://www.eevblog.com/forum/repair/behringer-europort-epa300-(300-watt-portable-pa-system)-fuse-keeps-blowing/msg1699277/#msg1699277

I want to build a Dim Bulb Tester for a unit which has a 320W raiting and has a 3.15A H 250v fuse in it.
 
1. What wattage of a Dim Bulb Tester i need to build for this test to protect the board?
2. Will the fuse blow even if i will use the Dim Bulb Tester?

Thank you!

[donkey]

Ok friends,

I used a 95W bulb in my current limiter.

What do we have so far: I made a dim bulb current limiter today and tried the unit.

Observations

1. I am getting a relay like clicking sound somewhere in the circuit.
2. I feel like i have programmed the unit with the Arduino's blink sketch . The unit have the exact response as the Arduino's blinking sketch, only with one difference; Arduino blinks an light emitting diode but my unit blinks the dim bulb current limiter's bulb instead, almost with the same frequency.
3.The fan of the unit and the equalizers leds on the front panel turns on for a fraction of a second and off for a fraction of a second and this loop goes on with the bulb blink.

What i should look in the circuit?

What may cause this problem?

If i will desolder the (8,9,10,11) pins as i noted in the image ( it is the primary stage i suppose ) Will the unit start if every part before the transformer's primary stage is not faulty?




Any help will be very valuable.

Thanks!

[donkey]

Hello friends!

I have solved my issue and want to complete this thread with my conclusions in case it may be useful for someone else.

I build up a 95W Light Bulb Current Limiter and connected my 300W system on it. What i have observed a blinking light bulb effect with continues 1 seconds of on/off cycle.

And the user eblc1388 in the forum responded me with this valuable message:
Blinking is absolutely good news. You are nearly done.
Use two 95W bulbs in parallel.


What that means was i needed to add up some extra wattage. I added a second 95W Light Bulb in parallel to the system and blinking is gone and i observed a working unit without any shorts.

Thank you!

[Seekonk]

The ticking is a big sign. To me it indicates the switch mode power supply is turning on with the high meg resistor charging the boot up cap. Problem is it won't sustain itself with its power winding.  That means there is a short after the power supply. Could be in the diode after the transformer or......The amplifier section is shorted.

This is a case where the dim bulb method doesn't exactly work.  To test you need to get the amplifier section powered.  That could be done by lifting a leg of the supply's output diode and inserting the bulb there so that section can be powered. Or do it the old fashoned way by getting out the trusty ohm meter.