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ArcticMyst Security by Avery

Test-load torment - wth is going on!?

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Apr 28, 2010
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I was up late last night building myself a nice little test-load. As you know it's pretty simple stuff, put it all together with a switch to flick between 6x IN4001s and 4x IN4001s. I've got a nice convenient socket to plug the multi-meter leads into and aligator clips for hooking it up to the driver.

Well it's finished and the DAMN thing is giving me VERY strange numbers. It doesn't agree with my other test-loads and it's driving me NUTS! I checked all the joints, double checked the circuit. I'm too stupid to figure this out right now...

testload1.jpg


testload2.jpg



On the RED setting it's operating ok, but giving lower numbers than my basic red testload. It's when I flick the switch to BLURAY setting that things get weird.

Increasing the driver by 10mA then flicking to bluray here are the numbers... someone tell me I'm an idiot and point out what I can't see:

testloadgraph.gif
 





Joined
May 4, 2009
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My guess would be that your switch is the problem, perhaps it simply won't pass more current

Instead of a swith you could like what i did on my test load and simply wire all the diodes in series
and then just connect a red wire with aligator clip after four diodes and a violet/blue wire with
aligator clip after all six diodes. That way its all soldered down and the color of the wire will
tell you whether your wired up to test for red diodes or violet diodes.
 
Last edited:
Joined
Apr 28, 2010
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hmmm. yes, that would make sense wouldn't it... I'll try that out tonight. Thanks Gryphon, I hope you're right.
 
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By-passed the switch and it's still behaving badly. I now suspect that 1ohm resistor... I drove the driver with 11.4v and got a linear increase through the range... I think this testload is dropping the voltage more than it should be and we're running out of steam... I'll buy some different 1ohm resistors and swap it out.
 

HIMNL9

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May 26, 2009
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Just an idea ..... can you please post a pic of the rear of the board ? (solder side)
 

HIMNL9

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Uhm, no, as far as i can see, nothing strange in the wiring .....

attachment.php


If the points marked in red are interruptions, and if the points marked in blue are NOT in short-circuit, i don't see anything wrong .....

Are you sure that the diodes are all good ? ..... and that the voltage at the input of the load is enough ? (higher than the dropout)
 

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