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Driver mayhem

Bogart

Member
Joined
Oct 18, 2009
Messages
62
Points
8
Well, I'm having some horrible luck with drivers lately.

So I had 3 drivers laying around that I use for testing diodes, configured with output leads and power connectors soldered on to connect to an ATX power supply. A Micro FlexDrive, a Micro BoostDrive, and one of the red AixiZ 500mA drivers. All were working.

Then one day I had the FlexDrive plugged into the power connector, and was careless and shorted a part of the bare driver board against the bare metal PC case. I think the PC rebooted, and the FlexDrive appeared to be toast. It behaved like an open circuit.

So I desoldered the dead FlexDrive, configured a brand new one for the highest current range, and soldered it up to the harness. When I tried to power my test load with it, it behaved the same way. As an open circuit.

I can see 4.95v measuring from the input points on the driver board, but no output.

Then things got even stranger. I plugged in the Micro BoostDrive, which had been working fine up until now, and something seems to have gone awry with it as well. Powering my test load using 6 diodes, it puts out 1200 to 1400mA, depending on the pot adjustment. It also gets very hot very fast, and on the input side consumes 2.67A. Not right at all.

Inspecting it visually I can't see anything wrong.

The cheap red AixiZ driver, on the other hand, continues to operate as it always did, using the same power supply.

This one really has me scratching my head. The power supply seems fine. It continues to power the PC just fine, and I measure around 5 volts from the 5V rail, both when powering a laser driver and not.

I guess next I will try another MicroBoost and see if it behaves any differently.

:can: :huh:

Edit: The new MicroBoost works like it should...
 
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Bogart

Member
Joined
Oct 18, 2009
Messages
62
Points
8
I've tried it using both 4 diodes and 6 diodes, which should drop 3.08 and 4.62 respectively, plus whatever the resistor drops (depending on current).

I used 6 in all my MicroBoost tests.

I realize after posting that this thread is not exactly constructive or useful. More of a vent.

I can only conclude now that I somehow killed all 3 of these drivers (or maybe the one flexdrive was never good to begin with).

Even looking at the shorted one, it doesn't make sense that it died. Looking at where the arc mark is on it, that part is connected directly to the positive input on the driver board, so the short should have gone straight from that point (which connects directly to the + input), to the negative "grounded" PC case, without any of the driver components being in the [short] circuit.
 
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123splat

New member
Joined
Jan 14, 2011
Messages
428
Points
0
Boggie,
First thing is to check the supply (you said it is ok, but check again, preferablly with a scope and a different load). That being O.K.,
Second thing, check your dummy load in detail,, measure voltage drops oat each diode (and/or searially, adding one diode at a time), it is odd to short a diode rather than butn it open, but it can happen. that could reduce your load's total voltage drop (and maybe increasing current draw) for each shorted diode, and confuse, if not smoke, your drivers.
May not be the cure, but it only costs time to verify. Good Luck, Splat
 




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