FS: Faulty rkcstr drivers

[Mohrenberg]

I've got a batch of 9 faulty rkcstr drivers.

I am unable to pinpoint the the problem with them so I am looking for offers if anyone wants them. They all exhibit the same problem.

They will run for probably a maximum of 30 seconds, and the current will begin to jump around rapidly. The current never seems to jump above what it's set at, but below. It will continue to hop around 10-15mA and steadily decreases untill output current is at 0, then they stop working.

If you let them rest for a bit they will begin this process again. I seem to be having this problem with slightly more than 10% of the drivers, and it seems to be a problem with both fixed and adjustable, assembled and unassembled.

So i am guessing it's a problem with one of the components, probably not the resistors since the problem is with both fixed and adjustable.
I tried swapping parts of a good driver and bad driver but couldn't seem to single out the problem...(front side parts only tested)

My knowledge with electrical components is too limited for me to understand what could possibly cause it.

I'm open to offers on these if you think you can repair them...
should i accept an offer, i'm selling these AS IS.

 

[Slipstream]

Why dont you send them back and get good ones?

 

[Mohrenberg]

I doubt I could. I receive the drivers as unassembled kits.
I wish we could just figure out what is causing this problem so it could be fixed...

 

[Slipstream]

OH.. yeah i doubt you could.. maybe the oven soldering didnt get all the components

 

[Mohrenberg]

only like 15 of 50 were done that way, and only like 2 of those have the problems, so it's not associated with that. i had this same problem way back when too.....it's nothing new...just a lot more noticeable when you assemble 50 drivers at a time

 

[daguin]

Is there a quick test for this? Maybe using a dummy load? Do they display the inconsistency with the dummy load?

Peace,
dave

 

[brtaman]

Does the voltage regulator have enough voltage to work with? Could be falling out of regulation?

To my knowledge that is the only active component on the driver, provided the caps, resistors and traces are ok, it would be the only possible source of the problem. So it is either falling out of regulation (Vin too low) or the regulator itself was damaged during soldering.

Just use a spare if you have any and replace it on the driver see if it solves the problem, if it does, the regulators should be about a buck a piece in low quantities, might be worth your while to jump to the local electronics store or order some with your next batch of components.

I believe they are LM317s in a smaller package or a regulator within this family.

 

[Mohrenberg]

Dave, you can see this with the test load, that how i check the drivers before i use them.

on a laser, it will basicly flicker and eventually shut off completely.

 

[ndrew2505]

check all your connections matt. i use the oven method and dont seem to have any problems.

 

[blu-ray laser]

how much? I could probably fix these for $10 each, which should cover costs of any components if needed.

 

[larrball]

Matt, are they the new V4's that ryan was selling about 2 month's ago?
I have 2 that i haven't done anything with as of yet and wondered if they might be the same.