[UPDATE] V4 BlitzBuck, Available Soon!

Re: BlitzBuck V3, Available Soon!

Actually, in about an hour, I will begin assembly of the first BlitzBuck V4 prototypes. If all goes well, the next shipment will be V4s with a much more durable potentiometer, more access points, and better heatsinking.

EDIT: So bad news: I just realized that the boards I have been waiting to prototype actually have the wrong pinout for the IC. If I can hand-make the new board (may be doable for the circular design), then I should be able to keep production on schedule. However, we'll find out if I can do it by hand in a bit.

Re: BlitzBuck V3, Available Soon!

I went to the electronics store on the weekend and got a massive 50W power resistor to replace the small one on my test load. I did more testing with the blitzbucks and they are still doing the same thing :thinking:

I have various drivers waiting to go into builds, so I tested those and they were all rock solid. I don't think it's my test load or power supply any more, but I'm not sure it's the blitzbucks either since both of mine are doing the same thing. Any thoughts?

Re: BlitzBuck V3, Available Soon!

That's really weird. I doubt that you got sent TWO bad ones. And no one else has noticed similar things happening. Didn't you say you would get me pictures?

Re: BlitzBuck V3, Available Soon!

Pictures of what exactly? (I forgot)

Edit:

Re: BlitzBuck V3, Available Soon!

Alright. So you're right, the output current did rise, but not significantly. I was asking for pictures of the raw driver. However, I have an idea for what the problem could be: it could be that the sense resistor is warming up and therefore dropping in current. However, that doesn't happen on any of the other ones.

Further... those drivers are heatsinked, right? The only way the driver could be increasing the current is if it is drawing more current from the PSU. does the input current increase?

Re: BlitzBuck V3, Available Soon!

Yes, they are heat-sinked and the input current is increasing as the output current does.

Re: BlitzBuck V3, Available Soon!

Hmm, so it is a driver problem. Then it may be the current sense resistors. You wouldn't be able to heatsink the sense resistor, would you? And get me pictures of those drivers?

Re: BlitzBuck V3, Available Soon!

The Al blocks look rough on top, but on the bottom side where they are touching the components I sanded them smooth. No idea where the sense resistor is, what should I heatsink?

http://i.imgur.com/0OI2X.jpg
http://i.imgur.com/t6Xwg.jpg

Re: BlitzBuck V3, Available Soon!

The sense resistor is the little tiny chip resistor between the two pins on the small IC in the first picture. I wish I could see the drivers without the heatsinks on them... then I could tell if they were screwed up >.<

Re: BlitzBuck V3, Available Soon!

I checked the soldering beforehand, and nothing was messed up from what I could tell.

Re: BlitzBuck V3, Available Soon!

Hmm. Nothing was misaligned? You sure your heatsinks didn't short anything?

Re: BlitzBuck V3, Available Soon!

Wolfman29 said:

Hmm. Nothing was misaligned? You sure your heatsinks didn't short anything?

Click to expand...

I used plenty of non-conductive thermal adhesive between the heatsink and the driver, so it's extremely unlikely that it shorted anything. I tested it in the low current mode before putting the heatsink on, and it did the same thing then too.

Re: BlitzBuck V3, Available Soon!

That is so weird. Was it getting warm in low current mode? It may be the case that you, by chance, got two drivers with defective ICs. I haven't accounted for this yet because it seems extremely unlikely, but it is possible. No one else has ever exhibited this problem before and there seems to be no problem in assembly.

However, it does still seem to operate properly, no? Besides the increasing current? So couldn't you use that increasing current to your advantage, set the initial current slightly low and then have it ramp up to the final current?

Re: BlitzBuck V3, Available Soon!

It could be, and yes I was experiencing it getting warm in low mode. It does seem to still work properly yes, but I'm afraid to hook it up to an LD because of the unstable current/voltage and the heating is still an issue because I don't think a >30s duty cycle would be healthy for the driver.

Re: BlitzBuck V3, Available Soon!

Wolfman29 said:

That is so weird. Was it getting warm in low current mode? It may be the case that you, by chance, got two drivers with defective ICs. I haven't accounted for this yet because it seems extremely unlikely, but it is possible. No one else has ever exhibited this problem before and there seems to be no problem in assembly.

However, it does still seem to operate properly, no? Besides the increasing current? So couldn't you use that increasing current to your advantage, set the initial current slightly low and then have it ramp up to the final current?

Click to expand...

Wolfman, I have stated I had this same problem both in low and high range also on V3. I also have a V2 that is running solid with no problems what so ever. With that being said your now stating for the end user to hook their diode up set it to an arbitrary number and hope that you can judge your run time in order to "hit the brakes" or power off in time to stop from an overcurrent event.. "blown diode". That doesn't instill a warm and fuzzy feeling about this particular ramping up problem. Too much of a gray area for me.

If you were to get my driver and ARGlasers would you be able to test them out to chase this anomaly?

Re: BlitzBuck V3, Available Soon!

To Arg: Odd - it should not be getting that warm at all in low power mode - some warmth is okay, but too much is... very bizarre.

To Jander: It didn't seem like the ramping up was too much from what I saw in the video - from 2.05A to 2.09A in about 30 seconds. That's not that much, especially for these strong little buggers. Nonetheless, it is a concern of mine. Note that it was a suggestion if he wanted to get the build up and running. It was definitely not an instruction, simply something I would do if I got frustrated and wanted to complete a build sooner rather than later.

All that said, you're completely right, I have absolutely no idea what could be causing this other than defective parts. However, ARG has glued heatsinks onto his drivers, so I would be unable to debug. Would you like to send me yours, Jander? I can pay for shipping and I can buy even the driver off of you (whatever you paid).

Referring to the above quote though: Arg was the first person to report the problem, so that's why I said no one else has ever exhibited the problem before.

Note that this never happened in any of my tested boards, which is why I am so confused. I threw out all of the boards with obvious flaws that I noticed in my quality inspection that I did before I shipped them out to Clif, so these ones must have no visible signs of flaw.

I'd like to check it out though, very much so. PM me.

EDIT: I just had a thought. Is it possible that the small black chip near the edge of the board is getting warm? That may indicate a problem as well, because that should not be getting warm at all.