I recently added a few AMC7135 chips on my 4x7135 KD V2 driver. The chips added were the ones rated at 350mA and the chips on the original driver were rated at 380mA each. I’m not sure if this makes a difference as people said it shouldnt but now I have lost the low and medium modes. It doesn’t matter what group I set the driver at, as I cycle through the modes low & med won’t work (High > blank > blank > high, etc) but the others come on like it’s supposed to. Any idea why this is happening? I thought maybe it was user error so i did the same on another driver with the same results. Anybody added the 350mA chips to their V2 drivers with no issues?
Using the AMC chips rated at 380mA won’t give me any issues. Thing is I bought a hundred of those 350mA suckers from Fasttech.
Any photos of the modded drivers? I did not think that 350mA or 380mA would cause any type of problem. If it was a different chip it might. If the chips were bad I would think it would just short the driver. It would sound more like a driver issue, or a possible short or jumpered pins on the controller. I have used the 350mAS chips on a 380mA (V2) board before and they worked.
I’ll take some pictures when I get home. I inspected the solder joints with a magnifying glass and was sure all the contacts were pretty clean. Of course my eyes are not what they used to be.
The only time I've seen those symptoms is when the LED- solder point on the driver is contacting the order ground ring on the driver. Happens real easy as they are right next to eachother. ;)
JohnnyMac - I’ve had that happen to me numberous times (shorting the LED- to the outer ring) which basically makes the driver direct drive with only on & off (1 mode). In this case, I lose certain modes (low & medium, but high and flashies modes still work) but is still regulated per multimeter. Any thoughts?
I updated the photos in the original post and I still can’t figure it out.
I guess I’ll save these AMC chips for the 105C instead.
Hmm...I forgot that you said you still had strobe and SOS modes. I have no clue at this point. Can we get a pic showing your soldering of the stacked chip from the other side? We can only see the ground soldering. Perhaps seeing the positive connections on the 7135 something might spark a thought.
In the first pic there is a wiggly line from the output pad (white wire) to the ground ring. Is that a solder hair? I solder to the pill at one of the ground tabs to avoid this. The IC looks clean. Is it possible to accidentally reprogram the chip?
Solder hair? That’s a term I never heard of before. Maybe it’s hair from my GSD. His damn hair is everywhere. I brush the guy at least once a day. Sometimes my wife thinks I’m cheating, “who’s hair is this?”
After I took the pictures, I scraped that area you mentioned to bare PCB. No difference. Well, it’s back to the drawing board. I wonder if I desolder all the chips and use the same ones if it might have some effect. Time to bring out the heat gun.
I got a reel of AMC7135 parts recently and after a bit of troubleshooting for why a known circuit was suddenly not having med or low mode I figured it out. The problem is that these AMC7135 parts are slow to turn on, meaning that any PWM dimming will not work. In my case high, strobe, and SOS all worked because they turned on the light with 100% duty cycle (ie no part of the PWM was off). I modified the firmware, the software in the microcontroller, to allow for longer PWM cycles that would in turn allow the AMC7135 to fully turn on. It sucked because I lost several hours on the problem trying out other things like how much or little capacitance was used for the output capacitor. I have no idea how many parts are like this, but I can say that my last reel didn’t behave this way. For a preprogrammed module like you have the parts probably won’t work. The company that used to make the AMC7135, Addmtek, was bought out. Maybe they changed the parts along the way. If anyone ha a suggestion for a similar part made by a different manufacturer I’d love to hear it.
