Bad drivers help: amc7135 and a20dd-s08

n10sivern · 2018-12-17T23:19:06.000Z

So, going through my stuff and I have a package of drivers I’ve managed to mess up years ago. I have several 7135 drivers that will not work even after new MCUs. Are they toast or is there a part that commonly is the issue? Also, I have an A20DD-S08 driver I built years ago and then you turn a light on it steps down in brightness every second until dim/off. Any ideas? Fixable or junk?

Cereal_killer · 2018-12-18T02:17:20.000Z

Also, I have an A20DD-S08 driver I built years ago and then you turn a light on it steps down in brightness every second until dim/off

One of the voltage divider resistors has something wrong, either a cold solder or its missing all together or its bad (likely the low half of the v divider, though I have no experience with that particular driver it should be R2)

n10sivern · 2018-12-18T06:42:51.000Z

Thanks. Replaced R1 and R2 and works like a champ now. Any ideas on the Nanjg drivers?

Cereal_killer · 2018-12-19T00:37:53.000Z

Just guessing here but you seem to like to tinker (like I do)… Bridge their voltage protection diodes (D1) and see if they power up.

tkd15 · 2018-12-19T04:15:11.000Z

I messed up a few nanjg105 drivers in the past. All of them were due to the bad D1 diodes that caused higher voltage drop. You can measure the D1, see if it has higher number than the normal one.

n10sivern · 2018-12-19T04:19:47.000Z

What’s the replacement for the D1 diode? Can I just bridge it and delete it? Doesn’t it provide polarity protection? Will the D1 diode from the FET drivers will work?

tkd15 · 2018-12-19T15:25:19.000Z

I bought a pack of 100 for $1 from aliexpress but can’t find the link in my computer, sorry. ~~Just remember vaguely that I searched for smd 0805 diode in their site.~~

Have this description with my leftover diodes, “1N5819 S4 sod323 smd diode”.

Cereal_killer · 2018-12-19T05:43:26.000Z

n10sivern:

What’s the replacement for the D1 diode? Can I just bridge it and delete it? Doesn’t it provide polarity protection? Will the D1 diode from the FET drivers will work?

I’m only recommending a bridge for a test to see if that’s your problem or not. If it is the driver will run as it’s ONLY job is polatory protection.

Yes nearly ANY SOT-23 low voltage drop diode will work, one from a FET driver would be just fine.

If you have time and don’t mind checking (cause now I’m curious) you could simply “bridge” it (as a test) with a pair of tweezers.

n10sivern · 2018-12-19T14:52:13.000Z

I tried on a few and bridging it didn’t cause them to work