simple confusion about UD2.7c LEDs

[justin66]

[deleted irrelevant information]
basically when powering UD2.7c  the OCD and power led should be present. in my case OCD LED doesnt turn on. it only turns on when tripped. is it something to worry about?

[acobaugh]

The UD2.7C will light the power and OCD LEDs on power up until it receives feedback and an interrupter signal.

For testing without a proper interrupter, I've found a bright white LED flashlight will work in a pinch, shined directly into the ST fiber receiver.

It sounds like you have a problem with the board that always lights the signal LED sounds. That shouldn't happen. I'd double check you don't have any cold solder joints or bridged joints. Beyond that, I'd have to sit down and stare at the schematic for a few minutes to guess where the problem could be. Perhaps others will chime in.

Good news is it sounds like you have one good board. You can use that with your DMM and scope to compare against.

[justin66]

The UD2.7C will light the power and OCD LEDs on power up until it receives feedback and an interrupter signal.

For testing without a proper interrupter, I've found a bright white LED flashlight will work in a pinch, shined directly into the ST fiber receiver.

It sounds like you have a problem with the board that always lights the signal LED sounds. That shouldn't happen. I'd double check you don't have any cold solder joints or bridged joints. Beyond that, I'd have to sit down and stare at the schematic for a few minutes to guess where the problem could be. Perhaps others will chime in.

Good news is it sounds like you have one good board. You can use that with your DMM and scope to compare against.

the driver works every way i test it but the OCD LED doesnt turn on when powered with out interupter.

[Mads Barnkob]

Depending on the type of signal from the optical receiver, you have to invert or non-invert the interrupter signal.

I use a optical receiver with different polarity than Steve Ward did, in the 2.1b, so I was at first running 200uS off, on for the rest of the time. But since you do not have a optical receiver installed yet, it could be that it expect a low for signal and it resets at start.

[justin66]

thanks Mads, i appreciate your work and answer. i will try fitting ST, hope its going to sort out, have a nice day.

[Hydron]

The OCD at turn-on thing with the UD2.7 is caused by the UVLO IC. This design isn't the best (the UVLO stops working at very low voltages as it was just a quick hack based on what I had on hand at the time I implemented it, after which it was copied and added to the UD2.7 design), so I wouldn't sweat it as long as the driver actually works.

[Mads Barnkob]

The OCD at turn-on thing with the UD2.7 is caused by the UVLO IC. This design isn't the best (the UVLO stops working at very low voltages as it was just a quick hack based on what I had on hand at the time I implemented it, after which it was copied and added to the UD2.7 design).

It has been one of my reasons to not share schematics too early, errors get copied super fast. So I only posted pictures of the PCBs instead, when they were populated, so one day I notice my website gets some traffic from a Russian forum and I follow the reference link. Only to find a exact copy of my single side UD1.3 driver where they also had copied the optical receiver facing inwards on the board, because I had it flipped on the original board and just hacked it in place

[justin66]

The OCD at turn-on thing with the UD2.7 is caused by the UVLO IC. This design isn't the best (the UVLO stops working at very low voltages as it was just a quick hack based on what I had on hand at the time I implemented it, after which it was copied and added to the UD2.7 design), so I wouldn't sweat it as long as the driver actually works.

thanks for replying, i found the pesky problem, there is JP1 and JP2 jumper point that i totally forgot to install and short out after installing jumper near 9v buck regulator the ocd led turns on if i jump those, so i think its the one that turns on UVLO.

[acobaugh]

I'm still not sure everything is right here. Without the UVLO jumper installed, the UVLO function is effectively disabled. That means it shouldn't matter how UVLO is set/calibrated. Without the jumper, a properly functioning ud2.7c should light the OCD LED at startup and no interrupter signal.