UD 2.7C Build

[Mads Barnkob]

I just connected the three indicator LED’s ( signal, OCD and power), powered up the board and to my surprise the OCD light came on as well as the power light.
Is this normal ? Board still has no Inductor, C33 or any of the jumpers installed. I am hoping that is the reason for the OCD trigger, otherwise I made a mistake assembling it.

It sounds perfectly normal. OCD should trip until it gets a reset signal from your interrupter.

[Thunderstruck]

Thanks Mads ! I started to get a bit nervous to tell you the truth. Now I can continue building my interrupter.
I’d like to be able to understand how this thing works in detail, but desire is just not enough sometimes, that way I would not worry about silly things.

Would UD2.7 be able to drive this:
https://www.easternvoltageresearch.com/flexibrute_halfbridge10.html

Seems like a neat setup, everything is there including the PCB - love working with PCB’s because it minimises the possibility of making a wrong connection.
Decent IGBT’s too...

[Thunderstruck]

I did not install 2 components on my board Slot-7 Phase Lead Inductor  and  C33 Capacitor.
Would someone please be able to tell me value of the capacitor if the board is going to be used to drive a full bridge based on IXGN60N60C2D IGBT's ?
Also the inductor is a complete mystery to me, there is no info on inductance, just Slot-7 from Coilcraft. Is there anything else I can use and what inductance value should it be ?

[Thunderstruck]

Interrupter is almost complete, Attiny85 is missing because programming is a bit more complicated than I expected.
But, it is partially functional without  the Attiny, enough to check if UD2.7 is working correctly.

I connected them together using a bit of fibre optic cable, and to my horror UD did not react to the input ! Input signal LED stayed firmly off.
After a bit of scoping and tracing the signal I discovered that I did not solder one side of D13.
Note to self: Missing solder joints are bad for functionality
After I soldered the diode, signal LED came on and started flickering in sync with the interrupter.

So far I confirmed that the UD powers up ok, and receives the signal.
I need to check if the outputs for GDT’s work correctly, is it possible to do that without C33 and the inductor in place ?

[Thunderstruck]

Update:

Today I connected a couple of GDT's to the UD aaaaand I got mixed results. Good news is that half of it is working - GDT 2 works as advertised, GDT 1 - nothing !

Let's start from the beginning:

UD is supplied with 24V DC, connected to profdc9's interrupter via IF95T fiber optic receiver.
65-70kHz signal is supplied to the feedback connector.
I made 2 GDT's for testing purpose only and connected one to each output.

Board powers up fine, power LED comes on, signal LED turns on as soon as the interrupter is turned on.
( Earlier OCD LED would turn on too, it would turn off as soon as the signal is supplied to the board - just like Mads predicted, but since I fixed that solder joint on D13 it does not come on any more )

Image 1 shows output from GDT 2 which looks fine, and output from GDT 1, which is not so fine.

So, I did some signal tracing...

GDT 1 is driven by  a pair of Mosfets, U1 and U2
Mosfets are driven by IC9, UCC27423
U1 - is driven by pin 7
U2 - is driven by pin 5

I compared the output signals on pins 5 and 7 on both UCC's  ( IC9 and IC10), and discovered that pin 5 on IC9 outputs strange waveform ( pin 7 on IC9 outputs the same waveform as pin 7 on IC10, so probably it works fine ).

Image 2 shows output from pin 5 on IC10
Image 3 shows output from pin 5 on IC9

So, I think that I have faulty UCC27423. I do not have any spare ones, but I am more concerned with removing the existing one without a desoldering station.

Image 4 shows the offending part.    At least solder joints look good....

By the way, as far as GDT waveform is concerned, do not ask me how I did that because I have no bloody idea.
I even started a separate thread to document my attempts - mostly failures to produce a decent waveform from a GDT.

[profdc9]

Beautiful assembly job!

By the way, if you attach a 3.5 mm female plug to the Sound +/- input, you can try out the sound interrupter feature.

Make sure you adjust the minimum Ignore Interval and Pulse Width when you use it so that you don't try to pulse the coil too often or too long.  Start with a short pulse width if you have any doubt.

Also, you can hook an earphone up to the digital + output if you want to listen to your interrupter before you use it with the coil, or you can look at it on your scope.

Also, you can solder header pins into the ISP connector if you want to use the board with a AVR programmer directly so you don't have to use a separate fixture.

Dan

Interrupter is almost complete, Attiny85 is missing because programming is a bit more complicated than I expected.
But, it is partially functional without  the Attiny, enough to check if UD2.7 is working correctly.

I connected them together using a bit of fibre optic cable, and to my horror UD did not react to the input ! Input signal LED stayed firmly off.
After a bit of scoping and tracing the signal I discovered that I did not solder one side of D13.
Note to self: Missing solder joints are bad for functionality
After I soldered the diode, signal LED came on and started flickering in sync with the interrupter.

So far I confirmed that the UD powers up ok, and receives the signal.
I need to check if the outputs for GDT’s work correctly, is it possible to do that without C33 and the inductor in place ?

[Thunderstruck]

Happy to say that both outputs are working now ! It took some time to resolve, but it was worth it.
It turned out that UCC is not faulty, it was something much much more basic - poor solder joint on U2 mosfet.
Anyway as you can see below, wave forms are quite good, a bit of ringing but that is to do with GDT's I suppose.