CNC lathe Boehringer VDF 250 C pulse encoder sensor board burned PCB

Hello!

The damage was caused by a failure (short circuit) of one of the tantalum capacitors.

First of all I'm looking for a datasheet for the DC/DC converter module Fortec 24-5/2W in the second picture.
It's probably 24Vdc to 5Vdc/2W converter, but i'm mainly interested in the pinout. It has 12 pins, some of them are connected together.

I managed to found a datasheet of some related DC/DC converter module with the same pinout:

Datasheet at the attachment. The DC/DC converter module is still working.

Now I'm looking for a datasheet for the diodes marked in the picture. They are in the SMA (DO-214AC) package. One of the diodes is still working - measurements show that it's a Schottky diode.

I managed to identify the diodes. They are SS14 (marking code S4) datasheet attached.

Damaged component in the SOT-23 package is connected between the 5V (output from the DC/DC converter module) and ground. Bottom right pin is not connected. I think is's probably an over-voltage or ESD protection device.

The last question is how to connect the damaged copper trace connected to the cathode of the left diode in the SMA package. It seems strange to me that the cathode of the left diode would be connected exclusively to the one ceramic capacitor. Perhaps both diodes in the SMA package should be connected in parallel?

matic napisał(a):It seems strange to me that the cathode of the left diode would be connected exclusively to the one ceramic capacitor.

This may be some kind of inrush current limiter but not 100% sure about that. I don't think it could be a peak detector as such detector does only work with AC voltages and provides the output signal to other circuits, meaning that the cathode should be connected somewhere else in addition. There was no connection between cathodes of both diodes for sure - no single sign of track remainings on the right pad, which has a clear and sharp edge. The cathode of the left diode was probably connected elsewhere, if it was connected anywhere at all.

Because I can see no room for any additional track/connection around that missing pad, as well as no visible trace of via on the other side of PCB in this area, I would leave it as it is - with that cathode exclusively connected to a single capacitor.

EDIT: What do you think about those? It's obvious that the track marked with red line goes inside the PCB (inner layer) so it could be some via close to the missing pad (yellow line) which was connected to that track. I really see no other options here.



Is it possible to remove some part of that burnt PCB from the top to see if there is any sign of via underneath?

Vogelek23 napisał(a):What do you think about those? It's obvious that the track marked with red line goes inside the PCB (inner layer) so it could be some via close to the missing pad (yellow line) which was connected to that track.

The track marked with red goes to the "Input 24V" via connected to the anodes of both diodes (don't ask me why it's not simply connected on the top layer of the board). The other end of this track goes to the resistor which other end goes to the indication LED only. Strange enough there is another indication LED connected to the cathode of the right diode "24V output" power rail.
I also grinded the burned area of the board (layer by layer) with a Dremel and I didn't find any signs of other vias/tracks on the burned part of the board.


I also wonder why the burned area of the board is mostly under the left diode, through which, according to the data established so far, practically no electrical current flowed, except for the short inrush current pulse that charged the ceramic capacitor (the value of this capacitor is 100nF).
I also don't see any reason why the left diode is a 1A schottky type, since a standard small rectifier diode in SOT-23 package can handle such a inrush current.