This is for troubleshooting and repairing a no heat problem on Stratasys Dimension BST 1200 3D Printer
If it is already broken... there is no harm in digging into if further...
Step 1: Background
Should I get it????
I was allowed to power it on but that was the extent of the testing.
It failed start up with a code 14.133. Heater failure(I checked later and went back)
Visually it looked good.
Included was 18 partially used ABS and Support cartridges
10 factory sealed NEW cartridges
about 50 print plates.
And the original software and manuals.
The print head cover was missing.
Step 2: Testing
Working blind as I was unable to find any documentation...
I used a multimeter to check the heaters and found that both have 2 internal elements and all 4 were within the same reading. about 225 to 255 ohms in this case. The thermocouples in the head were good as well.
Time to inspect the electronics cabinet...
There is a service manual available for the 768 elite online from hackaday... I suspected that the electronics should be similar.
Found the code and the checks all look like I have a bad PDB or Power distribution board.
Opened the case and sure enough the F1 fuse is blown. Board bottom left-ish beside the 9 pin connector.
From the service manual I have a GEN2 board
From the back of the machine I had to remove the left panel to remove the connectors for the PDB from the back of the board.
Step 3: Find the Problem
So play safe...
A little reading of the service manual and the section of the PDB that has the blown fuse is the 120VDC section. this is a little weird since the status LEDs on the board clearly show that the 120VDC is working normally...
No Schematic to work from... and replace board as a solution...
That said the board is broken, it is more than likely that I cant possibly break it any further.
I Started with a visual... I noticed the signs of a hot component between the 2 heat sinks on the bottom right.next to the 2 red film capacitors.
It is not so burned to be able to read that it is a US1M diode (Got lucky on this one), it seems to read funny; it passes diode test on my Fluke in both directions...
Replaced the diode and fuse (3.15A 250V) and reinstalled the board... Power on and POP!!! Fuse blown again.
More boad probing and I found that the diode is input protection from the MOSFET on the lower right of the board.
Resistance measuring of the MOSFET shows 3.5 ohms from the gate to Drain as well as the Gate and Source...
MOSFET visually looks fine, got me there...
I replaced it with the current replacement part and had to insulate the back of the the MOSFET from the heat sink using Kapton tape.
MOSFET - 20N60C3
Step 4: Test Print
Upon reinstallation of the board the machine now operates normally...
The part shown is a test print from the machine library.
I calibration is probably needed but for now I happy to have a functional high quality printer with a massive amount of material to work with.
I hope that this helps...
In my case This went from an expensive mistake...to an incredible bargain!