Sunday, April 4, 2010

Two Steps Forward...

Some large number of steps back.

This week we got the mobo programmed!
The Tx and Rx lines on the serial cable I hacked together were reversed, whoops. With the motherboard programmed (extruder still playing hard-to-get) we actually got the machine sorta running.

Now, we also found a solution (or, as I explain later, not a solution) to the
regulator problem.
The problem is the lack of regulators. The solution was jumping the 5v ATX line to the 5v output on the regulator pad, thereby supplying the board with 5v from the PSU. In practice, this was 6.4v.

This solution worked fine, though we were not able to make the board that sparked work (probably dead now). With two SMD 2.3 boards and one SMD1.2, We got it to connect to Replicator G with about 12 hours worth of resetting, plugging in, resetting, etc. After an 11 minute "print" (no extruder), there was a smell like ozone in the room. I ignored it. On the next startup, the smell returned, stronger. Ten seconds into operation, there was some serious sparking, smoke, and fire from one of the stepper boards. Capacitor c-6 had blown up.

Ouch. The capacitor has rotated perpendicular to its original orientation, and there is a hole burned into the board blow it. I am not yet sure if the chip itself is dead. if it is, that leaves us with only one SMD 2.3 board that still works... not much of a machine. The SMD 1.2 is on loan, and not meant to be a permanent addition to our machine.

With one week before presentation, classes starting tomorrow, and very little money left with which to order parts, this development is pretty bad. I have ordered more capacitors, some real linear regulators, and some resistors that were near the blast that might need replacement. The chips themselves may need replacement too, but I want to diagnose what we have and not spend money we don't.

Here's a shot of the board with the capacitor removed.

On a non-reprap note, I also dropped my laptop on the serial cable's USB end, and tore out a USB port. No way do I have the money to replace that ><;. I've simple amputated it for now. That leaves me with only one USB port. This is not, as may be intuited, a good week of work.

Oh, and my dog died. No, seriously.


  1. I think trying to run without regulators is not a good idea. you might have been able to do something like that if you had actually applied 5v from a good regulated supply, but if you don't modify the circuit, what happened is to be expected. Sorry about the dog.

  2. :-(

    I hope next week will be better!