Day 4: Port-au-Prince, Haiti

There have been moments at work where engineering just doesn't seem worth it.  Politics, egos, and the almighty bottom dollar often get in the way of creativity and obfuscate genuine problem solving.  At times, I have felt that I am not making any difference and that I embarked upon the wrong path.  I realize that I do contribute toward improving health care indirectly through my work with medical devices.  Even so, there is so much disconnect in my R&D job from the people I hope will benefit from my labor.  Where is the human connection?

Nurses, doctors, EMT's, & translators tending to patients and their families -

My heart too yearns to serve

Then, there are moments like today.  These are the moments when your vocational hopes become reaffirmed.  Where I had pretty much given up hope on repairing that X-ray machine after toiling dozens of hours on it, suddenly a burst of fruitful insight came to me today!  

The path to this revelation began after I spoke with the X-ray tech from Miami.  He had gone through my e-mail documenting all my troubleshooting steps I had performed to date.  Strangely, he suggested diagnosing a certain board that had came well after the main power distribution node according to the schematic.  I questioned this suggestion but put faith in his experience with these machines.  Sure enough, I discovered a blown fuse!  Still though, it didn't make any sense.  I had previously probed the input to the main regulator and found absolutely zilch voltage.  Since this PCB the tech suggested I test came well after that main node, it shouldn't have been getting power in the first place.  No power equals no tripped fuse.  Enter another mystery. 

I was about to give up hope and go back again to document my work today for future volunteer engineers, but the tech's seemingly crazy idea kept coming to me.  What could he have been thinking about that would trip that fuse?  Certainly, no power should be coming to that board at all with no input voltage at the main distribution node.  The next steps would be to probe the voltage rails at that board, but those rails are impossible to access due to its position in the system.  In any event, it must be getting power.  How else could that fuse have been blown?  

Then it came to me!  If I start with the premise that power is in fact getting to that PCB alone and not to other digital boards as I discovered, it follows that the elusive power supply somehow must be feeding into that board.  If I follow the path from the input power of that board with the tripped fuse, I should find the power supply.  One panel that could actually be disassembled later, there it was!  And what's this?  It's not only somehow connecting to the blown-fuse board, it's directly connecting to it!

The mystery was now unfolding! I had mistakenly started with the assumption that the electrician who had previously worked on this machine had connected everything properly with the exception of the floating ground wire I had come across the first day.  With the discovery of the power supply, I found that its +24V output, which should have been going to the main distribution node, was actually going to the blown-fuse PCB!  After reconnecting the main voltage regulator, I even found the proper regulated voltages at its outputs!  Given that the connectors were identical, there must have been some confusion and hence an unintended switch.

I didn't want to get too excited yet because there may still be other problems to work out, but my heart was nonetheless racing with excitement.  My instincts were telling me that I came across the true culprit.  I calmed myself down by taking a little break and went out for some beers at the United Nations bar.  After enjoying some good company and two Prestige brews, I returned to the hospital via the secure shuttle and got back to work in Radiology.  

Fortunately, thanks to the advice of an Engineering World Health contact of mine, I had packed some glass-tube fuses.  However, the blown fuse was actually a through-hole part that looked more like an electrolytic capacitor.  I attempted to remove the open fuse with a 25-W soldering iron and some solder wick I had donated to Medishare, but to no avail.  The cheap-O RadioShack iron just wasn't getting hot enough for solder to flow.  I even used some desoldering tricks my senior tech at work taught me, but still nada.  

I decided to just leave the fuse on there since the circuit was already open anyway.  Its real estate on the board was not sufficient anyway for the glass-tube replacement.  This is what I ultimately did:

1. Soldered some leads from the bottom legs of the through-hole fuse
2. Salvaged a fuse receptacle from a random useless PCB from another X-ray machine beyond hope
3. Soldered the other end of the leads to the poles of the receptacle
4. Inserted the 1A-250V glass-tube fuse
5. Wrapped up the receptacle and fuse with electrical tape to prevent electrical shorts
6. Bonded taped assembly somewhere on the PCB with sufficient clearance with non-conductive epoxy

My "workbench" in Radiology -
where my vocation was reaffirmed (reworked PCB in the foreground)

After I finished these board-reworking steps, I performed a few more safety checks with and without AC power being fed to the device.  I then hooked up the reworked board  and one last linear-motor controller board and fired up the machine.  With my heart pounding in anticipation, I anxiously waited for the moment of truth.  As the monitor and X-ray electromechanical systems sequentially turned on, I raised my fists in the air with uncontrolled excitement.  With the Haitian X-ray tech's help, we performed a sample scan and was greeted by the beautiful interior of one of the previously toasted boards!

A baby receiving an X-ray
thanks to God's graces!

While allowing the fruits of my labor to sink in, I was almost in tears in realizing the difference I had just made.  The week before, two patients died because there was no X-ray.  To put this all in perspective, imagine how many Haitians could have been saved in the time this machine was out of service, which was a whopping 7 weeks!  As I'm writing now, tears are starting to well up within me as I now think about those patients that really needed this resource often taken for granted in the States.  It is in this moment that I am so grateful for God's graces leading me here to Haiti.  I was so worried that with my nonexistent clinical skills, I would just be a burden on this mission.  On this medical mission, though, I have directly seen the suffering  and my heart has become many time over heavy since I got here.  While I busily engineer in Radiology, I am poignantly aware of the dying right outside my doors.  Though it is not me who tends to them, I nevertheless hear the cries which weigh my heart down.  With every fiber in my being, I become thus impelled to restore this vital resource while very much cognizant of how integrated I am in the cycle of care here.  With a much lifted heart, I give thanks to the Holy Spirit for divining a purpose here for me.  

Today was good day.  Today, I have been affirmed by my vocational call as an engineer for others.