Adventures in Mass Spectrometry

For the most part, I quite enjoy what I do. Running a lab, working with students, and learning about the ancient past using a select few molecules is really, really interesting!

But there’s a downside. See, I have to run a lab, and when things break, I have to fix them. The most important thing for which I am responsible is a $350K mass spectrometer. Anytime something breaks, or runs out, or whatever, I crack out the lab checkbook and spend a thousand dollars or so to get it going again – on the assumption that I can figure out what went wrong.

There are common problems: The filament might burn out or acid might get drawn into the system. Then there are less common problems – the ones where I scratch my head wondering why it’s not working. I had one of those recently.

It started as a simple problem: The filament burned out. Cool, I can fix that in about an hour, and the instrument is out of commission for a day. Well, gee, since I had to shut it down anyway, I decided to perform the annual maintenance on the mass spectrometer. I cleaned the source (size of my fist, ~80 parts including little wires and screws). No problem. I changed out a vacuum pump. No sweat. Turned it on again, pumped everything down. Looks great! Turned on the source. Got the three beams I’m supposed to have. The whole thing couldn’t have been smoother. I left the lab to do something else.

Then, something happened.

When I returned a few minutes later, my beams were gone. Weird. I shut off the source and turned it on again. (Funny that mass spectrometers can be a little like computers. “Did you try shutting it down and turning it on again?”)

BBZZZT. No beams.

I shut it off. I tried again.

BBZZZZZZTTTTT! No beams. And definitely not a sound you ever want to hear coming from a mass spectrometer. That’s 3000 volts I was turning on, and BZZZT is BAD!

I shut the whole system down again and re-cleaned the source. I probably had a wire crossed, right?

Yeah. Two days later I had the system all together again and tried to turn on the source: BBBZZZZZZZTTTT – Sizzle-sizzle.

Uh. Yeah.

Head scratching. The electronics were the culprit, obviously. I don’t do electronics. I do vacuum. I do glass capillaries. I do 100% phosphoric acid. I’ll even do hydrofluoric acid (sometimes). I don’t do electronics.

Now here’s the fun part. Thankfully, this wound up being a great experience. Oftentimes, electronics issues become a nightmare of chasing around charred components. I braced myself for a long and difficult process, and expected that the whole thing would cost the lab at least $4000 dollars. Ugh!

It was suggested to me by an engineer from the manufacturer of the mass spectrometer that I should find a local electronics shop. (A great suggestion! Thanks Roger!) As it happens, we have an electronics shop here at the University, and the guys over there really like getting out of their office once in a while. They came over to look at the electronics (on which I could find no evidence of damage). It was a field trip to them, and it wound up being great comic relief for me.

Picture this: Two adult men kneeling in front of a circuit board that handles 3000 volts of electricity. We all know something is wrong, but we don’t know where.

“OK, turn it on,” says the first.

Click. Pause. BZZZZTTTTT!

“Ooh! Cool!” says the second.

“There it is,” says the first.

“Yeah, shut it off.”

Click. Silence.

The two men crown in and start touching things. Wiggling things. Then cleaning things.

“Turn it on again.”

Click. Pause. BZZZZZTTT!

“Ooh! Wow.”

“Turn it off.”

Wiggle, wiggle. Prod, prod.

“Turn it on again.”

Click. Pause. BZZZZZTTTT!

Me: “Should I shut it off?”

“Oh, yeah, probably.”

Seriously, they looked like they were having the time of their lives. Meanwhile, I’m flipping out a bit about 3000 volts arcing across a circuit board. They were completely nonchalant about it.

Now, I do realize that their comfort has everything to do with their experience, and that my own discomfort is the reason why I’ve said since the beginning that I won’t screw with electronics. Undoubtedly, I do the same thing to students and other lab users when I threaten them with bodily harm if they break anything on the mass spectrometer, then I proceed to pound on it with my fist. It’s all about experience.

I just found it completely humorous.

Well, they found the problem. A little capacitor I’ve named Sparky. The next day, they came over and traded Sparky for another capacitor. It took them all of an hour, and that included us socializing afterwords.

The next day, I tried turning on the source again, bracing myself for another round of BBBZZZTT.

Nothing.

But hey! Beams!

It was fixed!

We’re running again!

I asked the guys from the electronics shop what we owed them. Their response: Nothing. They had the parts on hand, and it was a fun escape for them.

So what I thought would be a $4000 job wound up costing exactly nothing. And I made some new friends. (Thanks Bob and Wade!) AND the mass spectrometer is running GREAT!

I wish all repairs went like this.