Compressor failure

Unfortunately I had another bad session with my airbrush this weekend, but before I was able to do more testing I let the airbrush compressor overheat and the ‘safety mechanism’ on the Fengda AS-200 means you are basically done until you let the thing cool off, and then open it again as I wrote in an earlier blog.

Safety Mechanism

Imagine if you and your mate Fengda (he is adopted) are sitting in a bar.  He picked you up with his car, and the plan is to have a couple of beers before he will drive you back home. But hey, look who came through the door! A couple of old friends who used to live in the same town you and your mate still live in! You have much catching up to do and you buy the guys a round of beer, and before you know it is 3 am in the morning and both you and Fengda are incredibly drunk.

You do have to get home at some point, but it would be irresponsible to have Fengda drive you in the state he is in. He just keeps going though. He says he is an even better driver when he has had a couple of beers. You start arguing and you tell him he should give you his car keys.

Suddenly Fengda storms out of the pub, sprints to his car and slashes all four of his tyres.

After you both walk home and sleep it off, you meet up with Fengda again. You take the bus to get a couple of new tyres. You just can’t figure out why Fengda didn’t just give the keys to you or the barkeeper instead of his dramatic little show, but you are too tired to start about it, and so if Fengda who still smells of booze and puke.

The Red Button

I know by now that there are three things you might notice when the Fengda AS-200 compressor is overheating:

1. The engine noise will occasionally fluctuate even though you are not using the airbrush.
2. The engine will shut down.
3. The compressor can not be restarted. The red button simply does not click and nothing happens when you try.

Before I opened the thing up or even had the overheating situation, I had read the safety instructions and saw that there was a safety mechanism in place to prevent overheating. It gave me a safe and cozy feeling. After my first overheat I let the thing cool down like the instructions said, even though I already noticed the red button did not respond and I found it hard to believe it somehow would again after letting the thing cool off. After an hour or two the red button still made no sound and the compressor still didn’t start, so I decided to open the thing up even though some of my greatest technical achievements are changing a light bulb and resetting a fuse switch.

The above picture is not what I found though. What I found was that what was on the underside of the red button (the black tube where the red and yellow wires end up on the left side of the picture) had come loose, and the spring that was between that part and the red button which made the button do anything had also popped out and lay somewhere next to the engine.

As said I am not very technical when it comes to these things, but I was able to deduct what should go where and quickly had it working again.

The yellow wire

This week I had another overheat, and after letting the engine cool down I opened the compressor up again to do this same trick. Unfortunately this time I was not able to get the button back to working condition since the yellow wire which is soldered on to the button contraption had come loose in the struggle to get it back together. The difficult thing I found was keeping the contraption together while at the same time making sure the wires don’t get stuck between the sides of the compressor and don’t rest directly on the engine so they could possibly get damaged once the thing gets heated.

Soldering on

I bought myself a soldering set and spend a few hours trying to get this to work. Unfortunately even though I have watched a few videos on soldering, this job turned out to be too much for me.

This result wasn’t acceptable even for my standards, and the thing fell apart when I even started thinking about putting it back together. I wanted to add more tin, but the heat had already melted the plastic through heat conduction and things went from bad to worse from there.

It’s a shame really, because I actually got a bit further than I had expected. What was probably a bit too much for me was that this was more than just soldering a wire together with a piece of metal. There was a third part that had to be joined, and in the end I was unable to correctly join these together. I used too much tin and there was too much heat in all parts so even the plastic melted.

Of course the repair job is purely my lack of expertise and experience with this. Good experience though!

So, was this a safety mechanism?

I am wondering if this really is the way Fengda has designed it. The instruction manual advises to use the thing for not longer than half an hour, an advice I have to say I frequently do not follow although I also have to say that if this is a mechanism that works as intended it at least does what it should: it keeps me from further using a device that is already overheating.

But the manual also talks about the device being equipped with a thermal switch. It tells me to let the thing cool down for at least 30 minutes, but does not say whether or not the DIY button fix is required. It could be something is just not working as it should.

Cheap

Whether or not the Fengda way is to passive aggressively slash the tyres rather than give you the keys I just don’t know, but I do know this compressor is about 25 euro’s in the Netherlands. That is probably about as cheap as you can get a compressor.

In the end it was my own mistake to not return this thing to the store when it didn’t work after letting it cool down. I find it hard to believe you have to send the compressor back to the factory every time it has overheated. If that is the overheating protection, than I am glad I tried to fix it myself. In the end though I will have to literally pay the price, by buying a new compressor.

Hopefully I can do that tomorrow so I can finally get back to some actual modelling!

Groetjes,

Dan