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The Apeks Quantum Dive Computer – Part III October 12, 2008

Posted by Chris Sullivan in Equipment.
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OK, so I’ve abandoned all hope of my poor Quantum (#1 of 2 that I own) ever working again, and I’ve sealed it’s fate by taking it further apart. There are 3 #000 Phillips Screwdriver screws holding the circuit board to the front of the unit. Removing these allows the board to be removed exposing the back of the screen.

Front of the Quantum PCB

Front of the Quantum PCB

You can see at the bottom there are 3 traces labelled SW1, SW2 and SW3. These correspond to the “A”, “Mode” and “B” switches respectively. They are also considerably worn, and one of the problems with the unit was that the Mode switch was inoperative. While my little digital camera does a good job of rendering these parts, it’s difficult even when wearing my glasses to actually see what’s going on there. I doubt I could align the probes on my voltmeter to check it out thoroughly.

Just above SW2, there is a row of contact points, There’s another one only half visible at the top of the picture just above the TP31label, extending off to the right.

The switches are mechanical, and the plastic bit that you press pushes a thin metal bar, tapered at the end, into a very small plastic ring. You can see the three rings below, although one is mostly obscured. The black part in the centre must be conductive, but it looks like plastic.

Quantum with PCB Removed

Quantum with PCB Removed

The three rings are held by an irregular octagonal bracket that also holds what must be the conducts that connect the screen to the circuit board. These just look like little plastic strips (shown below), and it’s hard to imagine how they could conduct electricity, much less align all those closely spaced contact points on the PCB. There’s another equally unlikely looking bit of plastic on the top that I’m guessing provides power to the screen.

Connectors from Quantum PCB to Screen

Connectors from Quantum PCB to Screen

Putting it all back together, the unit didn’t work as well as it did when I took it apart, which wasn’t very well. I’m not sure if the plastic strips are supposed to go in one way or another, they’re not marked. At this point I’m giving up until the other one breaks, and I can take that apart as well and make one good unit from two.

Inside the Apeks Quantum

Inside the Apeks Quantum

The black on the screen is actually a backing. It came off leaving a transparent screen. Now I need to consider what computer I’m buying next. My friends all have Cochrans, but I’m not convinced for the simple reason I mentioned earlier that you can do a gas switch manually under water – I’ve seen that crticism from others so it’s just not me whining about it. I think that’s an important feature for contingencies and also for managing air breaks from high PPO2 breathing. Apologists for this limitation say “plan your dive and dive your plan” but every diver has to deal with Mr. Murphy from time to time, when plans go awry.

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1. deepstop - October 12, 2008

Part 1 and Part 2 of this post are elsewhere in this blog.

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