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Apex repair


Jon Lazar

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My Apex is broken.  I unboxed it last month and started running it on my frag tank to get the hang of Fusion and the new interface.  Then one day it went kaput.  Since I bought it 18 months ago, Neptune says it's out of warranty.

 

So I opened it up to see if there are any obvious signs of damage, and found a melted surface mount capacitor (C34).

 

P5280175_zpsqomlmfge.jpg

 

 

P5280174_zpsfeo5xlac.jpg

 

I plan to buy a replacement controller, but I'd like to try to fix this myself to have as a backup.  How do I figure out the capacitance and voltage for a replacement part?  I've asked Neptune but I expect they'll be reluctant to tell me for liability reasons.

 

I realize that once the capacitor failed, other parts may have been damaged too.  But I think it's worth trying to replace the part that's obviously failed and see whether it works.

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Sometimes they're laser etched. But I don't see any markings. It's adjacent to an open among and a connector (bnc) so it could be a DC block or an integrator configuration. The capacitor itself may be OK. The photo makes it look like there may have been a solder bridge under the cap. It's worth it to pull the capacitor to clean up below the cap and to see if there are any markings on the back side of the capacitor.

 

Sent from my SM-G930V using Tapatalk

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looks like you're playing with fire :)

I personally wouldnt risk it on a DT but I have to admit, it would be cool if you fixed it!

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I personally wouldnt risk it on a DT but I have to admit, it would be cool if you fixed it!

 

Me either!  What I want to do is fix it and keep it as a backup.

 

What I'd do is run it on a non-DT "sandbox", like a hospital or quarantine tank with no livestock in it.  That way I'd have more confidence it's good to go as a backup unit.

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Jon, what symptoms is the unit showing? The area around the capacitor looks like it's covered in flux. Flux can become conductive in humid environments. Get some flux cleaner and a flux brush and clean that area up. Look for other areas on the board with flux residue and clean those as well. Some flux is water soluble so you can check for that first. Now, if I had to guess, that circuitry is probably used to interface to one of the probes (since that chip is a linear op amp and its placed next to what appears to be a BNC probe connector). That alone doesn't seem like it would take out the Apex.  

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Tom,

 

The Apex has all the right lights but doesn't connect to other devices or the network.

 

I'll try cleaning up the flex and see if that makes a difference.

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  • 3 weeks later...

Not yet; I had other fish things to do this week.  But I'm still hopeful.  

 

I'll remove C34 and make sure the solder isn't shorting across the two pads.  

 

Then I'm going to remove C33 and test it's capacitance, and compare that to C34.  I'm going to make an assumption that C33 and C34 are the same, because the architecture around the two op-amps looks the same.

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(edited)

Looks like the solder flowed across the base capacitor; you may be able to apply heat and wick that away without removing the capacitor (provided that is what I'm seeing in the picture). Why that much heat was generated in that location is puzzling though. 

Edited by madweazl
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  • 2 weeks later...

Looks like its shorting the circuit by the melted solder.

Its should be a simple fix with the right tools.

Not sure if its will fix the Apex but worth a shot. What you got to loose?

Let me know if you need some soldering tools, I bought the tools recently to kick start a project to build my own aquarium controller.

Planning to connect 8 power sockets based on programming/timer logic which can be controller from web/mobile interface and a feed button.

Pretty basic but plan to add PH, Temp and water flooding sensor soon.

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(edited)

I removed the cap, cleaned up the excess solder and flux residue, and replaced the (same) cap.  The board behaves like before:  all lights come on and it looks ok, but it wont connect to other devices or appear on the network.

 

I'd like to order a replacement cap but my meter doesn't measure capacitance.  I measured the form factor and it's 0.02 x 0.05in.  But I don't know what the capacitance is, and I'm not experienced enough to make an educated guess what it should be.  There's only so many options.

 

So I'm at the same point.  I don't know whether the capacitor is the cause or just a symptom, and I don't know how to figure out what qualities a replacement capacitor would need.

Edited by Jon Lazar
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  • 2 weeks later...

I removed the cap, cleaned up the excess solder and flux residue, and replaced the (same) cap.  The board behaves like before:  all lights come on and it looks ok, but it wont connect to other devices or appear on the network.

 

I'd like to order a replacement cap but my meter doesn't measure capacitance.  I measured the form factor and it's 0.02 x 0.05in.  But I don't know what the capacitance is, and I'm not experienced enough to make an educated guess what it should be.  There's only so many options.

 

So I'm at the same point.  I don't know whether the capacitor is the cause or just a symptom, and I don't know how to figure out what qualities a replacement capacitor would need.

 

I am not an expert by any means but I find that the Fluke multi-meter basics site is a very helpful tool. You may have already seen it but I thought that I would share since it has a good detailed explanation for testing capacitors.

 

Anyway, here is the link to the Fluke site -

 

 http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/digital-multimeter-fundamentals.html

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