View Full Version : Problem running Jebao powerhead off Apex - not sure what's broken

03-10-2017, 05:10 PM
Here's my headache this week ... usually I'm pretty good at diagnosis but this one has me stumped. I would welcome any suggestions at this point..

I have a single Jebao RW-20 in my tank alongside two Tunze 6105's, all controlled by my Apex (I run through several profiles over the course of a day giving some really neat flow effects.)

Anyhow, I noticed that the Jebao was no longer turning on. Given that these are expected to have shorter operational lifespans, I assumed the pump had given up and it was time replace it.

So I went to Concept and bought a new one. Came home, plugged it in, and, nadda. Ummmm ok. So, that's strange?

Tried the one again but on its own controller. Started up and ran just fine.

Conclusion: The Apex to Jebao controller adapter must be the culprit.

Go back to Concepts. Return the new powerhead. Buy a new adapter. Go home and plug it in and....... nope, powerhead still doesn't start up.

Conclusion: maybe the powerhead is no good after all.

Back to Concepts. Return the new adapter. Buy yet another powerhead. Still no go.

Conclusion: The Apex must be the problem?

To test the Apex, I plug the Tunzes into the port. But they run fine. Ok, I guess the good news is that it ISN'T the Apex?

I try the Jebao on the other port, still no go. Connect up an unused VDM module I have, try the Jebao on there, and still no go.

Um ... ok. Maybe it's the cable? I test each pin on the cable and each wire shows connectivity. I try mixing and matching pins to see if there's a short, and, it appears the cable is fine.

So here is where I'm left:
- The Apex appears to be working correctly.
- The cable to the adapter appears to be working correctly.
- The Jebao powerheads appear to work correctly when on their own controller.

What exactly am I overlooking?

I have now made 3 trips to Concept to return gear and exchange. I am highly reluctant to make a 4th trip and ask for yet another equipment exchange until I have some better idea what exactly I need to ask for.

Any suggestions?

PS. I suppose it wouldn't hurt to make a new cable anyhow even if the old one tested out fine. It is just a small piece of cat5 network cable so maybe those wee tiny little wires aren't enough?? But seriously given the fact the port is meant for network cable connectors, why wouldn't a regular network cable work? (And it tested out fine with a multimeter, so I don't know??????????)

03-14-2017, 04:08 PM
Did you manage to figure it out?

If not have you checked the voltage with a multi-meter? If your controller adaptor needs a power supply did you check that?

From what I understand there is the 24V power and the control voltage so if either is too low or too weak that would explain it. The voltage can read correct when not connected and then drop off when it tries to run the pump.

03-14-2017, 04:32 PM
Thanks for the follow up, actually I did figure out what was wrong and it was the adapter after all.

What threw me off at first was that the multimeter showed it was still outputting 24v, so I assumed it was OK at first. But it turns out it wasn't allowing any amperage to go through. I'm a little murky (maybe a lot murky, lol) on my understanding of AllThingsElectrical, but I thought a resistor would reduce both voltage and amps, not just amps. But maybe they just affect amps? If not, I'm not sure what it would be that would restrict amperage but keep voltage constant.

Here's how it played out...

I decided to try testing amps instead of volts so I switched the multimeter setting and touched the leads to the output. Got a reading of something like 0.001 mA. Then tried the working controller and measured that. Blew the 400mA fuse in my multimeter.

Lesson #1: I probably don't know how to properly measure amps. It occurs to me that a device tends to draw what it needs, if that happens to be over the rating of the power supply you'll burn out the power supply. (Learned that lesson the hard way a couple times.)

Lesson #2: Although Canadian Tire sells Mastercraft multimeter tools, they do not sell the fuses that Mastercraft multimeter tools happen to use. Nor does Home Depot, apparently. Surprising to me because these stores seem to be big, and have a lot of stuff in them for sale. Just apparently not 400mA 250V .75" fuses. But I digress.

Lesson #3: I did get two different readings from the two different devices before my ability to measure amperage was taken away from me, so I concluded it must be the adapter, went back to Concept, got mocked accordingly, and bought back the adapter I had returned to them a few days prior. And sure enough, now I have a working powerhead again.

The last piece of irony is that I have the old powerhead working now, so the new one I bought is still in a box. I'm tempted to go return it rather than have it sit and take up space (which is what it's doing right now, .... and it's what, about $150 give or take, which is too much for it to sit around unneeded). Except that I'm sort of afraid to go back to Concepts at this point and ask to return it... :lol:

03-14-2017, 10:36 PM
Glad to hear you got it figured out.

A resistor in series will reduce current. It seems to me that they use it in such a way that it divides the voltage in the adaptor. At least from what I remember when I was reading up on the DIY version.

What you will see with a bad power supply is full voltage when there is no load. When you try to power something with it, the voltage drops because it is no longer producing enough current to maintain the voltage. The trouble is, it can be difficult to test the voltage when everything is connected.

For testing amperage you need to have the meter connected in series, which again can be difficult. You take the positive power source and run it to the meter and then run the other lead of the meter to the device. On most meters you also have to move the red lead to the amp connection.

03-14-2017, 11:02 PM
That makes sense about how to measure amperage, thanks for that!

So indeed, I would probably have had to measure it in series to have noticed (although I'm not sure how I would do that without cutting cables so maybe it's for the best). I just stuck the leads to the outputs and saw "24v" so I assumed it was OK when in fact it wasn't. I guess the other option would have been to try to Frankenstein some kind of connector from the power supply direct to the powerhead and see if it would run at full bore 24v, then that would also have pointed to the adapter being the issue, although same sort of thing in that either cables are getting cut at that point or wires jammed into the plugs or alligator clips and probably shorting something out in the process. ("Well, the power supply WAS fine before all of this.....").

Anyhow thanks for the help!