DOS Repair

Ecotech Marine
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2mk

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I would recommend sending honlite a message and ask about your specific model required. If they bare the name on the pump, they will have a replacement. Seeing as Neptune clearly didn't design the pump, I would bet money that they cannot keep the manufacturer from selling replacements directly to customers. I would have said honlite might not sell individual units, and require a minimum order quantity, but that clearly isn't so, because they have an entire aliexpress store selling individual units lol.

To be honest I probably wouldn't bother trying to find a replacement motor, as the seller seems to allude that it is custom made or modified for the task of peristalsis. I would try to find the whole unit. It may end up costing you just as much as sending it in for service, but if you document your work, others can save a lot.

A slight bit of sacrifice on your part can save the community as a whole a ****ton of money. If you have this issue, 100 other people will also have this issue. If all 100 of those people went out and bought new DOS pump for $300 then the community as a whole just lost $30,000 to Neptune. When they could have just spent ~100 per person. ($10,000) Just making this thread and drawing attention to the issue of motor failure is awesome work @2mk in doing this you probably gave a lot back to the community already.
Good Point. I just sent honlite a message and see what they have to say.
 
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Fritz
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2mk

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Also I think it would be beneficial to request the admins make a sub forum for repairs for any and all equipment. Organized by manufacturer and product would be ideal to allow people to locate and fix their equipment.
How do I do that?
 
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2mk

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Update. Stepper motor pump seller claims the motor is the same, but external fitting is different.
 
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DangerDave

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Does anyone know where to get the 4 roller heads for the DOS?

I do :) They can be ordered from avast marine. They used an identical roller assembly. I’ve changed the roller assembly in both heads on three dos units. They’re all much smoother and quieter now. One of them is used as an atk for up to 25 gallon a day changes, which is why I ordered them. Also it reduces the small risk of developing a syphon because there is always a head pinching the line.
 
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2mk

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I do :) They can be ordered from avast marine. They used an identical roller assembly. I’ve changed the roller assembly in both heads on three dos units. They’re all much smoother and quieter now. One of them is used as an atk for up to 25 gallon a day changes, which is why I ordered them. Also it reduces the small risk of developing a syphon because there is always a head pinching the line.
Interesting. I thought GHL is the only other dosing pump that uses the same pump head unit as I had seen with a pump head that looks identical but in a different color. Do you have to re-calibrate the DOS after the 4 rollers upgrade?
 
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DangerDave

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Interesting. I thought GHL is the only other dosing pump that uses the same pump head unit as I had seen with a pump head that looks identical but in a different color. Do you have to re-calibrate the DOS after the 4 rollers upgrade?

I did recalibrate. I'm not sure if it was required, but I recalibrate them after any major changes (tube length, etc).

 
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Oberst Hajj

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I do :) They can be ordered from avast marine. They used an identical roller assembly. I’ve changed the roller assembly in both heads on three dos units. They’re all much smoother and quieter now. One of them is used as an atk for up to 25 gallon a day changes, which is why I ordered them. Also it reduces the small risk of developing a syphon because there is always a head pinching the line.
Thank you. From what I could tell it is not directly listed on their site, but a search turned it up. There are no photos of it, but they do state that it works with the DOS. I'll post some photos once I get the two I just ordered.

Here is the direct link to the pump head.
 
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2mk

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Before you replace it, swap the wiring harnesses. So if you try to turn the right motor, the left one spins. Turn the left one and the right one spins. See if the problem follows the motor or the wires.
What should happen, if you have a bad motor, is that the bad motor still won't spin and the good one will spin. This will verify the motor is indeed bad. However, if the 'bad' motor now works and the good one doesn't, then the problem lies somewhere between the connector and the controller. Whether it's just a bad connector or a problem with the circuit board or a problem with the apex, we'd have to figure out later.

This is just a quick a very quick test to confirm the motor is bad. You don't want to spend $65 and wait 2 months for it to ship from China just to find out it wasn't the problem.

PS, if you do this, label the motors (good/bad). Once you start moving things around, you're eventually going to forget which one is which.
Update on Your original suggestion.

Before even opening the unit and swapping the harnesses, I made another try in testing to see if the motor works. The last time I tired it was some time ago and it did not work. But this time is a different story.

It's been off line and unplugged from 1Link for some weeks.
The DOS has no current connected to the unit at all for some time.

The test was performed using the two manual button on the DOS unit plugged into 1Link

I removed both pump heads and pressed the manual buttons. To my biggest surprise, the problem motor on the left works again as if nothing happened!

When I reinsert the pump head again and re-tested, it made a buzzing sound and does not turn.

Removing the pump head again and manual retest results in a working motor again.

Reinstalling the pump head again and retest again resulted in a working pump with pump head!

It is safe to conclude that the problem stepper motor works whenever it wants. That is not safe to use, and not reliable at all.

I don't know what to make of it. Anyone with any clues of insight in this situation?
 

infinite0180

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Interesting. I thought GHL is the only other dosing pump that uses the same pump head unit as I had seen with a pump head that looks identical but in a different color. Do you have to re-calibrate the DOS after the 4 rollers upgrade?
Avast used to make a pump that used what appeared to be the same blue head the ghl used with the 4 rollers. Then they redesigned and built a new version, they ditched the blue pump head but used the 4 roller head with the new design. Thats why they sell just the roller piece, because they use it in the newer pump they make..
 

Oberst Hajj

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Avast used to make a pump that used what appeared to be the same blue head the ghl used with the 4 rollers. Then they redesigned and built a new version, they ditched the blue pump head but used the 4 roller head with the new design. Thats why they sell just the roller piece, because they use it in the newer pump they make..
Do they still make their pump, I only see the replacement parts listed for it.
 
Zoanthids
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2mk

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Update Repost

Before even opening the unit and swapping the harnesses, I made another try in testing to see if the motor works. The last time I tired it was some time ago and it did not work. But this time is a different story.

It's been off line and unplugged from 1Link for some weeks.
The DOS has no current connected to the unit at all for some time.

The test was performed using the two manual button on the DOS unit plugged into 1Link

I removed both pump heads and pressed the manual buttons. To my biggest surprise, the problem motor on the left works again as if nothing happened!

When I reinsert the pump head again and re-tested, it made a buzzing sound and does not turn.

Removing the pump head again and manual retest results in a working motor again.

Reinstalling the pump head again and retest again resulted in a working pump with pump head!

I don't know what to make of it this time.

Is there something wrong with the power supplied by the main board to the motor?
Or is the problem with the motor itself?

I am sure I am not the only that encountered this problem before.
All replies from anyone with any clues of insight in this situation is appreciated?
 

Oberst Hajj

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Not to hijack this thread too much, but what exactly wears out on the heads that makes them need replacing? There is not a lot too them. The only thing I can think of is that the seat for the pump shaft loses tolerance over time?
 

DangerDave

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Not to hijack this thread too much, but what exactly wears out on the heads that makes them need replacing? There is not a lot too them. The only thing I can think of is that the seat for the pump shaft loses tolerance over time?

Just replace the hose and zip ties. I find the hose has to be just the right length, any shorter or longer will cause a quick failure of the hoses.
 

CEReefer

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I have no particular wisdom to impart .... but am interested to see how you do this :). I replaced a motor on my GHL with a manufacturer sourced spare part, but so far have not had to fiddle with my DOS. I'd be surprised if the DOS motor/dosing head were anything other than a standard OEM item.
Do you have a picture of the GHL motor?
 

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