6101 and 7091 - how to tell which is bad?

[Obi-dad]

I have a 6101 controlled by the 7091, and the prop sometimes will briefly spin when the power is plugged in but usually doesn't run at all. The 7091 lights are on and cycling. I cleaned the pump and prop assembly with vinegar even though there was no calcium buildup. This has been running for years, no Ca buildup when running the Ca reactor instead of the old 2 part dosing I used to use (which had a lot of build-up).

I took the cover off the 7091, no signs of corrosion (does not sit inside tank cabinet).

I took the junction box cover off, and measure 24v on the power supply wires when it is on, so the power supply seems to be ok - but prop is not spinning, so I guess it could still be the power supply is dropping out under load.

I measured 7.8v across the blue and red wires, and another 7 or so from the blue to the other wire. Does that sound correct?

How do I tell if the issue is in the motor, or the controller? Or the power supply even though it measures OK?

 

[rvitko]

Yes, the controller signal is 8V, If the pump runs with no controller, that will tend to point to a controller issue but I think everything you describe points to a dead/dying pump. If you ordered 6101.015 on tunze.com, it is essentially a 6105 retrofit, a complete 6105 pump without power supply or magnet holder.

 

[Obi-dad]

is there a way to bypass the controller to test the motor directly?

 

[rvitko]

You would just unplug the controller at the junction block on the end of the pump cord. The only thing plugged into the junction box should be the power supply for this test.

 

[Obi-dad]

Lol, I didn't realize that was an option. The motor runs fine without the controller plugged in, so the motor and power supply work.

No corrosion inside the 7091, and I don't see any burnt components. There are some electrolytic caps, maybe they are failing/close to failure. New controller is not in the budget this year, do you have any ideas which component is likeliest to be the problem?

 

[rvitko]

The most common issue is the cable, it may have a break inside it or a wire not soldered to the board, 3 of the 5 wires should be soldered to the board, the other 2 are snipped.

 

[Obi-dad]

After I plug it in, it runs while I am in the room, but when I come back in later it is not running (the last post I wrote where I said it runs fine was just after plugging it in). I tried another power supply with 7091 not connected, same results. So now I guess it is the pump itself, correct?

 

[rvitko]

Yes, that would be correct. The cheapest repair path would be to order 6101.015 on Tunze.com, this would be an upgrade to a 6105 without magnet holder or power supply (complete 6105 pump only). I would do this reasonably soon as this set will be discontinued next year.