ZWO EAF problem

[Nikodemuzz]

Hi all!

I've run into problems with my EAF, which I use with ASIAIR. The AF functionality has worked fine for me so far, but now it is failing me for some reason. When I try to initiate the AF sequence, it takes an image, after which it usually moves the focuser. However, now I get two beeps and an error message: "EAF abnormal or movement range not enough, try adjusting the step size." 

Nothing has changed since last time when everything worked just fine. Well, I did change a filter. I can move the focuser manually to the focus point, and beyond, so physical limits should not be the issue.

Have you run into the same issue, or would you otherwise have any suggestions how to solve this? I'm drawing a blank. It tells me to adjust the step size, but why would it suddenly be a problem, and how should I change it?

[Stargazer33]

Have you had a windows update recently?  They can mess up the USB slots. I would try reinstalling your USB drivers.

[Nikodemuzz]

6 minutes ago, Stargazer33 said:

Have you had a windows update recently?  They can mess up the USB slots. I would try reinstalling your USB drivers.

I'm running ASIAIR, so no Windows involved.

I tried adjusting the step size, no effect.

[Nikodemuzz]

More findings. Even the manual focus (with motor focus) does not perform normally. If I "rack" the focus with a fast speed, it on occasion moves nicely for a while, but then there is a little rumble from the focuser and it stops with two beeps. Sometimes it gives me the beeps right away and refuses to move. With a few retries it moves again.

At this point I'm thinking it might be due to the temperature? It's -21C outside, and this is the first time I'm using the scope in these temperatures. Could it be that the focuser operation becomes janky enough to cause the focuser to trip, possibly due to overcurrent? If this is the case, how could I remedy it? The scope is a Takahashi TOA-130F.

[Nikodemuzz]

1 minute ago, Nikodemuzz said:

More findings. Even the manual focus (with motor focus) does not perform normally. If I "rack" the focus with a fast speed, it on occasion moves nicely for a while, but then there is a little rumble from the focuser and it stops with two beeps. Sometimes it gives me the beeps right away and refuses to move. With a few retries it moves again.

At this point I'm thinking it might be due to the temperature? It's -21C outside, and this is the first time I'm using the scope in these temperatures. Could it be that the focuser operation becomes janky enough to cause the motor to trip, possibly due to overcurrent? If this is the case, how could I remedy it? The scope is a Takahashi TOA-130F.

 

[Scooot]

1 hour ago, Nikodemuzz said:

 

One of the grub screws holding the focuser shaft hasn’t come loose has it? Maybe it’s slipping. 

[Nikodemuzz]

12 hours ago, Scooot said:

One of the grub screws holding the focuser shaft hasn’t come loose has it? Maybe it’s slipping. 

Thanks for the suggestion, this occurred to me as well. I tightened the screws but it didn't help. I suspect I have to adjust the focuser on the scope. It may be gripping too tight, or the lubricant might not be suitable for these temperatures.

[Nikodemuzz]

12 hours ago, Scooot said:

One of the grub screws holding the focuser shaft hasn’t come loose has it? Maybe it’s slipping. 

Actually, re-thinking my findings from yesterday, I can't rule out slippage yet.

As I racked the focuser back and forth when I was investigating last night, I noticed that the numeral focuser position where focus was achieved was changing. For example, when I started the scope was roughly in focus at focuser position 19000. When I stopped, the focus was achieved at around 25000. To me this is as clear an indication of slippage as it gets, somewhere in the system. The grub screws gripping the shaft being the obvious candidate.

The screws are tiny and there is a lot of weight on the focuser. I wasn't too impressed with that engineering solution when I installed it. I'll have to think if I can improve it in any way. On the other hand, a softly turning focuser doesn't need a huge amount of torque to move. The soft rumbles from the focuser indicated that it is not working entirely smoothly. I'll have to inspect it as well.

[Scooot]

5 hours ago, Nikodemuzz said:

Actually, re-thinking my findings from yesterday, I can't rule out slippage yet.

As I racked the focuser back and forth when I was investigating last night, I noticed that the numeral focuser position where focus was achieved was changing. For example, when I started the scope was roughly in focus at focuser position 19000. When I stopped, the focus was achieved at around 25000. To me this is as clear an indication of slippage as it gets, somewhere in the system. The grub screws gripping the shaft being the obvious candidate.

The screws are tiny and there is a lot of weight on the focuser. I wasn't too impressed with that engineering solution when I installed it. I'll have to think if I can improve it in any way. On the other hand, a softly turning focuser doesn't need a huge amount of torque to move. The soft rumbles from the focuser indicated that it is not working entirely smoothly. I'll have to inspect it as well.

Hope you fix it. You should have a bracket of some sort taking the weight of the EAF so once it’s all attached there’s very little tension on the shaft. Maybe just take off the EAF and re-seat and tighten everything a little so you can rule out slipping?

Edited December 8, 2021 by Scooot

[Nikodemuzz]

1 hour ago, Scooot said:

Hope you fix it. You should have a bracket of some sort taking the weight of the EAF so once it’s all attached there’s very little tension on the shaft. Maybe just take off the EAF and re-seat and tighten everything a little so you can rule out slipping?

Thanks Richard! What do you mean by the bracket?

I took down the scope yesterday and today I tested it again indoors (my shed is around +4C). In a level position (on a table) and warmer temperature, there was no problem. No rumbles, smooth operation. I only got the beeps when I reached the physical limits of the focuser. 

With my logic this is pointing towards the focuser getting too stiff in the cold, causing the EAF to fail. I'm assuming the motor is protected by shutting it off if the current spikes (jamming or physical limits) or if it fluctuates suddenly (slipping or janky spots in a focuser).

I'm still not sure if the problem is because the focuser becomes stiff and uneven in the cold, or because the EAF slips on the shaft. Could be both, one caused by the other. More investigating needed.

[Scooot]

12 minutes ago, Nikodemuzz said:

Thanks Richard! What do you mean by the bracket?

I have this support bracket on mine, it holds the EAF straight etc without excess tension on the shaft and coupler. I think there are different sizes for different scopes. 

 

[Nikodemuzz]

42 minutes ago, Scooot said:

I have this support bracket on mine, it holds the EAF straight etc without excess tension on the shaft and coupler. I think there are different sizes for different scopes. 

Thanks, I get it now. I have the same bracket installed (or similar at least). I don't think the EAF would work at all without it, I think it would just turn itself around the shaft. 😄

[Scooot]

5 minutes ago, Nikodemuzz said:

Thanks, I get it now. I have the same bracket installed (or similar at least). I don't think the EAF would work at all without it, I think it would just turn itself around the shaft. 😄

Oh yeah, probably would 😃

[wimvb]

That sounds very much like the cold playing tricks. Shrinking metal parts can cause connections to become loose, and most gadgets weren't designed to operate in cold weather. I was one of the early users of the Pegasus FocusCube, and ran into trouble when the device stopped working at temperatures just below zero. The fault turned out the be the USB chip inside the controller that couldn't handle low temperature. Pegasus Astro was very fast in replacing the chip and solving the issue. Now the focuser works flawlessly even at -25 C. Most of the devices that we use and their parts, are intended for indoor use, yet we expect that they perform in extreme conditions.

[jjosefsen]

I have heard multiple people complain that the new 5V version of the EAF doesn't work well in the cold.

Is this perhaps the 5V version?

 

[wimvb]

9 hours ago, jjosefsen said:

I have heard multiple people complain that the new 5V version of the EAF doesn't work well in the cold.

Is this perhaps the 5V version?

 

Interesting. I had planned to buy the EAF for my second scope, but now I think I will pass and either stay with the Pegasus or invest in a Sesto Senso.

[gorann]

Yes, most likely the cold! The solution: Make a  camp fire, stock up with some sausages and a bottle of Finish Koskenkorva vodka (to keep warm and clear your vision) and focus manually

[Budgie1]

What about wrapping a dew heater around it?

[Len1257]

On 14/12/2021 at 23:12, Budgie1 said:

What about wrapping a dew heater around it?

So a 12V dew heater instead of a 12V EAF! The move from 12V to 5V was welcomed by those who didn't like the extra 12V power cable, it now looks to be an ill considered change.

 

[900SL]

I've just encountered the same issue with a ZWO EAF at -15c. 

First clear night in ages and the EAF is saying 'EAF abnormal or movement range not enough, try adjusting the step size." 

I've checked my settings, no changes from the last sessions. 

The EAF appears to be moving hundreds of steps on the first move, resulting in completely defocused stars, which it then cannot process. It stops at that point and I have to manually adjust focus back to the start position. 

[PhilB61]

I think it is normal for the EAF to run a significant number of steps, possibly in the hundreds, at the start of an auto focus routine, so that it can start from an out of focus position. If the initial position is wrong, or if something has slipped (possible with crayford style focusers) then the EAF may be hitting some hard or soft limit whilst trying to achieve the start position.

Edited January 2 by PhilB61

[900SL]

6 hours ago, PhilB61 said:

I think it is normal for the EAF to run a significant number of steps, possibly in the hundreds, at the start of an auto focus routine, so that it can start from an out of focus position. If the initial position is wrong, or if something has slipped (possible with crayford style focusers) then the EAF may be hitting some hard or soft limit whilst trying to achieve the start position.

I think this was cold related. It's never failed to work previously. I haven't changed any settings, and I manually focused first and checked FWHM before starting autofocus.  The EAF ASI Air routine  moves 5 x the autofocus step size, which was set to 30 as usual. The focuser however moved several hundred steps, so stars were completely defocused and the AF routine would double beep and stop with the quoted error message. It's a R&P focused, decent TS unit 

I've since checked the EAF for any loose screws etc, all seems in order. I'll try again next clear night

[PhilB61]

Just seeing the current temperatures in Helsinki, I can image such cold temps can create all sorts of issues both mechanically and electronically. Not an issue we generally have in this part of the UK especially in recent years

[900SL]

14 hours ago, PhilB61 said:

Just seeing the current temperatures in Helsinki, I can image such cold temps can create all sorts of issues both mechanically and electronically. Not an issue we generally have in this part of the UK especially in recent years

Indeed! It threw up a number of issues. My mains extension lead is outdoor rated but the insulation lost any flexibility, similarly any non silicone cables. I'll have to check none fractured on packing up.  I had to change the cooling temp of the 533mm pro from the usual -10C. I think the focuser grease turned to thick wax. My tablet had battery  issues and I was concerned I'd damage the star book 10 led screen, so I used an insulated bag with a hand warmer inside. It may have been below the limit for my scope lens cell, hopefully no damage there

Doing anything was complicated by the cold 🥶 I needed thick gloves and parka, and you make silly mistakes