Loud Grinding Noise and Two Beeps when Slewing

ZWO AM3 Equatorial Mount Troubleshooting
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Craig Dixon avatar
Craig Dixon avatar
The mount starts to slew normally and after a second or so, it moving and I hear a loud grinding noise. I get two long beeps and it stops. The ASIAir log from this morning just says "2025/02/26 05:56:40 Mount GoTo Home POS failed".

I have a 2 month old ZWO AM3 and have experienced this problem twice now when manually slewing the mount via ASIAir (To point the scope to so I can place a flat panel on top) and once this morning when the mount tried and failed to return home after an imaging session. The grinding noise is very concerning and sounds like two gears grinding. It's powered via it's own 12V 5amp power brick.
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Gilmour Dickson avatar
Gilmour Dickson avatar
I had similar noises with my AM5 which was caused by lower voltage as a result of too long a length of DC supply cable.  After sorting my power setup it has never happened again.  But at the time it was horrendous.  I know you say it has it's own 5amp supply, is it a quality supply?  Are connections clean and solid?  Could the power supply be getting fed with less than ideal power?

How much weight is it carrying and how high from the point of RA rotation is the weight?  I guy I know with a C8 had similar issues and solved it completely with counterweight bar and weight.
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Craig Dixon avatar
Craig Dixon avatar
Thanks so much for your response, that's really helpful. I'm using a cheap power brick from amazon and was initially using a long cable. My ASIAir was giving me a low voltage warning so I ditched the long cable. My current power setup is as follows:

12V 5amp power brick into the power cable extension that comes with ASIAir, then into the mount. The output cable on the power brick I'm using is very short so I thought it best to extend this to make sure I don't get snags.

Based on your experience, I'd say that this is likely the cause.

It has a ZWO FF65 with mono setup and all the usual accessories on top so nowhere near weight limits.
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Richard avatar
Richard avatar
Lower voltage is my thought as well. I use a different mount to you (Skywatcher EQ6-R) and the sound the mount makes during the slew changes based on the slew rate. At full speed, the mount makes a higher frequency whine when slewing, but when I reduce the slew rate, it makes a slightly louder but lower frequency sound when slewing. When a lower voltage is supplied to a mount, the slew rate can drop which in my above example will change the sound during the slew and may make you think it's grinding or a problem (harmonic mounts may differ, I don't know). Can you adjust the slew rate on ASIAir to see if you can hear different sounds when slewing?

With good quality 12v output bricks, the voltage output can be slightly higher (~12.5V, per the Pegasus astro plug linked below) to take into account for voltage drops under high load. Check the manual for your mount to see if there's a recommended minimum operating voltage. I use the below PSU for my Pegasus Power Box advance which powers my camera, dew heaters and mount without any issues.

https://pegasusastro.com/products/power-supply-units/
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Gilmour Dickson avatar
Gilmour Dickson avatar
Craig Dixon:
Thanks so much for your response, that's really helpful. I'm using a cheap power brick from amazon and was initially using a long cable. My ASIAir was giving me a low voltage warning so I ditched the long cable. My current power setup is as follows:

12V 5amp power brick into the power cable extension that comes with ASIAir, then into the mount. The output cable on the power brick I'm using is very short so I thought it best to extend this to make sure I don't get snags.

Based on your experience, I'd say that this is likely the cause.

It has a ZWO FF65 with mono setup and all the usual accessories on top so nowhere near weight limits.

You are very welcome.  I am sure that low voltage is the issue.  I would get a high quality 10 amp supply.  I use a battery system so don't run a transformer.  But I am fully convinced the grinding and beeping is power related.  Maybe you could try it on a charged car battery and see if by a process of elimination you can confiirm... A lot of these cheap power supplies give a relatively low voltage as well.
Tony Gondola avatar
Tony Gondola avatar
I would check the amps your amazon supply is actually capable of delivering under load. A lot of cheap stuff on amazon is really bad so it might not be giving you what it says on the label. Power supplies are not an area where you really want to skimp.
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Craig Dixon avatar
Craig Dixon avatar
I'm glad this seems like a simple fix and not a warranty return so thanks for all the responses. The cheap power supplies have been a concern for me for a while and I did a bit of research about what PSU to get for the AM3 and ASIAir, etc. Most comments online were relating to batteries so were irrelevant to me. Those who were plugging in were using just standard power bricks so I just stuck with that.

I have one of these in my observatory, which powers my EQ6-R Pro and another ASIAir with everything else:

https://www.google.com/search?client=safari&rls=en&q=nevada+ps08&ie=UTF-8&oe=UTF-8

It's brilliant but the product has been discontinued. If I could find something similar, I'd be much happier than using power bricks. I have access to mains power so battery power via an eco flow or similar seems unnecessary. My current setup for the AM3 is:

Mains power with a long power cable into one of these boxes:

https://www.amazon.co.uk/Masterplug-IP54-Weatherproof-Electric-Box-Grey/dp/B00B0X8CYC/

The box sits between the tripod legs on the floor and contains the two power bricks:

https://www.amazon.co.uk/Multibao-Adapter-Transformer-5-5x2-1mm-5-5x2-5mm-Black/dp/B0B5G6QFN5/

And I use the DC 1.5m male-female extension cables you get with an ASIAir. One goes in the AM3 and the other goes in the AM3.

In an ideal world, I'd get another Nevada PSU, plug it in inside my obey and then run some cables 5-6m away to my AM3 setup and plug straight in.

Can anyone recommend a suitable PSU or solution?
Tony Gondola avatar
Tony Gondola avatar
You could do a quick test using a battery, just to see if this is your problem. Batteries are actually pretty great because you'll get a very clean voltage from them. Power bricks that are converting from AC have to have a lot of filtering to work well, something you won't find that on the cheap ones. Think about about what an AC to DC converter has to do to convert an AC sine wave to a straight line DC current and you'll see the issue.
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Gilmour Dickson avatar
Gilmour Dickson avatar
Craig Dixon:
I'm glad this seems like a simple fix and not a warranty return so thanks for all the responses. The cheap power supplies have been a concern for me for a while and I did a bit of research about what PSU to get for the AM3 and ASIAir, etc. Most comments online were relating to batteries so were irrelevant to me. Those who were plugging in were using just standard power bricks so I just stuck with that.

I have one of these in my observatory, which powers my EQ6-R Pro and another ASIAir with everything else:

https://www.google.com/search?client=safari&rls=en&q=nevada+ps08&ie=UTF-8&oe=UTF-8

It's brilliant but the product has been discontinued. If I could find something similar, I'd be much happier than using power bricks. I have access to mains power so battery power via an eco flow or similar seems unnecessary. My current setup for the AM3 is:

Mains power with a long power cable into one of these boxes:

https://www.amazon.co.uk/Masterplug-IP54-Weatherproof-Electric-Box-Grey/dp/B00B0X8CYC/

The box sits between the tripod legs on the floor and contains the two power bricks:

https://www.amazon.co.uk/Multibao-Adapter-Transformer-5-5x2-1mm-5-5x2-5mm-Black/dp/B0B5G6QFN5/

And I use the DC 1.5m male-female extension cables you get with an ASIAir. One goes in the AM3 and the other goes in the AM3.

In an ideal world, I'd get another Nevada PSU, plug it in inside my obey and then run some cables 5-6m away to my AM3 setup and plug straight in.

Can anyone recommend a suitable PSU or solution?

I was just about to suggest a desktop power supply like you linked in your first link.   But how to find a good one?   I have heard people talk very positively about pegasus products specifically the 10 amp supply for their powerbox (and downstream cameras, mounts, accessories etc):  https://www.firstlightoptics.com/pegasus-astro/pegasus-astro-power-supply-unit-21mm.html
Craig Dixon avatar
Craig Dixon avatar
Can I just buy something like this, put it in the weatherproof box and run two cables from the output?

https://www.amazon.co.uk/inShareplus-Universal-Regulated-Switching-Transformer/dp/B088ZQ96SC/
Craig Dixon avatar
Craig Dixon avatar
I've ordered one of these so I'm hoping that this solved the issue.

https://www.nevadaradio.co.uk/sharman-sm-10-10-12-amp-switch-mode-power-supply-new-two-year-warranty
Mel Martin avatar
Mel Martin avatar
Craig Dixon:
The mount starts to slew normally and after a second or so, it moving and I hear a loud grinding noise. I get two long beeps and it stops. The ASIAir log from this morning just says "2025/02/26 05:56:40 Mount GoTo Home POS failed".

I have a 2 month old ZWO AM3 and have experienced this problem twice now when manually slewing the mount via ASIAir (To point the scope to so I can place a flat panel on top) and once this morning when the mount tried and failed to return home after an imaging session. The grinding noise is very concerning and sounds like two gears grinding. It's powered via it's own 12V 5amp power brick.

Your issues are surely the weak power supply. 

I heard the same sounds and beeps on my AM3, immediately replaced with this power supply:
https://starizona.com/products/portable-power-station-96000mah-307-2wh?_pos=2&_sid=4efe28723&_ss=r

Altho ZWO says the ASIAIR can power the mount, that's not my experience, so I use both power outlets on the power brick, one to the ASIAIR, one to the mount.  Never had a problem since.
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Craig Dixon avatar
Craig Dixon avatar
Unfortunately, I’m still having intermittent problems with this despite powering the ASIAir and AM3 with a 13.8v regulated power supply. I managed to catch a video of the issue here:

https://youtube.com/shorts/MM_cPYIUqmc (Sound on)

Has anyone experienced this?
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andrea tasselli avatar
andrea tasselli avatar
I bet it's either the motor struggling or the geared reducer. Without opening the fella you'll never know…
Craig Dixon avatar
Craig Dixon avatar
It’s only 5 months old so looking like I’ll have to contact the retailer.
andrea tasselli avatar
andrea tasselli avatar
Do it right away!
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