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HEQ5 Pro - Malfunction


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From my experience HEQ5's perform well on 13.8v regulated supply, but wouldn't recommend anything higher.  They will function at 12v provided the supply can maintain 12v under load.  The supply should be capable of supplying 12v at a constant current draw of 2A, but ideally with a 3-5A rating so that it has the headroom to cope with the initial inrush current as the motors begin to start slewing the mount.

Other possible things to look at are communications.  We often see posts where a mount performs fine from the handset, but when connected to a computer (even a dedicate astro PC) issue occur.  This can be due to USB hubs, EQDIR cables, or even a bandwidth issue due to an imaging camera sending so much data that the PC software times out the mount as it can't respond in a timely way. 

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8 minutes ago, AstroKeith said:

Connecting to the car cigarette lighter socket is safe, but does it mean using long cables?

As I rule, I wouldnt try to solve such problems by raising the supply voltage. Two wrongs dont make a right! however a lot of people get away with it. Dont go above 13.8V.

For instance, if the problem is voltage drop when the stepper current steps, then that voltage drop will still occur at any voltage if the same cable and connectors are being used. So your mount will see a supply voltage that isn't steady.

If you have a multimeter it would be interesting to measure the resistance of the power cable that produces the problems. If its an ohm, which is quite likely then the 1 amp spikes from each stepper motor could produce a 2v drop.

The proper solution is short heavy duty cables, with a power supply that has a low internal resistance. A lead acid or lithium battery generally have very low internal resistance.

Hi AstroKeith!

 

The cable is the 2m one provided from Sky Watcher, if you say it is safe, i am a little more confident... i´ll try it.

The only drawnback is that i live in a 4th floor apartment, with no elevators! Lol

I am going all the way down the stairs with this beefy mount head, in order to test it next to the the car! Lol...

No stress at all! No pain, no gain!! Lol!

Thanks for the tip about the batteries i can use!

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1 hour ago, symmetal said:

When doing the alignment it starts moving in Dec, and as soon as it tries to move in RA as well, (so more current drawn) it shuts down. Try slewing manually in both axis at the same time and it will shut down too I expect. A better rated supply will solve your problems. 🙂

AstroKeith has just said much the same thing. 

Alan

Symmetal my friend...

Check mate, bro!!!!😉

The mount shut off at the exact moment i pressed the second arrow!!

Now i will test the 12v PSU from the car cigarrete lighter! I let you all know about the the results, my friend.

Again, thank you all very much for your help and support! 

 

Clear skies and peace of mind for all!

 

 

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38 minutes ago, malc-c said:

From my experience HEQ5's perform well on 13.8v regulated supply, but wouldn't recommend anything higher.  They will function at 12v provided the supply can maintain 12v under load.  The supply should be capable of supplying 12v at a constant current draw of 2A, but ideally with a 3-5A rating so that it has the headroom to cope with the initial inrush current as the motors begin to start slewing the mount.

Other possible things to look at are communications.  We often see posts where a mount performs fine from the handset, but when connected to a computer (even a dedicate astro PC) issue occur.  This can be due to USB hubs, EQDIR cables, or even a bandwidth issue due to an imaging camera sending so much data that the PC software times out the mount as it can't respond in a timely way. 

malc-c, thanks for your advice.

Do you think a 13,8V 3A is ideal for the HEQ5?

I do not know if i can find a 13,8V 5A PSU here in my city!

Thanks man!

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18 minutes ago, Antares Orion said:

The mount shut off at the exact moment i pressed the second arrow!!

Glad it's confirmed it's just a power problem.  🙂 The 5A rating of your supply is fine, it's the drop in voltage at the mount when a higher current is drawn which is the issue. It's easy to lose 0.5V or so between the power supply and the mount when drawing a few amps, enough to drop below the minimum mount voltage. A 13.8V supply is recommended, as it will allow quite a bit of voltage drop before the mount fails. A fixed 13.8V supply is probably preferable than a variable voltage one, just to avoid the possibly of changing the voltage during use. If you don't think that'll be an issue then the variable supply is fine. A 5A rating or higher would allow you to power some accessories too.

13.8V supplies are used in the amateur radio field so if you have a shop selling ham radio or CB equipment they will have 13.8V power supplies.

Alan 

Edited by symmetal
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50 minutes ago, symmetal said:

Glad it's confirmed it's just a power problem.  🙂 The 5A rating of your supply is fine, it's the drop in voltage at the mount when a higher current is drawn which is the issue. It's easy to lose 0.5V or so between the power supply and the mount when drawing a few amps, enough to drop below the minimum mount voltage. A 13.8V supply is recommended, as it will allow quite a bit of voltage drop before the mount fails. A fixed 13.8V supply is probably preferable than a variable voltage one, just to avoid the possibly of changing the voltage during use. If you don't think that'll be an issue then the variable supply is fine. A 5A rating or higher would allow you to power some accessories too.

13.8V supplies are used in the amateur radio field so if you have a shop selling ham radio or CB equipment they will have 13.8V power supplies.

Alan 

Hi symmetal, yeah man... hope the things get back to normal! I was very frustrated... but you all teached me a lot about this voltage troubles.

I found this one. But 30A it's a lot. This way i could not use my anti-shock device, cause it is 10A limited. 

I'm gonna ask the seler if this kind of PSU has his own protection against high voltage peaks, etc... Screenshot_20230603-150559_MercadoLibre.jpg.3f534f9589b7e36be821e10391580356.jpg

Edited by Antares Orion
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27 minutes ago, Antares Orion said:

I found this one. But 30A it's a lot. This way i could not use my anti-shock device, cause it is 10A limited. 

If your protection device is inserted between the power supply and your astro gear it will be fine. The 30A is the maximum the power supply can deliver if it's required to do so. If your astro gear only consumes say 5A maximum that is all the power supply will deliver to it.

According to ohms law V = I * R, (voltage = current * resistance) it can be rearranged as I = V / R or R = V / I

If your equipment draws a maximum of 5A from 12V then its load resistance is 12 / 5 or 2.4 ohms.

If supplied with 13.8V the maximum current it can draw is then 13.8 / 2.4 = 5.75 amps so your protection device will be fine. It's worth fitting a 10A fuse in the +ve wire from the power supply anyway as extra protection in the event of getting an accidental short circuit in your cabling. 🙂

In reality your equipment will be using less than the 5A anyway most of the time, only likely peaking to around 3A or so when slewing in both axis at once.

Alan

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5 hours ago, Antares Orion said:

malc-c, thanks for your advice.

Do you think a 13,8V 3A is ideal for the HEQ5?

I do not know if i can find a 13,8V 5A PSU here in my city!

Thanks man!

I think Alan has really covered things with regards to voltage drop and the headroom 5A has to offer.  Once moving, the steppers will draw around 1.8A, but its the initial current that they draw in order to start moving the mass of the mount and scope attached.  Having a well balanced set up will help reduce that surge, but it can still cause the voltage to drop slightly under the load, and these mounts are quite finicky about voltage drop.

 

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On 03/06/2023 at 20:40, malc-c said:

I think Alan has really covered things with regards to voltage drop and the headroom 5A has to offer.  Once moving, the steppers will draw around 1.8A, but its the initial current that they draw in order to start moving the mass of the mount and scope attached.  Having a well balanced set up will help reduce that surge, but it can still cause the voltage to drop slightly under the load, and these mounts are quite finicky about voltage drop.

 

Hi malc-c, hi there guys!

Thanks for your attention, yes the explanations were great. Electronic stuff always was a little complicated for my "mechanical" brain!! Lol!!

I am inclined to buy one of this Nobreak PSU

Screenshot_20230604-173322_Chrome.thumb.jpg.55f20831d899c43b788466879ac7f40c.jpg

This one is 13,8V 5A, and  can be used connected to a battery, in case you are in some remote location!

The conectors are sealed and the hole package is more portable.

I'm worried about that another model i've posted before, cause its connectors are all exposed... i am not sure if it is safe to use it outdoors.

 

 

 

Edited by Antares Orion
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It looks rather cheaply made but as Malcolm says, if it works then that's fine. The output cables look quite short so you may need extension cables which increases the number of connectors in series. Also check they are wired centre positive. It will still need to be covered when outside to avoid dew forming on the case. It's not earthed either, like higher power output switch mode supplies usually are, so you may get some tingling sensations when touching the mount. Not dangerous as such but can be unpleasant. 

The 30A supply you mentioned will need fitting in an enclosure with the mains terminals separately covered as well so entails a bit more work, but once done will be able to adapt to any setup you have fairly easily.

Alan

Edited by symmetal
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I was going to post similar comments as Alan, especially looking at the battery wires and terminals, but there is nothing to help scale the item.  The earthing issue is also worth noting, and if the product turns out to be a cheap Chinese product (I did try a google search but nothing came back) then if any tingling is felt the PSU should not be used.  If I was using the scope outside then I would look at something more suited such as this which is designed to maintain voltage in damp and cold conditions.  Granted at £55 it's not cheap, but may well be a better investment.

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