12v power cable help

[scitmon]

I recently took delivery of a Pegasus Powerbox Advance, and last night was trying it out.  When it came to try and connect my Sesto Senso Focuser, I discovered that the Sesto 12v socket would not take any of my 12v power cables apart from the one supplied with it (cigarette style one which I'm trying to move away from).  

So my question is, will purchasing an adapter work and what size do I need if so? 

The only indication I have found about what size the Sesto takes is a thread on CloudyNights that says it is a 2.5mm size, but that was unconfirmed.  How will I know the polarity will match?

 

EDIT: further research indicates that the sesto is 2.5mm centre positive.  So I'm going to go ahead and get a 2.1mm to 2.5mm adapter as I believe the polarity also matches.

Edited March 15, 2022 by scitmon

[Stuart1971]

Yes the polarity should match fine, most Astro kit that uses these type of cables are always centre positive….well I have never seen one that is not in 15 years in and out of this hobby….

2.1mm is probably slightly more common on kit than 2.5mm but they are both used, so it’s worth having a selection of cables, although there are many of these 12v power cables that with take both as they have a clever little spring loaded clamp in the centre section, so will fit in both 2.5 and 2.1 sockets

[Carbon Brush]

If you don't mind digging into things...
The DC power connectors used on many mounts can be troublesome. They are cheap devices, made without proper contact plating or decent mechanical retention.
At best they are easy to dislodge in the dark, or as things move. Fit cable ties bases or similar nearby to discourage inadvertent unplugging.
There are very good arguments for replacing them with something else.
For example XLR connectors are popular for 12V power. There is a vast range from different manufacturers.
They were good enough for Apollo missions and still very popular for stage (ab)use.

Adding an adapter means more connections to play up.

@stuart1971. I also have yet to see anything astro that is not centre positive.

However, a cheap multimeter to check the lead allows you to avoid risking destroying an expensive mount!
I'm sure if the adapter lead is faulty, the seller will refund the £1.99 or whatever it cost, but not a mount or PSU repair.

HTH, David.

[scitmon]

Thanks for that, I like to keep my mount powered separately anyway just to lighten the load on the rest of my equipment.  Interesting take on the adaptor, perhaps I'll purchase a dedicated lynx 2.1 to 2.5 mm cable on my next order with FLO, but for now I'll see how the adapter goes.

[Stuart1971]

12 minutes ago, scitmon said:

Thanks for that, I like to keep my mount powered separately anyway just to lighten the load on the rest of my equipment.  Interesting take on the adaptor, perhaps I'll purchase a dedicated lynx 2.1 to 2.5 mm cable on my next order with FLO, but for now I'll see how the adapter goes.

These will work with both 2.1 and 2.5mm and are right angled which can be tidier too, they also do straight ones…

https://www.amazon.co.uk/Power-2-1mm-2-5mm-Angled-Degree/dp/B016BJGZ2U?th=1

[Richard_]

Yep, the Sesto focuser requires a 2.5mm DC connector whilst the PPBA requires a 2.1mm DC cable. I have the same focuser and PPBA as you and I also have a Beelink Mini-pc which requires a 2.5mm DC cable. I bought two cables from Dewcontrol using the following link: 

https://www.dewcontrol.com/Power_Cables_-_All_Types/p3099125_13437763.aspx

You can specify the cable length and connector types. As my PPBA and mini-pc are mounted to my telescope I measured up what length of cable I would need (about 20cm) and chose 2.1mm as connector 1 (PPBA) and 2.5mm for connector 2 (mini pc or Sesto). The cables are much nicer than the image shown on the website, the cable is a soft, black silicone which doesn't go stiff in the cold. See the attached pictures showing these nice, short cables plugged into the two left DC ports of my PPBA and the aforementioned accessories. Over the past half dozen sessions, they have worked very well and I have zero issues with them. I can easily recommend! 

As an FYI, I originally had one of the Lynx cables which worked perfect for cooling my ASI533 from my ASI Air, however, when I tried using this cable with the PPBA it wouldn't work even though there was a solid connection. 

 

Edited March 15, 2022 by Richard_
Added more pictures!

[StevieDvd]

Careful

Some Vixen power supplies are/were -ve centre. 

 

[scitmon]

On 15/03/2022 at 10:42, Carbon Brush said:

Adding an adapter means more connections to play up.

How right this turned out to be!  Bought an adaptor from Amazon to connect the Sesto to the Pegasus.  Tried to move the focuser and it fails with a high pitch noise associated.  I feared the worst and thought I'd bricked it.  Went back to the supplied cigarette style power lead and it worked fine!

I suppose it could also be the Pegasus but I seriously doubt it.  

Looks like I'm going to buy a dedicated cable after all.

[scitmon]

Ok I am still having issues.  I got my cable from Dew Control as @Richard_ recommended, but I'm still having issues getting the Sesto Senso to work.  Same issues as before.   I'm trying to power the Sesto, a mini pc, 2 heater bands, my main ZWO camera and the guide camera from the Pegasus.  I don't understand what the problem is.  I do see the voltage drop below 12v when trying to slew the focuser, is this a problem?

Edited March 19, 2022 by scitmon

[scotty38]

What are you using to power the Pegasus? I'm powering the same sort of kit with mine and have no trouble at all but I'm using the 25-30A supply from FLO

[scitmon]

I'm using the https://www.firstlightoptics.com/batteries-powerpacks/nevada-ps-08-6a-8a-regulated-linear-power-supply.html

 

Also, the Sesto has no problems working from the same power supply, when using the supplied cigarette lighter style cable.

Edited March 19, 2022 by scitmon

[scotty38]

Ah ok the slightly smaller version of what I have. I assume 6/8a is enough???? Does the focuser work ok with nothing else connected?

[scitmon]

Yes I beleive so.  I'll try using it without the camera a dew heaters running tomorrow.

[Richard_]

3 hours ago, scitmon said:

Ok I am still having issues.  I got my cable from Dew Control as @Richard_ recommended, but I'm still having issues getting the Sesto Senso to work.  Same issues as before.   I'm trying to power the Sesto, a mini pc, 2 heater bands, my main ZWO camera and the guide camera from the Pegasus.  I don't understand what the problem is.  I do see the voltage drop below 12v when trying to slew the focuser, is this a problem?

I'm powering three dew heaters (running on full power, two in RCA ports and one in DC port), ZWO camera cooling, Sesto Senso and mini pc which is all running outside as we speak. I'm using the pegasus PSU and everything is running OK! My voltage is about 12.8V according to the Pegasus Unity Platform software. 

What point are you getting the failure? Are you getting everything set up and connected, and only when you ask the Sesto Senso to move is it dropping out? Or does nothing work at all when you plug everything in? I'm not sure if it's related or not, but I found the USB-C port on the Sesto to be a bit flippant and you need to ensure you've pushed the cable deep enough into the port for it to connect and show up on the mini pc. 

[scitmon]

Everything works fine connection wise, it doesn't drop out.  However, when I command the Sesto to move to a focus position, it starts to move then almost immediatly gives up, followed by a high pitch noise coming from it.  Do you happen to notice what voltage yours drops too when its moving the focus tube?  

[Richard_]

Oh, that doesn't sound good does it? I know tha some mounts don't like slewing when presented with less than 12V so perhaps the Sesto Senso is the same when the voltage drops? 

I haven't checked what the voltage is during an auto focus routine or when moving it as I've honestly not had the need to check it. I'm watching my images come in for another half hour or so, so I'll keep my eye open on the voltage during the next anudocus routine. 

Stupid question (talking from experience), does your focuser have a lock screw which has been screwed in? Does the calibration process in the PLL PLAY app work fine? 

[Richard_]

OK, so an auto focus routine just ran in NINA and there was no significant change in voltage as reported by the Pegasus Unity Platform app. It was flickering between 12.8V and 12.9V which it is continuing to do so after the auto focus routine has finished.

Maybe the small steps in my AF routine isn't enough to drop voltage or perhaps your power supply is struggling to modulate the voltage when all the devices are drawing current at the same time? 

[Pixies]

On 15/03/2022 at 11:28, StevieDvd said:

Careful

Some Vixen power supplies are/were -ve centre. 

 

The Super Polaris motor controllers were 9v centre negative, 5.5mm.

Which is handily the same as a guitar effects pedal power supply!

[scitmon]

Ok I've just done some more testing of the Sesto in isolation.  I don't think the problem is voltage associated as it holds well above 12 volts when failing to slew in these conditions.  I did see a jump in amps from 1 to 3 amps when failing to slew through the Pegasus, and as the socket is rated for 5 amps I don't see why that should be a problem.

I switched back to the cigarette style power connection, slewed (and it worked), and saw the amps draw was not nearly as much, I'd say 1amp to 1.5 amps.

Why does the amps jump up so much more through the Pegasus!?

Edited March 20, 2022 by scitmon

[scitmon]

Ok the problem is clearly with the Sesto Senso.  It's failing to slew with the high pitched noise even when off the telescope, and powered with its own cable in isolation.  I'll have to contact @FLO to see what my options are.