SkyWatcher SynScan FlexTube 250 Azimuth motor won't stop spinning

[bnk]

Greetings.

I recently purchased a SkyWatcher SynScan FlexTube 250. I'm powering the 12V input of the SynScan module with an AC mains power supply that outputs 12V @ 1.5A.

I find that when I use the SynScan iOS app, when I try to do alignment (regardless of method) or use the in-app buttons to move the telescope, any movement of the azimuth motor causes it to spin forever--I must power off the SynScan module to make it stop. This is not the case with the altitude motor: it slews exactly to the desired position when doing alignment, and when I press either the "up" or "down" buttons in the app, the motor steps only a single step and stops.

I'm mystified what might be causing the azimuth motor to spin without stopping once started. Has anyone seen this behavior, and if so, can you please advise how to rectify it?

Thanks very much,

-Brad

 

[johninderby]

Sounds like a power supply problem. Is your power supply a voltage regulated one? Also at least 2a is a good idea.

Erratic behaviour of a Synscan system is usually down to power supply issues.

Edited July 11, 2021 by johninderby

[bnk]

Thanks. I was initially using a 12V @ 1.5A mains AC power adapter. I've now switched to a 12V @ 2A one, but get exactly the same behavior: once the azimuth motor begins turning, it doesn't stop, and I can only get it to stop by powering it off. The altitude motor continues to function correctly.

UPDATE: the hand controller elicits the same behavior exactly, so it's not a problem with the iOS app.

-Brad

 

Edited July 11, 2021 by bnk

[Clarkey]

If you are confident the 12v supply is delivering the required power, it sounds like a fault. I would contact the supplier.

[bnk]

I've now tried powering the SynScan with a car cigarette lighter port, which definitely ought to be sufficient amperage and voltage. Exact same behavior: once the azimuth motor starts, it won't stop.

I will ask the supplier for assistance, but am concerned as to whether they will offer it. Because there was an extreme shortage of FlexTube 250s in the UK during the pandemic, and as I wanted to give my son one for his birthday, I ordered from B&H Photo in New York, and paid the international shipping and import charges. I don't know if B&H can offer any remedy other than for me to ship the faulty base back to New York (!), or if SkyWatcher could help by offering repair at a UK-based facility (or even if they could, if they'd be willing to for a unit purchased from a US supplier).

If I don't have any good warranty options given the international nature of the purchase, are there SkyWatcher service centers in the UK that could repair the base for a fee?

Thanks very much,

-Brad

[tomato]

Hi Brad, I think OVL are the UK distributors for Skywatcher,

http://www.opticalvision.co.uk/astronomy_faqs.html

If you are prepared to waive your new scope warranty there are some good people on SGL who might have a go at fixing the problem, but there are no guarantees that they can fix it. Have a look at this thread:

 

[Geoff Lister]

Hello Brad, and welcome to SGL.

I have the same system, with the older, V3, Synscan handset. Several years ago, I had problems with the azimuth axis control; not exactly your problem, but it would not align or give fine positional control. The problem was inside the azimuth gearbox cover. There is a motor control board, with several ribbon cable connectors going to the motor and the 2 encoders (motor position and, if moved manually, axis position). One of the ribbon connectors was partly disconnected from its pins. It was difficult to see, as it was on the underside of the board, and the ribbon cables have very little slack. I managed to re-seat the connector, (using manual dexterity and a dental mirror!), and the mount has behaved perfectly since.

From your description, it looks as though the motor position control loop is not getting the encoder feedback.

I have used my mount with 1.5A and 2A plug-top supplies, but the Synscan system is likely to give problems if the internal voltage drops below about 11V when doing a maximum-rate slew in both axes simultaneously, usually during the alignment auto-slew to the 2nd alignment star. This voltage drop is often caused by poor power-connector contact or thin/long (higher resistance) power leads.

Geoff