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Skywatcher 250p SynScan GoTo (Help required with SynScan setup)


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Interestingly I looked through the images you sent me of the board prior to repair, then the ones I took for reference before working on the board,  and then on the one you sent the other night and it would seem the board had a jumper on those pins all the time.  I can only presume it was supplied to you like that....

Fingers crossed it does what its supposed to do.  Just wondered if its possible to do a simple test inside.  Set it up as if you were doing an observing session, with the scope in the default home or start position as suggested in teh manual, skip alignment, but then select the moon.  Hopefully it will rotate and rise up to point to more or less where you would expect the moon to be in relation to your home.  At least you will know if its slewing to the approximate area of the sky  

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Guys,  just to provide some background. The OP purchased this secondhand with a damaged motor board.  I received and repaired the board back in December, and have been in communication with the OP to

I'm stumped.   The  HEX file used was the same as all the previous dobsonian boards I repaired.  Hopefully the previous owner supplied the PC direct cable so that using a suitable USB to serial adapte

???????? I'm totally at a loss.  The cheapest way to identify if its the handset or the motorboard at fault is to get an EQDIRECT cable form FLO  for £33 and then download ASCOM and EQMOD.  If the mou

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I posed the question about the jumpers to OVL  - This was the response

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There are only two configurations for MC003. Please see below,

 

Model no.             Model                                                                         Jumpers

0x90                     MC003 for Dob Tracking 8" to 12"                   JP1, JP2, JP3 all open

0x91                     MC003 for Dob Goto 8" to 12"                        Only JP1 short

I've asked for better clarification as to why if JP1 is short the scope would move in the opposite directions, and what is meant by Dob tracking and Dob goto when the MC003 is fitted to all goto mounts - and what the hex reference is (0x90 0x91) related to.   As you can see, trying to get  detailed information that is easy to understand is often not as straightforward as it may seem.  Hopefully OVL will come back with more details

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Jumper removal fixed the problem with inverted controls, but the other problems still there unfortunately :(  I don't know what is the solution for this problems now. 

Scope slewing now to the correct directon, but not where the target should be, here is video example(sorry about the mess, Work in progress :D ) Target - moon, settings entered to the handset - is todays date, correct coordinates etc, time entered 20:00:00, at this time the moon will be where the picture of Buddha is on the wall (see video) however scope behave really strange as you can see. Plus another problem is that speed rate is not changing, the only speed is working properly is maximum - 9. Another video will show what i mean.

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A few years ago, I had problems with the azimuth axis on my Skyliner 250PX, particularly jumpy operation at the lower slew rates. The connector on one of the ribbon cables was partly pulled off the pins on the underside of the control board. I think it was from one of the encoders, and it was not obvious without unscrewing the board. It looks as though there was a post-design modification to feed the ribbon cables through some ferrite rings, probably to meet EMC emissions/susceptibility requirements. This makes the cables effectively shorter, and thus a tight fit under the board. I re-seated the connector, and have not had problems since.

Geoff

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0978.mov  - To my untrained eye it looked as if it was trying to rotate passed the vertical point (thanks for showing us that, but it won't do the motors any good trying to drive passed the stop that restricts the movement further)  Now according to the jumpers JP1 needs shorting to place the motor board into goto mode so maybe by removing that jumper it also removes the option to read the encoders which is why it's trying to drive through the 90 degree point, but when shorted the scope moves in "reverse" which isn't a help either.   Now from what I understand these mounts used DC Servo motors and physical encoders to feed back their angular position, which is why you can manually push them to a target and it can keep track of its location.  The encoder data is pre-processed by the smaller 14pin ICs before being passed to the relevant PIC, so there could be a possibility that these have been damaged by the previous owner when he shoved 12v up the handset port.  Again, and not trying to be judgemental, this is assuming the encoders are plugged in ? Also at around 20 seconds  in to the video there is a noticeable but short pause / stutter as if both motors stop and restart.

0979.mov -  At the beginning the motors don't sound right, they sound as if they are binding on something, or that the power supply to the mount isn't rated enough current to cope.  a 12v supply that can deliver 2.5 - 3 amps is required , can you confirm the specs of the power supply being used.   The fact that the scope is stuck but you can hear the clicking as you try and move it would suggest that instructions are been sent and processed by the motor board, but either there is not enough current to get passed the stalled position, or there is something physically preventing the mount from moving.

Other than that I'm at a loss.  The fact that the scope will move in both directions on instruction from the handset confirms the repair to replacement the two reprogrammed PIC micros worked, but the scope itself has other issues which would appear unrelated that repair.   I'm guessing that if you took the scope back to a repair agent they would flush you a lot of cash for a complete set of replacement motors, control boards and a new handset, plus any parts like gear sets that may be faulty.

I would take a look at the motors, and if there is a way to adjust any meshing see if that improves things.  If you have access to another power supply that has enough current rating try using that.  If none of that resolves the issue, but the scope still tracks at sidereal rate, then the choice is yours to use the scope manually, purchase a complete new goto kit and have the scope serviced, or cut your losses, flog some of the parts or sell the scope as faulty, and look at getting a replacement.  

Sorry, but I have nothing else to offer - any diagnosis of the motor board is beyond my level of expertise, and even then given how damaged the board was around where the capacitor was fitted it's impossible to say if any shorts or breaks have occured on the inner layers (the boards have four layers of copper traces.).  I hope you can resolve this issue, and hopefully other forum members can chime in here and comment on the videos and possibly come up with a possible solution.  (Geoff just posted as I was typing - which would suggest that the encoders might be the first thing to look at, along with the meshing of the drive)

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I will double check all the wires and connections. I'm using 12v 5amp adapter, which I believe more than enough for this mount. About the encoders, I don't think they are working at all. As when they are in enabled handset not getting any data from them(when I manually move a scope with encoders turned on) same when they are disabled. Another interesting thing, when encoders are on coordinates changing weird. I'll post a video in a couple of minutes

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"The SynScan hand controller contains a built-in self-diagnosis program. To run a full test, you first need to make a “Loop-Test Plug” by referring to Appendix E and the following instructions:

• Short the pin-2 (TX_RS232C) and pin-5 (RX_RS232C) of an RJ-12 plug.

1. Insert the two “Loop-Test Plugs” into the corresponding ports of the SynScan hand controller."

Does anyone know if I need a special cable for this test as I only have two cables, handset to control box, and control box to az box.

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In 0982.MOV - at the end you rotated the mount through quite a few degrees (my guess at least 15)  but the handset only showed the movement a single arcsecond from 06 to 07 - My guess is that IF the handset is expecting feedback and not getting it then it just continues to drive the mount.  If they are disabled then it will display its calculated position... which in theory I would expect the mount to stop.  For example if something had an altitude of 40 degrees then the scope should raise itself 40 degrees as "calculated" by the handset and then stop, even with encoders off.  Why it's trying to drive the ALT way passed 90 degrees I have no idea 

 

3 minutes ago, Kinoshnik said:

"The SynScan hand controller contains a built-in self-diagnosis program. To run a full test, you first need to make a “Loop-Test Plug” by referring to Appendix E and the following instructions:

• Short the pin-2 (TX_RS232C) and pin-5 (RX_RS232C) of an RJ-12 plug.

1. Insert the two “Loop-Test Plugs” into the corresponding ports of the SynScan hand controller."

Does anyone know if I need a special cable for this test as I only have two cables, handset to control box, and control box to az box.

You don't need this - all that does is echo a test "hello" sent out from the handsets TX pin back to its RX pin   It doesn't actually test anything else other than confirm the handset is sending commands - as the motorboard is responding to the pressing of the NSEW buttons communications is established.

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Thank you :) I've ordered PC cable to reflash firmware, if it will not make any difference, I will get board replacement from OVL, factory quote for two boards upgrade + delivery 139£. :)

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With the shops reopening it might be worth locating your nearest retailer (There is one in Tring) that could have a look at the scope first.  let them try and reflash the firmware (although I don't think the motor board needs it, but the handset may have been flashed with the wrong firmware, but I doubt it as its a standard firmware that is used for most mounts and dual purpose - EQ or ALT/AZ).  The fact that it's sending commands to the mount, the mount moves suggests that the basics such as communication between the handset and motor board is established, and that the commands are being responded to, yet it fails to stop or have any idea where the actual tube is pointing is baffling.   I wouldn't want you to shell out £100 on a new board and still have the same issue as the encoders are at fault...  Which is why I would have a shop look at it, or send it off to OVL for an estimate first 

 

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Just read through the manual, and watched the 0978 video again.  As no alignment was done, does the scope have any idea where it is.  Whilst the default home position is pointing the scope North whilst the tube is horizontal and on the presumption it resets its co-ordinates to 0000000 then you would have thought it would have worked out where it is, unless that glitch means something ?

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