Dobson Autotracking dead?

[marsalek]

Hello everybody,

after a failed attempt to connect my laptop to the autotracking (not GOTO) Skywatcher collapsible Dobson 8", the scope does not move any more using the hand control. When I power it up, the "1/GUIDE" button ligths up and afterwards the "SET" and "GO" keep simultaneously blinking at 1 Hz frequency while the "1/GUIDE" keeps lighting. No response to pressing any buttons on the hand control. What is the meaning of the blinking pattern on the hand control? I have not found any descriptions in the user manual.

What I did probably wrong was, that instead of using a USB to RS232 (+/-15V levels) converter, I took a converter between USB and USART (TTL levels 5V / 0V). Or the converter itself was broken, as I never had the opportunity to test it before.  On the other hand, the input communication circuitry in the autotracking Skywatcher is the L293DD that should withstand much more. Or the problem was that I am running the scope with 16.0 Volts what is still within the requirements but could have been a problem for the USB/USART converter. So I am now quite helpless.

Thank you in advance for your help!
Best regards

Karel

PS: The inside of the motorised unit looks like the one depicted in this document
http://www.eacocon.it/dobsoniani/FlexTubeGoTo.pdf

[Cornelius Varley]

The flashing LEDs on the handset usually indicate a damaged MCB.

[marsalek]

Dear Peter,

thank you for the reply. MCB is, as I assume, motor controller board, isn't it? Is this the PCB with the RJ45, RJ11 and the circular power connector? Does Skywatcher sell it separately?

Thanks

Karel

[Cornelius Varley]

Yes, thats the board the has possibly blowm. Ypu may be able to get a new board from a Skywatcher dealer or inporter.

[marsalek]

Hi Peter,

thanks for the reply.

Guys, does anyone have any technical info regarding the pin assignment to the autotracking hand controller unit or any schematics/firmware of the autotracking electronics for this scope? I'd like to try to repair it myself.

Thanks in advance!

Karel

[Gartut200]

How long you had the scope. You should be covered by your electronics warranty? 

[marsalek]

Here is a photo of the electronics board, that is probably broken. Any info about this elecrtonics is welcome! The microprocessors on the top are two PIC16F886.

Thanks

Karel

[marsalek]

Dear Gartut, I got the scope just recently, but it was used one, two years old. So no warranty at all. I probably killed it by myself by connecting it with a TTL logic signals on pins 2, 3 and 5 on the RJ-11 connector for the autotracking hand unit. I thought that I can connect the scope directly to my laptop running Stellarium, but probably I need the GoTo hand unit for that. I am not sure anymore ...

Regards

Karel