 |
Last updated: 4 June 2010 |
![[Home!]](../../images/mighty_etx.jpg){kind=small} |
|
Sent: Tuesday, June 1, 2010 13:54:02 From: Michael Slevin (micksl@ntlworld.com) Hi everyone before I begin I would just like to thank Mike for a fantastic site. Keep up the good work. So here goes. I have an ETX 60 with an external 12v sealed lead acid battery attached. Last week as I was using the scope the battery fell and the leads shorted. The autostar went blank but the led on the etx was still lit. Blown autostar me thinks. Lucky for me im an electronics engineer so I started off by opening the autostar and connected a 9v battery to the unit (pic 1) the autostar fired up ok. Leave the autostar unplugged. Ok what now? as you probably know the autostar is powered from the HBX socket on the ETX base a check on the pins here verified that no power was present (pic 2)So time to open the base I must stress that doing this Will invalidate your warranty but as the battery caused this it will be invalid anyway. The fix was very easy. Getting In to the base is another matter. First you need to remove the plastic cap under the base to reveal the "nuts" you need to remove (pic3)For me this first nut was impossible to remove due to the plastic protruding through the holes in the nut used for locking. The only way I could do it was to heat a pair of long nosed pliers and melt the plastic through the holes. (Try to remove without melting first) Drastic yes but it worked. Once this is off you will see a washer also a disk with small runners in it and a 3 pronged piece of metal (pic4) once removed you will see the white nut that is attached to the R/A locking lever. Unscrew this and the base will separate. Next you need to remove the fork with the control panel unscrew the A/Z lock and remove it. Tip the base over and you will see 5 screws 3 large 2 small. Unscrew all 5 and the fork will slide out. Now you have the fork removed remove all the screws and remove the cover. Now you can see the control board (pic5) my first impression of the board was not good the soldering was very poor with dry joints everywhere which would surely lead to problems in the future. I carefully re soldered all the joints on the board (only attempt this if you are confident with soldering) Now to the fix I attached the internal battery pack switched on and checked for the autostar voltage none was present. Next I checked the 0V line all good so the fault is in the +v line. Tracing this back I discovered it goes to the on/off switch. So I soldered a piece of thin insulated wire from the switch to the HBX socket (pic6) checked the voltage all good. Switched off the unit connected the autostar which fired up no problems. Whilst the scope was in bits I decided to remove all the grease I could see and replaced with wd40 but this is up to you. I also cleaned the encoders with a small piece of tissue. Re assemble the scope in reverse order until you get to the white nut. Now this bit is trial and error im afraid the white nut needs to be finger tight so the base moves freely. There is a link to this on the site http://weasner.com/etx/techtips/2008/etx60_repair.html By Chris Erikson. Well that's it I hope you all understood my ramblings and I hope it helps people with dead autostars. If anyone needs further help please let me know ill do my best to help you. Mike Slevin England
Go back to the Tech Tips page.
Go back to the ETX Home Page.