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I think I have narrowed the problem to a capacitor replacement on the main board. The capacitor is burned on the end and my inline fuse keeps blowing. The capacitor on the main board is labeled C8 but I do not know what to replace it with or where to buy one.
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First of all; it is DANGEROUS to fix a power supply if you don't know what you are doing. Thus; don't even think about to open power supply tower, if you are not qualified enough.
If you are a qualified person, you can go on with below steps by taking risk on your own.
You must discharge biggest capacitors in order to avoid any fatal electrical shock. Even it is disconnected from electricity plug, power supply may keep high voltage in it for long time. Once you discharge big capacitors; you may diassemble power supply tower. At your question you mentioned about burned power supply which makes it a little bit easier. (I assume you discharged big capacitors) Once you open psu tower; do visual inspection on each capacitor. If there is a burned area start with it. Remove blowed capacitors and replace them with same valued new capacitors. If you can't see the values on blowed capacitors; you need to find board diagram of your psu. Otherwise you can't find suitable one to replace. Besides; check form of other capacitors. If there is a change on any capacitor's form, replace them too. The best way to find out dead capacitors is using capacitor testers. If problem caused by another type item; its not easy to find it as finding bad capacitors.
This model LX200 classic has weak capacitors that blow out with age. Go to the Yahoo LX200 group-- post a message with the problem for "Ron Sampson" he can repair the board if it is broken. Also Dr. Clay and Andrew also post to this web site--- they know a lot about LX200 electronics.
Something else is wrong. The first thing to try is a new DEC cable and a new hand controller cable for the runaway slew, and hand controller issue.
If new cables do not fix the problem then contact Ron Sampson on the Yahoo LX200 group-- just post a message for him there. He can repair Meade electronics at a reasonable cost if you send him the boards.
He can also repair the hand controller including the internal ribbon cable and the LCD screen.
Try the new cables first- check this web site for a wiring diagram: http://www.mapug-astronomy.net/
or contact www.scopestuff.com they may have one already made-up.
A fellow by the name of Ron Sampson can repair hand controllers and main boards on Meade telescopes. He does very good work. All you need to send him are the board(s).
You can contact him by posting a message on the Yahoo LX90 or LX200 group forums. http://tech.groups.yahoo.com/group/lx90/
Good luck-- by the way he repaired the hand controller for our astronomy clubs 10 inch Meade LX200, at a very reasonable cost.
I have never seen a scematic published on the internet for the old Magellen hand controller. However there is a fellow that repairs LX200 and LX90 hand controllers who probably does have a schematic.
Go to the LX90 or LX200 Yahoo Group, sign up and post a message asking for help from Ron Sampson. You can send him the controller and it's VERY likely that he can repair it a nominal cost.
Hope that helps you-- by the way he repaired our Astronomy club's old LX200 Classic hand controller which had burned out circuits, and can even repair the keyboards and the screen.
C1 and C2 are on the input of a voltage regulator. The fact that they burn, could mean that their voltage rating has been exceeded (check the voltage across them), or that age has caused their failure. The classic uses about 18 volts into the power panel - see that it is not higher than that. The handpad would not be a cause for this to happen as it is not the source of the power. Replace the caps with similar ones, but with higher voltage rating - 50v is fine. But check your power supply first!
C1 and C2 are on the input of a voltage regulator. The fact that they burn, could mean that their voltage rating has been exceeded (check the voltage across them), or that age has caused their failure. The classic uses about 18 volts into the power panel - see that it is not higher than that. The handpad would not be a cause for this to happen as it is not the source of the power. Replace the caps with similar ones, but with higher voltage rating - 50v is fine. But check your power supply first!
You have a standard lx200 problem. If you transported your scope a lot with the drives "locked" it damages the RA and DEC drives. If you keep using it, the motors burn out and start drawing too much current. This sometimes blows the motor driver chips on the motherboard which are getting very rare.
The burned out tantalum caps can be replaced with better aluminum electrolytics very cheaply. If the ones in your Autostar burned out, they often burn up the ribbon cable. Also, they often take out U11, a 74LS14 chip on the motherboard. Also a cheap repair. You should take the Autostar apart. If they are burned up, it will be obvious. If your ribbon cable survived, you should replace the caps with aluminum electrolytics. I believe they are 6.8 uf.
So, if you can work an ohmmeter, measure the resistance of the two drive motors with the plugs unplugged. If it is about 14 ohms they are ok. If they are about 3 or 4 ohms, they are toast. Check the worm drives for end play. If there is just a little, you can adjust them. The battery jack on the control panel often breaks the solder joints on the board, causing one of the problems you describe. You can check that and replace/resolder as necessary. The on/off switch often fails and gets intermittent. These are also cheap and can be replaced. I don't repair these for a living but I repair a few of them for friends in the club. These are pretty common problems.
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