Help !

[brian nordstrom]

Hi , I was wondering if any one out there has any idea on a problem I have .
I brought a Meade 70mm ETX with autostar 494 for an mate and his family , a whole 1400 objects , yippy !!
Any way it arrived today from a fellow IIS'r from Sydney and the scope its self is in really good condition , with the heavy duty stainless steel tripod and adjustable wedge , a bonus I think .
Well on booting up the hand controller , its 2 line screen is blank except for the line of small red squares along the top .
Reading the manual and experimenting I have found the speed controller on the slews up to MAX works , hard doing this blind but do'able , the set ups are are impossable with no screen to guide me thru .
I am not to pissed about this as it was a steal , and anyway my questions are ,
#1 , is the later Auto star compatable with this mount ?
#2 , has any one out there have an old one lying around for sale ? and
#3 , the manual does not mention the southern hemesphere any where so is the 494 even compatable here ? if not ???
Thanks in advance , and I look forward to any help :thumbsup:.
Brian.

[traveller]

A long shot, but open up the HC and check for any loose connections. I had similar problem with a Celestron HC and it was a faulty connection. Just need a small philips screw driver and five mins. Good luck.
Bo

[brian nordstrom]

:sadeyes: Bo , I had a look and the hand controller is a sealed unit , eg. no screws !! .
Thanks for that mate and if the worst comes to the worst I will pry it open with a sharp knife as it cant hurt ;).
Brian.

[traveller]

That's a shame. Maybe a light tap with a hammer :shrug::P

[Poita]

You can get the case open on them, see here:
http://www.weasner.com/etx/autostar/as_schematic.html

[Barrykgerdes]

Hi Brian

I bought an ETX 70 a few years ago to find out how to fix some of the problems.
1. Repairing the focus control when it runs off the end of its control.
2. The stability of the simple tripod. This was the cause of the telescope often falling over and wrecking the focus and plastic drive components.
3. How to drive a 494 controller from Stellarium

See Mike Weasner's pages on the ETX60/70/80

The ETX worked pretty much as expected out of the box but the 494 controller is a bit of a dog to use. However I managed a shot of the moon with an LPI.

To connect to a computer it needs a special cable #506 that converts the RS232 to TTL for the utility socket on the base.

I modified the battery box to take an external power supply because I intended to run it for long periods connected to a computer while we wrote the interface to Stellarium

Eventually the AZM drive started to get jumpy. I managed to get it apart with great difficulty and found that the plastic AZM drive was broken rendering it forever useless. This I have since found is a fairly common problem. I made partial repairs and got the unit working for a couple of days but it soon broke again.

Since then I have come into possession of a couple of early old type DS2114 type mounts with broken Altitude bearings and faulty 494 controllers. I remade the bearings successfully. I do have an extensive workshop. I then salvaged th ETX70 OTA and cut the pivots off and cleaned up the tube. I then made a bracket to attach the OTA to the mount.

It works perfectly now. I also modified the battery carrier for external power. They need 12 volts rather than 9 volts else you will regularly get the motor fault indication when slewing.

I next purchased a 497 controller (Bintel Sell Them) which is quite compatable with the mount and connects to the computer with the #505 cable OK.

I now have a nice little goto telescope. Any offers?

Barry

PS I still have the parts (the undamaged one) from the old ETX70 mount. Also check the cable numbers from the Meade web site. I may have got them wrong.

[brian nordstrom]

:) thanks Peter , I will look into this in more detai on the weekend .
Brian.

[brian nordstrom]

:eyepop: OUCH ! , I looked at Mike Weasners page , a lot to take in .
Are you saying the 497 will run the ETX70? with the #506 cable ?
Thanks mate.
Brian.

[Barrykgerdes]

Hi Brian

I prised open an old 494 controller with a knife but it does not go back together again. I could not see any broken clips but something stops it from clipping back together.

The #506 cable is designed to go into the base of the mount in the Aux. socket. It is a "live" converter that converts the RS232 line into a form that can be used by the controller. The conversion is slow so some programs don't control the scope well. That is why we had to make a special control for Stellarium.

The #505 cable plugs into the 497 Autostar and interfaces direct with the RS232 of a computer.

Naturally if there is no COM1 port on the computer you will need a USB/RS232 adaptor.

I have not tested it because I fried my #506 cable but I think it will drive whatever controller is used on the mount.

Barry

[AndrewJ]

Gday Brian

The 494 will happily work in the Sth Hemi,
as it uses the sites latitude to determine which way to go.
As Barry noted, the 494 uses a different cable to the 497s.
The 494 cable has an active electronic lump in the middle to convert rs232 to Meades proprietary I2C Aux bus protocols.
The 497s just use a simple 3 wire cable.
All models can be controlled via a PC,
but a 497 type handbox is going to be a better bet,
as it has far more functionality for standalone usage.
Also, the 497 can have its firmware updated/patched,
whereas the 494 cannot.

Andrew

[brian nordstrom]

:shrug: Umm ?? , so a 497 will work in place of my broken 494 but I need a #506 cable , that will plug into the HBX port of the mount and the 497 controller as well , as I see the 494 is hard wired ... , or does the #506 plug into the ???? Lost me there....
Thanks for your patience. Guys.
Brian.

[Barrykgerdes]

Hi Brian PM sent.

With that scope you have the following choices.

1. Use the 494 and connect to the computer with the #506 cable from the Aux socket on the base.

2. Buy a 497 controller and connect to the computer with a #505 cable plugged into the 497.

The ETX will work much better with a 497 and a #505 cable but if you have a #506 cable you can still connect the computer to the telescope via the Aux socket in the base.

Barry

[AndrewJ]

Gday Barry



Not so sure here, and i dont have a 506 to test with.
The Firmware has to "actively" poll the Aux port to work with a 506 cable,
vs use the std Tx/Rx interrupts with a 505.
The 497 firmware doesnt appear to do this polling,
( based on 497EP and Audiostar code )
As such, i dont think a 497 will work properly with a 506.

Andrew

[Barrykgerdes]

Hi Andrew

Yes I need someone to test it. I fried my #506 cable so I am no longer able to test and I don't see any point in getting another one. I have offered my now unused 494 to Brian for the cost of postage.

Barry

[brian nordstrom]

:) thanks Barry , PM un recieved?
Brian.

[brian nordstrom]

:D Thank you so very much Barry I am in your debt .:thanx: .
Brian.