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Non-Working Autostar 494 with EXT80-AT TC-HELP!

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#1 RRMichigan

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Posted 22 November 2019 - 01:20 PM

Hello All.

 

I have an EXT80-AT TC that apparently has a dead 494 controller. With batteries installed, the red light comes on in the motorized mount, but the controller does not function at all. No LEDs light up...nothing. I did pop the controller apart too see if anything was obvious inside, but all appears like new. The spiral cable appears good as well, not even any stretch in it at all in it. I bought this second hand from the original owner and she said she had only use it a few times and everything worked. I believed her as the scope had the appearance of being like brand new when it arrived.
Has anyone had experience with this particular problem and any pointers as to what I can check? I have been all over the internet, weaslers site, etc., to no avail.
I am trying to avoid buying (if I can) another used 494 controller online just to find out that was not the problem or that the next controller could have possibly arrived DOA as well, since the 494 is an old model. They are pricey and I would be in the same predicament that I am now (how would I know for sure if it is the controller or the drive?). BTW: I do not know anyone with a controller I can try. That has already occurred to me.

Just looking for advice I suppose, before I lose hope and toss it in the dumpster. LOL.



#2 sg6

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Posted 22 November 2019 - 01:35 PM

My best guess is that the pin that supplies power is not making contact at one end or the other, after that a break in the cable (pin to thin wire break) at the connection ends.

 

Slight catch is I do not know the relevant pin at either end for you to use a meter on.

 

My #494 just works, occasional garbage on the screen but I do get power. Usually a power cycle helps me but not relevant to you.

 

Not sure if Meade supplies the pin configuration.

 

Does gently holding the connector up or down cause power to be applied?


Edited by sg6, 22 November 2019 - 01:35 PM.


#3 RRMichigan

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Posted 22 November 2019 - 02:07 PM

My best guess is that the pin that supplies power is not making contact at one end or the other, after that a break in the cable (pin to thin wire break) at the connection ends.

 

Slight catch is I do not know the relevant pin at either end for you to use a meter on.

 

My #494 just works, occasional garbage on the screen but I do get power. Usually a power cycle helps me but not relevant to you.

 

Not sure if Meade supplies the pin configuration.

 

Does gently holding the connector up or down cause power to be applied?

I did check the pins on both the connector on the cord (and cleaned them) and also, the opposing wires in the mount jack. They are all even and in their correct positions out as well. Jiggling, moving or pressing the cable end in the connector does nothing. I even tried mildly stretching and bending the spiral cable in case their was a loose wire inside, all to no avail.
The fear I have is that perhaps something inside the base that supplies power to the controller may be bad, but I have no true reason to believe that. I am trying to avoid just getting another controller if I can as I fear that may be just throwing good money after bad. But also, I am smart enough to realize that it may be my only option. I guess I was hoping someone had this exact same experience and could maybe shed some light on the issue of how they resolved it.
As for Meade, forget it. Their support line does not return calls or emails. I am sure their stance is that I should just buy a new scope from them. Good luck there. Were it not for the price I paid for the used EXT80AT, and knowing what I now know about the overall quality and build of the scopes, I would never buy a new one and could not recommend it to anyone else. Overall I suppose I am trying to salvage something out of the mistake I made. My primary reason was to get a low cost solution for tracking purposes, as I already own better manual scopes.



#4 sg6

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Posted 22 November 2019 - 02:22 PM

Add another post:

Appears that pin 1 is 12v/9v and pin 8 is Ground (0v) where looking into the HBx port Pin 1 is on the right hands side and Pin 8 therefore on the Left hand side;

 

https://www.instruct...ical-wiring-mo/

Has a decent diagram showing the numbering and the position with the "sticking out bit". You will work out what I mean.

 

First will to check the cable pins at either end - I think they cross over so 1->8, 2 ->7, 3->6 etc. Maybe just go by color as not 100% sure. Anyway you are doing a continuity check. You want to verify either a break or no break in the cable and pins.

Then apply power to the scope and check the pin voltages at the scope.

Then check voltages at the end of the cable appling any cross over.

 

If power all the way to the HBx/cable connection then it would seem to be the HBx socket or connections of socket to the board.

 

Would half suspect a break inside of a power lead - seem to think it was not uncommon after some time. People tended to pull things in and out and not overly gently. Or Meade never really soldered the wires in. Many are pretty thin wires also.

 

Don't think any support gets back to anyone, immaterial of who it is. Then you have to get someone that has an idea and few have. And none will say to pull it apart either. As then people say they did as informed and want it repaired free. Have to consider their side of the fence I am afraid.


Edited by sg6, 22 November 2019 - 02:29 PM.


#5 RRMichigan

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Posted 26 November 2019 - 09:40 AM

Thanks for the connector wiring info. It'll give me something to check.

By the way, the replacement 494 controller I ordered arrived yesterday. I plugged it in, clicked the "on" switch, and no go. The base light comes as usual, but the controller does nothing, no lights, no LED, etc. So I am fairly convinced the issue is internal in the base. Perhaps the wiring connection to the controller or in worse case, the board inside is shot.
I will do the testing as recommended by you since it'll only take a few moments, but now realize that no matter, I will have to tear into the base and do some investigating.

 

I understand what you are saying about Meade support, but the only question I left for them on answering machine and email was a question of whether the internal clock battery being dead may affect anything that would cause my controller not to work. I did not ask anything about taking the scope apart. So my original complaint about Meade support stands. LOL.



#6 RRMichigan

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Posted 27 November 2019 - 01:20 PM

Add another post:

Appears that pin 1 is 12v/9v and pin 8 is Ground (0v) where looking into the HBx port Pin 1 is on the right hands side and Pin 8 therefore on the Left hand side;

 

https://www.instruct...ical-wiring-mo/

Has a decent diagram showing the numbering and the position with the "sticking out bit". You will work out what I mean.

 

First will to check the cable pins at either end - I think they cross over so 1->8, 2 ->7, 3->6 etc. Maybe just go by color as not 100% sure. Anyway you are doing a continuity check. You want to verify either a break or no break in the cable and pins.

Then apply power to the scope and check the pin voltages at the scope.

Then check voltages at the end of the cable appling any cross over.

 

If power all the way to the HBx/cable connection then it would seem to be the HBx socket or connections of socket to the board.

 

Would half suspect a break inside of a power lead - seem to think it was not uncommon after some time. People tended to pull things in and out and not overly gently. Or Meade never really soldered the wires in. Many are pretty thin wires also.

 

Don't think any support gets back to anyone, immaterial of who it is. Then you have to get someone that has an idea and few have. And none will say to pull it apart either. As then people say they did as informed and want it repaired free. Have to consider their side of the fence I am afraid.

Got the unit tore down last night, but that is about as far as I got. I did manage to check for voltage to the 9/12v and ground wires in the HBX jack (pins 1 and 8), but registered none.
This weekend I will test continuity from the power source wires (PP3) to the HBX port input points on the PCB to see if that is the problem. If not, there is not a whole lot more I can do after that. The small PCB board, by all appearances, looks fine on both sides. Nothing burned and no wires broken anywhere. It is odd that the red light comes on when powered up, so I know at least, that power is getting to the board somehow.

Is there anyway to test the Autostar controllers separately, at least to see if they at least power up with lights? Not sure of the voltage supply it would need? There is always that small possibility that BOTH controllers are bad, and that I have been racking my brain and putting a lot of effort into other areas for naught. I mean, what if the problem was with the controllers all along?!

 

Attached Thumbnails

  • IMG_20191126_205216 (Medium).jpg

Edited by RRMichigan, 27 November 2019 - 01:29 PM.


#7 RRMichigan

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Posted 02 December 2019 - 09:06 AM

OK. Spent some time this past long weekend checking continuity on the circuits. From the power source (the PP3 connector and wires) to the circuit board, good. I could not find the path of + and - from the on/off switch but did note that no power is coming to the HBX port in the "on position". Ground, yes, positive, no. Those paths from the switch obviously run on printed paths on the board and I could not trace them.
What I decided to do was to run a jumper wire from the + power supply input directly to the + pin on the HBX port, which did bring my second 494 controller to life (the original controller was indeed dead, as it did not work). I soldered that jumper in place and hot glued it. From what I could tell, the only drawback to this method is that my on/off switch no longer controls power to my Autostar 494 controller, but rather my power connection instead, will be the on/off (I use a 12v battery pack with a cable feed). I greased the gears properly and reassembled the unit.
Running the scope thru a few tests I did find there are still problems, the main one being the Autostar programming does not ask me for my location (only date and time), so when it begins to align, the Alt motor tries to slew to stars that are not above the horizon, and of course stalls, as if it were set for a southern latitude...Also, the drives in both axis seem sluggish and unreliable. I will have to look into whether the controller can be reset to factory and then start fresh from that point. Not sure about that.
I may have to consign myself to the fact that this scope will be a manually operated one only. Not sure how much more time I want to invest in it. I feel it is past the point of any decent return for me already.....

Attached Thumbnails

  • IMG_20191127_212358 (Medium).jpg

Edited by RRMichigan, 02 December 2019 - 09:13 AM.


#8 RRMichigan

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Posted 04 December 2019 - 11:35 AM

Managed to get the horizontal drive to work correctly. Did a complete disassembly and reassemble after noting that the order of the clutch plate, bearing and washer/race were in the incorrect order/orientation (I originally followed directions/pictures showed on a repair page on weasler's EXT page - which is wrong). I oiled the thrust bearing lightly, greased the center post nylon shim, then put the parts back into the proper order and assembled, taking care as to proper tightening of the clutch bolt (trial and error). Voila! I can now move the scope in both axis from the arrow keys on the controller. Did manage to reset the 494 controller and entered the proper info (location, date, time, (did NOT have a telescope model entry like it should have, just a focal length option, so I entered 400mm), tried to perform both align processes several times, but to no avail. The scope tries to direct the OTA below the horizon with motor still running, even though the stars it displays are actually overhead at the time. I am unable use tracking (my primary objective over everything else) because the align process must first complete, and as stated above, does not work. UGH!



#9 jgraham

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Posted 04 December 2019 - 11:50 AM

I have an ETX-80 with the #494 controller and I'll check it when I get home. You might post this in the Meade telescope forum. That might be the place to get help with the mechanics and controller.
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