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LX200 No ALT control

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#1 cavefrog

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Posted 11 October 2013 - 12:43 PM

I do not know if something else happened at the same time, or if what I did screwed it up.I found a source for 10u 35v tantalum caps. I wanted to do some prevention maintenance by replacing these. The first wrong move was to not try the scope before replacing the caps. but at the moment, I have NEVER had any trouble from this scope at all. From the day I bought it, up till now. The last time I ran it was about 3 months ago. I opened the handbox, and took out the PCB, disconnecting the ribbon cable. Then I cut the old caps out (c1,c2,and c3) leaving their legs in the board. Then noting polarity, I soldered the new caps to the old legs. I put the handbox back together to try it out before I headed for the mainboards. and came to a screaching halt. Now the ALT buttons do not work. I opened the box again to check polarity on the new caps, and they were correct. I also resoldered each one. still the same result. The ALT does not work either with the direction buttons or from goto.
My question is ... do any of these caps have anything to do with the problem? The handbox lights up fine, and does not appear to have any other problems besides the ALT disfunction. could the changing of the caps altered something else, like on the ALT motorboard? is there some way to test the ALT motor, like swapping it out with the AZ motor?
I am looking for any suggestions here, mostly from someone that has LX200 component level experience like George.
I sure hate that I tried to better a functioning scope and ended up like this.
Two other things... I tried changing the handbox cord and got the same result, and while pressing the ALT buttons the current meter shows no rise in current like the AZ does when working.

Theo

#2 jrcrilly

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Posted 11 October 2013 - 01:23 PM

The handbox doesn't directly control anything. It just tells the motherboard what to do. You could lose some button functions if the keyboard matrix went out but it would be odd to lose only two, and for those two to be so related in function. The problem is elsewhere.

Since it had been a few months, is it possible that you forgot to install the dec motor cable?

#3 cavefrog

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Posted 11 October 2013 - 02:04 PM

OMG! how stupid! Yes, I forgot to install the dec cable. :o
I have done this before, but was not doing anything but setting up. I think I wanna delete this post for embarrassment. but , I won't. What a relief. Thanks John. I was scared I had done something bad to that irreplaceable ribbon cable. I am Proud for people like you that got some common sense.

Thanks again, Theo

#4 jrcrilly

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Posted 11 October 2013 - 05:04 PM

I'm thrilled to hear that's all it was. The easy fixes are always the best! :jump:

#5 n1wvet

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Posted 17 October 2013 - 11:33 PM

Welcome to the very exclusive club of "Those who forgot the DEC cable". I am the president. It usually happens in the dark with a crowd waiting to look through the 'scope. :foreheadslap:

#6 cavefrog

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Posted 17 October 2013 - 11:39 PM

:grin:






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