Roger, I suspect that the processor chip has at least some EEPROM,
electrically erasable programmable rom, or flash memory where items
that are not likely to be changed frequently will be saved. I know that
the Motorola equivalent of the 68300 family of chips do.
Ted

Roger Hamlett wrote:

>>Hi All,
>>
>>I have had my wedge mounted 10" LX200 for over 6 years now and until
>>
>>
>recently
>
>
>>had only ever had one problem with it, which was the mains power supply
>>failing.
>>
>>Last week a very strange problem has appeared. I have searched the
>>
>>
>archives
>
>
>>but cannot find anything like this.
>>
>>After powering up I now have the following symptoms:
>>
>>1. The local time clock constantly displays 00:00:00 - and my attempts to
>>
>>
>set
>
>
>>the local time are ignored.
>>
>>2. The sidereal clock constantly displays 00:00:00
>>
>>3. The RA display runs 'backwards' (ie, Westerly motion) at what appears
>>
>>
>to be
>
>
>>clock rate. And the RA display can be held constant by slewing East at
>>
>>
>the
>
>
>>slowest slew speed.
>>
>>4. The telescope is actually tracking in RA at the correct rate, and the
>>
>>
>slow
>
>
>>motion controls work correctly in all directions and axes.
>>
>>5. My Lat/Long settings are intact and correct.
>>
>>So it seems there is a problem causing the sidereal clock to be stopped,
>>
>>
>and
>
>
>>the scope is updating the RA in a westerly direction to compensate for the
>>normal tracking motion. It is as if the world has stopped rotating, but
>>
>>
>the
>
>
>>scope is still moving West, so the RA is updated accordingly!
>>
>>End result: the scope's stored position is moving further and further away
>>from where it is actually pointing, and this makes slewing almost useless.
>>
>>So, does this mean I have to get a new main board etc, or is there a known
>>solution for this problem? Or have I just missed something totally
>>
>>
>obvious?
>
>
>>Any suggestions from the experts will be much appreciated!!
>>
>>
>Interesting.
>I'd say 'change the battery'. This is inside the front panel, and is a
>'button' cell, like those used to power the clock on PC motherboards. If it
>hasn't been changed in 6 years, it is due to fail, and may well have done
>so.
>So I'd try changing this, before looking for anything worse. Sometimes when
>this type of battery fails, the behaviour can be very 'odd', with some parts
>of the chip keeping working to lower voltages than others. The Lat/Long, is
>often held, even when the voltage is too low to run the clock.
>The LX200, actually contains two clock chips (DS1202, replace with DS1302),
>so the odd behaviour, might be explained if one had stopped, rather than
>both. These are reasonably cheap chips, and if you are electrically
>competent, or know somebody who is, replacement of these alone, is probably
>the next stage, as is a check of the two diodes, that power the chips (if
>the one from the 5v rail had failed, the chips would only be running
>entirely off the battery - if this had then failed as well, the behaviour
>might make sense).
>If you look through the posts here, you will also find that there is a
>repair company, who might well be able to service your board, and given that
>the main logic still seems to all be working, this would be cheaper than
>replacing the board.
>
>Best Wishes
>
>
>
>
>
>
>

View index by [date] [author] [subject]
Previous message: [M]: Re: Lunar observing with Meade SCT's, Maurice Collins
Next message: Re:[M]: OTA weights, Email address hidden
Next message in thread: Re: [M]: Re: Stopped LX200 clocks...strange problem, Roger Hamlett
Previous message in thread: Re: [M]: Stopped LX200 clocks...strange problem, Ted Van Sickle