the universe is no match for human stupidity

branzzz · Post by **branzzz** » Fri Nov 17, 2006 2:18 am

argh...i just damaged my 2 day old nexstar 4...

i have 2 ac adaptors lying around at home. one is a 12v that i use for my other hobby, the other isa 19v that i use to power this laptop.

i just made a mistake of connecting a 19v laptop ac adaptor to my nexstar 4gt. just after i turned it on, there was a loud popping sound followed by some smoke coming from the battery compartment. after i put some batteries back in and turned it on again, the vertical axis motor started to move on its own. i tried turning it off and on again several times and currently, the vertical motor seems to be okay, moving where it is commanded to. but i'm worried that the circuit boards inside the 4gt have been damaged.

i wonder how can i check that everything is really okay. i hope its just a fuse that blew, and not a damaged board...

Post by **weixing** » Fri Nov 17, 2006 11:06 am

Hi,

i just made a mistake of connecting a 19v laptop ac adaptor to my nexstar 4gt. just after i turned it on, there was a loud popping sound followed by some smoke coming from the battery compartment.

Sound, look and smell like the "blowing up" of capacitor(s)...

after i put some batteries back in and turned it on again, the vertical axis motor started to move on its own. i tried turning it off and on again several times and currently, the vertical motor seems to be okay, moving where it is commanded to. but i'm worried that the circuit boards inside the 4gt have been damaged.

If the mount can point and move at your command when you run on batteries, I think the damage may only limited to the voltage regulator for the external power supply. But to make sure, bring out and try out a full observation session to confirm that it's working first.

i wonder how can i check that everything is really okay. i hope its just a fuse that blew, and not a damaged board...

If you know some friend that good in electronics, you can ask them to check for you or you can send to Astro Scienitific Centre to have it repair, but I think it'll cost a bomb. So, if it can work on batteries, just use only batteries lor... I think it not worth to get it repair.

Have a nice day.

IceAngel · Post by **IceAngel** » Fri Nov 17, 2006 4:40 pm

Oh My God!! Heart pain!!

Should take it to repair real quick..

sad to hear that

branzzz · Post by **branzzz** » Sat Nov 18, 2006 12:53 am

if its just a voltage regulator blown, can i just use my 12v power supply? its already regulated to 12v...

Post by **weixing** » Sat Nov 18, 2006 9:02 pm

Hi,

if its just a voltage regulator blown, can i just use my 12v power supply? its already regulated to 12v...

My best guess is that it may not work or may not work properly depend on what is damage in the Nextar 4.

Also, is that 12V power supply came with the NexStar 4?? Please note that not all 12V power supply can be use... you must make sure the polarity of the 12V power supply output is the same as what the NexStar 4 allow or you'll blow something else.... Hmm... it may be possible that the "blow up" is cause by the polarity of your 19V power supply output is different from what the NexStar 4 will allow and not due to the higher volatge... usually 7V higher is not high enough to blow something that fast, but a wrong polarity will... especially those polarised capacitor.

Have a nice day.

branzzz · Post by **branzzz** » Sun Nov 19, 2006 6:55 am

i just tried it...after plugging in the 12v regulated that i had, the scope seems to work perfectly fine... only two things have changed:

the scope seems to slew at a much faster rate, whereby after about 15sec of slewing in the horizontal axis, the motors suddenly become quieter as if the gear noises are gone, while slewing.

if i were to set it on saturn, after 2-3 hours it will go into a death slew. if i stop it, the horizontal motors stop working and i have to turn it off and on to get them to work again.

Post by **weixing** » Sun Nov 19, 2006 12:23 pm

Hi,
Did you actually test on the field and try alignment, GOTO and tracking?? So, the alignment, GOTO and tracking is still working, but can't track long or with go crazy, right?? Does it have this issue when using batteries??

Hmm... if using batteries still got this problem, something in the motor control circuit or the motor itself may be damage. If using batteries don't have this problem, just use batteries and forget about it.

Have a nice day.

branzzz · Post by **branzzz** » Sun Nov 19, 2006 4:23 pm

yeah it works fine with both batts and the ac. i actually welcome the increased slew rate. the align, goto and everything works okay and so far it only into the death mode once.

Post by **weixing** » Sun Nov 19, 2006 6:53 pm

Hi,
Then it may be just a non-critical component that blown off...

Anyway, did you check the polarity of your 19V power supply?? Is it same as the 12V power supply??

By the way, just make sure you label your power supply clearly and don't mix up again... you may not be so lucky next time.

Have a nice day.

branzzz · Post by **branzzz** » Sun Nov 19, 2006 11:51 pm

i have no idea how to check the polarity of the power supply. one is a standard 19v laptop adaptor, the other is also a laptop adaptor but i bought it from simlim tower as a 12v...