Furious... but saw jupiters bands. Any electronics whizz's around?

[upahill]

Hi All,

Went to pick up my new 6" newt on a meade LXD75 GOTO mount today.

300 mile round trip, £100 in fuel burned and £450 cash spent.

Had it all set up in the lounge and working perfectly so decided to take it out for a spin, instead of finding a extension lead I opted to use the battery pack, what I didnt do was check the polarity.

Now the scope wont power up, so I have obviously blown something on one of the boards, which is very upsetting as I didnt even get to use it once.

In desperation I carried on setting up the scope and managed to catch a glimpse of jupiter and for the first time saw the bands, amazing the difference a good quality 6" makes over a chinese cheap 8"

Turned to the moon and saw amazing clarity, put in the 6.5mm eyepiece and was just blown away with detail.

I really, really want to fix this rookie mistake, so if anyone can offer any pointers it would be appreciated. My electronics knowledge extends to GCSE level and I can use a soldering iron

Sam

[Paul M]

Bad luck there

You may be lucky and find an internal fuse that's blown.

Back in the day, the standard reverse polarity protection was a chunky diode across the supple terminals such that it was reverse biased, ie no current would flow through it. But apply reverse polarity and it looks like a dead short to the supply and blows an inline fuse.

Sometimes the protective diode would die too.

So in the right hands it might be a cheap repair.

Or maybe not....!

And the lord said "let there be Tapatalk"

[rory]

i cant be of help, but i will say im keeping fingers crossed its an easy fix for ya .

[Steep]

Open the beast up and use the mark 1 eyeball on it. You're going to have to do that at some point anyway. (:

[Moonshane]

hope you get it sorted. I agree, a fuse is likely the cause (I hope). try googling the actual kit you have and 'fuse' and see if that helps. I bet someone will have done the same thing.

[upahill]

Theres quite a few people who have done it, no definitive cure though - theres no immediate signs of a blown component so no easy fix here.

Still cant believe there isnt a diode to protect it.

Need to find my alan keys....

[upahill]

I got in touch with Telescope House and they have said I can post it to them, 10 days and £120+ potentially and hopefully I will be on the road again.

[Paul M]

After a bit of googling it looks like Meade don't integrate reverse polarity protection in their electronics.

That'll be their punishment for people who lash up batteries rather than purchase their bespoke kit!

I've read up on a number of reverse polarity incidents with various Meade mounts and some make happier reading than others

For example one chap just had a bit of burned track on a PCB . Another had carbonised IC's

Best bet would be take it to a competent electronics hobbyist or workshop. Sadly electronic workshops usually start at £50 for the first hour or part there of. But if that hour and a couple of quids worth of off the shelf components gets you running that to me would be light relief.

I used to do a lot of repairs but as components got smaller and my eyes and patience got older it got too much like a chore. I mean, Surface Mount Components!! Who ever thought they were a good idea????

Any way, again, good luck!

[Paul M]

I got in touch with Telescope House and they have said I can post it to them, 10 days and £120+ potentially and hopefully I will be on the road again.

If they are a registered dealer does that mean the repair won't invalidate your warranty?

[Mikea]

That's probably the best option, I'm afraid. ICs generally are not tolerant of reverse polarity power supplies and will not usually show any visible signs of damage. Have you confirmed that the battery pack polarity was in fact reversed?

[upahill]

Im 99% sure, but have since changed the connectors, in reality though its the only thing that could have done it.

The real kicker is I had been to maplin and bought all the stuff I needed to make a better battery pack, just didn't want to build it first before playing so used the included one.

[upahill]

Well I have sent it off to Telescope House, so now just a waiting game.

I have been told up to 10 days, just need to resiist the temptation to buy more things whilst its gone.

[jonathan]

They will probably just replace electronic boards until it works, and send the broken bits back to Meade as a repair job (or just bin them).

A costly mistake that you won't likely make again!

[upahill]

They will probably just replace electronic boards until it works, and send the broken bits back to Meade as a repair job (or just bin them).

A costly mistake that you won't likely make again!

Agreed. I am angry that there was no protection built into the device, but at least its a lesson well learned (providing they can repair it)

I have been reading a bit about adding diode protection, but it seems a bit too complex to make worthwhile, same with bridge rectifiers.

Best solution I think is to run it off the mains power from now on

[jonathan]

Best solution I think is to run it off the mains power from now on

Or apply big labels!

[upahill]

Haha simple solutions are often the best

[Moonshane]

best thing to do if it's critical is have different connectors for each pole so it's not possible to connect wrongly. hope you get sorted and not too expensively.

[upahill]

Well anything more than the quoted £120 and I will probably cut my losses. Just excited to get it back now

[knobby]

Fingers crossed for you

[upahill]

Cheers, it was so amazing to see the bands on jupiter.

Just a shame this has blown my eyepiece budget Might have to sell the car... of the daughter.. or the dog...

[upahill]

Woohoo! Just paid them and its winging its way back to me So excited to finally get a proper first light.

Managed to pick up a couple of eyepieces and barlows dirt cheap from Astroboot too

Time to sort out this battery back now and compare polarity with the mains adapter.

[Paul M]

Great news!

I was wondering how you were getting on yesterday.

[sgazer]

sounds like EXACTLY the sort of thing that would happen to me. Glad you are getting it sorted and as an electronics engineer I do find it terrible that they couldn't have fitted a measely 5p diode which would have stopped a whole lot heartache for a lot of people.

[Uhwaz]

by not fitting 5p diode makes them 100quid on repairs ofc they wont fit it in ... its good bussines

[Neil_F]

by not fitting 5p diode makes them 100quid on repairs ofc they wont fit it in ... its good bussines

Haha, you hit the nail right on the head there Uhwaz. As mentioned above, a battery pack with different connectors for different polarity, ie male-female on one line, and female-male on the other.