Current leakage NJP

[LewisM]

Setup my "new" Takahashi NJP today, and powered it up with the Tak 12V/24V mains converter that was included in the package.

Grabbed the hand controller paddle, and almost dropped it (I knew better, despite the brain telling me to let go!) - was getting shocks from it!!!!

Somewhere in the system, there is obviously a current leak - I presume it is probably the hand controller, as touching other parts elicited no tingling (the current is SO low - thankfully LOW amperage - as to only tickle like one of those trick handshake thingies).

I am no electrician, so when I disassemble the hand controller, what should I be looking for - a frayed wire, a wire touching the metal casing, or? Only feel it at certain points like the face securing screws and hook.

I am sure it will be a simple fix, but I sure don't want to be out hot and sweaty or cold and dewed up touching that thing :eyepop::cool3:

Other than that, WHAT A MOUNT! Sure does sound like a gas turbine spooling up when it ramps up to slew :) Quieter than the EM400 too, without that odd "reversal" sound.

[rmuhlack]

I get the same thing with my mounts. Solved the problem by running an earth wire from the tripod leg to a grounding peg.

[Hans Tucker]

Might be something wrong with the hand controller cable which just plugs into the hand controller. If you know someone with an EM mount you could try swapping hand sets. Weird though. I have an NJP Temma 2 (not the PC) and have never experienced this, though I don't use the Tak 12V/24V mains converter. To better understand and fault find the problem I would think you would need the wiring diagram. Work out which pin the power comes through and using a multimeter, test (continuity test) from the pin at the end of the hand controller cable to the case. I would also do this with the hand controller cable removed from the hand controller, test the connector on the hand controller to see if there is a short to the case.

[Hans Tucker]

Just another idea...could you try and remove the screw fixing the hook/loop to the hand controller. A very remote chance this screw might be touching the cable connector inside the hand controller.

[Shiraz]

quite normal for a switch mode power supply - they include a leakage capacitor directly back to the mains to short out high frequency (RF) noise. Small amounts of mains current can pass through the capacitor in the other direction - annoying. Do as Richard suggests and earth the mount to a grounding peg - that will also protect you in the very unlikely event that something major goes wrong with the PS.

[LewisM]

Good idea Hans - will do that tomorrow.

Not really phased by it, since I will be running it all from the laptop anyway, but I do want it rectified for when I DO occasionally use it out at dark sky site just for visual. I doubt I will run it Temma PC either Hans - may end up selling that unit on Astromart (Yanks LOVE those kind of things :) )

Might try your suggestion too Richard. It certainly is VERY mild - almost like the slight tingle sometimes felt from water taps etc.

[LewisM]

Will do - any best poin t to attach the ground wire? I have the mahogany wood tripod, so attaching to that won't do much good :) Just to say the large cap bolt head that secures the mount head to the tripod head adapter?

Just use a tent peg OK, or better a ground screw?

[rmuhlack]

Attaching to the cap bolt should do the trick in your case I would think. My grounding wire is connected to a heavy duty tent peg, which does the job. I've basically banged it all the way into the ground so I dont trip over it

[Octane]

I think you should swap it with my G-11. No electric shocks, guaranteed!

H

[brian nordstrom]

;)Glad you have this mount Lewis , Earth's are 1/2 the system .
Glad you love her , yes fraid's happen to us all , sweet mount mate :thumbsup: .
Brian
( HEQ5 ( non GOTO) ) owner and lover .

[issdaol]

Lewis this will make sure you are well grounded from now on :-P

Plus it might keep that NJP tethered so you cant sell it he he :-P

[LewisM]

That is a shocking suggestion H :cool3:

[g__day]

I find it surprising that gear available in Australia has current leakage detectable by human skin. I got a Canon camera with mains power supply like that once - you could feel it tingling on your skin when you held it - so it went right back to Canon with a rather unimpressed user saying not impressed!