Topic: Fuse blows no load (Read 9213 times)

jaymac · « **on:** September 23, 2013, 03:58:50 pm »

Having got myself a rtr Pt 569 3x motors 1esc was surprised it had no fuses . Ran it dry all working . Fitted a 40amp fuse cos thats whats in my Wiesel switched on the r/c and plop fuse gone tried another same agin . removed fuse setup tried and all ok tried in the water for a few minutes nothing burnt out .Though a disaster in other ways to be discussed in another topic
Before I start taking things apart ie disconnect a motor or 2 major task for me
any other thoughts on causes

grasshopper · « **Reply #1 on:** September 23, 2013, 06:42:15 pm »

Can you draw your circuit and where you fitted the fuse exactly?
Was it in the main line coming from the battery to the ESC or elsewhere?

jaymac · « **Reply #2 on:** September 23, 2013, 07:19:37 pm »

Hi in the main Positive from Batt to Esc

Tug-Kenny RIP · « **Reply #3 on:** September 23, 2013, 07:54:18 pm »

You must be taking over 40 amps. After that experience, I would have put a meter on the line to test the amps !!

Ken

malcolmfrary · « **Reply #4 on:** September 23, 2013, 08:02:51 pm »

Silly question time - it IS a 40A fuse?

jaymac · « **Reply #5 on:** September 23, 2013, 08:15:32 pm »

Ken my little meter only does 10amps
Malcolm thats what it says on the packet

Blade Type Auto Fuses 40 Amp

Maybe thats why Graupner dont fit any

john44 · « **Reply #6 on:** September 23, 2013, 08:18:30 pm »

what motors are they? can you get in to see? What battery and connectors are fitted
and what is the ESC rated at.

john

jaymac · « **Reply #7 on:** September 23, 2013, 08:34:12 pm »

John I have no info on anythings rating all is accessible and they look as big as my graupner 600 The Battery is 8.4 nimh
there is a Pic here of one of the motors
http://www.modelboatmayhem.co.uk/forum/index.php/topic,44816.0.html

kmmbcwebmaster · « **Reply #8 on:** September 23, 2013, 09:16:07 pm »

If I'm not mistaken they look like there johnson 550 motors and under test I have had a draw of 20amp under load from one of these motors

jaymac · « **Reply #9 on:** September 23, 2013, 10:20:10 pm »

I'm saying it blows without any load ie no motors turning and instant on power on

derekwarner · « **Reply #10 on:** September 23, 2013, 10:47:59 pm »

As grasshopper suggests......."Can you draw your circuit and where you fitted the fuse exactly?"....from you latest comment it sounds like a dead short wiring fault

......
Possibly best to let a multi meter walk over each wire in the circuit/s......... Derek

jaymac · « **Reply #11 on:** September 23, 2013, 11:07:43 pm »

Derek its simply in the positive lead from the battery to the esc a dead short ? possibly but I would expect some sign of that running without the fuse .Only guessing. Multis are only for checking batteries for me

not mastered owt else

NFMike · « **Reply #12 on:** September 23, 2013, 11:44:23 pm »

Quote from: jaymac on September 23, 2013, 11:07:43 pm

Derek its simply in the positive lead from the battery to the esc a dead short ? possibly but I would expect some sign of that running without the fuse .Only guessing. Multis are only for checking batteries for me not mastered owt else

If the fuse is in the supply line from the battery how can you be running 'it' without the fuse in?
Is there a separate supply for the RX (and servos) and it is only those you are 'running'? In that case the esc is probably duff.

RAAArtyGunner · « **Reply #13 on:** September 23, 2013, 11:54:47 pm »

Can relate to your difficulty with multi meter etc, as I am not a lecky, or brilliant with wiring, as some others are on this forum, but your description does seem to indicate a dead short.

The suggestion to draw up the circuit, is a sensible starting point, as all else is pure guess work/speculation.

There are some really helpful "electrically" capable forum members and a drawing will help them help you.

Not to mention us others, who want to learn and do not want to fall into the same pitfalls.

Don't know if photo of the actual fuse setup may assist or not but you never know.

derekwarner · « **Reply #14 on:** September 23, 2013, 11:59:31 pm »

I am not suggesting checking current draw as you have previously indicated a 10 Amp limitation
Having said this....a compact multimeter will check for stray conductivity

& I also have very limited knowledge of electrons & their mysterious black paths........

Derek

old shrimper · « **Reply #15 on:** September 24, 2013, 01:21:03 am »

subscribe to this one
a photo would do in stead of a drawing

jaymac · « **Reply #16 on:** September 24, 2013, 05:46:56 am »

Quote from: Plague on September 23, 2013, 11:44:23 pm

If the fuse is in the supply line from the battery how can you be running 'it' without the fuse in?
Is there a separate supply for the RX (and servos) and it is only those you are 'running'? In that case the esc is probably duff.

The connectioin twixt batt and esc by tamiya I simply fitted Tamiya extension and then fitted Fuse in th positive leg To run without fuse just remove extension . There is no seperate feed for the RX though have a feeling in me water the R/c Saturn might be a bit iffy . Will knock up a rough drawing later today
thanks for all other input

kmmbcwebmaster · « **Reply #17 on:** September 24, 2013, 06:32:46 am »

Quote from: jaymac on September 23, 2013, 10:20:10 pm

I'm saying it blows without any load ie no motors turning and instant on power on

I understand that but was just advising that if solve this problem will have the same problem when underload with a 40amp fuse if they are johnson 550 motors.
plus from your description it sounds like who ever made this boat knew of this fault hence no inline fuses fitted
have you tried fitting inline fuses to each motor rather than from main feed ?

jaymac · « **Reply #18 on:** September 24, 2013, 09:32:45 am »

Hi just going through the early stages of sussing out the cause / Inline fuses to each motor possible last reort . As for whoever built Ha! this is a Graupner premium Line model RTR albeit I never got it first but doubt it had ever been used or tinkered with. for some reason I;m a bit iffy about the RC it is a saturn and nowt much in their manual

old shrimper · « **Reply #19 on:** September 24, 2013, 09:38:44 am »

what happens if you disconnect 2 of the motors does it still blow the fuse ?

imsinking · « **Reply #20 on:** September 24, 2013, 09:54:16 am »

Hmm , I'm just wondering if it's a 'momentary' feedback from the E S C ? as it's immediately after switching on . . .
In that case independent fuses to each motor would be the answer, fuses somewhere are a must ,weeds , garbage round the prop etc, will possibly lead to a VIKING death for the electronics or even the boat . . . we've had a few 'smokers' here , electronics mostly . . . it's not a pretty sight watching a grown man CRY

Bill

malcolmfrary · « **Reply #21 on:** September 24, 2013, 10:06:01 am »

Quote from: old shrimper on September 24, 2013, 09:38:44 am

what happens if you disconnect 2 of the motors does it still blow the fuse ?

Finding out if there is a dud motor is a good step, as is fusing each of the motors. Not much point fusing a single motor, but when there are 3 of them on the same ESC....
If it blows the fuse with all motors disconnected, it indicates that something is amiss in the ESC causing a massive current drain during switch-on.
I can't see the RX making any difference, it's running off a 5 volt supply from somewhere and has been shown to work OK by the initial tests without the fuse.

jaymac · « **Reply #22 on:** September 24, 2013, 10:25:06 am »

Ok here is the circuit as such

jaymac · « **Reply #23 on:** September 24, 2013, 10:27:42 am »

Quote from: old shrimper on September 24, 2013, 09:38:44 am

what happens if you disconnect 2 of the motors does it still blow the fuse ?

No Go area soldered i'm afraid

Off to do a bit of Sailing now Much less complicated

old shrimper · « **Reply #24 on:** September 24, 2013, 10:31:33 am »

a pair of side cutters will fix that

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