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[Happy Harry]

Good Evening all,

As a last ditch effort before I admit defeat, can anyone see a blatant fault on the attached image that would lead to the fuses blowing immediately upon throttle being applied. The exact nature of the fault as i can best describe it is as follows:

When connected to a 7.2v battery, circuit turned on, everything powers up normally (no fuses blow), I get 3 red lights on the Power Distribution Board indicating all is well(?). When I test the rudder it functions as expected, when I test the throttle, the fuses on GP 2 and 3 on the PDB blow instantly whilst the fuse in GP 1 which powers the BEC and the second ESC continue to function and I get normall throttle response on the centre motor.

I have disconnected the Port and Starboard motors which connect to the P94 Dual Esc so there is no load going being drawn but again the fuses blow immediately whilst the centre motor continues fine.

I have tried absolutely everything I can think of with this over the last 24hrs and gone through more fuses than my local garage has in stock!

Have I made a basic mistake here that I cannot see, any help or suggestions welcome.

I have already spoken to Dave at Action and he's happy to take the unit back and check it for me, but I really think it might be my wiring at fault rather than his excellent equipment!

Thanks in advance for any help

Regards

[DickyD]

Do what I do if I have a problem electricwise.

Take some close up, clear photos of your wiring showing all the connections and e'mail them to Dave and see if he can see your problem before sending anything back.

[Shipmate60]

Harry,
Can you take a close up of the connections on the P94.
What happens if you disconnect the P94 and connect the other speed controller to the throttle channel?

Bob

[DickyD]

Shouldn't the fuses on your power distribution board be all 15 amp. You are using one 15amp and two 10amp.

[Happy Harry]

When it blew the first two 15 Amp fuses I lowered them to 10 Amp in that part of the circuit to prevent any damage as I tried to find the mistake I had made. I hope this makes sense!

[DickyD]

That will make the problem appear worse.

[DickyD]

Think we need a close up of the connections on the P94 as Bob said.

[Happy Harry]

Dicky,
My logic would say that the two 385 motors would pull way less than 10 Amps each (I've checked each motor and it is not binding or sticking, neither is the propeller shaft), there for I lowered the Amp rating to 10 on each side of the circuit just while I check it. I would of though that was the safer way to go. 15 Amps is a heck of a current to pull instantly so I'm trying to prevent damage. Am I missing the obvious reason it would make it appear worse?

I've tried the Condor ESC both on its own and as part of the P94 circuit and it functions fine in both circumstances.

Thanks to all for suggestions so far. I think I will take some detailed, clear pictures to send to Dave prior to sending the unit back. He may spot my schoolboy error and sort it out by mail/call

Regards

[DickyD]

Probably best, let us know what happens.

[Happy Harry]

A couple of quick close up's, one think I have not motioned is that I have extended the power wires between the P94 and the PDB to about 25-30cm to allow better installation. I've done this by soldering on 14AWG silicone cable to the originals.

Hope the photos are of use, I need to do this in daylight and make a proper job of it for Dave!

[malcolmfrary]

Should there be insulating shims/washers around the transistor fixing screws?  A heat sink makes a pretty good short circuit, which does nothing at all until the transistors switch on, then it blows the fuse, hopefully before any damage is done.

[Shipmate60]

From the pics I cant see anything obviously wrong.

Bob

[Shipmate60]

Which pic Malcolm?

Bob

[malcolmfrary]

The upper one in reply#9.  Mr Jacket might know better, knowing more about the units intimate details than me.  In all the power transistors that I've run across, the tab has been live to one of the wiring pins, and when fixed to a heatsink is usually electrically insulated from the heatsink.  I just couldn't see any in the picture.  With the circuit de-powered, a tap around the tabs and screws with a multimeter on resistance should reveal much.

[FullLeatherJacket]

Harry's P94 is perfectly standard and was tested before it was despatched. I can't see anything obvious which would cause this problem, but Harry has had to send back another complete installation to us before. It will be illuminating to have a look over this one. For sure his work on the actual plastic build of this model is awesome - he works true plastic magic, this bloke.
FLJ

[Happy Harry]

Quick update,

Sent my electronic laydown complete down to Dave (at Action) who found my error (a stray strand of wire (14 G)) had caused a short. Dave worked his magic, sent it back and it now works a dream.

Can I just say a thankyou to Dave who I know was preparing for a show but still took the time out to turn around my equipment in just a matter of days. Excellent service sir.

Thank you

[FullLeatherJacket]

Now I have to make an admission.
I have a customer called Harry Kootstra in The Netherlands who has an identical model and installation set-up to this one, and I had thought that "Happy Harry" was that gent. It is his plastic magic to which I was referring above, and his earlier installation from another model which was returned to us. Harry K was also having identical problems but hasn't contacted me for a while on the subject. He certainly hasn't returned anything for our inspection so I assume he's sorted it.
You can therefore imagine my confusion when I read that I'd fixed it and sent it back! The penny has now dropped and I apologise to Neil "Happy Harry" Harrison if he puzzled over the earlier references as much as I did.
Helluva coincidence though, isn't it?
FLJ