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[catengineman]

Hi all you electronic wizards out there,

I have once again got some trouble with my electrics in the Tito Neri.

One of the super strong steering servos has burnt out at the cable entry, inc the board so I have had to change that.
I have purchased yet another Mtronik 15 amp Viper ESC which I have fitted to control the bow thrust motor
All the wires are separated ie: electronic from electrical
I have a brand new 6volt SLA supplying the receiver and the light system (later switched OFF)
All the BEC's in all three ESC's are disconnected as I run from the SLA

Now the problem,  I have a glitch which I seem not to be able to get rid of, I have swapped all the servo and ESC leads around to different positions and still I end up with this same fault.
The only way I seem to loose it is when I operate with only the two steering servos and the two drive motors.
I have refitted the electrical parts in the bow of the vessel and the receiver midships then vice versa then with one side or the other I have shielded the receiver all to no avail.
The glitch is worse when I operate the third ESC for the thruster to the extent that the ASD's will travel almost 90deg
The motors are suppressed and I have even removed any extension lead plugs by soldering the wires (shielded by hear shrink) to make sure that it is not a connection problem at those points.
I have disconnected my cooling pump system (esc's been moved) and this inturn has disconnected the fire monitor pump system so there is no fault coming from that, nor the bow winch, nor the stern winch (all disconnected)
All the systems ESC's, are powered from 12volt SLA's in series.

help please I am at a loose end as to why , what , how this should plague me.

Pictures of the burn out which I think maybe due to a trapped cable giving HR.

Richard,

[malcolmfrary]

From the description, it sounds like the mis-behaviour happens when heavy demands are being made on power.  I would check out the negative wiring run - looking specially for any thin bits where power and control cant help but run together.
This can cause the signal voltage going to a servo or ESC to be changed by the load imposed by another item.
The other thing is supression.  Even if capacitors are fitted, there is nothing to say that they are working.  Small capacitors are notoriously difficult to test with simple test gear, but usually, if they look OK, they are.  Usually.

[Robert Davies]

A few random questions from when I've (finally!) solved glitches in the past :)

When does the glitch present?  (on the water or on the bench?) Twitching servos or ESC cut-outs? Both?!

What's an ASD?

Shouldn't ESCs be parallel wired? If they're wired in series, like Christmas tree lights, one fails, they all fail.

Does the receiver's battery voltage check out? Any way to check it 'under load'? Try swapping a different 'known good' battery in to power the receiver.

Are the receiver's pins/sockets clean and tight? ( <- very recently caught me out! <blush>)

Have you tried alternate channels? (Different crystals) Possible environmental interference. eg My Volvo's power bus emits low level interference at 40.1mhz, well outside our usage, but just an example nonetheless.

All I can think of for now.... :)

-Rob

[catengineman]

Hi Rob,

Glitch pressent very slightly on bench but bad in swimming pool
ASD Azimuth Steering Drive
ESC's all red leads together all black leads together
Batteries connected to give 12 volts (longer amp hour)
As far as I know the pins are OK and any joins have been soldered rather than with plugs n sockets
have tried various configs with receiver and I am using a duel conversion rec & Xtail as I was told that they were the best thing since sliced bread (Hu mug am I or what)

I have seen a zero glitch module from Mtronik which say's it will clean up any "cr#p" in the signal from the rec to the esc and have enquired as to availability of said item. I even thought about soldering the wires into the rec to make sure that the contacts were good.

Richard,                       frustrated and skint

[Robert Davies]

Have you tried powering the receiver via the BEC from one of the speed controllers?

If you have, fair enough, if not remove the RX battery and try the BEC power supply from a speed controller - I have suspicion, but no more than that, that it is a low output voltage/current issue from/via the receiver.

I recently fitted cooling fans to the heatsinks on my motors. The instructions with the fans said to plug them into a free RX socket..... Plugged them in, and the combined current draw caused glitching on a massive scale - I suspect because the rx was shutting down and rebooting multiple times a second. Supplied fans with their own switched supply and sweetness and (no!) light returned.

-Rob

[Doc]

Just for 'grins', try disconnecting the third ESC, the bow thruster, from the receiver and see what happens.  Can't remember exactly what it pertained to, but seem to remember something about a third ESC causing such a glitch before (don't ask me, I have no idea why).
 - 'Doc

[Tug-Kenny RIP]

Hi Catengineman

My thoughts  ....

There is an overload of current here and your analysis is on track. may I suggest you drop the Rx voltage to 5 volts and fit a large capacitor to the supply  (IE  1000 microfarad at 50 volts).  The 6 volt line may be actually over this value.

To analyse further, does it happen at slow speed on the bench ?

Try disconnecting the SCR's and try only one in circuit at a time. Running the speed from fast to slow to see what happens.  Also I tend to use 20 amps versions  (belt & braces man here !!).  You did mention that the servos on the steering were satisfactory, so the fault is in the power system to the motors. 

I have seen the oscilloscope waves put out by by these ESC's and it's fascinating.  ( I will try and film the result as soon as I get my motors running on the bench again... I did promise once before :) )

Hope this helps

Ken

[Robert Davies]

There is an overload of current here and your analysis is on track. may I suggest you drop the Rx voltage to 5 volts and fit a large capacitor to the supply  (IE  1000 microfarad at 50 volts).  The 6 volt line may be actually over this value.

Building on what I said earlier, and Kenny indicated above, using the supply from a BEC in one of the speed controls will get you a nice 5 volt supply to test out this theory with.

BECs step down the speed controllers input voltage (in your case 12v) to supply 5v to the rx.

Next!! :)

-Rob

[malcolmfrary]

Thought on the mess in the servo - it has a rather larger motor than the standard size, so presumably draws more current.  If its only power supply is via the RX lead, this will mean that all of its power is coming via the RX, and might well overcome the RXs ability. 
The damage in the photo must have been caused either by a faulty component within the servo, or the leadcarrying too much current, or both.  This same excess current might have done something within the receiver to give further problems.

[wombat]

My thoughts.......

If you are running the Rx direct of the SLA, you could be feeding it with more than 6.5V - possibly 6.8V if the battery is fully charged. This may explain the burn up in the servo - if they had used a 6.3V tantalum capacitor it could very likely have gone into meltdown: they tend to go inot short circuit, same as if they had been reverse connected.

If the Rx is designed for 4xNiCd = 4.8V the extra voltage could well be affecting the performance of the Rx, by affecting internal bias points. As has been suggested pot down the voltage to 5V using a suitable regulator.

How are the reciever cables connected - if there are long runs overlapping, you can get crosstalk, especially if the inputs are CMOS with no terminating resistors.

Another possibility is that there is a differential on the grounds - try linking the grounds on the batteries for the motors and the electronics

WOm

[catengineman]

Hi there to all,

I have had a bit of a holiday from the tug today as frustration got the better of me and spanner has ordered me to calm down.
Why is it that it is only MY build that is giving trouble when all the various tugs I have altered and refitted for capt jack have worked totally fine without ANY problems.

Oh well can I ask wombat if you can translate the last post, sorry mate but although I am a chief engineer on a ship this electronic stuff is giving me a head ache. I was told the best voltage for the rec and servos was 6 volt and if it came from a SLA this would be the best supply to have.
I may have got this next bit round robin but other than the servo motors the motor grounds change with direction of the current from the esc'c. the two 12 volt batteries are linked and to my knowledge it is not possible to link in the 6volt SLA as 12 volts would back feed into the 6 volt or I would end up with 18 volts.
as I said I have probably got that bit all ar## over t#t

Heavy oil, gas oil, petrol, paraffin = suck squeeze bang blow easy peasy for mesy
Model boats nightmare in garage

Richard,

[wombat]

Hi CatEngineMan,

Sorry if I am a bit obscure in what I say, too much time spent with other sparkies..... the thing you have ot remember about electronics is that they are seldom as logical as you think they ought to be.

The voltages for batteries are an approximation - a 6V SLA will typically be more than 6V because of the physics of the battery. The recieve could have been designed for 6V, but if it is using modern devices, it is more likely that it will be designed for 5V operation, so if you run it on more than 5V then you can get problems because you are running outside the design envelope - bit like overloading an engine - you might not break it but it certainly is not going to be worknig at its best.

From my little experience, the recievers are designed for 4*NiCd which gives 4.8V typically - a 6V SLA will have approximately a 20% overvoltage.

Grounding is a black art - really it is. I see a potential (Pardon the pun) if you have the Rx power on a separate battery to the power section and you have no link between them - all sorts of odd effects can happen because of the way the current flows. At work we had a system where the difference between the system working and not working was moving a ground lead by 1M. 

If you have not got a good link between the gorund used for the electronics and the ground for the power, any spikes on the power system (such as the ESC) can inject onto the electronics ground and signals and have all sorts of odd effects. To get an idea do a google on differential mode and common mode interference.

Probably fogged the situation even more - but I suggest trying a link between the the grounds on the batteries. Use a decent wire not a skinny thing.

Wom

Wom

[malcolmfrary]

For "motor ground" read "ESC ground", at least as far as power supply is concerned.  If doing full supression, the cases of the motors should be grounded.
With all model boat installations that I have seen, the negative lines of all power supplies should be commoned, preferably with nice heavy wire.  There are variations in model flight controllers, where this is not always the case.

[Umi_Ryuzuki]

If I were to hazard a guess, the steering servos may be stalling.
If the servos are stalled, they may be drawing more amps then the lines can handle in an
attempt to overcome the stall.

Make sure the ASD are clear to swivel, and do not hang up, before the end of the servo travel.
It could also be that the motor gear drives are over powering your steering drive and causing a stall.

 ???

[catengineman]

Thank you all for the input,

Wombat,   Wow now my head really hurts   I have spent several hours tinkering ie: soldering / unsoldering wires to this from that and so far I may have found a cause (says he with a lot of hope)
 One of the ESC's that controlled the drive motors has a bad wire (cracked at the resin, half of the wire is broken so that would give a higer resistance)

malcolmfrary,  I have linked across all the motors etc where it is possible even the ESC's

Umi_Ryuzuki,  The servo's are free it is just sort of electrical as it still happens if the servos's are out of the line

Richard,

[catengineman]

I thought that I would repost a reply to all those that have assisted me    THANK YOU

Sorry for the short post earlier (osteopath appointment) I have dug around the bad wire and solder repaired the bad bit then I have insulated this and strengthened the area with the hot melt glue stuff, on the first round of tests this seems to be working fine and the glitch has all but gone.
I say all but gone as the ESC is only loose in the tug and the other electrics are just laying where ever they want even the antenna is just drooped over the side of the vessel.  I have purchased some more wire and I am going to reposition the whole system  (glutton for punishment) but I think that if I can move the ESC's further away from the rec then I may have a better chance of getting a clean signal from it to the various items.
Oh yes and in the test period I have NOT fitted any fuses to the power lines (less exposed electrical areas, and fewer bad contact areas) though this may only be while I test the system.

[malcolmfrary]

When I was learning my trade many years ago, one of my bosses offered the following wise advice-
"You can get as technical as you like, but look for broken wires first." 
Advice that I remember every time I forget to follow it, and eventually find the problem was a bit of duff wire.
Once you have found a broken bit it is often possible to work back and account for the problems.  Hope this is the case.

[catengineman]

How to say this is hard when I cant find the button for happy jumping bunnies with balloons floating through the air.

From the start line you may have worked out that the tests carried out today have prove to be good great fantastic.

I have spent the day shut up in the garage reinstalling the various bits n bobs to my tug, water pump (only one though) stern winch 12 volt, bow winch 12volt, anchor winch (now 12volt) three ESC'c, 2 steering servos, 2 home made switchers                  (1 forward/revers - 1 either or) 2 12 volt batteries, 1 6 volt battery the receiver and yes every bit of wire that is required to operate that lot.
The ESC's are now located in the bow area and the main electrical wires all run Port side where as the electronic system wires run Stbd side, I have NOT fitted any fuses as on One test glitching (slight) was seen and upon returning to non fuse system glitch vanished.  All the wire replaced is the silicone type and any joint to switch etc is soldered.

So at this moment in time I am happy or as the song goes:

I'm H - A - P - P - Y    I'm H - A - P - P - Y    I KNOW I AM I'M SURE I AM   I'M   H - A - P - P - Y .

Richard    A BIG THANK YOU TO ALL THAT ASSISTED

[Capt Jack]

About time too !!!. At least that will stop you spitting your dummy out then !!!

[catengineman]

I'm that happy I took Tito out to the pond no the LAKE  and when I had got all set up at the lake side the heavens opened up, still if you cant sail in the wet stuff.

I anchored for s short while before taking my small bits box in tow during a storm much to the amazement of a few elderly persons whom I would think were locked out of the B&B they were staying at. Then a chap asked if I was a member of the Lowestoft club (err NO) they have not replied to my e-mails. nor HIS, he was at work and would love to have the time to sail.

So happy old me.

Richard,

[Tug-Kenny RIP]

She looks good Richard....One happy bunny, by the sound of it.   

Makes it all worth while . Well done


Cheers...Ken

[catengineman]

Thank you for the remarks and now all I await for is some GOOD WEATHER to put the tug back in the wet stuff

Toying with the idea to replace some of the equipment (Bigger motors - fire monitor pump anchor ball activated when anchored )

Though I should learn from the past

Richard,