I think my integrated motor driver chip shorted.

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My train controller is a short circuit from + to -. The H-bridge, VNH5019A, seems to be a short. It was rated for 5 amps, the battery shuts down at 7 amps and there's a 5A fuse. I thought it would be ok...

 

Back to the frypan! Good thing I have another one.

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Perhaps its time to add a fan too!

Good luck with the repair.

 

Jim

 

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The tolerance on the Fuse might be a bit wider than you expect, and it therefore might have been able to draw a fair amount over 5 A before it blows.

The physical fuse, also, takes a while to overheat and blow, especially if the overage is just a bit over, (unlike the circuit suddenly drew 20 A).

 

JC

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Fried the new one on. Waiting for it to cool. I'll put a 3A fuse in as the loco draws just over 2 amps dragged to a stop with all 16 wheels spinning. It got the rods jammed and stalled the motors.

 

 

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This part has 50 different type of protection built in...you probably have some issue with your hook up..post your schematic.

 

These things are automotive rated and extremely rugged  AEC-Q100 qualified..

This package, specifically designed for harsh automotive environments offers improved thermal performance thanks to exposed die pads.

 

https://www.st.com/resource/en/datasheet/vnh5019a-e.pdf

 

By the way---are these  real parts?  I got some apparent Chinese ripoff clones of some self-protected fets  ($0.48 vs $3.00 each, in volume)...I was doing qual test & noticed the current limit didn't kick in..thought that was strange.... apparently the clones were just plain fets.

But at least they were extremely rugged ripoffs...I thought heating them would kick in the thermal limit...but while torching them with a soldering gun to about 400+ degrees they kept PWMing a 20-30 amp load at 20kHz  like it was a spring day.

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Thu. Aug 16, 2018 - 01:18 AM
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Normal fuses are not much good for protecting electronics.

Could it be that your H-bridge has some kind of fault and it does not switch properly, which causes it to heat up too much and eventually self destruct?

(Unlikely, It does have internal thermal safeguards etc.

 

Euhm, VNH5019A-E is rated for 30A continous.

https://www.st.com/resource/en/datasheet/vnh5019a-e.pdf

 

Those automotive rated chips should be pretty reliable if used properly.

It may be something like a bad GND connection, Oops, also covered.

* AEC-Q100 qualified
* ECOPACK ® : lead free and RoHS compliant
* Output current: 30 A
* 3 V CMOS compatible inputs
* Undervoltage and overvoltage shutdown
* High-side and low-side thermal shutdown
* Cross-conduction protection
* Current limitation
* Very low standby power consumption
* PWM operation up to 20 kHz
* Protection against:
* Loss of ground and loss of V CC
* Current sense output proportional to motor current
* Charge pump output for reverse polarity protection
* Output protected against short to ground and short to  Vcc

Maybe some fakes from China or a direct lightning strike?

Every chip also has a limit to the ESD discharge it can handle. Maybe add some MOV's or Transorbs?

 

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

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avrcandies wrote:

This part has 50 different type of protection built in...you probably have some issue with your hook up..post your schematic.

 

These things are automotive rated and extremely rugged  AEC-Q100 qualified..

This package, specifically designed for harsh automotive environments offers improved thermal performance thanks to exposed die pads.

 

https://www.st.com/resource/en/datasheet/vnh5019a-e.pdf

 

By the way---are these  real parts?  I got some apparent Chinese ripoff clones of some self-protected fets  ($0.48 vs $3.00 each, in volume)...I was doing qual test & noticed the current limit didn't kick in..thought that was strange.... apparently the clones were just plain fets.

But at least they were extremely rugged ripoffs...I thought heating them would kick in the thermal limit...but while torching them with a soldering gun to about 400+ degrees they kept PWMing a 20-30 amp load at 20kHz  like it was a spring day.

 

 

That's why I was surprised it shorted when the motor stalled.

 

They came from digikey a few years ago.

The largest known prime number: 282589933-1

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WHERE is your complete schematic?  In lieu of one, we'll assume the 200V you are applying to pins 8 & 21 is the problem wink

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Torby wrote:
My train controller is a short circuit from + to -. The H-bridge, VNH5019A, seems to be a short. It was rated for 5 amps, the battery shuts down at 7 amps and there's a 5A fuse. I thought it would be ok....

Were you pulse width modulating the H-bridge? If you were and might have tripped the thermal protection, for how long was the part driving the short?

- John

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My train controller is a short circuit from + to -. The H-bridge, VNH5019A, seems to be a short. It was rated for 5 amps, the battery shuts down at 7 amps and there's a 5A fuse. I thought it would be ok...

VNH5019A seems to be a short...... Is the bad train merely sitting there shorting out the part?  Did you drop a paper clip across the tracks somewhere?   What testing have you performed?  This may sound silly, but it is assumed you are using a DC supply & not just a transformer that is trying to supply AC.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Thu. Aug 16, 2018 - 11:10 PM
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If we were playing Monopoly would this be the "Short Line Railroad"?

Jim

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The schematic is in KiCad which I haven't installed on this yet-again different computer.

 

A wheel slipped on the axel and jammed the rods. Was driving less than a second.

 

Only 200v? Na, more like 15Kv cheeky Powered by a 14.8v lithium battery. I'll have it back together shortly. "Now, where's that fuse holder?"

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Image result for train wheel slipped on axle

Which axle was it?

 

 

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The schematic is in KiCad which I haven't installed on this yet-again different computer.

That's interesting, since I figured out the exact issue and solution, but it is on my other computer.

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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OK, train buffs, why does the middle wheel not have the raise rim to hold the train centered on the tracks?

 

JC

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DocJC wrote:
why does the middle wheel not have the raise rim to hold the train centered on the tracks?

Its a model, so the middle wheel is the actual driving wheel, these usually have a soft rubber rim to provide better traction.

This works better on models as they don't have the weight to provide the traction a real train would.

 

Jim

 

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DocJC wrote:
why does the middle wheel not have the raise rim to hold the train centered on the tracks?

No flange on the middle set of wheels also allows it follow tighter curves in the track than it could otherwise.

Letting the smoke out since 1978

 

 

 

 

Last Edited: Fri. Aug 17, 2018 - 10:34 PM
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Got it, thank you!

 

JC

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The loco is a 2-8-8-2. All wheels have flanges. It weighs 21 pounds and is 44 inches long.

 

Had a chance to work on it today. The chip is changed, but something else was wrong, so I went "fish guts" and pulled out all the manufacturer's circuitry. Almost finished. I have tomorrow afternoon off, so I should get it finished.

 

 

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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so I went "fish guts" and pulled out all the manufacturer's circuitry

Like what?  Isn't it just a motor & wheels, or is there some other stuff? 

 

I have tomorrow afternoon off, so I should get it finished.

Good, since we are waiting at the platform to be picked up. 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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From the size of the engine, I'd guess it is an engine of the Garden Railroad (G scale) size  http://grw.trains.com/news/product-reviews/2006/03/aristo-craft-2-8-8-2-mallet-locomotive .  From the description on that page, it may use Digital Command Control (DCC).  A brief description is given in the first couple paragraphs in https://www.nmra.org/beginners-guide-command-control-and-dcc .  I'm a bit surprised that both motors draw less than 5 amps when pulling a load.  Two of my old-fashion (i.e. DC to the motors) Half-O (HO) scale can motors take about 1.5 amps when pulling about 10 cars up a hill.

 

Alan

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Nope. Not a DCC loco. It's track power converted to R/C. You are correct, it's an Aristocraft Mallet.

 

There are PC boards and gillions of wires inside so you can switch it between different modes of operation.

 

 

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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The full text of this article is available to Garden Railways Magazine subscribers only.

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Its interesting to see how expansive some niches are.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Yes. We have a magazine.

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It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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I got KiCad installed on this computer. Haven't found a good way to show a kicad schematic other than PDF, so here's a PDF.

 

http://outsidetrains.com/mls18/E...

 

 

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It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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What are you talking about....WHERE is the part?   How do you expect any help?

 

My train controller is a short circuit from + to -. The H-bridge, VNH5019A, seems to be a short

 

 

Your 7803 is backwards ...Vin should be on the left!  But why run the micro at 3.3v then the other things are running at 5V?

Then get rid of 74HC04

The fet symbols should be much bigger than the solderpad symbols

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Sat. Sep 8, 2018 - 03:18 PM
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I thought all Xmega were limited to 3V3? Are the more recent E5 different in that regard then? Otherwise that is why he's using 3V3.
.
EDIT crikey phone keyboards are a pain to use!

Last Edited: Sat. Sep 8, 2018 - 03:29 PM
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 thought all Xmega were limited to 3V3?

Ah, yes---how sad.  Perhaps use a regular AVR mega

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Simple! The board behaves crazy because it's a "loco" board. devil

 

edit the 3V3 regulator should really be a low dropout type, don't know the brand of regulator you are using but the ST type shows 2V dropout voltage therefore the regulator isn't regulating.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

Last Edited: Sat. Sep 8, 2018 - 10:48 PM
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hehe

 

The silly motor driver won't see a "high" unless it's 4.5 volts. That's why the 74HC04 chip. Didn't notice that in the spec sheet before I bought them. Have new one in place and, at least it's not shorting. While heating the board to change the chip, the 47uF through-hole cap unsoldered, and I had trimmed the wires very short to get good contact between the board and the fry pan. "Rats. I'll have to put in another." Would you believe that's the only 47uF 35v cap I have on hand? Doesn't seem to work without the cap, which makes sense. It's a 10KHz system and there is a long wire from the battery.

 

In SMD regulators, the usual pinout is backwards from what you're used to. That tripped me up once, but I was able to rotate the part and solder it on anyhow. Since then, I check for that.

 

Hmm. The 5v comes from an external source. Perhaps I should check it. Been busy with other things again.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

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Ok. Having a little trouble here working on anything. The Colonel insists I spend all the time working on the pool. "Now get the plants out of the bogs." "Now move that big rock." "Now put the big rock back." The pool is beautiful, clear, all chemical levels are where they're supposed to be, but the only thing he thinks about is "got to work on the pool." https://www.youtube.com/watch?v=... Since that video was made, we got the fish out, emptied the pool, filled the pool...

 

Stole a few minutes away. Thought maybe the problem was the 5v was too low. Nope, 5.06. The logic inputs to the motor driver are all nice levels. The PWM pulses on /D2 and have nice 5v logic levels.

 

The /FS output is always low. Curious. Ok. The FS goes low on:

 

1. Undervoltage: 16.8v is right in the range. I measure 16.8 on all 3 of the power pins.

2. Overtemperature: Well, I'm outside in the low 90's (F). Can hold my finger on the part and doesn't feel warm.

3. Overcurrent: Everything is disconnected from the motor outputs. Ohm Meter shows continuity where there should be -- motor output pins to motor connector (which is disconnected from the motor) and not connected where they should not be like v+ or v- or adjacent pins or....

 

I don't have another of these chips. The one I took out is definitely a short between V+ and V-.

 

Dang, I thought I'd find of the problem while composing this. The "Diligent Analog Discovery II" you guys sent me is very useful.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead. 

Last Edited: Thu. Sep 20, 2018 - 07:54 PM
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re video ... laugh

The fish seem nonplussed.

 

"Dare to be naïve." - Buckminster Fuller

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The fish are happy back in the fish pond. Catching them was quite a task.

The largest known prime number: 282589933-1

It's easy to stop breaking the 10th commandment! Break the 8th instead.