PCA9865 Smoke and Burn Out

Projects General Guidance
1

Hi,
I've used these modules in the past to control multiple servos
with no issues.
In my new project, I'm using 3 modules to control 48 SG90 servos, 5v 10A power supply for the servos and Arduino ,for now, get's its power from PC USB.
After a couple of seconds, the modules smoke and burn out.
I have triple cheked the wiring, all correct, chaning the modules as instructed in the Adafruit lesson.

What's wrong ??
Power supply for the servos not sufficient ? I measured max 0.2 A each. I don't have space for a larger one but I can use 3 separate power supplies.
Would that save me from throwing away burnt modules ??
Does it have anything to do with servo limits ?

I'm lost. Appreciate your help.

2

Start by posting a schematic of your project showing how each of the components are connected and powered

3

adafruit_products_MultiBoard_bb-1024
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4

Pls note: board 2 and 3 are hooked to the 10A power supply through the screw pins

5

You need much much more current than this. We often recommend at least 1A per servo. This is because has a stall current that is drawn for a short period of time. You will not see this on a meter, you need to look at an oscilloscope.

6

That's what I thought. But please see the following link where he uses a 2A power supply for 48 servos. I'm using a 10A one.

7

In this post, with the same problem, they say these boards can not handle more than 4A.

8

Are you using the Adafruit boards or some clone?

This one?

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or one like this?

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9

What on the PCB smokes and burns out?

Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.

Can you post some images of your project?
So we can see your component layout.

Thanks.. Tom.... :smiley: :+1: :coffee: :australia:

10

Here's what I'm using, bought from Amazon. I think it's a clone

pca9865
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11

That one has the tiny MOSFET on it with an unknown current handling.
Notice the the Adafruit model has a big one than can easily handle 6A.

1 Like
12

Thank you Tom. There's really not much to post. Pls see post 3 photo that shows chaining the modules and post 6 as the project.

13

Ah, ok Jim but I've used them before with 36 servos and a 10A power supply. They are still running after 4 years with no issue. That's what drives me nuts.

14

The exact same ones!
There are some without the MOSFET

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This one does not have the MOSFET that burns out

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15

Instructables are well known for being rubbish written, in the main, by people with an inflated idea of their own knowledge.

Never try and learn something new from one of these pages unless you can spot the inevitable mistakes they contain.

16

Ok, thanks. But it was to show you a set up like mine so you'll have an idea

17

So which boards were you using before?

1 Like
18

He uses the one without the MOSFET

19

Jim, THANK YOU ! I really appreciate your patience and help.
I don' recall what I used before but you are right. The ones I'm using have mosfets. They look exactly the same but now I can see the difference.
I'll try to get the ones without mosfets. and report back.

20

just be careful. The ones without the MOSFETs will handle alot of current but may not be reverse polarity protected.

2 Likes