Pages: [1]   Go Down
Author Topic: Cooked PCB  (Read 664 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello!, I wonder if anyone can help to solve a problem I am having. I have been making a lot of mistakes which has resulted in frying a bunch of PCB's. Here's what I am trying to achieve:

I have stripped the parts from an Epson Scanner (Epson Perfection V30). On the main EPSON PCB there are four pins which connect to a bipolar stepper motor.
Using an Arduino UNO board, I would like to record the number of pulses which are sent to the stepper motor during the scanning process. Sounds simple enough?

The motor is quite small but I am concerned the pins are being sent a voltage which is too great for the Arduino board to handle. Also, how/what/where can I connect a ground?

Does anyone have any suggestions as to how I might go about this?
Logged

USA, FL
Offline Offline
God Member
*****
Karma: 14
Posts: 689
A life? Where can I download one of those?
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

It's hard to say how/what/where to connect anything if we don't know what the specs are on your motor.  Try finding a number on the motor and looking it up.  It should tell you how to hook it up.

Even if it's small, it could be a 12V, hell even a 24V motor...
Logged

//LiNK

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Its tricky, the exact specs I have requested from the manufacturer but they are based in TAIWAN so communication is difficult. They said they would dig out the data sheet for me. Otherwise, I have looked up the specs for a nearly identical model which states:

NEOCENE
2T42A223 - C
EM - 543
24V
5.8 Ω
Step Angle: 3.75°

I have a strong feeling its 24V. On this basis, how should I proceed?

Thanks for your time! Arthur
Logged

USA, FL
Offline Offline
God Member
*****
Karma: 14
Posts: 689
A life? Where can I download one of those?
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

For the connections, you need the datasheet.  Are the wires colored?

But for hooking it to an arduino, I would start with a 100K resistor between the Arduino and motor.  If you can't get any readings from the Arduino lower that value in increments.  How are you powering the motor?
Logged

//LiNK

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Aha OK without illustration its a little difficult to articulate. What I propose to do is to connect the 4 pins on the EPSON board to the arduino board, so I do not intend to connect the motor. The pulses are sent to those pins and I want to use Arduino to record the number of pulses. Does this make sense?
Logged

USA, FL
Offline Offline
God Member
*****
Karma: 14
Posts: 689
A life? Where can I download one of those?
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Aha OK without illustration its a little difficult to articulate. What I propose to do is to connect the 4 pins on the EPSON board to the arduino board, so I do not intend to connect the motor. The pulses are sent to those pins and I want to use Arduino to record the number of pulses. Does this make sense?

Yep.  I am looking at the Neocene website.  The motor you have has to be old because they don't even have the numbers on their list.  http://www.neocene.com.tw/epstm.html

It seems that you have to use the trail and error routine.  First is to find how to power the motor.  I would bet a dollar that it is 24V.

Hopefully they come through at finding the datasheet.

My question stills stands, are the wires coming off the motor colored?  On the board, are there any ICs with markings on them.  Post a pic of your setup, that would help quite a bit.
« Last Edit: April 11, 2013, 11:26:09 am by codlink » Logged

//LiNK

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Well there is an AC adapter which connects to the board. The supplied plug reads:

EPSON AC ADAPTER
MODEL: A392BS
INPUT: 220 - 240V
50-60HZ  0.3A  25W

OUTPUT:
13.5V --- 1.2A

There's lots of other stuff, IC's on the board. I will try and get hold of a camera to post a pic. Bear with me..

Thanks
Logged

BHZ, MG, Brazil
Offline Offline
Sr. Member
****
Karma: 10
Posts: 346
Android developer; Arduino enthusiast
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The AC-DC adapter is just a hint, since there might be step-up or step-down converters near the motor, specially because the motor is rated for 24V. They would have used a lower rating motor if it were to be run at only 13.5V, in order to save a couple bucks.

Another point is that you cannot connect the motor to the Arduino directly, or you may simply fry the arduino: the current drawn by a running motor is way higher than the 40mA the Arduino can provide, and even higher when the motor is starting.

Build yourself an H-Bridge using MOSFETs (both P and N) and a couple 2N2222 or get a L293D, which is an IC capable of running 2 DC motors or a single stepper with up to 600mA per channel (it has 2 channels). There are several shields out there than has all this ready for you, and one of the best out there is made by Ladyada (based on the L293D). Any shield based on the L298D will also suffice for you.





Logged

Learn to live: Live to learn.
Showing off my work: http://arduino.cc/forum/index.php/topic,126197.0.html

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

OK here are some annotated images http://arthurprior.com/index.php/miscellaneous/temp/
I have hosted them on my website as they are a little too large to post here.
This should give a good indication of what I'm up to. Any help greatly appreciated!

Logged

Offline Offline
Jr. Member
**
Karma: 4
Posts: 67
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I've never attempted anything like this, but it seems like you just need some kind of level converter (simple voltage divider maybe?) to get the voltage down to safe levels for the arduino.  Then you could use an interrupt on a digital pin to count the pulses.  Does that sort of motor controller require a certain load to function properly?
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 36
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

when you say "a certain load" does this answer your question:
Quote
Well there is an AC adapter which connects to the board. The supplied plug reads:

EPSON AC ADAPTER
MODEL: A392BS
INPUT: 220 - 240V
50-60HZ  0.3A  25W

OUTPUT:
13.5V --- 1.2A

So I think the motor controller runs off 13.5V, 1.2A?

I can get my head around stepping down the voltage before I connect it to the Arduino board, but where I am really stuck is whether or not I need to ground something? If so, I really cant imagine how this would work (see images: http://arthurprior.com/index.php/miscellaneous/temp/)

Thanks, Arthur
Logged

texas
Offline Offline
God Member
*****
Karma: 27
Posts: 862
old, but not dead
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Whatever voltage your stepper runs on has to be referenced against something that we will call ground.  You would connect your micro board ground to this ground.  You need to protect your input pins using something like this:

Logged

Experience, it's what you get when you were expecting something else.

Denmark
Offline Offline
God Member
*****
Karma: 15
Posts: 731
Please don't send questions as PM!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Why not just read the input pins of the dual H-Bridge on the Scanner PCB ?!?! There is absolutely no need to go this way to count the steps. Also, you know how many steps the motor has per turn, so you can calculate how many steps it takes to move the scanner from one end to another.

// Per.
Logged

Pages: [1]   Go Up
Jump to: