Help reverse engineer some parts

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slugsie
 
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Help reverse engineer some parts

Post by slugsie »

I recently got hold of an old surplus HP/Compaq Tape Library, and figured there would be some useful bits in it that I could salvage. After stripping it down I ended up with some ribbon cables (always handy), some transport rods, and a 4x20 LCD (very pleased with that).

I also recovered 3 motors with rotary encoders, and a barcode reader, and I need some help figuring out the interface to these.

The motors:

They are all virtually identical. They consist of a RS-540SH brushed motor (although each has a slightly different sub-code, but they're essentially the same), with a daughter board soldered onto the motor contacts at the rear of the can. The board doesn't have a lot of info on it, but there is a number - NCI-2 0022 94V-0 - split across 3 lines (no luck with finding a data sheet for that unfortunately). The connector has 6 wires, black, brown, red, orange, yellow, and green. A little bit of prodding around and I found that the motor is powered off the yellow/green wires, so that's a start. There are also two optical sensors set not quite 180degrees apart (presumably so it can sense motor direction as well as speed). It's these that I'd like help figuring out as I've never used a rotary encoder before, so no idea how to interface to them. If it's any help the encoders have a p/n H0A0971-N51. I'm guessing that each encoder is matched to a pair of wires on the connector, and probably give a pulse?

The barcode reader:

I have no idea where to begin with this one. It has the following part numbers: CPQ P/N 124928-001, DEC P/N 29-33949-01, BANNED/004RI HC-008001575. A Google on them finds plenty of sites listing them as parts, but no information or data sheets. The connector has 6 wires, purple, brown, blue, white, green, red. I'm guessing that there is two for power, and the rest are some form of serial communications, maybe with a clock/data pairs? Any idea how to begin to figure this out?

Just as a FYI, I'm pretty much an electronics novice, but I'm keen to try and learn. I've got a few Arduinos, a soldering iron, and a decent multimeter at my disposal.

Thanks in advance for any help.

waltr
 
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Re: Help reverse engineer some parts

Post by waltr »

The board these parts connected to is the other half of the clues to help you solve the mystery.
Optical sensors on the motor:
Are they photo-transistors (probably)? Use your DMM on the diode scale to determine which pin is the emitter or collector.
Also use the DMM, diode scale to determine the anode/cathode pins of the LEDs. Very likely the LEDs are IR so you need a known IR photo sensor or a camera without an IR blocking filter to determine if they 'light up'.
It is usually safe to assume the the LEDs max current is 20mA so keep current down to 5 - 10ma.

The reader will be much harder to figure out. First to to determine the power pins and what Voltage (the board it connected to is a help). The work out the other pins will probably require an O'scope since as you guessed it will have serial data. There may also be a detected pin and maybe a data framing pin.

Good luck and have fun.

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slugsie
 
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Re: Help reverse engineer some parts

Post by slugsie »

Thanks for the response.

Unfortunately probing the transistors in-situ is problematical as there is virtually no space between the board and the motor housing. I'll have to de-solder the board to do that.

Image
Image

However I looked more closely at the part number on the sensors and I misread them originally - the 0 and O are virtually identical. It's actually HOA0971, which lead to Digikey and a Datasheet:
http://media.digikey.com/pdf/Data%20She ... OA097X.pdf
So now I just have to figure out what that all means. ;)

As for the bar code reader, I kinda guessed that I'd need an oscilloscope. Unfortunately that's pretty much out of my reach at the moment, so I'll probably never figure that one out unless I get lucky.

waltr
 
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Re: Help reverse engineer some parts

Post by waltr »

Ok on finding the data sheet for the opto-interrupter.
Basically, its just an LED, always on, then a photo-diode with all the circuitry to output a TTL level digital signal.
Next step is to determine the motor board's supply Voltage.

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Renate
 
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Re: Help reverse engineer some parts

Post by Renate »

It's hard to see the value of those resistors there, but it looks like R2 is 150 ohm.
Is there only one resistor of that value? Then the two IR LEDs must be in series and running on about 5V 12 mA
If there is another 150 ohm resistor then the IR LEDs are separate and running on about 5V 22 mA supply.
Is R1 2.2k?
The photo transistor can run on anything, I'd just use 5 V,

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slugsie
 
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Re: Help reverse engineer some parts

Post by slugsie »

There is a matching pair of resistors on the other side. R1 is 330ohm, and R2 is 150ohm.

According to the motor data sheet it's designed for anything between 4.8v and 7.2/9.6 (depends on variant, can't tell with these ones). So a 5v supply should be OK for everything?

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Renate
 
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Re: Help reverse engineer some parts

Post by Renate »

Oh, then it's easy!

The two 330 ohms are connected together at one end.
These resistors are the pullups for the phototransistors, so the common point of the resistors is your +5V
Find the wire that goes to the +5V.
The "uncommon" end of the resistors is the two outputs of the two phototransistors.

The two 150 ohms are connected together at one end.
These resistors are the series resistors for the IR LEDs.
Is the common point of these two the same +5V connection as the phototransistors?
Find the wire that goes to this +5V (if it's different).

Use the diode setting on your DVM to find the return point for the LEDs.

All you have left to find is the ground to the phototransistors.

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epascual
 
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Re: Help reverse engineer some parts

Post by epascual »

Hi,

Got the exact same stuff, but I don't remember from which kind of device.

All resistors are connected to the same point at one end, which is Vcc. The GND is the 4th connection point from the left, when looking at the connector from the outside.

Regarding the supply voltage 5V should be ok, since supposing their Vf is 1.5V, it will give approx. 10mA direct current when limited by the 330 ohm resistor. But I have measured 60mA total consumption without any other connection that Vcc and GND (end even up to 80mA depending on the encoder position, and thus if the sensing PTs are passing or not. Any idea where the extra mA do come from ?

So to sum up, when considering the connector pins from left to right and holding the assembly with the encoder upside, the wiring is :
- (green) motor 1
- (yellow) motor 2
- (orange) Vcc (5V or 3.3V ?)
- (red) GND
- (brown) OUT 1
- (black) OUT 2

Colors are the wires ones (the cables attached to my parts are exactly like yours)

Hope this helps

Regards
Eric

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