Hohner Pao2179 Encoder

[Riggy]

Anyone recommend a supplier or repairer for Hohner shaft encoders?

 

[Sidewinder]

Yep, I would expect, but, would need more info on the device.

 

[Riggy]

Cheers Sidewinder. Model number is PAO2179/480 - fairly basic directional pulse generator by the looks of it. Has been on a machine stored outdoors over winter, power to it, no output. Is that sufficient? If not let me know.

 

[Sidewinder]

When you say no output, if it is a TTL 6 channel, A, B, 0 & Comp, then the pulses are very short!

You need to check it with a scope & 5V power supply really.

Can you post a pic as I cannot resolve the part number.

A replacement may be as cheap as a repair TBH, but I can't say at this stage.

 

[Riggy]

Sidewinder, apologies for the delay replying. Photos attached, hope these help you to help me!

Another photo

 

[Riggy]

Seems I can only upload one photo at a time - obviously my competence!

 

[Sidewinder]

Is the encoder off the machine, I am interested in the mounting arrangement also, as there are different types.

Another thing that would REALLY help is details on the machine and where it is from, as Hohner had different devices for different markets.

As well as OEM specific units.

The connecting plug looks like a Std TTL "Heidenhain" type unit?

Is it?

 

[Riggy]

Thanks for your patience, our broadband only really works in the mornings, so I'll try to load more pictures.

 

[Riggy]

Thanks for your patience, I can't seem to upload any more pictures (I can email them to you if you like?), so I'll try to describe the encoder and application.

It is TTL as you say, there are only four terminals used on the plug: A, B, and supply + & -. Input shaft is I guess 12mm, mounting is 3 x M6 holes around the input shaft, approx 40mm pcd. There is a "window" on the back end plate through which a row of LEDs can be seen (two light up on power up and stay on all the time, none of the others ever light)

The application is on the carriage head of a band mill, used to measure the position of the carriage (and therefore the tree trunk) relative to the saw blade. The control system which the signal goes into is a system designed specifically for this application, I guess 1980s vintage retrofitted to this machine, replacing a valve system. The "computer" is a self contained operator interface, mains and encoder in, with relay outputs to drive carriage backwards and forwards.

Current situation is that carriage (and encoder) been stored outside over winter, worked previously (though I didn't see it work). Customer has spare computer, swapped this, same outcome (i.e. measured value display doesn't change when encoder shaft turned). Shaft turns freely, LEDs on back of encoder don't change. Continuity of all four cores between encoder plug and computer input terminals checked and fine.

I don't have access to a scope (and as I haven't used one for the best part of 30 years, I'm not sure one would be much use!) but from the above I'm 90% sure it's the encoder - but I'm always open to other ideas.

 

[Sidewinder]

OK it does seem like the encoder.

It also seems like a bespoke unit.

You don't know the make of the bandmill do you?

The best thing to do is get it down to me.

I will PM you a shipping address, I can either get it fixed, or a replacement, even if we have to build a replacement encoder onto the same shaft & into the existing housing.

As an aside, are they using swaged & set or stellite tipped blades on the mill?

I would guess a 6 or 7" blade?

Oh, if you have machine drawings these would help also, as we can ensure that we get the pin out's right, to suit the machine in case they are not standard, it ensures that there are no mix ups!

Scans, pictures or photocopies are fine.

The supply voltage to the encoder is 5V d.c. Yes?

Also it is good encoder end, I would guess so as you have an LED showing, which I would guess is the power indicator.