guess the wires

Brad93 · 2024-11-23T17:18:58+0000

Accidentally ripped the wires out of the tacho on the lathe.

Anyone familiar with these little units fitted to colchester/harrison machines

Bullet2012 · 2024-11-23T18:04:32+0000

Agroshield · 2024-11-23T18:39:00+0000

Is this the class of Colchester known as the VS models?

There is a manual with some sort of wiring diagram here:

https://www.scribd.com/document/654516497/Colchester-VS3250-Manual

It looks like it has a constant surface speed function, which involves a spindle speed sensor.

Possibly relevant pages are 44, 120 and most especially 122. p.122 is attached in case it helps.

Brad93 · 2024-11-23T18:56:02+0000

you're a diamond i think that may help!

Brad93 · 2024-11-23T18:56:42+0000

This is my one, other wise fell off without much movement, brittle from age i suppose

pressbrake1 · 2024-11-23T19:02:35+0000

How do you accidentally pull out the tacho :laughing:

Agroshield · 2024-11-23T19:02:42+0000

This is what I use to download from Scribd without registering:

Scribd.VDownloaders.com - Scribd.com downloader

Scribd.VDownloaders.com is a scribd.com downloader. Just input an url, we will response url with download link.

scribd.vdownloaders.com

Brad93 · 2024-11-23T19:22:23+0000

pressbrake1 said:
How do you accidentally pull out the tacho

to test e stop etc i had the front skirt off machine resting on box, walked past and brushed it with my knee.

Weakest link was the tach wires

Brad93 · 2024-11-23T19:23:30+0000

as seen here

Woody.v8 · 2024-11-23T19:31:20+0000

pressbrake1 said:
How do you accidentally pull out the tacho

Many of the lady's have fell foul to this ...... :scared:

Brad93 · 2024-11-23T21:33:25+0000

Right I've wired it up as per that drawing, which seems to correspond with the original wires that remained in situ.

No joy. Could be the unit is broken - a few people have mentioned having a problem with theirs on the Harrison VS330.

not done it yet · 2024-11-23T23:24:38+0000

I fitted a cheap chinese rpm read-out to my LJ Mk ll. I’ve never bothered to fit it onto my 5”. I just set at the approx correct speed and change it a bit if the surface finish isn’t good enough.

minimutly · 2024-11-24T00:43:11+0000

Best thing you can do is bin it. You're old enough and experienced enough to know what speed your at. And if you need more, or less.

Munkul · 2024-11-24T06:48:27+0000

minimutly said:
Best thing you can do is bin it. You're old enough and experienced enough to know what speed your at. And if you need more, or less.

it'll be for resale or repair or something knowing Brad. It wants to be "right".

Good news is that there's loads of cheap tacho units that will probably retro-fit in place and work just fine

Agroshield · 2024-11-24T07:51:38+0000

Brad93 said:
No joy. Could be the unit is broken

Do you have access to a sillyscope? That would tell you something about the input to the display and eliminate a dead spindle sensor.

In the manual above, there is a small section early on concerning cutting forces (p50-54) and also a bit on the safety aspects of using emery cloth on a lathe. Hence, it could be educational for anyone to read.

Brad93 · 2024-11-24T11:43:08+0000

Agroshield said:
Do you have access to a sillyscope? That would tell you something about the input to the display and eliminate a dead spindle sensor.

In the manual above, there is a small section early on concerning cutting forces (p50-54) and also a bit on the safety aspects of using emery cloth on a lathe. Hence, it could be educational for anyone to read.

I do not i'm afraid. However i feel it's likely to be an issue with the board rather than the sensor.
I think the board should come on and show 0000 even with no impulses coming in.

I'm keeping this little lathe it's going to be my precision machine. And when i move house i will probably not be able to take the TOS SN40 with me.

Brad93 · 2024-11-24T20:12:31+0000

So this is the current sensor, it has four wires. Red, Black, Green, White.

I think it must use the hall effect?

So DC up the red and black wires, then an induced voltage back down the green and white?

So what I could do with is a tacho capable of working from this existing sensor and ring, otherwise i've got a project and i don't need anymore projects.

m_c · 2024-11-24T20:30:24+0000

That's a pretty standard looking opto slot sensor.
It's most likely a photo transistor output, which is basically a switched output.

It's the kind of thing that could be bodged together using a basic microcontroller (or Arduino for easiness), but I'd probably see if somebody would give the existing module a look over, as it might be a fairly simple fault.

Munkul · 2024-11-24T20:33:50+0000

Being 4 wires it's probably not a hall sensor, more likely an optical sensor like m_c says. You'll know for sure if you take the sensor off. Hall sensors are one sided only.

Brad93 · 2024-11-24T20:37:01+0000

Yes through google i've come to realise it is likely some sort of photo interrupter, so well spotted sirs.

guess the wires

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