anyone good with lathes?

Was called to a lathe this afternoon. Runs for a while and trips control circuit MCB which is 1a. Even without main motor running it will eventually trip. I have eliminated the coolant pump and 50v light transformer. Anyone had experience with sucha machine? its a harrison M400.

Yeah I have worked on suchlike 

on my first visit, the 2 pole MCB just visible between the 2 transformers had tripped. on re setting, there was smoke coming from the left hand transformer and again a trip. As the 50v lamp is no longer in use I disconnected the transformer. Operator reckoned it was only tripping after coolant pump was used so tried that, nope pump ok and still tripping. Even without starting the main motor the control supply trips. The heatsink unit in the centre of the panel must be for the DC brake on the spindle? 

What is the SY for?
There is also a lot of non compliant connections and wiring colours in there!

WTGrape is the brown in the Wago for?

Brown has no meaning in machinery standards.

If the MCB is only feeding the control tx, then it should only be going to the push buttons and relay coils, so it could be a relay coil going down after it has been energised for a while and warms up.

The SY feeds a flourescent LUV fitting above the lathe in place of the old 50v lamp. the wago is there because I disconnected the 50v transformer but still needed a 230v for the light fitting above. Its an old machine and no doubt lots of non compliant stuff in there. TBH my money is on the brake unit.

So the new fluorescent is on the 1amp MCB which trips?  Have you tried isolating that?

Geoff1946 said:

So the new fluorescent is on the 1amp MCB which trips?  Have you tried isolating that?

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It trips with or without the light on. 

turned out ( see what I did there?) to be the brake unit coil cooked. trouble is they are like gold dust so lathe might be finished if they cant get one!

revjames said:

turned out ( see what I did there?) to be the brake unit coil cooked. trouble is they are like gold dust so lathe might be finished if they cant get one!

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It can easily be sorted out even if the parts are not available 

Sidewinder said:

It can easily be sorted out even if the parts are not available 

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looking at a local rewinder repairing it.

Sidewinder said:

Yeah I have worked on suchlike 

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The power supply in the bottom centre of the panel is for the brake unit. Brake coil is cooked, no information available. Getting one made but they need to know voltage. PSU for brake is fed from a 73V winding on transformer which also provides 110v control voltage for rest of machine. I measured 68V dc on the output of the PSU with the brakes off (no coil attached) 68V seems a rather random rating never seen one like that before. I could have believed 48V. Machine is a Harrison M400 would really appreciate if you could advise on coil voltage. 

Thanks

I thought "mystery" coils could be rewound just using the weight and gauge of the removed copper. 

The concern I would have is whether there is an electronic regulator which has failed short circuit, so increasing the voltage onto the coil and killing it. 

Note I don't know anything about lathe controls as such;  just guessing and wondering what the semiconductors visible in your photo are for.

Any use?  Unfortunately no way of knowing what detail it contains without buying it.

https://www.machinemanuals.co.uk/manual.php?p=131

Geoff1946 said:

I thought "mystery" coils could be rewound just using the weight and gauge of the removed copper. 

The concern I would have is whether there is an electronic regulator which has failed short circuit, so increasing the voltage onto the coil and killing it. 

Note I don't know anything about lathe controls as such;  just guessing and wondering what the semiconductors visible in your photo are for.

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Thanks Geoff, not about to pay for a manual, I'm not SE so its up to the owner. I am thinking the semiconductors are some kind of voltage regulator. The power supply has AC on the input side all the time and only when the lathe is running does the DC side kick in to release the chuck. It would be useful to know what the coil voltage is supposed to be but no way of finding out short of finding another machine and measuring the voltage!

Have you tried the Lathes-UK website?

very helpful when I had an issue with my Denford Viceroy

kerching said:

Have you tried the Lathes-UK website?

very helpful when I had an issue with my Denford Viceroy

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Thanks I'll check it out

Another option is to email a bloke called John Mills. He has a very interesting ( if you like that sort of thing ) website called 

Double Boost. I'm pretty sure he has a Harrison but don't know which model it is

his email address is at the top of the page

Managed to find a free download of the manual. Not a lot of help in terms of voltage rating of coil etc. I did find out that the PSU is not working correctly either. So need PSU and coil.

Just scrap it and fit a DC injection unit if the customer is intent on having a brake.

Would need details on the PSU to make further comments.

Not sure the DC injection braking would work properly on this machine. The motor starts as soon as you turn the machine on. the internal clutch then starts the chuck rotating. The DC would only kick in when the motor stopped. The brake needs to be on every time the chuck stops. there is also a brake off button to release for manually moving the chuck during set ups etc. Currently looking at PSU, has a knackered main capacior and a burned resistor so although kicking out a steady 68v its not regulating it. Procedure is turning voltage up until brake releases then adding 6v. Once PSU is repaired I can consider the coil voltage which could be anything from 80 - 100v dc?