Colchester Triumph 2000 – Bridge Rectifier

[danielcvParticipant @danielcv]

you have to click into the white space to oopen the wiring diagram

[peak4Participant @peak4]

I don’t have one of these lathes, so am not in a position to check anything.
For what it’s worth Tony’s site does provide some explanation of how the brake works, but it seemed to vary with both time, and the manufacturer of the clutch pack.
A couple of paragraphs each side of the photo of the green lathe
https://www.lathes.co.uk/colchester/page9.html

The manual which seems easily available from Internet Archive doesn’t seem to cover models with an electronic/electrical brake.
https://ia600904.us.archive.org/34/items/lathe-manuals/Colchester%20Triumph%202000%20tour.pdf

Bill

[Pete RimmerParticipant @peterimmer30576]

https://www.lathes.co.uk/

Make sure you ask him if he has a manual with that EP495 wiring diagram. I found one with 12 diagrams from EP410 to EP472 but none show any braking components or indeed any DC circuits.

[danielcvParticipant @danielcv]

I think the question of the brake could be clarified here – this button on this lathe, does activate or deactivate the brake:

[danielcvParticipant @danielcv]

And here is the diagram where you can see that button as the STOP switch

[Pete RimmerParticipant @peterimmer30576]

That seems to indicate that when activated it holds the brake off and though it might simply be a handy pictograph the image implies a physical brake.

[Julie AnnParticipant @julieann]

The schematics posted by the OP come in two flavours. Both 3-phase power in, but one with a neutral line and one without. For the lathe in question it would be useful to know which variant. How many wires enter the control box from the incoming mains? Mostly likely four wires for no neutral and five wires if the neutral is present.

Given that the DC brake circuit has an input of 220VAC I’d hazard a guess that the lathe has a neutral connection.

Julie

[peter1972Participant @peter1972]

There is a wiring diagram here on PDF page 154 (document page E3-i):

http://vintagemachinery.org/pubs/182/6092.pdf

There is a diode bridge rectifier at bottom right. I looks like there may be a resistor and capacitor also within that item.

Has it been tested with a multimeter?

[Mark EasingwoodParticipant @markeasingwood33578]

Firstly I know next to nothing about electronics/machine controls.

The following is what I understand to be the case, through my own experience!

I own/use woodworking machinery, some of which are equiped with brakes, some work by injecting DC into the motor windings, they make a buzzing noise when operating.

Some work using an electro magnetic operated friction brake, these are DC powered and are “always on”, unless the start button is activated, or the brake release switch is used. The brake unit is on the fan end of the motor, the solid state rectifier is pushed into the back of the motor terminal box. There is no neutral supply to the machine, the 220v is provided by an “auto transformer”.

The brake unit can fail, the rectifier can fail, or the gap between the friction material may require adjustment, or the friction material may have worn out.

An example of a brake unit can be seen here on EBAY.

[SillyOldDufferModerator @sillyoldduffer]

The Tony Pete refers to is at lathes.co.uk.    Wonderful source of information and he sells manuals and stuff.

Unfortunately the circuit diagrams have been compressed by the internet and most of the text is unreadable.  Can you post the bottom page only, which might solve the problem. or zoom in on the area ringed in red?

 

No sign of a rectifier, but the circuit inside the ring appears to show two single pole relays, purpose unknown because I can’t read the text.  Relays might well be marked 1,2 for the 220vac coil and 3,4 for the switch contact.    If necessary draw the ringed area by hand?

I’d wait to see what others make of the circuit diagram and other information.   But, leaping ahead, if the broken part is a relay, it explains why no heat-sink, and why the part doesn’t look like a typical rectifier. (Though it might be.)

If we become confident it is a relay then a resistance test with a multimeter should show a highish resistance, say 15000 ohms, across the coil (1&2) and an open circuit between 3 and 4.  Also open circuit between 1 and 3 & 4 and 2 and 3 and 4. These tests are safe.

If the safe tests are all good, relay operation can be tested.   DANGEROUS so don’t risk it unless the tester is competent.   I’d wire everything up securely on a bench and apply fused power via a switch to make sure I don’t get electrocuted or burn the house down.    Anyway, applying 220vac to the coil (1&2) should cause a slight audible click and a multimeter between 3 and 4 should go from open circuit to zero ohms.

Good news:  relays and rectifiers of the size pictured are both common as muck and inexpensive.  Relay more expensive, about £10.  The problem is identifying what the thing is.

Bad news: might be difficult to find an exact swap making it necessary to adapt one.  How to do that is the next issue.

Be warned, I’m armchair engineering here.  Never been inside a Colchester, and might be joining the dots wrongly, especially as this one is mysterious.   Wait for those who know the actual lathe to comment.

Dave

[Pete RimmerParticipant @peterimmer30576]

Ok so thanks to the manual found by peter1972 above (which thankfully has searchable text) the brake appears to be an electromagnet operating against a spring-loaded brake caliper on a mechanical disk brake.

What’s concerning is that it’s said that the brake should be automatically applied when the machine is powered off yet Daniel says that the spindle turns freely. I would suggest following the service procedure on the braking system on page 42 of the PDF and verify that the mechanicals are in good order. It may be that there’s nothing wrong with that diode and it’s simply a matter of the braking system required an overhaul.

At least we now know that the recifier simply supplies DC current to the brake electromagnet.

[danielcvParticipant @danielcv]

well, taking the Diagram Mark brought, it shows the rectifier, see picture below, at the bottom right.
The other thing is, that the friend told me that: When the part is not connected, the lathe works and turns freely, no brake. When he connects the part, the circuit braker pops.

[Julie AnnParticipant @julieann]

The above diagram does not seem to reflect the lathe in question. First, there is no incoming neutral line and second, the control voltage, including the brake circuit, is shown as 110VAC with one side connected to the protective earth. This is a common arrangement, at least on the 3-phase machines I have in the UK. None of them have an incoming neutral line.

Until we have a definitive answer as to what configuration the incoming supply is, and what the control voltage is, everything else is speculation.

Julie

[MacolmParticipant @macolm]

It is possible that while the rectifier (if that it be) is rated at 220V, it is actually used on 110V. I failed to work out conclusively after a quick scan whether the brake needs to be energised to hold it ON, or to hold it OFF.

For faultfinding when short circuits may be present, connecting a filament lamp (say 100W) in series with the supply can make it easier to see where the currents are going, though of course do not expect it to work correctly like that.

[Robert Atkinson 2Participant @robertatkinson2]

OK So it looks like we have a lathe with a DC electromagnetic brake, a circuit that may not be exact (The resistor R1 and bridge rectifier VC1 do not seem to appear anywhere else in the manual) An item that is assumed to be a bridge rectifier and finally confirmation that removing the rectifier removes a trip fault.

So will the lathe run with the one of the “rectifier” AC leads disconnected (insulate the lead)? Obviously there will be no brake.

If it runs with it diconnected we then have some tests to do. Where in Africa is the lathe? I’ve spent some time in West Africa and their enginerring approach is “different”. Do they have a multimeter?
We need to find out if the bridge is shorted or / and the brake coil is damaned or there is another lault like a short to ground.

Robert.

[danielcvParticipant @danielcv]

The machine is in Cape Verde. The friend said he tested the rectifier with a multimeter and it is damaged.
At this point I have no further doubt if it is a rectifier or not. I think I will buy a compatible one and send it so they can test it

[Grizzly bearParticipant @grizzlybear]

Hi,

Hopefully, a better image.https://www.mig-welding.co.uk/forum/threads/colchester-triumph-2000.144405/

[Robert Atkinson 2Participant @robertatkinson2]

OK,
THe current rating is nothng like 35A. More like 2.5A  I’d go for one of these:
https://www.ebay.co.uk/itm/192234475778?

https://www.ebay.co.uk/itm/284302424450?

4A 600V SIL

With a choc-block terminal strip attached. Screw hole makes for easy mounting.

Robert.

[danielcv]

On danielcv Said:

At this point I have no further doubt if it is a rectifier or not.

It seems certain there is a rectifier under that black cover but if there is also a resistor, it would probably be important.

[Bob WorsleyParticipant @bobworsley31976]

If the spindle rotates then it is a DC injection brake. Somewhere they is a transformer to provide the low voltage fed tp the rectifier, something about 30V or so. If the spindle motor is 4kW then need a transformer about 6″ cube or so, but if an electronic brake then just a small DIN rail unit.

Just re-read the thread, what is the problem? What isn’t working? Seem to have assumed it is a brake?

 

[danielcvParticipant @danielcv]

The brake is not working anymore and if the assumed rectifier is connected, the circuit braker pops when switching power on. When not connected the machine works, but doesn´t brake.

I have now ordered the 35A rectifier and will send it to Africa. After some time I will post here how it went !

Thank you all for the great help !

[Mark EasingwoodParticipant @markeasingwood33578]

As Wingo and I said earlier, these DC brake units, if that is what it is, are “locked on” without any power to release them. So the spindle shouldn’t turn freely by hand, nor should the lathe motor start without the brake being energized either by activating the brake release button, or activating the the spindle motor contactor.

Therefore if the lathe is still able to run, or the spindle to be rotated freely by hand, then that might indicate a broken/worn out/badly adjusted brake unit, rather than just the rectifier, (or it could be both items). Or some other unrelated problem may be the cause of the tripping out.

[danielcvParticipant @danielcv]

It seems to me after all these analysis that, on this Colchester Triumph 200 (EP495) there is no fail-safe motor brake.
With power off, the spindle turns freely by hand, which rules out a spring-applied brake.

The rectifier in question supplies DC for the control / plugging (counter-current) braking circuit, not a brake-release coil.
When the rectifier is installed, it causes an immediate circuit braker pop; when removed, the lathe runs normally but without electrical braking. This strongly indicates an internal short in the rectifier, not a seized or misadjusted brake.

So the behaviour matches a faulty rectifier in the DC control/braking circuit, rather than a locked-on mechanical brake.

[Bob Worsley]

On Bob Worsley Said:

If the spindle rotates then it is a DC injection brake. Somewhere they is a transformer to provide the low voltage fed tp the rectifier, something about 30V or so. If the spindle motor is 4kW then need a transformer about 6″ cube or so, but if an electronic brake then just a small DIN rail unit.

Just re-read the thread, what is the problem? What isn’t working? Seem to have assumed it is a brake?

 

I’t not a DC injection brake, it is an electromagnetic device operating a friction brake. No transformer just a rectifier and series resistor. The series resistor is a separate component.

The KBPC3510 (35A 1000V) rectifier is overkill but will work.

Robert.

[danielcv]

<li class=”bsp-quote-title”>On danielcv Said:

It seems to me after all these analysis that, on this Colchester Triumph 200 (EP495) there is no fail-safe motor brake.
With power off, the spindle turns freely by hand, which rules out a spring-applied brake.

The rectifier in question supplies DC for the control / plugging (counter-current) braking circuit, not a brake-release coil.
When the rectifier is installed, it causes an immediate circuit braker pop; when removed, the lathe runs normally but without electrical braking. This strongly indicates an internal short in the rectifier, not a seized or misadjusted brake.

So the behaviour matches a faulty rectifier in the DC control/braking circuit, rather than a locked-on mechanical brake.

It might indicate a fault in anything downstream of the regulator.  With power off and before the fault developed could thd spindle be turned by hand. It would be unusual for 2 faults to develop at exactly the same time. If thd motor has a friction brake it will be pretty obvious just looking at it. Can you get a picture of the motor

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