Help with mini lathe speed PCB (can you help ID my wiring?)

[HankMcSpank]

Ok, so this is in part self inflicted - I bought a lathe where the seller said the speed board was bust - what he didn't tell me was that the wiring doesn't appear to match up with the user manual - great. So now I have a lathe with wiring I don't trust.

I'm reasonably literate in electronics (used to be a Radar Engineer & have also fixed musical instruments - valve amps etc...so the prospect of the large voltages on a lathe board is not offputting).

That said, if I can't trust the wiring, and the user manual wiring doesn't seem to mate totally....I have little option but to throw out a plea of help to the internet community.

My main goal here is to identify which are the AC mains 'input' connectors to the board, the DC output connectors (as well as some of the peripheral switches...but these latter bits are nice to haves!)

Ok, so here we go...

Lathe type = Sieg C2
PCB = XMT-2325 (but I guess any lathe using thyristors as the output devices might help!)

There are two main 'blocks' of connectors...

block 1 has six connections

below each connector has some ID written on the PCB as follows

Connectors 1 & 2 ....."Gang" (possibly a ground connecton?)
Connector 3 ....."L1"
Connector 4 ..... "L2"
Connector 5 ......"A+"
Connector 6 ......"A-" (these two look suspiscously like they could be the DC outs to the motor)

Ok, now Connector Block 2

Connector 1 ......"K1"
Connector 2 ......"K2"
Connector 3 ...."P1"
Connector 4 ...."P2"
Connector 5 ...."P3" these P1-P3 seem to go to the speed control pot & match up with the wiring diagram, so these ones at least are solved!

Connector 6 ....."P4"
Connector 7 ....."P5"
Connector 8 ....."P8"

There is one little connector block with just two connections at the other end of the board (near the Output thyristors)...one connector is labelled K1 & the other K2.


Ok, now to some photos

First an overall photo to orientate everyone...



& now a bit closer to illustrate the connections I mentioned above...



this photo illustrates the rats nest that I don't trust (eg I can see the fuse wiring has been modded to allow an external in line fuse connector (presumably for a faster change of fuses!)



And finally a close up of the output devices...



BT151s are thyristors - I was expecting this lathe to have a PCB using MOSFETS ....oh dear!


Many thanks in anticipation for any light you can shine on this!

[neilw20]

I have a XMT-2325 in my hand, but it is different. Typical !
L1 & L2. Power in via external double pole power switch, with a fuse in series with the active side.

Gang looks like a ground for the noise filter I don't have.
If it is already connected to ground, then it should be OK.
If not, then check carefully.

A+, A- go to to the armature - via commutator brushes. Permanent magnet motor I believe. First and second poles of switch are cross coupled.
A+ and A- go to switch, criss-cross wires, armature to other 2 free switch connections.

The forward reverse switch is a four pole two position switch, with a center ALL off position.

First 2 poles used as above.

Third pole (common) connects to K0
K1 connects to NO parts of switch. When forward or reverse selected, K1 and K0 bridged, to enable output drive.

Speed pot connected across P1 and P3. Arm of pot to P2.
P3, P4 and P5 connected to the fourth switch.
P4 is common. P3 or P5 connect to P4 for forward or reverse.

As for the K3 and K4, I have no idea. Not on mine, but I suspect it could be jog mode, or a tacho input. Where do the wires go?

R33 is IR compensation. If set too high motor running speed will be unstable as load increases. When set correctly, speed regulation should be almost perfect.

R29 is for setting the current limit. Above a certain load, it will run constant current.

R3 is to set either the minimum or maximum speed. Probably minimum so that at the slow end of the speed pot, something is still happening.

All live circuitry. Careful nothing earths out, like the pot wiring or ANYTHING.

T1 is the gate drive burst pulses.
IC's on bottom are LM324 and LM358.

Thanks for the device numbers. Mine were ground off to stop the Chinese being coped by their neighbors. Rocket science at it best!.

Quite a nice drive, but needs a clean (normal) mains supply.
What I mean, here, is if running from a generator, you must filter the supply, and put at least a 10uF cap across the mains to prevent it self destructing. Spare flywheel energy needs somewhere to go, and many generators will not absorb reflected power. I acquired 2 blown up units while doing a repair for a mobile hose/hydraulic van, running from generator.

This is from my traced out pencil wiring, from his lathe. I new that piece of paper should be kept (for 5 years) ... memories...
Ask for anything I have missed.

[HankMcSpank]

Hello Neil,

Many thanks for the excellent responce - I've more than enough now to be getting started with!


rgds,
Rob

[blades]

Don't know if this will help any, but LMS has all kinds of wiring diagrams available.

http://www.littlemachineshop.com/ref...ngdiagrams.php