Here is a list of all the postings Les Jones 1 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Coping with voltage spikes|
Tim, You are going to have to provide more information on the "LED". A single actual LED (I am assuming it is a white LED as different coloured LEDs have different forward voltages.) would have a voltage of between 3.0 and 3.6 volts across it when driven with it's rated current. As you are calling it a 12 volt LED it must contain something to limit the current and it may consist of more than one actual LED. Until we know more about the "LED" we can't work out a possible reason for it failing.
|Thread: Death of a PSU|
The TNY264 is also a 7 pin low power switch mode regulator chip. It would be nice to know the part number of the chip on the board as the picture is not good enough to read it.
|Thread: Son`s mini lathe Clarke CL300|
This is a link to the manual for the CL300M which contains a wiring diagram but not a schematic of the board. (Which I have not been able to find.)
Am I correct that when you say " mixed up he has said they were the ones going to the emergency stop button the on and off." that you mean that he connected the output of the on/off switch to terminals K3 and K4 and that he connected the wires from the emergency stop switch to terminals L1 and L2. If so I don't see that this would cause the varistor to fail but it almost certainly would have damaged other components as he connected the mains to the low voltage part of the board. The varistor is probably connected directly across the mains input to the board (terminals L1 and L2) so I think this just failed or failed due to a high voltage transient on the mains.
Telling us which wires you connected to the wrong place may help to identify what damage you have done. Tell us the correct places the wires should connect to and where you actually connected them. can you also post a picture of the under side of the board near the burned area.
|Thread: Voltage feeding DRO "usb" digital scales?|
I have always supplied this type of scale with 1.5 volts when using home made remote displays. I think you will find the remote power connections connect directly to the internal battery contacts. The recommended silver oxide cells are rated at 1.55 volts when new. I have used an LM317L to provide the 1.5 volts supply from the 5 volt rail for the logic in my remote displays. Although USB connectors are used on these scales they DO NOT use USB protocol.
Edited By Les Jones 1 on 01/07/2020 09:10:19
Edited By Les Jones 1 on 01/07/2020 09:25:05
|Thread: 3 Phase in a Model Engineers workshop|
One important question asked by Andrew Johnston on 14/6/20 at 09:31 has not yet been answered, I was thinking of doing a simple test using 6 old fashioned mains filament lamps of 60 to 100 watts rating. (All the same rating) The idea is to have three series connected pairs of lamps with each pair connected across the three phases on the motor. (Making the connection at the output side of the thermal trip that feeds the spindle motor is probably the easiest.) The brightness of the lamps would give a reasonable idea of phase balance.(50 watt GU10 bulbs could also be used as they are easier to obtain. ) Another test that could be done is to disconnect the spindle motor at the output of the thermal trip and see if the contactor stays in and the coolant pump motor runs. I am inclined to agree that someone is required on site who is used to working on three phase motors and tracing exactly how the contactor maintainer contact and interlocks are wired.
Edited By Les Jones 1 on 14/06/2020 09:21:39
It sounds like the contactor is not holding in. Is the start button just a push button switch or is it the type were the button actually pushes the contactor closed ? (It is probably just a push button as I have only seen the type were the start button pushes the contactor closed on hobby machines.) The start button is normally wired in parallel with an auxiliary contact on the main contactor. WITH THE MACHINE ISOLATED FROM THE POWER connect your multimeter set to a low ohms range to the two connections on the start button (You will probably get a reading of a few tens or hundreds of ohms at there will be a path through other circuits.) Now manually push in the main contactor. The resistance reading should drop to almost zero ohms.If you can post the internal wiring diagram of the machine that would be a great help to suggest other possible causes of the problem. I first thought the problem might be inbalance between phases but the fact that the contactor pulls in while the start switch is held in disproves this theory.
|Thread: component tester|
I think you need to give more details than just "A component tester" For example model number, manufacturer, the magazine article you built it from. I think it is expecting a lot for it to be recognised from just a picture of the display.
Edited By Les Jones 1 on 08/06/2020 08:47:59
|Thread: Lathe motor|
A series wound motor is a bad choice for driving a lathe as it's speed varies a lot with load. They can be reversed (Both when supplied with AC or DC.) but you need to change the internal wiring of the motor to reverse the relationship of the current through the armature and the field winding. If you supply some details of the motor that is fitted that may be a better option than the Kenwood motor.
|Thread: Clark CL430 question on threads|
If it gives a change wheel setup for any thread you should be able to work out the leadscrew pitch. If you can't work it out post the information here ant there will be may members that can work out the leadscrew pitch.
|Thread: Oscilloscope kits - any recommendations?|
7 BCD Scales
Static state of clock line between frames Low
Clock in the data on the negative going edge.
28 bits in a frame of data
CPI 2540 (Metric)
LSB sent first
Static state of clock line between frames Low
21 bits in a frame of data
Data is sent as two groups of 24 bits.
Static state of clock signal between frames Low
The first group is the absolute position. It has some arbitary value at power on.
48 bits in a frame of data
HF (Bin 6 scales)
Static state of clock line between frames High
Clock in the data on the positive going edge.
The data output is the number displayed on the LCD display.
24 bits in a frame of data
CPI 2540 (Metric) (2000 in imperial mode.)
This is only half of it as it would not let me include it all in 1 post. The rest is in my next post.
|Thread: Motor Reverse|
Assuming that the black cable is the only other cable going to the motor as well as the blue cable to the capacitor then if the black cable is two conductors plus earth then the motor can't be reversed externally. If it is four conductors plus earth then it probably can be reversed externally. If you are prepared to take the motor apart then it may be possible to reverse it. This may involve digging into the end of the winding to get at the point where one end of the start winding is connected to one end of the run winding and to an external wire. the connection between these winding ends would have to be separated and brought out as two separate wires.
|Thread: Cutting down a linear glass DRO encoder|
Here are pictures of my plug.
Looking an the Farnell website I think I have identified the connector as a Binder 680 series connector.
They are quite expensive so I think I wil try to make some kind of connector to test the scale. When I know it is OK I will fit a different connector to the scale.
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