Retrofitting a 1986 Maho MH400E

or the test pins are not connected directly on Vcc, but a resistor is between
John

Good inputs. Thanks. I did tie the 12V ground from the PC PSU, which is powering the EXE, to the 5V ground from the little PSU which is powering the 7i77. However, I can recheck the ground to that specific channel.

There is no resistance between the test pins and the VCC pins.
Mark

You should check if something connected to that scale is getting hot with time, like the EXE ( as far as i remember reading here ) or check for power supply ripple, but since that occurs only on one axis i doubt that would be it.
Check also if there is any possibility to measure the voltage going to the LED on that scale ( or is it a bulb ???? ), LED tend to lower the intensity as soon as they start to heat.

Good inputs. Thanks.

I reterminated the two ribbon cables. Need to take a break and recheck all my work before I install them. Is there an industry standard way to terminate the unsed wire ends? I'd just neaten them up and bundle them with heatshrink.


Attached are the two pin maps I have so far.



Mark

How the relay board gets the information for the feed on the axis (Spindle and Feed stop)? How the 4A1 relays is controlled and where that relay is?
John

Good question. At this time, I have no clue. I figured I'd wire it up, and then see if I could figured out the logic, and see if I needed it and if I could integrate it into LinuxCNC.
Mark

RotarySMP wrote: I reterminated the two ribbon cables. Need to take a break and recheck all my work before I install them. Is there an industry standard way to terminate the unsed wire ends?

Too late now, but to connect screw terminals to box-headers I use M20 individual wire crimp headers.

uk.rs-online.com/web/p/pcb-connector-housings/6812874/ (ignore the picture, the link is to a 2x12 plug)

I don't think that they do them full-width for 50 pin headers, but you can fit them side-by side and/or glue them together.
You need crimps and a crimping tool, but one advantage is easy re-wiring.

I do have the crimping pliers from Engineer for them, and used them on my 3d printer, but figured the ribbon cables were already here so I'd reuse them.

Many of the pins are also connected to screw terminals on the PCB, so there are probably less than 20 sockets to populate if you went with your suggested connectors.
Mark

I have ordered Grade 10 balls from eBay for my ballscrew and this is what they send me.

Those look like slingshot grade balls...