Troubleshooting the OS discrete single axis board

[Konstantin]

Hello.
I ve managed to make one PCB with the toner transfer method and it apparently worked out, I have checked it against the image file and it seems to be ok.

After populating the board I hooked it up to an old PSU I have salvaged from an old Star matrix printer. The PSU has 25v and 5v outputs. Using the 25 on the X4 connector the board lighted the two leds but only LED1 was stable, LED2 was turning on then dimming to off and presented irregular behaviour. I tried removing the 74HC1, 4030N and 4013N and using new ones but things didnt change much. Probing with didnt match to the instruction file. BTW my Newark IC1 IC3 and IC8 are labeled as MM74HC14N, CD4030BE and CD4013BE respectively. I hope there are the right ones, and I remember I have contributed to the making of the Newark BOM, so if the IC's are the wrong ones please advice.

The 7805 voltage regulator run a bit hot with 25v.

I have hooked up the PSU again right now and the leds turned on and stayed that way until I tried to check the voltage between VGND and E5, wich was 4.9V, and when I touched the VGND with my multimeter lead the LED2 dimmed a bit. If I touch the 7805 heat sink with a finger the LED2 would go off.

The IC1, IC3 and IC8 do receive the same 4.9v on its 14th leg.

I probed the IC1 and it looks like as described in the instructions file, then I completed probing everithing as described and it worked out fine. The 7805 seems just a bit warm now and does not heat up as before. I dont know what was happening before. I feel much better now.

As for testing if the FETS are working properly I am not sure where to connect the 270 resistor. I hook it up to the X9-1 terminal but I am unsure where is 5 VCD logic will be, can I hook up the other lead of the 240 resistor to E5 ? That will be 5 VCD logic power?

Another question:
Apparently I cannot use my 5v output from the PSU because the 7805 delivers 3.8v or something near that, so I wil need to use the 25v and calculate the current limiting resistors. The place to hook the current limiting resistors will be to the center leads of the stepper motor? On the X4-1 and X4-2?

Last question.
When hooking up the discrete unipolar to the LPT ( I dont have a breakout board yet) should I hook up the STEP and DIR to the leads that are not on the JP1 connector ? In the instruction file the LPT is connected to the one column connector past the JP1. What is the JP1 for then?



I hope it will be easy to read.
Konstantin.

[Konstantin]

The place to hook the current limiting resistors will be to the center leads of the stepper motor? On the X4-1 and X4-2?

I believe I was thinking wrongly about wiring the stepper to the board. I should get center leads togheder and connect them to the positive side of X4 connector. Right?


Konstantin

[pminmo]

My answers are mixed with your questions:

After populating the board I hooked it up to an old PSU I have salvaged from an old Star matrix printer. The PSU has 25v and 5v outputs. Using the 25 on the X4 connector the board lighted the two leds but only LED1 was stable, LED2 was turning on then dimming to off and presented irregular behaviour.

LED2 not stable is fine. Basically unless you hook up the probe pin the driver input for LED2 is open circuit and noise can make it oscillate (dim, because it's switching on and off rapidly) or be high or low or random.

I tried removing the 74HC1, 4030N and 4013N and using new ones but things didnt change much. Probing with didnt match to the instruction file. BTW my Newark IC1 IC3 and IC8 are labeled as MM74HC14N, CD4030BE and CD4013BE respectively. I hope there are the right ones, and I remember I have contributed to the making of the Newark BOM, so if the IC's are the wrong ones please advice.

There correct

The 7805 voltage regulator run a bit hot with 25v. (since I can't determine a how hot a "bit hot" is, but my guess it's probably ok)

I have hooked up the PSU again right now and the leds turned on and stayed that way until I tried to check the voltage between VGND and E5, wich was 4.9V, and when I touched the VGND with my multimeter lead the LED2 dimmed a bit. If I touch the 7805 heat sink with a finger the LED2 would go off.

Don't worry about LED2 it's ok.

The IC1, IC3 and IC8 do receive the same 4.9v on its 14th leg.

YUP

I probed the IC1 and it looks like as described in the instructions file, then I completed probing everithing as described and it worked out fine. The 7805 seems just a bit warm now and does not heat up as before. I dont know what was happening before. I feel much better now.

As for testing if the FETS are working properly I am not sure where to connect the 270 resistor. I hook it up to the X9-1 terminal but I am unsure where is 5 VCD logic will be, can I hook up the other lead of the 240 resistor to E5 ?

YES.

That will be 5 VCD logic power? YES

Another question:
Apparently I cannot use my 5v output from the PSU because the 7805 delivers 3.8v or something near that, so I wil need to use the 25v and calculate the current limiting resistors. The place to hook the current limiting resistors will be to the center leads of the stepper motor? On the X4-1 and X4-2?

Yes you don't need the PSU +5 with the 7805 installed, use the same as your motor supply, sounds like 25V. Two resistors one side of each resistor to the power supply, the other side of the 1st resistor goes to the ct of one winding of the stepper, the other resistor goes to the other ct of the other winding.

Last question.
When hooking up the discrete unipolar to the LPT ( I dont have a breakout board yet) should I hook up the STEP and DIR to the leads that are not on the JP1 connector ?

Either is fine, it would depend if you ever intend to use JP1 to make a clean hookup with the BOB on the website.

In the instruction file the LPT is connected to the one column connector past the JP1. What is the JP1 for then?

JP1 is a header for an ribbon connector, look at the bottom of the webpage at my prototypes. The fabricate easy and make a clean wiring setup. When you have multiple axis, then it makes it easy to swap boards if you have a problem to troubleshoot the problem. If you look at the document for the BOB it has a better pictoral on motor wiring.http://webpages.charter.net/pminmo/simpleBOB.pdf

Phil

[pminmo]

Originally Posted by Konstantin I believe I was thinking wrongly about wiring the stepper to the board. I should get center leads togheder and connect them to the positive side of X4 connector. Right? Konstantin

http://webpages.charter.net/pminmo/simpleBOB.pdf

Page 3.

Phil