7i52s replaced ic pin continuity question

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11 Nov 2020 14:01 #188997 by 3D-Master
hello,

i accidentally destroyed an ic and already have replaced it but when measuring continuity with my multimeter i saw that two pins have a connection (most likely on the board because i have ordered 2 ics and the other new one doesnt have a connection on these pins). There are 3 other same ics on the 7i52s and none of them has connection on these pins thats why im asking. Maybe there could be another component broken? Right now i dont want to connect the board to my 7i80 if i dont know if this is supposed to be or not.

i have uploaded a picture showing those pins.
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11 Nov 2020 14:50 #189003 by PCW
That's correct, U15 pins 7,8,15 are grounded
8 is chip ground, 7 and 15 are unused inputs
4,12,16 are 5V
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11 Nov 2020 14:54 #189004 by 3D-Master
Okay thank you!

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11 Nov 2020 19:15 #189024 by 3D-Master
so i got my little oscilloscope and measured TX0A and TX0B and it seems like i cannot get a step signal from COM0, COM1 and COM3. COM2, COM4 and COM5 have Step and Dir signals. I will try to resolder every pin of this ic, maybe one doesnt have enough contact or contact at all.

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11 Nov 2020 19:22 #189026 by 3D-Master
i have a different idea. It would be ideal to have schematics or even pcb files to see which pin i can measure continuity on the 7i52s (for example from U15 pin 1 to some pin on the 7i52s) but i dont think thats possible.

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11 Nov 2020 19:31 #189027 by PCW
Do you have the enable signal for TX0 set low? (pin 47 on the 50 pin connector) If not, the outputs will float.

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11 Nov 2020 19:45 #189029 by 3D-Master

Do you have the enable signal for TX0 set low? (pin 47 on the 50 pin connector) If not, the outputs will float.


i remember i had to add this but i dont remember what it did.

setp hm2_7i80.0.gpio.000.is_output true
setp hm2_7i80.0.gpio.023.is_output true

setp hm2_7i80.0.gpio.000.out false
setp hm2_7i80.0.gpio.023.out false

now i have step signal on COM0 as well but still COM1 and COM3 dont generate Step signals.

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11 Nov 2020 20:37 #189034 by PCW
COM 3 is buffered by U15 but COM1 is buffered by U6

Are the output levels OK? (close to 5V when high and close to 0 when low)

File Attachment:

File Name: 7i52schem.zip
File Size:234 KB
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11 Nov 2020 20:58 #189039 by 3D-Master

Are the output levels OK? (close to 5V when high and close to 0 when low)


always measured at pin TX0A/TX1A/TX2A/TX3A/TX4A/TX5A:

COM0: 0V/4.513V
COM1: 0.005V/4.495V
COM2: 0.007V/4.499V
COM3: 0.002V/4.514V
COM4: 0.005V/4.493V
COM5: 0.007V/4.500V

so basically around 0 and 4.5v

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11 Nov 2020 21:05 #189040 by PCW
Those look about right, assuming 5V VCC at the board is about 4.5V

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