Help troubleshooting Mesa 7i78

Hello all,

I recently bought a Mesa 5i25 and 7i78 that I'm trying to get to work.

My problem is that what every I do i cant get the step-signal to show on the 7i78. I have checked and tripple checked the 5i25 firmware. I can measure the pulses going in to the 7i78, but on the output connectors there no sign of them.
I have also noticed that the board is getting hot around the 4 SMD ic's next to the DB25 connector, seems to be warmest at the second IC (ISL32274), hot as in "I bet this is CC'ed hot").

Anyone else had this problem?
Any tip to help me troubleshoot would be greatly appriciated. If nothing else to help me decide to try and return the board.

/Peter

If any chip on the 7I78 gets hot when:
1. System is just powered up (linuxcnc not running)
2. No load connected (green connectors unconnected)
that indicates a bad board

Hi PCW,

Thank you for that input. It get hot without anything but the DB25 connected. And i havent come so far as that i can get in to LinuxCNC yet.
I will try to return the board.
/Peter

I was the one that sold the card, and this is the first time that I have a client complaining.
For this reason I am writing on the forum so that is public about what happens on this case, as I also do not have sure.

Can you please, Peter, provide instructions about what my client and myself your reseller should do?

Sending this card (or any card) to USA is much more than the value of the card itself.

Thank you,
EuSurplus

I will replace the card (I can add it to your current shipment)

But I would like the card back even if its shipped via slow boat
Its pretty rare to get a failure on a simple card like the 7I78
( I dont think we have had any 7I78 failures before )

So I would like to try and figure out what went wrong

At the same time i bought the 7i78 I also bought a 7i84. Would it be possible that it is a cascading fault originating from the 7i84? As the 7i78 doesn't work I have no idea about the 7i84. The power LED's(CR2 & CR8) and red I/O fault (CR6) is light.

I mention this because I would hate to receive a replacement and have it break because the root cause were somewhere else, but again, i have no idea how tough these boards are.
Is there way that I can verify that the 7i84 is functional? Can i connect it to a DB25 to the 5i25 without a daughterboard in between?
A quick googling for the ISL32274 (what I believe is a hot chip on my board) datasheet tells me it is doing something with RS-422, which makes me a bit nervous =).

/Peter

There's really no way a even a bad 7I84 can harm a 7I78

The ISL32274 is a RS-422 driver used for the TX part of a RS-422 serial interface to a serial daughtercard
(a 7I84 in your case)

The 7I84 LEDS sound proper for a 7I84 that powered but has no host communications running

Thank you for putting my nerves at rest =) It's easy to become a bit nervous in these situations.
I'll only ship the 7i78 then.
Thanks!

/Peter

Hello again,

I have just installed the replacement board and everything worked right out of the box, YAY .

Thanks alot for the support! Happy days!

/Peter