All the 0805's placing off position

[Zeus]

Hi all,

Been running a job with a variety of 0805's (using C0805 and R0805 CDF's) and also some ICs etc.

All the 0805s seem to be placed off to one side quite cosistently but the IC's etc seem to be put down well so I guess it cannot be the board fiducials.

I always force the ICs on to the fixed camera, mainly as if there is a repeat placement then the longer place time of using the fixed camera allows the vib feeder to recover.

Could the OTF camera be out of calibration or is there another reason?

David

[Mike]

First thing to try would be forcing fixed to see if it makes a difference.
Check that there's nothing stopping the mirror resting at its proper position - it sits on magnets, which may have attracted magnetic dirt etc. causing an offset 

[Zeus]

Thanks Mike,

Great ideas. I have already checked the mirror stops but I will do that again.

Early finish on Fridays so will keep investigating on Monday. I like the idea of forcing fixed to see if there is a change. I'll let you know how that goes.

Have a good weekend all
David

[Zeus]

Hi Mike and all.

I checked the mirror again but all seems good, no dirt stopping it reaching the stop as far as I can tell.

I changed the C0805 CDF to force fixed and placed another board. all the C's are placed bang on their pads but the R's and L's (yes a few 0805 inductors) are still off. They use their respective CDF's of R0805 and L0805.

So can I calibrate the OTF camera? On the Utilities menu there is a "Check Camera (Always)" option, which, when ticked, makes the machine check (and presumably calibrate) the fixed camera but that does nothing for the OTF camera. Can it be done via factory settings (scary screen)

If so, can you give me some simple procedure for this?

Many thanks
David

[Gopher]

It's right here, http://electricstuff.co.uk/forum/index.php?PHPSESSID=cebc0aa7d5f02977974cd3b0c6e236f8&topic=111.0 .
Procedure not as scary as it sounds, just make sure you follow the steps.

Out of curiosity, does the orientation of your 0805 parts affect the placement offset, is the offset the same across the whole pcb..?
If the OTF camera is out one would expect the pick positions to end up being incorrect, something you could spot by pausing placement and taking a peek.

[Mike]

There is a camera centre adjustment in the factory settings menu, but if this is something that was OK before and has started happening check for anything mechanical that might have moved first.
Also check the camera image in case there is anything obviously bad (e.g. failing capacitor distorting video) that might cause the imaging to be offset.
I'm sure there is someone here who has messed with camera settings that can give you more details on adjustment.
Make a backup of the rvdata.dat file before exploring the factory menu

[Gopher]

It adjusts itself using the image of the base of tool5  when you go through the routine, there is little to no input from the user.
Oh and the Check Camera setting does just that, check. If its out it tells you so and IIRC offers to cancel placement.

[Zeus]

Thanks all,

I have calibrated the OTF camera by "setting centre". I had to manually load a tool (No6) and I had to adjust the threashold away from 150 to get a good picture. Centre was a bit out so saved new setting. I then had to put threashold back to 150 to be able to run boards.

All 0805 now bang on pads so this is good news.


Thanks very much. I have only had this machine for the last 13 years and still I am learning!

David