Repairing PCI-6025E analogue inputs

[marko-cosic]

Hello,

I have an old NI PCI-6025E that pasees all the self diagnostic tests (DAQ Diagnostic Utility) and will self-calibrate, but actually doesn't work in practice:

Specifically:

-digital I/O works ok. Most of it anyhow... (line 0.0 is stuck high for some reason)

-analogue output doesn't work at all

One outputs ~4.4V continuously

One outputs 0V continuously

(regardless of what you do in NI MAX)

-analogue inputs don't work

ai0, ai1, ai2, ai3, ai4, ai5, ai6, and ai7 all "float" towards the 10V rail

ai8, ai9, ai10, ai11, ai12, ai13, ai14, and ai15 all "float" towards the -10V rail

(with the inputs tied to AI GND or +5V externally when viewed in NI MAX)

It's an old board that's new to me. I think somebody has fried the analogue input/output stages. I'd like it fixed for some little projects here but am assuming that an official fix on such an old board will be prohibitively (>$100) expensive.

Looking at the block diagram of the device on pp20 here:

http://physics.ucsd.edu/neurophysics/Manuals/National%20Instruments/6024E_6024E_6025E%20DAQ%20User%2...

One way that this particular could pass a self-test but failed to work (on the analogue inputs) is if the Analogue Input Muxes are frazzled, right? Are these the MAX337s on the board? (U14 being the one connected to resistor arrays that I assume takes all the inputs. Are there any other failures that could cause the self-test to pass ok, but the analogue inputs not to work? 

On the analogue output side the two LTC7545s are the DACs. Presumably these are ok but some buffer stage has failed if the self-test is passed ok but the outputs don't work? Is there any common point of failure to all of the above?

If I can have the analogue input working again that'll largely "do" for me. Any advice appreciated!

Cheers,

-- 

Marko

[chiara.a]

Hi, 

I'm Chiara, an Applications Engineer with NI.  I've been doing some research on this issue for you; it does sound as though the card might perhaps be broken, particularly if you think that someone might have overloaded the inputs in the past.  I noticed when researching that you have also asked about this issue on the cammakespace google group and that some people have offered suggestions about bypassing the Analogue Input Mux which you are trying; do let me know if you manage to find out the problem, and I can have a look at any possibility and the costs of repairs with us if it does turn out to be broken.

Regards, 

Chiara

[marko-cosic]

Thanks Chiara,

There are also some ADG509AKR multiplexers on the board (U5, and U8) and it isn't obvious which of these or the MAX337s (U4 and U14) are the input stage. I'm leaning towards U14 but don't want to touch the (working) downstream muxes for obvious reasons!

I don't suppose youd have access to a schematic for the card, would you? Enough to identify whether U5, U8, U4, or U14 are the first muxes connected to the analogue inputs.

Thanks,

-- 

Marko

[chiara.a]

Hi Marko,

I'm afraid I don't have access to the schematics myself - I think that may be the sort of thing that R&D keep to themselves for reasons of intellectual property.  Could you give me the serial number on your card?  I may be able to find more information on the specific parts which went in to it in that way, though as I say I suspect that it probably won't be much help in determining exactly which part does what.  

I can look in to the cost of repairs for you if you wish, but as the card is out of warranty there is a strong likelihood that costs may be rather high, so you may wish to consider investing in one of our newer devices such as the PCIe-6321.  I can put you in touch with one of our sales team to discuss your requirements if that would help.

Regards,

Chiara

[ls_guy]

Did this ever get fixed?   Which chips do the analogue input buffering?  I currently have 3 cards that have "floating" damaged input channels.  I have changed the OKI  m82c55 on them- which has fixed other 6025es previously- but has not fixed these.  

NI support- surely it's not "proprietry information" to disclose this???

[MSoni]

I have the similar issue of PCI-6025E Analog Input reads maximum values of 10V for Ch9 to Ch16 and reads 0V for Ch1 to Ch8

And this happens when PCI-6025E, PCI-6024E and PCI-6602 3 PCI cards are installed

Another observation is when the PCI-6024E is taken out the readings on PCI-6025E are improved reading 0V for Ch1 to Ch16. For consistent readings, more of testing is required to be done. But yes the requirement is to use all 3 cards together.

Thanks

Manish