FP-CTR-500 outputs are failed?..

[Puho]

We are working with a tandem FP-1600/FP-CTR-500, and we have set the 4 outputs of the counter module in toggle mode, using 2 counter channel to generate square-waves. All 4 output LEDs are blinking OK, but there are no change in the voltages of physical outputs (position 13, 14, 15 y 16 of terminal block). 24 VDC/ground of power supply is connected to pin V and C, and each different output has a fixed voltage level of 0.65 to 0.85 Volts aprox., even after power-up or general reset. By this way, there are no loads connected to those outputs. Can anybody help me?.

[Aaron_G]

It sounds like the FP-CTR-500 may have had it's outputs damaged. You mentioned that nothing is currently hooked up to the module, was something hooked up in the past? You will need to contact an NI Application Engineer ( www.ni.com/ask ) to arrange for an RMA of the module. One possible scenario for a failure such as you describe is if you were driving highly inductive loads on the outputs and the back-EMF was of a sufficient voltage to overwhelm the built-in flyback circuitry and damaged the on-board voltage regulator.

[Puho]

Aaron, The scenario that you have mentioned sounds like possible, but we are talking about a new module and nobody in our laboratory has memory of some connection or testing with inductive load or somenthing like that.By anyway we'll contact to NI Application Engeneer...Is there any possibility of failure at terminal board level? There is only one think about we can be sure: the part, component (flyback circuitry?) failed is a "common part" to all 4 output circuits. Thank you Aaron, and best regards.

[Aaron_G]

Since all four channels are failed, it is most likely that the voltage regulator was damaged. The two most likely causes of this are back-emf from inductive loads, or an over-voltage on the supply voltage to the V & C terminals. I do not think that the terminal base is likely to be at fault, but you can try wiring the power supply to the Vsup and Com terminals instead of the V & C terminals (they get electrically connected inside the FP-CTR-500, not in the terminal base), if the module then works, I would recommend a visual inspection of the pins at the bottom of the module, and if avilable trying a different terminal base to narrow it down.

Regards,
Aaron

[Aaron_G]

Since all four channels are failed, it is most likely that the voltage regulator was damaged. The two most likely causes of this are back-emf from inductive loads, or an over-voltage on the supply voltage to the V & C terminals. I do not think that the terminal base is likely to be at fault, but you can try wiring the power supply to the Vsup and Com terminals instead of the V & C terminals (they get electrically connected inside the FP-CTR-500, not in the terminal base), if the module then works, I would recommend a visual inspection of the pins at the bottom of the module, and if available, trying a different terminal base to narrow it down.

Regards,
Aaron

[Puho]

We have wired a "jump" from V&C to Vsup and Common inputs of terminal block (screw 29 and 30 for example), and nothing occured. Remember that it is possible to measure 0.6 to 0.8 Volts fixed at the Vout screws...This eliminates a terminal block failure. We think, as you do it, the failure is in the output voltage driver or regulator. Can we replace any component to repare the module? We have an electronic maintenance department in plant, and we would do it...What's your opinion about?

[Aaron_G]

I really do not recommend the self-repair option.

I must point out that opening the module and making any changes to the circuit board voids all warranties on the device. Additionally, whereas I have a fairly good idea of what components need to be replaced, there is no guarentee that what we believe are the damaged components are actually the components at fault. Furthermore, for the components that I would suggest as the likeliest possible cause, your electronic maintenance department may or may not have industrial rated components available to replace the components and would not be set up to fully test the module after it is repaired. The test fixtures at National Instruments for the FP-CTR-500 are set up to test the cou
nt inputs, internal clocks, frequency rejection filters, outputs, gates, input bandwidth and output bandwith.
However, if you feel that your department is up to it, and are willing to void the warranty, then I can tell you which of the components (by the way, these are surface mount IC's) are the likeliest to have been damaged.

Regards,
Aaron

[Puho]

Obviously, we are not sure about our "full resources availability" to repaire the module. We just are trying to do somenthing in a short time, avoiding the process of sending the module to USA etc etc. We'll be glade if you send us your suggestions or a brief list of probably failed componentes to be checked. Unfortunately, there is no way to implement a frequency measure system using a FP-CTR-500 module, without their own outputs...Thank you and best regards,
Eduardo

[Aaron_G]

Eduardo,

The two components that are most likely to be failed in this instance are U17 and U20. U20 is a MOTOROLA MC79L05ABDR2 and U17 is an ON Semiconductor MC74ACT125DR2.

Since it sounds like you are outside of the U.S., let me provide a little more detail on international return/repair policies. National Instruments does have return centers in locations other than the U.S. Depending upon the product, a return to one of these centers may be repaired at the center, or a replacement from the center will be shipped and the return will be sent to the U.S. for repair. Once the unit has been repaired, it is returned to the center's pool for the next customer who needs a replacement.

Regards,
Aaron

[Puho]

OK Aaron, We'll use that information ASAP. One comment: our technicians have found 4 components near of output power transistor, with the label "f". That sounds like "fuse" and they are all "open" (measured with an ohmeter) and linked at one point to Vsup. Is there any possibility of solution, if we replace all 4 components by 1 A standard fuses?
Regards,
Eduardo