Possible problem with PXI-1042 chassis supply voltages

[davidedalbosco]

I am currently facing a problem with an old PXI system.

A few days ago, I switched off a PXI-1042 chassis which contains a  PXI-8196 controller (still running Windows XP) and other modules.

Now, when I try to power it back on, I observe that the LED on the power button of the chassis stays green for a few seconds and then flashes red. From the manual, I read that this may be due to a faulty power supply tension.

The chassis power switch has an integrated LED. This LED indicates one
of three different conditions:
-If the power switch LED is steady green (not flashing), the chassis is
powered on and operating normally.
-If the power switch LED is flashing green, the air-intake temperature
has exceeded the chassis operating range.
-If the power switch LED is flashing red, the power supply outputs are
not within voltage regulation requirements.

At the same time on the controller, I see the led PWR OK flashing. Also this signal tells me that one of the power supply lines to the controller has a faulty value.

The POWER OK LED indicates the power status of the
controller. The LED will indicate one of the following states:
• ON steady—PXI and onboard power is on and within
regulation limits
• Blinking—One of the PXI or onboard supplies is operating
outside of the normal limits, or is not functioning.
• OFF—The power to the controller is off.

I faced the same problem (same LEDs flashing) in March 2023 and, on that occasion, I solved it by substituting the PXI-8196 controller with a spare unit.

At this point, I think there are three options:

1. The two controllers had the same failure independently
2. The PXI chassis power supply is faulty
3. The PXI chassis has a problem with the power supply that produces the failure of the controllers.

I performed another test: I took out the controller from the chassis and pushed the power button of the chassis. I observe the same behavior: the power button LED flashes red after a few seconds also without the controller.

What further tests can I do to convince myself that the problems lie for sure in the chassis and not in the controller?

Thank you in advance for the help.

Best wishes,

Davide

[Henrik_Volkers · Accepted solution]

On the back of the chassis is a monitoring subD 9 to check the voltages, the manual/spec show pinout and ranges

Also if available check with a scope .. and have a look at the ripple

  faulty capacitors are a common source of trouble...

[davidedalbosco]

Thank you so much for the answer. 

Actually I do not measure the 5V on the pin 2 of such connector. I measure 0V with the empty chassis and 2V when I insert just the controller into the chassis. All other pins have the correct voltage.

Would this indicate a problem in one of the supply lines of the PXI chassis?

Thanks again,

Davide

[Henrik_Volkers]

Yes, that is a strong hint for a power suplly problem.

Had something similar. Ordered a new PS .. quite easy to change them.

The PS is a buildup of multiple modules. you can try to replace the failing module... we changed the hole PS unit.

[kmarsh1084]

Was wondering if you can provide a link so I can buy a Power Supply for PXI-1042?

Thank you so much,

Kevin Marshall

[Henrik_Volkers]

At that time it was easy, just called NI for a quote.

If you call them today, they will tell you who to call...