6509 High voltage problems

[HagayA]

I'm using 6509 to control a board of FETs which pass 27V to RF switches. At first all worked fine but now some of the pins in the I/O board are not working properly which means that at "High" i get 1.8V instead of 5V and at "Low" 0V . Apparently something in the awakening process cuased the problem.

[Lorne H.]

HagayA,

It sound like either your 6509 is damaged or your FETs are damaged.

A few things to try.
1.  Measure your digital lines with a voltmeter with nothing else attached to the device.  Then use test panels in MAX to set the digital lines as output and set to low and high.  If you are not reading the proper voltage then your board is damaged.

2.  Measure your digital outputs under load, I would recommend a 1kohm resistor.  If you are not getting a 5V high and a 0V low then your board is damaged.

3.  Test the functionality of your FETs without using your 6509.

4.  Do a selftest on your 6509 using MAX.

I would recommend calling 866-ASK-MYNI if you think the board is damaged.

Good Luck,
Lorne Hengst
Application Engineer
National Instruments