Serial Ports stops working oftenly

Sensiva

Hello,

I have a NI-3100 controller that was working perfectly fine for 5 years, but lately its serial ports often stop working. The TX led flashes when strings are sent, but strings aren't actually coming out of the port. I knew that by connecting each serial port to the computer (one port at a time) and checked what the computer actually receives from the controller, and found nothing is actually sent, although TX flashed. I tried that with both types of cables (straight and crossed). However turning off the controller for few hours (over night) might get it back to work, and sometimes not.

Have you guys seen similar issue? If yes, how did you get it solved?

Thanks in advance

regallion

Try checking your power supply.

Read this post for more info: http://www.amxforums.com/showthread.php?8862-Serial-ports-stopped-working-power-supply-issue!&p=61613#post61613

John Nagy

While it can't hurt to check the power supply first, this is a well known failure pattern, and AMX will repair it for $150 if you are a dealer.
The return-to-function for a short period after a power boot is typical too.

This is discussed thoroughly in a number of other threads here.
The forum's search tools are limited and frustrating, but they are worth a try before you post a question, you can sometimes find exactly the detail you need.

vining

If it is the known capacitor issue you can find the thread which describes how to replace it yourself for just $1.50 and a little time. It also save you several weeks awaiting the return of your processor if you don't have an adequate replacement processor on hand.

FYI, it requires good eyesight, a steady hand and use of a soldering iron so it you're defiecient in any of these items you'll need to send it in for repair.

Sensiva

I will check the power supply voltage, then see the capacitor mentioned in other posts.

I used the search tool. But all discussed issues were about few non-functioning serial ports, with no IR or Relays.

In my case IR and relays are working fine, and ALL serial ports are dead, so I thought it might be another case.

I will check and update the thread later.

Thanks alot.

vining

With the dreaded CAP problem everything works except TX most of the time and your RX will work if the device provides unsolicated responses.

John Nagy

Right, the caps that fail put the carrier voltage on RS232, nothing else. So everything works except serial transmit. And it works fine on RS-485, which does not use the voltage. And it often works again briefly upon a power-up, probably the pulse charges the failing caps enough to function for a bit. And some devices are more sensitive than others - my AVR still worked after the TV no longer did.

All this is indeed discussed in great detail in at least a half dozen threads here.
Including the photos of the board for the 2000/3000 series where the problem is becoming epidemic, but the caps are relatively easy to replace. On the 3100/2100 series, they are much smaller and with leads so small and close together on the board as to make it a very iffy proposition for the do-it-yourselfer.

A good search function would make this forum so very much more valuable. It doesn't look like we'll get one.

Joe Hebert

Pictures of the capacitor fix can be found here:

http://www.amxforums.com/showthread.php?7064-Problem-Controlling-Sierra-Pro-Switcher&p=48733#post48733

John Nagy

Joe Hebert wrote: »

Pictures of the capacitor fix can be found here:

http://www.amxforums.com/showthread.php?7064-Problem-Controlling-Sierra-Pro-Switcher&p=48733#post48733

To clarify, the pictures are of the 2000/3000 series which are different from the 2100/3100 of the original poster here.

Joe Hebert

220 221 whatever it takes...

Hedberg

RS232 signals consist of a negative idle voltage which is brought to zero IAW the protocol. So, if no signal is being transmitted, the negative idle voltage should be detected from pin 3 (transmit pin) to pin 5(ground) on the AMX serial, port db9. We have had a couple of these things fail but I've never had a meter with me to check, but if I understand the problem correctly, the voltage will be missing between pins 3 and 5 if the capacitor has failed. Normally this voltage needs to be about -5 volts or greater (more negative). It is present on a working AMX serial port -- about -9vdc or so, as I recall.

We almost never use RS-485 equipment, but we have a number of installations with Sony EVID cameras connected RS-422, one of which had one of the capacitor problems. RS-422 continues to work (and maybe RS-485 as well). This is interesting because RS-422 to RS-232 converters are available for about $9 + shipping or about $19 through Amazon, including shipping. I've never tried one of these, but it seems that if someone had a need for just a serial port or two, it might make sense to try to run RS-422 at the master and then through the converter to the device. No re-programming would be necessary as the AMX masters do RS-422 and RS-232 simultaneously. I can't figure out if these devices require power on pin 3 of the RS-232 connector to operate or not.

RS-232 to RS-485 converters are available through Amazon for less than $4 including shipping. I ordered one just because it's so cheap. Have to wait to see if I can figure out how to get RS-485 to work.

If anybody wanted to check if RS-422 was still working with the cap failure, it would be a pretty easy thing to wire up two AMX serial ports to each other via RS-422 and check what happens. I'm not sure about RS-485. The only system we used RS-485 on was about seven years ago. There were some Hitachi cameras controlled though Eagle pan and tilt controller and my recollection is that there was an extra piece of equipment to make the RS-485 work, but I don't recall for sure.

John Nagy

This was posted before, and might be accurate, but I have not tested it myself:
Measure the voltage between pin 3 and pin 5 on the port. If it's hovering around zero, you've got the dreaded failed capacitor issue. If you've got several volts the port's OK.