SignalTraffic Forums

by **LarryC39** on Fri Jul 19, 2013 11:55 am

So the other day on one of our modern intersections the lights were in flash mode. Here's what's odd though. The green was still on while the amber was flashing. Time of day was normal operations so this wouldn't normally be in flash mode. I assume the monitor tripped but why the stuck green?

(around 15 & Mound for the locals)

by **notMUTCDcompliant** on Fri Jul 19, 2013 12:01 pm

Sounds like the mercury relay failed to drop out the heads, so controller was still running (or in stop time) and the watchdog kicked into hardware flash

by **LarryC39** on Fri Jul 19, 2013 12:48 pm

NEMA noob here. what does the mercury relay do?

by **coyttl** on Fri Jul 19, 2013 12:51 pm

LarryC39 wrote:NEMA noob here. what does the mercury relay do?

Cuts 120v to the Load Switches.

The flasher relays switch signal outputs between the load switches, and the flasher module. (Which is connected to hot 120v, not handled via mercury relay.

So if the mercury relay doesn't drop, but the flasher relays do, the output terminals would be powered by both the flasher module and the load switches. (Hence, the dual indication.) :)

by **SignalLab** on Fri Jul 19, 2013 3:43 pm

fire it back up and using the handle of a screwdriver, tap the relay a few times and it should drop so you can reset the monitor.

by **LarryC39** on Fri Jul 19, 2013 5:35 pm

SignalLab wrote:fire it back up and using the handle of a screwdriver, tap the relay a few times and it should drop so you can reset the monitor.

Traffic jam wasn't that bad...

Thanks Mike. I thought maybe a Triac was blown...I thought conflict monitors turned off the controller as well. seems like a bit of a design bug.

by **2070** on Fri Jul 19, 2013 6:27 pm

LarryC39 wrote:...I thought conflict monitors turned off the controller as well. seems like a bit of a design bug.

Only add "Stop Time"....

So you can what the switch packs are lit as at the time of the problem........

by **coyttl** on Fri Jul 19, 2013 7:39 pm

LarryC39 wrote:
SignalLab wrote:fire it back up and using the handle of a screwdriver, tap the relay a few times and it should drop so you can reset the monitor.

Traffic jam wasn't that bad...

Thanks Mike. I thought maybe a Triac was blown...I thought conflict monitors turned off the controller as well. seems like a bit of a design bug.

What Phil said -
The CMU/MMU will apply Stop time to the controller, to aid the technician in troubleshooting - so the tech could open the door, look at the controller screen, and see what it was doing the moment the MMU/CMU tripped.

by **LarryC39** on Fri Jul 19, 2013 10:53 pm

Aaaand on the way home tonight (big storm) we had one SB at 16 Mile trip. This time main street was stuck in red with an amber flash. (Presumably the arterial was stuck in amber or green with a red flash.)

by **2070** on Sat Jul 20, 2013 6:11 am

LarryC39 wrote:Aaaand on the way home tonight (big storm) we had one SB at 16 Mile trip. This time main street was stuck in red with an amber flash. (Presumably the arterial was stuck in amber or green with a red flash.)

Does Nick know what type of "Controller" is in it.

And is it one that has the cabinet "Piggy-Backed" to another???

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