DME - Distance Measuring Equipment

      Sir KDA-689 is use for showing information (distance) on both PFD 
KDA take data and convert it to ARINIC 429 and share it with IAPS( integrated avionics Processing system ) it contains various types of LRM ( Line Replacble module) like 1. Power ,FMC , IOC, CSU ,FGC) 
Aircraft Avionics from ROCKWELL Collins Pro line 21 and radio from GARMIN
 
VOR/ ILS. frequency Working fine only problem with DME

We also check system while KDA-689 connector unplug  but Same problem exists

is there any way to bypass the nose junction box PN333
 

I'm still trying to get the flow of this.

Is Nav Tuning from the Garmins or is there separate Nav Control Units?

If the Garmins are tuning, it looks like those tuning requests go to the DME Master Indicator (KDI-574) on pins 11, 12 and the J-Box on 70, 51. from there the J-Box feeds the request to the DME (KN-63)  on pins F, 6. The DME output goes back to the J-Box which feeds the Arinc Adapter (KDA-689) which outputs 429 data back to the GNS (I only see an output to the left unit).

If I'm correct, this still leads back to a tuning issue from the #2 (or right) GNS. I circled some wires to check on a previous post. The "RNAV REQUEST" signal from each Garmin looks to be the signal which tells the Master Indicator which side (GNS request)  to forward to the DME.

If those four wires (18, 19, 20, 22) check good from the #2 GNS..... the Master Indicator would be the most suspect unit.

Also, three of those wires are connected to each other via splices. To make sure one Garmin isn't loading them down, try each alone with the other GNS not in the system. In your case.... disconnect the #1 GNS to see if the #2 tunes and displays properly.

Make sure that common wire is good also....
  
     
 

Dear Sir
Yes nav tuning is from Garmin GNS 530 only
i think ARINC Adapter KDA-689 is only for Show information to Both PFD 
we also check wiring 18,19,20,22 of both GNS 530 found good
 
and these 3 splices behind of backshell of KDI-574 i also checked splices its in good condition
yes we dissconnect GNS1 and check with GNS 2 sometimes its work or sometimes not (intermitent condition)

when i  powered the aircraft on in morning for first 10 mintue DME working fine from both NAV selections 
but after that DME from NAV 1 stop working 
now we suspecting the GNS 530 and KDI 574 
maybe we will get GNS 530 and KDI 574 for testing in few  days.
 

If things are working fine for 10 minutes and then not..... it sure sounds like a component is heating up and then failing. I'b bet it is the indicator.