Mitsubishi VRF 6608 fault

[Unreal]

Hi all

After some help with a 6608 fault that has been reoccurring. The system is two condensers twinned up with 12 indoors. The system view is:

51(52,53) 01,02,03,04,05,06,07,08,09,10,11,12

There are no RCs

The AG150 always shows the fault at address 11 but 09,10,11,12 are always affected. The problem has persisted since July last year. I have swapped the board on 11 to no avail. I have remade off all connections at every indoor. I have checked cable runs and are mostly ran in there own tray with pipework. Checked the shielding, all the obvious things really. I have even swapped the little addressing board which was the last thing I tried in September and it hasn't faulted since I did that so I thought that was the problem until today!!! When the fault was called in again.. So now I don't know what to do... Last time it was faulting every day or so. I removed address 11 from the system and it didn't fault for 2 weeks so assume that there is something wrong with address 11 unless someone can advise otherwise... Also cable runs aren't out of range and I'm getting 29-30vdc at every indoor.

[install monkey]

6608 loss of voltage- outdoor transformer?
or noise entering transmission line- mnet screened cable run parallel to power supplies to indoors/- m net entering indoors via different hole to the mains cable

[CONROD]

I presume that 52&53 are main and slave BC boxes? What fan coils are connected to BC box 53?

[Unreal]

I presume that 52&53 are main and slave BC boxes? What fan coils are connected to BC box 53?

Its master and slave condenser and bc box

[Neddy]

What size is the transmission cable ? The shield should be grounded in one place only. Where is it grounded? Is the shield sleeved at each indoor so it doesn't touch any metal?

[Unreal]

What size is the transmission cable ? The shield should be grounded in one place only. Where is it grounded? Is the shield sleeved at each indoor so it doesn't touch any metal?

1.0mm and like I said ive checked all the obvious things like shielding ect. More than once.. I found a bad connection at one unit where it had not been put in tye terminals correctley but that didnt change anything. Im really stuck with this one.. Im putting the laptop onit this morning just to see if the monitoring tool picks everything up but im sure it will.

[Neddy]

Any star connections or is everything daisy chained? Has the AG 150 a power pack? It might be worth running a new cables to the problem unit if you have good access. I had a bad cable between a BC box and outdoor once before.

[Unreal]

Any star connections or is everything daisy chained? Has the AG 150 a power pack? It might be worth running a new cables to the problem unit if you have good access. I had a bad cable between a BC box and outdoor once before.

There was a star connection which was connected at the ag150 for 5 splits but I disconnected these last year so the ag150 is now just controlling the VRF. The ag150 has a power pack yes. That was going to be my next route changing cables, but thought I'd ask on here to see if anyone could help!! It was in fault again this morning when I arrived. Well when I say fault it was just showing the fault on the icons in the monitoring section. It didn't register as an actual fault in the malfunction menu or log.

[Unreal]

Think I might have found the problem. Found the cable that comes from upstairs to downstairs had been crimped through in a riser cupboard. It had been tucked behind the pipes so it couldn't be seen. It was very poorly connected with nicks in it and then taped up!! Just shows. Check every inch of the cable runs

[Neddy]

Glad to hear you got it sorted.