Daikin unit blowing PCBs and breaker

[leegally1983]

Hi Guys

I would appreciate some help, i have a site with 3 x Daikin RXS60BVMB we recently replaced the Inverter board, main board,Power module, cond fan motor and diode bridge as the unit was faulty. Once the parts were replaced and turned back on you can here the the relays on the PCB start to initiate but then suddenly there is a spark and then the power module pops and then the breaker trips out. Its does this every time its turned on, we tried replacing the new parts assuming they were faulty but it did it again. The problem is now that all three units are doing the exactly same thing which is really wierd!!!!

Things we have checked:
Compressor, Main isolater for water, comms cable i.e. wired up wrong, water ingress in electrics and pcb connections

none of these things are faulty, i am at a point now where i think i need a Daikin specialist but looking for some advice b4 i go down that route.

Thanks for reading

[frank]

If your mains power supply does not have a connected Neutral onto the unit, the Inverter PCB's can be destroyed at switch on.

Check that you have a good Neutral on the incoming supply and that the Neutral wiring inside the unit is complete.

One of the basic things they teach on the Daikin training course.

I know that it doesn't comply with BS7671-2008, but always connect the Neutral wire in the outdoor isolator on the terminal strip, not through the isolator. Reason being is that if the neutral breaks first when switching the isolator, you can leave the 'live' connected momentarily and this can pop the PCB's.

[leegally1983]

Makes sense i will check this straight away

[leegally1983]

Just a quick one tho will this cause the breaker to trip also??
Thanks

[Brian_UK]

The power module 'popping' will trip your MCB's, if not then it will pop it's own fuses.

[Paul84]

Hi fellas,

A broken neutral wont damage a PCB on a single phase unit. This is 100% true on 2/3 phase units where a pcb powers up on more then one phase. With no neutral the mains pass through the LOAD and short at the junction of where the shared neutral WOULD be.

No cross wiring of interconnecting wiring causes permanent damage.
I've only seen the power module pop due to DC fan motor or compressor

Any chance you been supplied the wrong power module part# 1289938 (Aust - may be diff)

Were all 3 units faulty on your first visit? Have you fitted the spare parts to 1 or 3 units.

Good luck champ

[leegally1983]

originally one unit was faulting on site as it was a important unit (LAB)we took the parts from another unit (empty office)on site to get it running then ordered up the new parts. We then attended site to fit the new parts on the unit (empty office)we took the other parts out of, this is when the unit began to start popping the power module and MCB. So we then took a power module and inverter board from another system (other empty office)and put it into this one and it popped the power module again.
From here we then ordered up a whole new batch of PCBs etc as we assumed they were faulty parts, returned to site and fitted them to find the same problem
Then a week later the original (LAB) unit faulted and upon checking found it popping the power module.

I must mention two months before all this started happening our installation team re-located all the condensors to outside as they were originally installed in a warehouse dont know if this is anything to do with it.

Lord give me strengh

[tareg70]

Hi pal check the or replace the three capaitor board ,there must be no volts balance.
good luck

[still learning]

frank is right, we also never put the neutral thru the isolator these days on inverters .
in a long shot, how is the wiring of the power supply, was it extened in a joint box to the new site outdoors ?

[Greengrocer]

What's the new Cable /pipe run? Size of power Cable?
Check for voltage drop on outdoor unit.