HRV: faulty controller and/or motor controller

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rembam

6 posts

Wannabe Geek

Topic # 232170 2-Apr-2018 20:49

Hi there,

I have a two-fan HRV system (Arizona Baby = galv box type) that was installed in 2008.

At the start of summer it stopped working: no power to wall controller; fans not operating. I have since discovered that a shorted wire going into the slave unit caused the fuse on the master unit motor controller to blow. I have since repaired the short, and the slave motor now runs fine. The slave unit has been reinstalled and connected to the master, and the whole system now works in the sense the fans run and the wall controller appears to be normal.

PROBLEM:

The fans no longer respond to the wall controller:

wall controller still picks up valid roof space temperature sensor data,
wall controller does not show any error codes, but
fans do not power down when the controller is switched off,
fans run constantly at full speed - they do not ramp down in response to temperature or user settings

NB: Controller has monochrome LCD display and black control buttons.

The problem is likely to be a fault in the wall controller, the motor controller on the master fan unit, or both. Possibly a dodgy data cable: the two controllers talk to each other via a grey cable - looks like RJ11 or similar; motor controller connects to motor via a red cable that plugs into an RJ11 (or similar) socket on the motor controller PCB.

HELP?: Does anyone know of anyone in the Wellington area who might be able to repair or help me repair this? Or be able to supply parts? Or diagnose? Or just advise? I don't have the equipment or expertise for this. I've made contact with an independent provider in Auckland who says he can diagnose and provide replacement controllers, but that would require me to ship the whole fan unit to him. I'd rather go with someone local.

I definitely do not want to use the HRV company for this, as their standard response is to try and sell me $2,300 worth of system upgrades. E.g., when it came to the non-operational slave motor, their conclusion was it was dead and I needed to replace the whole system. Had they looked, they would have discovered the loose wire.

Anyway, sorry for the long ramble. Any help gratefully received!

andrewNZ

1791 posts

Uber Geek
+1 received by user: 952

Reply # 1987368 3-Apr-2018 06:39

I'd be surprised if it's the wall controller.

It sounds like the short fried the electronic speed control and it failed on.

Location: Dunedin

rembam

6 posts

Wannabe Geek

Reply # 1987839 3-Apr-2018 19:42

andrewNZ: I'd be surprised if it's the wall controller.

It sounds like the short fried the electronic speed control and it failed on.

Tanks for your reply. Yes, I think you are right. For one, the wall controller itself is behaving normally. For another, there is no mains power connection to the wall controller, but there is to the motor controller. I am told a new motor controller will cost $350, which is better than buying a whole a new system. If I get another couple of years out of it, I will be happy.

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Aredwood

2520 posts

Uber Geek
+1 received by user: 913

Subscriber

Reply # 1987904 3-Apr-2018 22:27

The speed controller is probably just based on a TRIAC and some basic driver components (almost certainly very similar to a light dimmer circuit). The TRIAC is probably just shorted.

Try asking companies that repair electronics such as TVs and stereos.

rembam

6 posts

Wannabe Geek

Reply # 1988018 4-Apr-2018 09:37

Hi Aredwood, thanks for the lead! That sounds very plausible. I will make enquiries. Will also get a friend to meter out the board to try and confirm. In today's throwaway society, it will be interesting to see if there are any professionals out there who repair these sorts of things.

rembam

6 posts

Wannabe Geek

Reply # 1996453 15-Apr-2018 14:11

Update: I have now looked at the motor controller PCB, and am pretty sure it is the TRIAC, as suggested by others on this thread (thanks). The task now is to source a replacement part.

CURRENT PART:

No. 137S6, made by PJM electronics = surface mounted bidrectional thyristor.

Searching online, this translates to BT137S-600 series, readily available, including within NZ

Question: There appear to be several name variants. E.g., at /nz.rs-online.com, you'll find BT137S-600, 118 by WeEN Semiconductors and BT137S-600D by NXP (they also do a 600E). Does anyone know what the difference between these is, if any?

The plan is to buy a part, get an electronic technician friend to solder it in and see what happens. If it works, great, it's only cost me about $8 and a dozen beer! If it fails, then I can buy a whole new board (MOTOR CONTROL Ver 4b 171005, made by Invision in 2005) for around $350.

Thanks in advance for any advice/comments offered