# Forum Home Renovation Heating & Cooling  Help: Brivis HE20 - repair

## chrisp

Does anyone have any experience with repairing a Brivis central heating unit?  *A bit of background:*
A while back I had trouble with a electrical circuit intermittently tripping the circuit breaker.  I initially suspected that I had a faulty appliance so I did an insulation breakdown test on all the appliances.  All of them checked out okay except for the central heating unit that showed a little bit of leakage.  I left the central heating unit unplugged, but the tripping remained. 
The tripping fault was eventually found to be a rodent chewed cable.  This was repaired by an electrician.  In the process, the power outlet to the central heater (fitted by the heating installer) was wired with the active and neutral transposed.  This was fixed up too.  *The problem:*
The central heating unit has been left unplugged for several months now, but I thought I should plug it in in preparation for when it is next needed.  At first, nothing happened when I plugged it in (and I didn't expect anything to happen).  However, when I checked the controller inside, the screen was still blank. 
I figured that maybe I plugged it in but had forgot to switch it on?  I went under the house again to check.  It was on, so I thought I'd try the other outlet (its a double outlet) just in case.  When I plugged it in to the other outlet and switched on - something unexpected happened.  It went BANG! and there was a flash near the right-hand side vent (the one nearest the 'star' sticker).  :Shock:    
I turned everything off and removed the cover to look for any obvious problems.   
The nearest I can tell, is that the flash may have been near the blower motor.  The motor rotates very freely so I'm not convinced it is the motor. 
Also, I didn't realise it at the time, but the circuit breaker tripped too.  :Eek:  
Does anyone have any ideas or pointers as to what might be wrong?  I'll probably have to wait until the weekend before I have time to look further. 
Any advice and guidance would be much appreciated.

----------


## president_ltd

i have a Brivis HE30 here.  from memory when you restore mains power nothing happens until you hit 'power' on the Networker panel.  i.e. nothing shows up on the LCD inside the unit itself. 
one thing that does look a bit odd is that to my mind your unit is on its side.
at least for a HE30, its all top accessible, not side-accessible. 
if thats the case maybe having turned on power while its on its side is an issue? 
as far as what "blew", its not likely to be the motor as it would not have energized the motor as yet, it only does that when it is turned 'on'. 
from memory there is a fuse for the internal controller, maybe see if you can find that.
also follow the mains wiring and see where that goes.  maybe something is exposed that should not be?

----------


## chrisp

> i have a Brivis HE30 here.  from memory when you restore mains power nothing happens until you hit 'power' on the Networker panel.  i.e. nothing shows up on the LCD inside the unit itself.

  Good tip.  I didn't realise that.  I just need to get to a point where the power will hold (it tripped the CB).   

> one thing that does look a bit odd is that to my mind your unit is on its side.
> at least for a HE30, its all top accessible, not side-accessible.

  This unit is the HE20i - the 'internal' unit that would normally be roof (cavity) mounted.  However, I've had it installed under-floor.  I'm pretty sure it is mounted the right way up - it is sitting on its feet.    

> as far as what "blew", its not likely to be the motor as it would not have energized the motor as yet, it only does that when it is turned 'on'.

  I'm a little puzzled by that too.  The first time I switched it on, nothing happened at all (which is normal).  When I went inside to check the 'networker' it was still completely blank (no time, no soft key menus).  I did hit the power button on the networker but it didn't seem to make any difference. 
However, when I switched the underfloor unit off and back on (via the power point and after swapping the outlet), the second time it did make a noise.  I think that may have been a motor start-up noise just before the bang.  Maybe the system somehow remembered the 'on' from the networker? 
The visible motor turns very smoothly, but I'm aware that there is a second motor in these systems.  I recall in the past there was a noisy-bearing type noise in this unit, so maybe the other motor has seized up during the period of inactivity? 
I'll try and dig a little deeper on the weekend.  I think I'll check for an active-earth breakdown just in case a motor has a faulty winding.  Or maybe it has a rodent infestation?  
Thanks for your reply - it all helps.  :Smilie:

----------


## president_ltd

yep, there is two motors.  one for blowing the 'air', the other where the gas burner is (i guess related to efficient burning of the gas). 
i seem to recall someone on here had the 'service manual' for Brivis HE units, i'll see if i can dig it up and post it here....
that might give you some clues.

----------


## president_ltd

here 'tis....
(this might be a good addition to the 'library') 
it doesn't give a lot of detail for what you're seeing though... so i guess maybe see if you can see any blown fuses.

----------


## chrisp

> here 'tis....
> (this might be a good addition to the 'library') 
> it doesn't give a lot of detail for what you're seeing though... so i guess maybe see if you can see any blown fuses.

  That's an excellent manual.  I heard that a someone  :Wink:  recently sent the  librarian an early version of the installer's manual but yours is a later version and much  more comprehensive.

----------


## president_ltd

> That's an excellent manual.  I heard that a someone  recently sent the  librarian an early version of the installer's manual but yours is a later version and much  more comprehensive.

   :Smilie:  
credit where credit is due.  Anthony (atregent) sent that to me when i asked about either zone dampener wiring or networker cabling last year or the year before.  :Smilie:

----------


## chrisp

*UPDATE* 
I managed to have a look at the heater this weekend and I'm pleased to report that it is now going - and best of all the repair cost ~$35. 
What did I find? 
Firstly, I checked the resistance between the active/neutral and earth to see if I had a short to earth or not.  The reading on a multimeter was about 8~9 Meg ohm - not enough to trip a circuit breaker, but not as high as I would expect or like. 
I then mega-tested (@ 500V) the active/neutral to earth and get the same reading as the multimeter (8~9M).  *ABSOLUTELY MAKE SURE THE UNIT IS UNPLUGGED BEFORE PROCEEDING - you are literally risking death if you don't!*  
I then removed the 'flue fan' from the unit.  If you look at the second photo in the first post in this thread, the flue fan is visible on the right-hand side.  It is fairly easy to remove - 6 screws and undo a clip on a small rubber tube.  The flue fan assembly can then be dropped down.  A couple of wire prevent it being removed completely - but it doesn't matter for the repair. 
The fault is a control module (see Brivis - Heating - Appliance Spare Parts - Northern Gas and Electric - Melbourne and look for part number 62481363).  This was easy to identify as a fault as it had the distinctive "semiconductor gone up" smell to it. 
The module has a heap of cables connected to it, but they all just pull  out and most of them will happily sit close to their correct location.  I didn't  both writing down the cable arrangement, but please do so if you are  feeling uncertain. 
For those who just want to fix the heater and get on with their life, just obtain a new module and fit - it'll probably cost more than $35?.  It would have fixed my heater in one go. 
However, those of you who'd like to actually fix the module themselves - read on... 
(Please excuse the crap photos - I left my camera at a relatives house and I used a hand-held web camera instead.  The photos are BAD but you'll be able to get the gist of it.) 
The module looks like:   
If you carefully prise it open, there is a printed circuit board (PCB) and an aluminium base.   
So what was the damage?  Have a look at the next lot of photos...   
On several spots on the PCB there is evidence of 'tracking' due to conductive dust building up on the PCB.  The high voltages attract dust and slowly build up on the board.  Eventually, the dust grows and arcs over damaging the PCB. 
After cleaning the board (using Jaycar NA1008), you can clearly see where the arcing took place.  (Top right-hand corner of the PCB).   
Note, the PCB has been carbonised so just cleaning it won't fix it.  The carbonised material needs to be scrapped out.  It looks ugly but electrically it is clean.   
On the other side of the PCB, there is a blown resistor.   
This was replaced.   
The whole board was re-cleaned (again, using Jaycar NA1008).  It is important to get the board clean.  The back of the PCB was coated with PCB lacquer (Jaycar NA1002).  Don't skip the lacquer process, it is an essential part of the long-term insulation of the PCB.  I also coated the aluminium back plate too - but only the surface facing the PCB.  Don't coat the connector (or allow lacquer to run in to the connectors).  Also, don't coat the surface that has the TRIAC clamped to it (the TRIAC is the device with the paper-clip clamp on it).  Clean the old heat-sink compound off and apply a fresh coat (Jaycar NM2010). 
Also, don't forget to clean the insides of the plastic case.   
I'm my case, I reassembled the heater (a pretty straightforward process) and tried it out using an extension cord (I don't like things going BANG near me  :Rolleyes:  ).  The internal 'Networker' came on.  This is definite progress (and the heater didn't go BANG  :Smilie:  ), but when I turned it on at the Networker, it displayed 'service' and error codes 35 and 60.  The fan was also running flat-out. 
Below, on the internal networker panel, it showed "SA Therm" and "Motor O_C" messages (or something like that).  These implied that one of the motors was open circuit (burnt out) and that the supply air thermistor wasn't working.  It was hard to tell if these errors were real or not.  I checked the supply air thermistor using a multimeter (Note: turn the unit off and unplug first!).  It read 12.5k ohm (from memory) so I was reasonably sure it was alright.  I checked it again at the point where it enters the module and it was the same.  The main fan motor was okay - it was running flat out!, but the flue fan motor wasn't moving.  I checked its resistance (unplugged) and it gave a reasonable reading (~200 ohm).  I was confident that the error messages were artefacts of a different problem. 
I disassembled the heater and the module again.  The TRAIC that is under the paper-clip clamp was obviously faulty (cracked).  I don't know if I missed it originally, or whether it subsequently blew.  It didn't really matter - it needed replacing. 
The TRAIC was a BTA08-600C which is also the same as a BT137F-600 (Jaycar ZX7149).  I replaced this and tried again.  Good news this time - everything worked! 
BTW, I had a sense of déjà vu with this repair.  I've actually repaired these modules for a friend in the past.  The cause was the same - dust causing tracking and arcing.  But the damage was different.  Some boards just have tracks blown off the PCB and work just fine after cleaning and repair (and coating). 
Anyway, I hope this experience is useful to someone else. 
BTW, I don't work at Jaycar - I'm just trying to give others references to where they might obtain spare parts.   :Smilie:

----------


## president_ltd

nice one! 
our Brivis HE30 is whinging about a short circuit in the output duct temperature sensor - same thing as reported http://www.renovateforum.com/f195/br...34/#post745598 
maybe i'll open it up one of these days and take a look, if only to stop the flashing spanner on the networker panel!

----------


## Greolt

Wanted to first say a big thanks to Chrisp for his detailed write up. 
Started my heater (HE20) for the first time this season and it is flashing an error. 
Did a search for a manual and found this thread.  So I removed the component that Chrisp described and found some obvious problems. 
Carbonised dust on the PCB,  (see pics) 
Cleaned it up and found a damaged trace, 
Repaired and sprayed with circuit board lacquer. 
Replaced the unit thinking I had fixed an obvious fault and experience told me that will most likely be the end of that. 
Well unfortunately the error still persists.  :No:  
"ERROR service  HI 30"  is what the unit says.  The heater still works but I don't know for how long. 
Anyone got a service manual? 
Greg

----------


## chrisp

Greg, 
It looks like your board has cracked-over near the tacho input. 
It might be worthwhile checking the actual tacho sensor as well.  I'm guess this is the tacho used to determine the speed of the main fan motor? 
Also, if you look at the photos, you will see that the extra-low-voltage circuitry is isolated/separated from the 240Vac by a 5+ mm gap in the circuit board.  This isolation gap can be seen running diagonally across the board. 
Unfortunately, it seems that in your case that the extra-low-voltage part of the circuit may have been involved in the crack-over as some of the dust seems to be bridging the isolation gap. 
It might be worthwhile replacing the opto-isolators and the opto-isolated-TRIAC just in case they were damaged in the crack-over. 
It may also be worthwhile looking inside the main control module (the one with the LCD display) to see if there is anything obviously amiss in there too.

----------


## Greolt

Because I found a really obvious fault (damaged trace) I assumed that would be the problem. 
But now with your advise I will take a better look.  
Replacing the opto isolators and TRIAC will be easy and cheap, so I will do that. 
Thanks again, 
Greg

----------


## Greolt

Starting the heater up this morning it is not flashing the error.  I guess it will come back.  Intermittent faults are the hardest to fix. 
Decided to replace the aforementioned components anyway.  They are cheap. 
Replaced the two TRIACs.  They are identical. One drives the main fan (with heatsink) and the other drives the flue fan. 
Also replaced the three opto isolators.  One 4N35 and two MOC3020 triacs. 
Got it all back in and it is going.  Just have to see how it goes and hope for the best.  I am not so optimistic. 
This info is not much help for any future readers here.  Maybe I will have something more to add in coming weeks. 
Greg

----------


## chrisp

Just to provide a bit more information... 
As an oversight, I forgot to state the value of the resistor R7 that was burnt up.  For the benefit of others, the value is 100 ohm.  I used a Jaycar RR2550 ( 100ohm 1 Watt 5% Carbon Film Resistor - Pk. 2 - Jaycar Electronics ).

----------


## Ren11000

Thanks chrisp
have just ordered the resistor and Triac, excellent write up

----------


## Ren11000

> Thanks chrisp
> have just ordered the resistor and Triac, excellent write up

  The damage to my module was the same as Chrisps, with the help from Crisps write up I replaced the resister and Triac and the heater is working fine now . :Biggrin: 
just one question, The triac suplied by (Jaycar ZX7149) is not metal backed where the heat sink compound goes. Will this be a problem with overheating? 
Richard

----------


## chrisp

> just one question, The triac suplied by (Jaycar ZX7149) is not metal backed where the heat sink compound goes. Will this be a problem with overheating?

  I assume you have the fully-insulated-tab-package.  Just treat it the same has the metal-tab version - place the heatsink compound between the back of the package and the aluminium heatsink.  The heatsink compound improves the thermal conductivity by excluding any minute air-pockets that might otherwise exist. 
I've found a somewhat fuzzy photo that shows the heatsink compound.   
I'm pleased to hear that your heater is working and that my write up was beneficial.  :Smilie:

----------

