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SERVICEMAN'S LOG
Why can't I program MY alarm?
Dave Thompson*
Many moons ago, I wrote about an
alarm system I was having trouble with
at my then residence. I’d experienced
intermittent problems with it in the
final few months of its almost tenyear lifetime and it had finally
given up the ghost, which was a
real shame as it had been such
a good system.
Items Covered This Month
•
•
•
Bosch burglar alarm
Marantz SR870 receiver repair
Mitsubishi air conditioner
*Dave Thompson runs PC Anytime
in Christchurch, NZ.
Website: www.pcanytime.co.nz
Email: dave<at>pcanytime.co.nz
It had protected, without fault, a
couple of our dwellings with attached
workshops and had been disassembled and re-installed several times as
we’d moved from place to place in the
early days.
The problem with all electronic
hardware is that it is usually quickly
superseded and this alarm system was
no exception.
Of course, the alarm company who’d
originally installed it was more than
happy to pull it all out and replace it
with a shiny new version, with more
bells and whistles but apparently that
also meant changing all the sensors I’d
spent a considerable amount of time
and money on.
The sales guy was adamant they
were no longer compatible with newer
systems, a statement I viewed with
great suspicion. I was subsequently
vindicated when I learned that all my
sensors would have worked with any
new panel sourced from this company
(and probably dozens of others as well).
40
Silicon Chip
However, that deception aside, I
was not yet in a position to shell out
the amount of money they wanted
for a new system, especially as they’d
“given” us the old system as part of a
deal when we signed up to a monitoring contract with an affiliated security
company.
Back then, we got the basic system (which came with three standard
PIR sensors and a smoke alarm) if we
agreed to a two-year monitoring deal,
which was actually a win for both parties. We got a good quality, monitored
alarm system and they got a dollar
a day from us for a couple of years,
guaranteed.
From what the installers said as
they put the thing in, they had "sold"
a huge number of these package deals
and were run off their feet with installation work.
Unfortunately, now many years down
the track, that deal – or any others like it
– no longer exist, which is why I baulked
at the quoted cost of a new system.
Celebrating 30 Years
Before making any decisions, I
looked at all the alternatives. I wouldn’t
be much of a serviceman if I neglected
to do my due diligence!
The system we’d been using, the
Solution 6 + 6, was made by Bosch, a
company not known for making junk.
So although it was basic and essentially given away as a deal sweetener,
it was by no means a bottom-of-theline system.
We’d also added a whole bunch of
extra sensors to the "free" package, as
we also wanted to include our garage
and workshop, an altogether much
larger area than the standard package
was designed to cover.
Thus, we ended up with an array
of door and window switches, extra
smoke alarms and more PIR sensors,
with pet-safe versions of these detectors replacing the standard versions
that came with the package deal – all
at our expense, of course.
Overall, this system was rocksolid. I can only recall one instance of
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it going off with no apparent cause, the
dreaded false alarm.
Fortunately, it was in the middle of
the day and I was nearby, so no real
harm was done. Even though I knew
which zone and sensor was responsible, I never did figure out why it went
off and as it never happened again, I
didn’t lose too much sleep over it.
Newer isn't always better
In contrast to this, I have lost count
of the number of times the much newer
and far more sophisticated digital alarm
system (purchased from AliExpress) at
our new place has gone off over the last
18 months with no apparent trigger.
Like any electronic device, the more
complex it is, the more likely that it
will give problems. No doubt there is
a law named after some famous academic used to describe this phenomenon, but as I’m not aware of it yet I’ll
take a punt and call it "the Serviceman’s Law".
This new alarm system does have
several advantages over that old one
though. We now have features such
as wired/wireless sensor connections,
manual/keypad operation, RFID or
key-fob arm/disarm and both GSM
and copper-line connectivity for monitoring.
If required, I could use up to 99
sensors with the new system, while I
siliconchip.com.au
could wire in a maximum of only 12
with the old one (and even then, I’d
have to use some jiggery-pokery to
achieve that).
Still, that old system was highspec in its day, and as I said, it
hardly missed a beat until a few
months before it died.
As I wanted to keep using it at the
time, I’d needed to come up with an
alternative to total replacement, and
that meant finding a new main board,
or perhaps a whole new alarm panel,
which was a tough ask considering
the age of it.
As it turned out, I got very lucky.
On a local auction site, I found a
guy selling a brand-new panel and a
new, spare keypad for my exact system. He’d somehow ended up with
two panels and an extra keypad for a
job he was doing (I didn’t ask) and
now, a while after the fact, he was
cleaning out his garage and wanted
to be rid of it.
I was happy to part with a hundred bucks for the panel and keypad, which was a bargain considering what the alarm company wanted
for that new system.
The new panel included the steel
mounting box and power supply
board. All I had to do was disconnect
and remove the old box and then connect and mount the new one using the
same screw holes.
It was an easy task; I didn’t require
any diagrams or circuits as I just
swapped out sensor wires and resistors from where they were connected
on the old board to the corresponding
terminals on the new panel.
The most difficult and time-consuming part of the whole process was
programming the new board with all
our settings. This process also raised
an interesting philosophical issue. The
new main board had been pre-programmed by the alarm company who’d
imported it using their own unique installer code, which meant that I could
not fully program the alarm board as I
didn’t know the code; the seller didn’t
know it either.
There are two codes used in this
system, both of which have their own
levels of access to the system and its
various functions. The installer code
is used to program all the non-consumer related information into the
panel, such as telephone numbers for
remote monitoring, different options
for the various types of sensors, zone
Celebrating 30 Years
settings and other miscellaneous technical parameters.
Importantly, the alarm cannot be
armed or disarmed using the installer code, a necessary safeguard to help
prevent rogue installers going around
disabling alarm systems.
That said, installers can add "master" codes, which are used to disarm
systems, and they usually do so as a
service to the customer, mainly because most new alarm owners do not
have the desire to go poking into the
workings of the alarm system, nor do
they want to have to wade through the
manual in order to learn how to program in their own codes.
Those who are prepared to read the
instructions, or who are concerned
about others (namely the installers)
knowing their alarm codes are able
to create their own master codes, although this is about the only thing they
can do without requiring the installer
codes as well.
The main problem is that, for obvious reasons, the installer codes are
almost never released by the alarm
companies.
This raises the philosophical issue
I speak of; while it is fair enough for
installers to retain those codes if they
(or their affiliated monitoring company) have installed a "free" alarm
system along with a monitoring deal,
I bought and paid for this particular
panel outright, so surely I should be
privy to any and all codes and keys
used in the system.
Not knowing that installer code, severely limits what I can do with it, and
this is just not cricket. This would be
akin to me putting a BIOS or set-up
password on every computer I sold
and then charging a fee to anyone who
wanted to get into the BIOS to, for example, add another hard disk or alter
existing settings.
April 2018 41
To any right-thinking person, this
is not acceptable, and yet as far as I
can tell this is industry practice in the
alarm business.
There is a potential “back door”
though; the main logic board has a "set
default" button on it, which does exactly what you’d think it does, and that
is re-set any programmed settings back
to their factory defaults, including the
installer code and master codes. This
action can also be accomplished using
certain codes sent to the logic board
via any of the alarm keypads.
However, as always, there’s a gotcha
involved. There is an installer option
to protect that setting and this prevents the set default button or keypad
codes from being used to default the
system settings.
While the service/installer manual
specifically advises against using this
setting, as it requires the unit to be
sent back to an authorised agent for reprogramming (or in this case, requires
me to pay some guy to come out and
do it), this particular company chose
to ignore the instruction manual and
set that option to on, preventing me
from using it to default the settings.
Nice one.
I understand there are business and
security implications to this, however,
any bad guy would have to be pretty
clued up in order to go around accessing alarm systems and besides, it
would be a pretty obvious clue if the
alarm was disabled by someone other than the owner. Either way, in my
opinion, setting an installer code and
making it non-removable is not warranted, period.
In the end, I had to pay a couple of
likely lads to come out and remove
that installer code. They didn’t want
to do it, and certainly wouldn’t tell me
what the code was – not that it mattered; I neither needed nor wanted to
know it, I just wanted it defaulted –
but it turned out that they didn’t actually know it anyway.
However, I put my case in strong
terms that this was now my alarm
and as such, they or their colleagues
had no right to set any passwords or
codes into it that prevented me from
accessing any settings within it. After
a lot of back and forth and a few phone
calls to superiors and other installers,
they agreed to default the panel, trying all the codes they knew, including those used both past and present,
to default it.
They eventually chanced upon it
setting everything to default. Commenting that this code had not been
used for many years, they eventually
loosened up and showed me around
the programming side of things and
even demonstrated how to use a programmer board to make things easier,
and double-checked the option that
prevented the defaults from being set
was disabled.
In the end, we recognised we were
all servicemen and as such were kindred spirits. They knew I wouldn’t be
going around busting open alarm systems and were happy to share those
few tricks of their trade. I’ve engaged
them several times since to do alarmrelated work and it is nice to have a
connection to people with those specialist skills.
Well, that's one way to stop
it beeping
I bring the subject of this alarm
system up because last week the guy
who’d been renting our old place (the
one with the repaired system installed
in it) moved out.
When I went in to check the property out, I found he’d somehow disabled the alarm system; it was completely dead. When this bloke had
first moved in, he’d mentioned that
the alarm would be a welcome asset
as he had some expensive laser-cutting
equipment he wanted to set up in my
old workshop.
Obviously, something had changed
in the meantime, so I got in touch to
determine why the alarm was no longer working. He claimed that shortly after he moved in, it started displaying a
"mains" error on the keypads and because of this, the system beeped once
Servicing Stories Wanted
Do you have any good servicing stories that you would like to share in The Serviceman
column? If so, why not send those stories in to us?
We pay for all contributions published but please note that your material must
be original. Send your contribution by email to: editor<at>siliconchip.com.au
Please be sure to include your full name and address details.
42
Silicon Chip
Celebrating 30 Years
a minute, which it is designed to do.
Not knowing better, he’d climbed
up to where the main alarm panel is
located, opened the box and disconnected the mains connections and battery terminals, thus shutting the whole
thing down and killing the beep.
If he had called me, I could have
told him how to stop that beeping in
five seconds with the push of a keypad
button. However, he fancied himself a
bit of a DIYer and preferred to resolve
it himself in his own refreshingly nontechnical way.
I empathised though; that beep is
annoying. Every keypad has a piezo
buzzer, so any warnings are audibly
announced, along with flashing zone
LEDs, and in this case, the warning
would go on either until mains power
was restored or the battery went flat
(or someone physically unplugged it!).
During the quakes, we lost power
a lot, so I am intimately familiar with
that particular warning. Still, his response was a little heavy-handed, and
as it turns out, there were a few other
"command" decisions he’d made that
he wasn’t entitled to make as a tenant;
the alarm is just one example.
The first thing I had to do was dig
out the alarm’s service manual again.
With no power for over a year, I might
need to re-program it. I made my way
into the roof space and found the panel
door wide open and full of new residents.
A quick vacuum cleaned it all out
and I could then see he had simply
cut the wiring. Again, if he’d called I
could have told him where the master
switch was at ground level.
None-the-less I reconnected it all,
but when I flicked the mains switch
on, there was nothing, though when I
re-connected the battery leads, I heard
a beep and the keypads lit up with
fault indicators. At least the battery
was holding its charge; fortunately, I’d
replaced it not long before we moved
out so it was still fairly new.
However, the problem was still no
mains power. I broke out my line testing tools and worked backwards from
the panel through the system until
I discovered that the mains feed to
the panel was dead because this guy
had wired in an extractor fan for his
laser and had inadvertently killed
the alarm circuit, which caused the
mains fault.
He’d removed and taken the fan
away, so I used a junction box to re-consiliconchip.com.au
The Marantz receiver is tightly packed with components, making testing difficult.
nect the loose cables and with power
restored, the beeping stopped and the
fault cleared. All my settings had been
saved, but I changed all the codes anyway, just to be safe. Who knows, there
may be servicemen around who are not
as trustworthy as I am!
Marantz SR870 receiver repair
R. A., of Melbourne, Vic, recently
fixed his venerable Marantz SR870
Home Theatre Receiver. It has given
nearly 20 years of sterling service and
will now likely soldier on for another 20. The fault he discovered was all
too common and luckily, easily fixed.
Here’s his story...
While studying to be an engineer, I
worked as a serviceman and have dabbled in servicing ever since. Like all
servicemen, my own gear is the last
to be fixed. My 19-year-old Marantz
SR870 5.1 channel home theatre receiver had been playing up for well
over a year.
Every now and then, it would spontaneously power down then usually
quickly reset, sometimes repeating
the cycle then usually settling down.
Recently it played up more frequently
and now would sometimes not recover
at all for quite some time.
Eventually, I decided to do something about it. My initial thoughts were
to suspect a capacitor in the power
supply or maybe even a faulty fuse.
After removing the receiver from its
place in the system (no trivial task and
the reason for the procrastination), I
pulled the cover off and inspected the
power supply board.
Everything looked fine. No bulging
capacitors, the fuses looked rock solid
and were a quality type. The fault was
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so intermittent that waiting for it to
fail on the test bench was an exercise
in frustration. It was clear to me that
all mains power was being lost when
it did fail, so I did the easy thing and
replaced the mains cord, which had
some very sharp bends in it where it
was clamped in several places.
Back in use, it worked well for about
24 hours – then failed again.
The receiver was packed full of
components (as shown by the photo
above), had been well built and was
in excellent condition, so I was loath
to start pulling out components on
a search-and-destroy mission. Even
measuring voltages was impossible on
some of those nested PCBs.
Instead, I looked on the internet for
clues but there was little information
available. However, I came upon a
YouTube clip where an American technician worked on a similar receiver.
The interesting thing was that there
were lots of comments below the video, none of which related to the video
but were asking all sorts of questions
regarding receivers and faults.
The small power input PCB from the
receiver.
Celebrating 30 Years
The technician replied to all comments with patience and much insight.
So, I took a chance and asked about my
SR870. Overnight he replied, saying
that there was a common problem due
to poor soldering on the power input
PCB. In particular, he said to check the
soldered joints on the small standby
transformer and regulator IC.
I retrieved the unit and opened it up
again, then removed the PCB in question (shown in the previous photo).
It was relatively easy to get the PCB
out; I just needed to remove the big
main transformer to give some wriggle room and also work out how to unclip each small connector. Only two
of the five used the same locking tab
arrangement.
Using reading glasses with three
times magnification, I discovered that
at least one soldered pin on the primary of the transformer looked dodgy. So
I took macro photos and then re-soldered every transformer pin and every
pin on the aforementioned IC and put
everything back together.
Cutting to the chase, this completely
fixed the fault. Later, looking at the
photos on a large monitor, it was obvious that all three of the primary pins
of the transformer, along one side, had
faulty soldered joints (see the photograph below). All the other joints
looked OK.
My theory is that a flawed mechanical design caused this issue. The
manufacturing process required the
transformer to be first soldered to the
PCB, then two long self-tapping screws
went through lugs on the transformer,
through the PCB, through a standoff,
to the chassis.
Tightening these screws forced the
transformer into the PCB and thus
placed strain on the solder joints.
I was happy to have given the receiver another lease on life. Reflecting on it later, you might think that a
receiver that old should be replaced
by a newer “better” unit.
In fact, it was already superseded
when I bought it new (at a good price)
in 1998 as it only had Pro Logic decoding, not Dolby Digital or DTS.
April 2018 43
However, it has an analog 6-channel
direct input to cater for then-future decoders, so I have used it continuously
with a variety of DVD players with
6-channel outputs, plus PVRs and
other boxes over the years.
Hence, the amp is future proof,
which fits my philosophy of also buying the dumbest TV and using it with
an external set-top box (with built-in
media server/PVR/Fetch box/etc).
It’s much cheaper to replace a box
when technology advances than replace the amplifier or large screen.
The introduction of H.264 compression is one example where this philosophy pays off.
Also, I reflected on the good electronic design that utilised 1000+ electronic components that still work
perfectly 20 years after manufacture, 25+ years after it was designed.
Would today’s replacement actually
be “better”?
Researching possible new replacement units, a popular brand has a
7-channel, 115W/channel (single
channel driven rating), and weighs
just over 8kg, retailing at about $1000.
The old Marantz weighs 14.4kg,
most of it being the power transformer. Rated at 110W/channel (two channels driven), its multi-channel performance would easily eclipse the new
unit due to the much beefier power
supply.
So I am glad to have given the old
Marantz a new lease on life. I also still
have the original RC2000 remote control – the “Remote of the Gods” – but
that is a story for another time.
Mitsubishi air conditioner repair
J. N., of Mt Maunganui, New Zealand, recently faced a common problem with his home air conditioner;
spare parts were becoming so expensive and difficult to get that it looked
like it might be cheaper to replace the
whole thing than repair one small
fault. Luckily, he managed to get it
going again anyway...
As a semi-retired electrical/electronics technician, I like to do any
servicing or repairs on our home appliances myself. The one time that I
decided not to, it ended up with me
finishing the task anyway!
About a year ago, we had an extra
Mitsubishi heat pump installed in our
house, adding to our existing old but
faithful Mitsubishi MCFH-A18WV. I
usually service the old unit myself but
we decided to have both units serviced
by the installer of the new unit before
winter set in.
They arrived and proceeded to service both units and found that the old
MCFH-A18WV would turn off OK but
the internal fan kept running.
According to the service engineer,
the problem was in the main Electronic
Control (EC) PCB and it would have to
be replaced. I requested that they give
me quote for the supply and installation of this unit.
His estimate was around $300-500
for the part plus labour, which made
me flinch! I asked him to please check
this out with a firm quotation.
A couple of days later, the company
came back with very pleasant news indeed. It appeared that because our old
unit was so outdated that there was
only one PCB in stock in the whole of
New Zealand and the agents were prepared to let us have it for only $32.90
including GST! Well, of course, we
agreed.
Several days later, our service engineer turned up and duly replaced the
Electronic Control PCB, only to find
that now the internal fan motor did
not work at all!
After a lot of testing, he now announced that the fan motor had burnt
out one of its windings and also that
the main EC PCB was probably corrupted and would have to be replaced
again!
By this time, I was beginning to
think that we should bite the bullet and
replace the whole unit. It was agreed
to get a further quote from Australia
for parts alone, ie, the fan motor and
a new EC PCB.
In the meantime, I decided that it
would not do any harm for me to investigate myself. I was able to download
the circuit diagrams and went about
conducting my own tests.
All seemed well until I came to
check the fan motor stator windings
which involved one main winding
and four separate coils, providing different fan speeds.
Sure enough, the main stator winding showed an open circuit on my
ohmmeter. This did not make sense
until I re-checked a separate circuit
diagram which showed in very small
detail that this winding was protected
by a fuse.
Where was the fuse, as none was in
sight? The penny dropped; it was embedded in the windings and was obviously a thermal fuse.
I simply bypassed this fuse by temporarily altering the wiring and the retested the winding to find that it read
the required 79-97W. At switch-on, the
unit operated as it should, so the new
EC PCB was not faulty.
True to their word, I received a
phone call from the servicing company to inform me that a new fan motor
and EC PCB would cost over $1000
plus labour and GST.
I am not sure what they thought
when I informed them that the unit
was working fine and we would not
need the new parts.
Since then, I have removed the fan
motor and installed a new thermal fuse
as best as I can, to protect the motor,
and I am still going to attempt a repair
one day on the old EC PCB which had
been previously removed. In the meantime, our good old heat pump is still
SC
chugging along.
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Celebrating 30 Years
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