Looking at your picture, right above where the transformer leads connect
to the terminal strip, there is an electrolytic capacitor right above a
small bridge rectifier. I can't quite tell but the capacitor could be
swollen and shorted. The 3 terminal voltage regulator is above that
capacitor attached to the aluminum plate heat sink. Those are the main
components of the AC to DC power supply and if one of them is shorted,
that could kill the power transformer. ^_^
On Sat, 23 Nov 2013 17:10:37 -0600, The Daring Dufas wrote:
I'm surprised you knew *where* the transformer leads entered the board,
because I didn't say, so, but I see what you're talking about.
Also, I'm surprised you knew that was a bridge rectifier, because, well,
because I didn't - but - looking at it from the side, I can see four
uninsulated legs, which indicate it has four leads, one of which is
Here is the same picture, but, with a few things marked that I know of
(including the electrolytic capacitor I think you're talking about):
I looked and touched and that cap seems OK visually; but, of course,
it's probably 20 years old...
For the first time, I'm wondering if it's not just a new transformer,
but, that I probably need to replace the entire board...
You could try www.tech-man.com for a used replacement board, bearing in mind
that any used replacement board is likely to be close to the same age as
I would tend to upgrade to a current system.
Yes. Voltage spike, lightning strike, leg dropped across from power
company, or some moron accidentally touching the neutral in the breaker box
to the other leg of the incoming power. They can cause both to fail. All
are sudden over voltage conditions.
This email is free from viruses and malware because avast! Antivirus protection is active.
It is a real simple circuit. There is an NPN transistor (Q1) that drives the
relay. The black diode is across the relay coil to protect the transistor.
The other diode is a zener in series with the 2.4 k resistor to the base of
the transistor. When the battery voltage is above 9.x volts, the zener will
conduct and turn on the transistor that will in turn operate the relay. The
relay will make the connection from the red wire to the battery (W1) to the
J2 terminal marked power. It will supply voltage to the alarm panel until
the battery voltage drops below the zener diode conduction point.
Charge your battery for a while and see if it will light a simple tail light
bulb. Measure the battery with the bulb connected and lit.
You should. That Omron relay contats can be open or closed.
Is it NO or NC relay? Is the coil good? Have you metered them out?
What is the findings? Did you looked up the specs. of that very common
On Mon, 25 Nov 2013 20:16:21 -0700, Tony Hwang wrote:
Since the D135A is to protect the battery, I assumed it's not
actually *required* for operation.
So, I concentrated first, and foremost on replacing the AC power
Luckily, that worked!
Sort of ...
My next step is to replace the battery.
If I were a repair technician, I'd have all these parts in stock,
but I don't, so, it takes me a while to get them from the
PS: The application calls for a 12V, 5AH to 7 AH gel cell.
Assuming I get something in that range, are they all pretty much
alike, or are there caveats to buying these gel cells?
That was a FANTASTIC explanation!
You're one of the reasons why the USENET is so great!
Thank you very much for that detailed explanation.
I picked up an electrolytic cap, and I will replace it, and test the
battery-protection circuit out.
It failed this loaded test. So, now I know I have a bad battery and a
Luckily, the *new* 16.5VAC transformer arrived.
It sure tested funny:
a) Secondary output = 20VAC
b) One side to ground = 3.5 Volts
c) The other side to ground = 1 Volt
Anyway, the moment I plugged that transformer in, the battery charging
circuit came to life at 13.6 Volts:
And, the alarm system control panel powered up & beeped (almost) normally:
With the battery in, or out, it gave the following error:
*ALL ON, SYSTEM TROUBLE*
And, when I tried to read the error, it merely said:
*CALL FOR SERVICE*
I'm not sure how to get the actual service problem, but, I am pretty
sure it's the battery now that the new transformer is in place.
So, I'll google for a good source of batteries online.
(Any suggestions or are they all essentially the same?)
You should have roughly 16.5 V AC (maybe a little more) between the two
screws marked "AC" with the wires disconnected. If you don't have that,
your transformer died. These transfomers often have an internal, non-
replaceable fuse; if it goes out, you replace the transformer. A local
electronics shop (not Radio Shack) probably stocks them; if not you can
get them online. This is a standard size; $20 plus shipping is a good
Get any 12 V light bulb, except a headlight, from a car (preferably your
car), disconnect the battery from the alarm system, and connect the
light bulb across the battery terminals. The dome light is often easy
to get to and a convenient shape. This will draw somewhere between 0.25
and 2 A from a working battery. The battery voltage under load will go
down a little, but if it goes way under roughly 11.6 V, the battery is
If the battery voltage doesn't go that far down, leave the light bulb on
the battery for a few minutes, then disconnect it. Measure the battery
voltage, then reconnect the battery to the alarm (with a working AC
transformer connected to the alarm) and measure again. If the alarm is
successfully charging the battery, the voltage will have gone up by a
noticeable amount - like at least half a volt.
Alternatively, if the battery is more than about 5 years old, just
replace it; it's probably bad. There may be a date code on the battery,
or you may know when the alarm was installed or last serviced. Computer
UPS batteries do a similar job and I can only get about 7 years tops out
of them, even with the brands I like.
You have a sealed lead-acid or "gel cell" battery, and they come in
several standard sizes and capacities. The label inside the door calls
for a 7 Ah battery, but there is a 5 Ah battery installed in your panel;
if you can confirm that the label matches the hardware, it's probably
better to install a 7 Ah battery. The manufacturers are always tweaking
the specs (if not the actual battery), so your size battery may be
advertised as a 7 Ah, 7.2 Ah, or even 7.5 Ah. Any of these will work
as long as it will fit in the panel. Also, note that the "7 Ah" size
can come with 3/16" wide or 1/4" wide tab terminals; matching what you
have now is best. Some 7 Ah batteries with 1/4" terminals are sold with
reducers for 3/16" terminals, which also works.
I have had good luck with both Panasonic and Powersonic sealed lead-acid
batteries, and bad luck with everything else I've tried, including BB
Battery, UB, CSB, and Power Patrol. I'd be inclined to trust a Yuasa,
based on experience with their flooded batteries, but I have no
experience with their sealed lead-acid batteries. The local hardware
stores carry some (look for the emergency light / EXIT sign parts), a
local battery store may have them, the local electronics store will, or
you can order online from Digi-Key or Mouser. I checked Amazon and a
few sellers there are showing *pictures* of a Powersonic battery but
probably *shipping* some junk battery. Caveat emptor.
For a 7 Ah battery online, $23 to $32 plus shipping is a good price.
Locally, add $5 or so to that for shipping, plus however much the store
marks it up.
When you get a new battery, write the current date in marker on the new
battery and maybe on the inside of the alarm panel door.
The capacitor (that blue cylinder) on the power supply sure is an
interesting shape. It shouldn't have that dent near the right end.
One test you can do: unplug W1 and W2 from the battery, unplug the
wires from J1 (PWR) and J2 (GND), and unplug any other wires from that
power supply. Measure the resistance between J1 and J2, and between
W1 and W2. If it's less than a few hundred ohms on either reading, the
power supply may be bad.
Maybe. Have you ever measured the AC line voltage in your house when
the generator starts up? Does it go a lot above 120 V on either leg?
132 V (120 V + 10%) is about as high as it *should* go for a sustained
period of time. If it's more than this, you have a problem. Also,
try measuring each 120 V leg as you or a helper turns a heavy 120 V
load, like a microwave oven, or a hair dryer or space heater on full,
on and off. You should usually see a slight voltage dip under load.
If the voltage goes *up* when the load is on, you might have a loose
neutral, which is bad. Call an electrician or the power company.
I think you have a combination of a marginal battery and a marginal
power supply (inside the alarm box). As long as AC power was on, it all
sort of worked. When you interrupted and restored the AC power, the
power supply or battery tried to draw too much current from the
transformer, which blew the fuse in the transformer, and may have also
finished off the power supply. Then, the alarm ran for as long as it
could on the battery, until it shut off for low battery voltage.
If you have to hire someone to fix it, don't hire whoever did that
wiring originally. It looks a mess.
Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.
I'm totally guessing here, but I think the transformer may have
blown when you tripped the generator, and the alarm ran on batteries
until they were exhausted. Then, the alarm shut down to prevent
destroying the battery. Although the 13.5 V seems really
high for a 12 V gel cell not being charged. So, there may be
another fault, such as a shorted rectifier in the alarm panel.
That would blow the transformer. But, then the panel should have
run off the battery for at least a while, and in the process
partially discharged the battery. So, it is a bit puzzling.
On Fri, 22 Nov 2013 15:54:59 -0700, Tony Hwang wrote:
I should mention that I was pretty sure I smelled burnt "plastic", but,
since the garage door was open, I wasn't sure if it was coming from
outside, as it was windy, or if it was from the garage.
But, the smell *was* within minutes of the alarm wailing three loud
beeps before dying an untimely death.
The funny thing though, was that the Generac accident was the day
before, so, if it burned up at the time I smelled the burnt plastic
smell, that was a day after I had messed with the main breaker panel.
On Sat, 23 Nov 2013 11:00:25 +1100, Phil Allison wrote:
That makes a lot of sense, since the battery, in and of itself, should
power the system adequately.
I have a new transformer on order, although I belated realized there is a
"limited lifetime warranty" on the ELK-TRG-1640, as described here:
Anyone ever take them up on their "limited" lifetime warranty?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.