Re: Alarm system transformer + power supply (would both go bad at once?)

["tm" <No_one_home@xxxxxxxxxxxxxxx>]

"Danny D'Amico" <dannyd@xxxxxxxxxx> wrote in message
news:l6r5lv$4a2$1@xxxxxxxxxxxxxxxxxxxx
> On Sat, 23 Nov 2013 11:39:11 -0600, Nightcrawler® wrote:
>
>>>I don't see a fuse on the Radionics D2212 BLT circuit board:
>>> http://farm3.staticflickr.com/2866/11014946826_4ecdea2144_o.gif
>>>
>>>And, I don't (yet) see a fuse in the Radionics D2212B LT diagram:
>>> http://farm3.staticflickr.com/2861/11014840755_8169e24a57_o.gif
>>>
>>>And, I don't see an inline fuse in the "rats nest" below the board:
>>> http://farm8.staticflickr.com/7409/11014945176_770ebeea29_o.gif
>>
>>> I'm not sure what to make of these measurements:
>>>1. Battery hooked to power supply is 12.87VDC:
>>>   http://farm4.staticflickr.com/3675/11012106735_6462c93b69_o.gif
>>>2. Yet, battery hooked to PWR and GND blades of power supply = 0VDC:
>>>  http://farm4.staticflickr.com/3671/11012333553_83db5107c8_o.gif
>>>3. Battery hooked to just GND blade on the power supply = 12.87VDC:
>>>   http://farm8.staticflickr.com/7360/11012206866_fdcb4a46a6_o.gif
>>>4. Battery hooked to just PWR blade of power supply = OVDC:
>>>  http://farm6.staticflickr.com/5516/11012206746_15cf8b97f4_o.gif
>>
>> What are the voltage measurements of the pins by the
>> capacitor?
>
> Are you asking me to check the DC voltage across the capacitor
> of the D135A low-battery disconnect circuit?
> http://farm6.staticflickr.com/5504/11013315874_62a158a0de_o.gif
>
> Specifically these two points, where I had previously measured the
> resistance (with no power to the circuit) across that same cap?
> http://farm6.staticflickr.com/5484/11013352723_e91013b313_o.gif
>
>> What connects to J1 and J2 (GND and PWR post, respectively)?
> J1 on the D135A board goes to gnd on the Radionics D2212B board.
> J2 on the D135A board goes to pwr on the Radionics D2212B board.
>
>> That black object between J1 and J2 is a relay.  This relay needs
>> to be activated by something, and I am guessing a power failure
>> deactivates this relay, enabling the battery back-up.
>
> I do not know the answer. Here's a closeup of that relay:
>  http://farm3.staticflickr.com/2894/11013237706_28045e3abe_o.gif
>
> All I know, for sure, that's bad is that the ELK-TRG1640 transformer
> has a blown secondary (open circuit) but I don't know what blew it:
> http://farm6.staticflickr.com/5527/10989885984_72d64103f6_o.gif
>
>> So, are J1 and J2 inputs with the connector being the output, or
>> vice versa?
>
> I think the D135A low-battery disconnect is supposed to be taped
> to the battery, which turns off the circuit at 9.5V but otherwise
> does nothing else; so that's why I think it's weird that I get
> 0 volts across J1 and J2 when the battery is hooked up.
>
> To see if it was the battery, I charged the battery on a car
> charger (6 amp limited) and I was surprised to see the battery
> only took about 30 ma (I had to measure it since it was too low
> for the car charger gauge to show any movement).
>
> After five minutes, I took it off, and the battery measured at
> 13.5 volts (some of which might be surface charge):
>
> Then, I hooked that battery to the D135A and measured across
> J1 and J2 again (which seems to be the 12VDC input to the
> alarm circuit board).
>
> 1. The voltage across the battery inputs was 13.31VDC:
>   http://farm4.staticflickr.com/3780/11016175513_af16f7c34e_o.gif
>
> 2. The voltage across the PWR and GND (J2 & J1) spaces was 0V:
>   http://farm4.staticflickr.com/3786/11016128584_20e6cba24f_o.gif
>
> 3. The voltage across the battery & the GND (J1) was 13.31 VDC:
>   http://farm4.staticflickr.com/3772/11016174693_48beeeeed8_o.gif
>
> 4. But the voltage across the battery & the PWR (J2) was 0 VDC:
>   http://farm6.staticflickr.com/5511/11015955585_26a8e37a41_o.gif
>
> I don't understand that.
>
> 5. The voltage across the electrolytic capacitor was 0V:
>   http://farm6.staticflickr.com/5508/11016126814_909b0dc00d_o.gif
>
> 6. And, the capacitor leads appear to have heated up at one point:
>   http://farm4.staticflickr.com/3795/11016173493_914e59eb22_o.gif
>
> So, could it be that the 16.VAC transformer opened up a secondary
> when the battery protection circuit opened up a capacitor?
>
> Seems unlikely, doesn't it? Especially just from turning off the
> main breaker with the generator kicking in the day before?
>
>
>

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.


tm