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

[Tony Hwang <dragon40@xxxxxxx>]

tm wrote:
>
> "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
>