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

[Danny D'Amico]

I'm not sure what to make of these measurements:

1. Battery hooked to power supply is 12.87VDC:

1. Yet, battery hooked to PWR and GND blades of power supply = 0VDC:

2. Battery hooked to just GND blade on the power supply = 12.87VDC:

1. Battery hooked to just PWR blade of power supply = OVDC:

This makes no sense to me; but I'm not an EE.

Does this (repeatable) information above tell us anything about the power supply or battery?

Note: This dent in the capacitor was due to it being pressed down against the transistor (I pushed it away):

[trader4]

Don't screw around with testing it with a new transformer, buying a transformer, battery, etc. You have a battery that reads 13.5 volts without a load. Put it in the alarm. If the alarm doesn't power up and the battery still reads around 12V, you know there is more wrong than the transformer. Then you have two choices. Either find out what's wrong with the alarm and fix it, or buy a new panel. And if you wind up having to buy a new panel, they typically come with a battery and charger.

[krw]

A Simpson 260 isn't good, by itself, either. At 20K/V, it's not going to provide a significant load. A resistor (pick your poison, depending on battery) and any hi-z meter will work better. There is nothing magic about Simpson 260s.

I'd measure before replacing anything, though the battery is likely toast no matter what else is bad. Don't replace it until you're sure that's the only thing that's gone.

[Danny D'Amico]

The strangest thing happened when I took you up on your suggestion!

A. The battery, connected to the power supply, was 12.87 volts:

B. I also read 12.87 volts at the very edge of the power supply, so, the wires are good:

C. I then got 12.87 volts between the battery and the GND spade on the power supply board:

D. But, the strangest thing is there is no voltage between the battery and the PWR spade of the power supply:

I'm not sure what to make of those conflicting results.

[Danny D'Amico]

Yes. 13.8 volts is "normal" for an open-circuit voltage. The voltage is highest after charging, and then goes down, over time, depending on the type of battery.

I have no qualms about replacing stuff, but, I am trying to debug first, *what* needs to be replaced (other than the transformer, which is on order).

Right now, I'm trying to figure out why the power supply board has 0 volts across the PWR and GND pins, even with 13 volts at the inputs.

[Nightcrawler®]

What are the voltage measurements of the pins by the capacitor?

What connects to this connector?

What connects to J1 and J2 (GND and PWR post, respectively)?

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.

So, are J1 and J2 inputs with the connector being the output, or vice versa?

[Nightcrawler®]

The transformer is obviously dead. Replace it immediately. This will at least let you know if the system will work with the transformer functional. Step two would be to figure out what is wrong with the battery back-up. Have you checked for fuses, yet?

[The Daring Dufas]

That module attached between the battery and the panel is a battery saver module. The panel will work without it and I believe it's shorted out and is what blew the transformer. If you or one of your friends can repair circuit boards, get him/her/it to take a look at it because it's a fairly simple circuit. I would remove the module and hook the panel's power leads directly to the battery. Hopefully, the battery charging circuit on the panel's circuit board is not damaged. ^_^

TDD

[Danny D'Amico]

That's exactly how I'm (trying to) handle it.

I don't have any problem replacing anything that tests bad; but, just throwing parts at a problem isn't what I'm trying to do.

Of course, that means I need to look closely at the circuit board, as that's the first step of any diagnostic procedure.

Looking at the BOTTOM of the circuit board, I find something interesting at each end of the electrolytic capacitor leads:

It almost seems as if the capacitor overheated, but, it it not an open circuit:

[Danny D'Amico]

I just realized, that's *not* a power supply board!

It says it's a "D135A Low Battery Disconnect", part number

79-04360401 (where the last 4 and last 1 might be another digit).

Googling, I find these datasheets:

Which say: "The D135A works with compatible control panels to protect the battery from deep discharge in the event of an extended AC power outage. Disconnects the control panel from the battery when the battery level drops to 9.5 VDC."

I find an installation guide here, which explains that the sticky tape is because the module is supposed to be stuck onto the top of the battery:

[Danny D'Amico]

I don't see a fuse on the Radionics D2212 BLT circuit board:

And, I don't (yet) see a fuse in the Radionics D2212B LT diagram:

And, I don't see an inline fuse in the "rats nest" below the board:

[Danny D'Amico]

You are correct! I had thought it was a "power supply" but it's not. A sticker says it's a "D135A low battery disconnect", which is apparently supposed to be sticky-taped to the top of the battery.

Googling, it's a 9.5 volt cutoff (as you said, to save the battery from a deep discharge). I'm surprised you could tell that from where you sit, because I only just realized that myself now.

You seem to be familiar with this stuff but I must ask:

What is the "it" in the sentence above? The battery? Or the low-battery protection board?

Before I do this, may I clarify the suggestion?

Should I remove the D135A low-battery protection board, and then, connect the battery directly to the black and red power leads of the Radionics D2212B (LT) circuit board?

[Danny D'Amico]

Are you asking me to check the DC voltage across the capacitor of the D135A low-battery disconnect circuit?

Specifically these two points, where I had previously measured the resistance (with no power to the circuit) across that same cap?

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.

I do not know the answer. Here's a closeup of that relay:

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:

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:
2. The voltage across the PWR and GND (J2 & J1) spaces was 0V:
3. The voltage across the battery & the GND (J1) was 13.31 VDC:
4. But the voltage across the battery & the PWR (J2) was 0 VDC:

I don't understand that.

1. The voltage across the electrolytic capacitor was 0V:
2. And, the capacitor leads appear to have heated up at one point:

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?

[RTS]

Dud, it looks to me like you got a bad module.. the Cap is bad just to look at, and since you need the relay to close to pass the voltage to the terminals, anything in that hold-in circuit that?s bad will disable that.. discard the module, if you still need a low voltage disconnect feature, try

the Elk 965 will disconnect the power when voltage drops below its threshold ..

rts

Are you asking me to check the DC voltage across the capacitor of the D135A low-battery disconnect circuit?

Specifically these two points, where I had previously measured the resistance (with no power to the circuit) across that same cap?

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.

I do not know the answer. Here's a closeup of that relay:

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:

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:
2. The voltage across the PWR and GND (J2 & J1) spaces was 0V:
3. The voltage across the battery & the GND (J1) was 13.31 VDC:
4. But the voltage across the battery & the PWR (J2) was 0 VDC:

I don't understand that.

1. The voltage across the electrolytic capacitor was 0V:
2. And, the capacitor leads appear to have heated up at one point:

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?

[Tony Hwang]

Hi, First of all, did you check the battery by hooking up a 12V automotive bulb to really see it is holding good charge at 12V? Secondly remove one leg of diodes and check them, one may be Zener type. do the same with capacitor. Remove any two legs off the circuit and check that transistor. The other K1 is a relay, you can check it same way. Then go to next step which you are trying to do now. First thing first. If you can find a URL for schematic, it'll be lot easier to TS.

No power supply on your work bench? If so you can use it as well. I have a lab. grade power supply with several commonly used voltage o/p. Very handy item to have.

[The Daring Dufas]

"It" is the low battery disconnect. Connect the power leads you remove from the D135A directly to the battery to see if your system operates. I haven't worked exclusively in the alarm industry for many years but I would get into alarms from time to time. Your alarm system is at least

21 years old. The date code on the small round bridge rectifier on the circuit board looks like it was manufactured in 1992. ^_^

TDD

[Danny D'Amico]

It seems that all three test bad:

1. The transformer has an open secondary
2. The low-voltage protection module has an open cap
3. The alarm system simply beeps when I plug in 12VDC

I plugged the 13.5V battery, without the ELK TRG1640 ac charger and without the D135A low-voltage-protection board, into the Radionics D2212B alarm system board.

The alarm beeped continuously, without any other indication of working, and the current I measured was 98 ma continuous:

Can all that really happen simply by shutting off the 200Amp main breaker without also turning off the automatic power generator?

[Nightcrawler®]

[The Daring Dufas]

It actually looks like someone has replaced that electrolytic before. Oh yea, looking at your other pictures, it now looks like the board was manufactured in 1998. ^_^

TDD

[The Daring Dufas]

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. ^_^

TDD