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

"Danny D'Amico"

** There must be a fuse inside that unit - wired in series with the 16.5V secondary. ** It's probably worn out . ** Open circuit testing a gell cell tells you nothing. ** The voltages on the transformer went high enough to cause a big increase in current and fuse failure, maybe something inside the alarm box failed too. ** Get a new tranny and a new battery and try them - the battery first.

... Phil

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?

I apologize. As the record shows (in alt.free.newsservers), I had a problem with aioe.org triplicating posts, which, after a while, caused aioe to drop all posts due to "too many errors". Pan, my news client, didn't tell me, so, all posts were lost.

So, I didn't have access to aioe.

When I asked what to do, people said to switch to Solani. But, Solani *forces* you to have a single followup! You can't possibly have a followup to the groups you posted to. I asked alt.free.newsservers *why* Solani does that, and, the answer came back they can do whatever they want (so, the point is, that it doesn't make any sense).

I can't win either way.

After a few days, Aioe let me back in (this is a recurring theme with them); so, hopefully, this will get to both groups (and also alt.free.newsservers) because I'll send it via aioe.

Of course, it could just go nowhere ... and I'll never know, because Pan won't warn me until it's too late (but that's in another thread to news.software.nntp).

** I see no warranty details - all "Lifetime Limited Warranty" means is that there is a time limit on the warranty.

Also, they claim there is a PTC in series with the secondary to prevent overload damage.

PTCs self reset once they cool down.

IME a tranny that is well made, moisture sealed and has a PTC in the output ought to last 10 to 20 years.

.... Phil

Me neither. I'll call them on Monday (they're not open weekends).

It has had plenty of time to cool down! I think the burnt plastic smell gives me a clue. :)

Ah. I see. Mine is at least ten (maybe twenty?) years older.

That would explain why it blew once, and then died. I did smell burnt plastic; but the garage doors were open so it dissipated too quickly for me to identify from where. It was only a while later, after testing it, that I realized the power transformer had blown.

I guess the good news is that the newer transformer will survive that, if when I put it in, that's the case of the shorted power circuit.

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

1. Battery hooked to power supply is 12.87VDC:
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1. Yet, battery hooked to PWR and GND blades of power supply = 0VDC:
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2. Battery hooked to just GND blade on the power supply = 12.87VDC:
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1. Battery hooked to just PWR blade of power supply = OVDC:
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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):

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.

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.

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?

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?

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

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:

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:

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:

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?

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:
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1. The voltage across the PWR and GND (J2 & J1) spaces was 0V:
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2. The voltage across the battery & the GND (J1) was 13.31 VDC:
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1. But the voltage across the battery & the PWR (J2) was 0 VDC:
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I don't understand that.

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

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:
   formatting link

1. The voltage across the PWR and GND (J2 & J1) spaces was 0V:
   formatting link

2. The voltage across the battery & the GND (J1) was 13.31 VDC:
   formatting link

1. But the voltage across the battery & the PWR (J2) was 0 VDC:
   formatting link

I don't understand that.

1. The voltage across the electrolytic capacitor was 0V:
   formatting link

1. And, the capacitor leads appear to have heated up at one point:
   formatting link

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?

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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.