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

[technomaNge]

You shoulda got here a coupla years ago, Robert Bass would sell anything to anybody.

technomaNge

[Tony Hwang]

Hi, 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 relay?

[Tony Hwang]

[Nightcrawler®]

Ditch the old and get the new. Many available:

(Hey, I finally remembered to copy the proper link. I know, what a moron...)

[Danny D'Amico]

Thanks for that advice. The sticky tape was covering the traces:

So, following your advice, I peeled it mostly off, and looked with a magnifying glass as you had suggested:

The 1,000uF 35V capacitor leads are burnt a bit, but, it could have been a replacement cap for all I know, as the cap is not shorted nor is it an open (it's about 350 ohms steady).

However, the fact is that this sequence shows *something* is wrong with that D135A battery-protection board:

1. The battery is 13.31V
2. Connecting this way is 13.31V:
3. But, connecting this way is 0V:

[Danny D'Amico]

Thanks. If it comes to that, I'll start fresh. I have 24 zones to deal with though ...

[Danny D'Amico]

That's why I only want to spend the $104 to replace it. It *does* have overload circuit protection besides.

I've done plenty of smoke tests in my life. This will be one of them.

Heh heh ... here is a board I built many years ago to test impedence (j omega stuff). I wired a diode to house current! You'll notice the diodes. Particularly, you'll notice that the nichrome wire resistor has the same impedance as the the capacitor. (I couldn't find an inductor of a large enough size.) FRONT:

BACK:

Also notice this circuit, where I used 555 timers (I think that's what I used), way back in the 80's, to measure capacitance and resistance simply by counting the flash rate ... FRONT:

BACK:

I did those circuits in the early 80's but, of course I know about the shape of the diode curve and which is the anode and which is the cathode.

Everyone knows this basic stuff... even we accountants.

[doug]

Before you start pratting around checking diodes, capacitors and the like you should disconnect all the external wiring to the circuit board and power the board up on its own to verify that the field wiring or expansion modules are not the cause of the problem

Doug

[Nightcrawler®]

I hope that you realize that you are not getting a reading off of the capacitor. Most likely that is the resistance of the other components on the board.

[Nightcrawler®]

I am certain you may find something that works, and is probably better than the ancient thing that you are playing with.

[Nightcrawler®]

Great idea, Doug. After he removes the old system, and installs the new one, his pet project on the side will be getting the old system working. :-)

[tm]

Use the meter test lead (red) to touch the red battery lead to the output terminal briefly. You should hear the relay pull in. Then the power terminal should be at 12 volts. This board depends on AC power being applied to the alarm unit and some battery charging current needs to be available to arm the battery protection board.

tm

[Tony Hwang]

Hi, You checked the state of that Omron relay? Is it it NC or NO relay. Is the contacts closed now or open, is the coil OK? Diode, and Zener... If you are going after ICs, Huntron tracker comes handy.

[Danny D'Amico]

I used to use a capacitance meter (I forget what we called them way back in the 80s in one of my lab classes), so, I'm familiar with the fact that it's hard to measure capacitance.

However, I did think (errantly perhaps) that the capacitor would show as a short or as an open if it were "blown".

Since it showed with resistance, I wasn't sure, what I was reading. I *did* expect the voltage to climb slowly, since the meter would have been supplying charge to the capacitor's plates; so, the fact that the resistance was steady should have been a good datapoint.

What I will likely do is take a trip to RadioShack and buy a 1,000 uF 35V electrolytic of a similar size and see if I can wire it back up.

I wanted to first draw the circuit so that I could figure out how to test it though.

So, thanks for pointing out the faux pas in my measurement. I appreciate the correction.

[Danny D'Amico]

Oh! That would make a huge difference since the AC transformer is out of commission at the moment (waiting for the replacement to arrive).

Thanks for that helpful advice!

Maybe I should only test it with the AC transformer in place?

[tm]

Just bump it with the 12 volts from the battery. That will pull in the relay and latch the output. When the voltage falls below the 9 volt limit, the relay will drop out and disconnect the battery completely.

Just for the fun of it when you go the RS, you might pick up an in line fuse (3 amp or so) and put it in the red battery lead. that will keep the fire from starting. :) Get yourself a supply of fuses just in case. I don't see any fuses on the boards at all.

When you get this working, next thing to do is disconnect all the other panels from the main unit. Tag all the wires so you know where they go. That way, you can narrow down any power issues to just the main board.

[tm]

The bottom three terminals with the Green, Red, and red and black wires are the power to your external panels. Normally, the green is a data line, the black should be a negative 12 volt line and the red should be +12 volts. If someone mixed up that wiring, it could present a short circuit to the power supply and battery. You might want to go through all the mess and clean it up. A fault there could also explain the transformer failure.

[The Daring Dufas]

Easy pal, it's hard to diagnose a problem with even simple electronic systems without hands on it and doing things to test it that actually come out of your subconscious. I mean things you've done for so many years, that you do them without thinking. I'll play a hunch on gear that's broken because I've seen so many failures of the same type or similar equipment for many years. I often find problems using just my eyes and my nose. I use a small flashlight or my lighted magnifying glass to look to look for cracks or loose components on a circuit board. I often do a wiggle test on vertically mounted components like the filter capacitors to check for broken solder joints on a circuit board then I often twist the board when it's powered up to check it for bad or intermittent connections. It's often a big mistake to assume another fellow has done tests that I would do without thinking about it. ^_^

TDD

[Michael A. Terrell]

There is a hell of a lot that you don't know. None of these give you accurate information about a capacitor.

[Stormin Mormon]

A good tech on the scene can take meter readings, and observe things that us key board professionals won't see.