Connect with us

Seeking Schematics

Discussion in 'Security Alarms' started by Jeff Wisnia, Jul 5, 2004.

Scroll to continue with content
  1. Jeff Wisnia

    Jeff Wisnia Guest

    Hi all,

    My home is fitted with a 19 year old wired intrusion alarm which has
    worked faultlessly since it was installed by a sub to the the general
    contractor who built the place. The only service it's required has been
    changing the backup gel cell every few years.

    I'm a retired EE with many years of experience designing solid state
    control systems. I have the technical knowledge and tools to service 20
    year old electronics down to the component level. Proper documentation
    makes the job easier and avoids my having to "reverse engineer" a device
    just to find out what should be going with it's circuitry.

    The core Control Panel in our home's system is a Guardaware CU-22

    The followng accessories are also used:

    Moose Products, Inc. MPI-11 Siren Driver module

    Corby Industries Model 86 Latching Relay (Used to bypass an IR motion

    Guardaware LM-1 (I haven't yet figured out its function, but I suspect
    it might be used to blink the green "Loop Closed" LRD's on the keypads
    to indicate that the alarm's was tripped, after the "Burglar Bell"
    output has timed out.)

    We had some unusually severe lightening storms here last week which
    knocked out power to the neighborhood. Coincidentaly the CU-22 had the
    driver transistor for it's "Burglar Bell" output relay go leaky so the
    relay was pulled in anytime the CU-22 was powered by it's ac source,
    regardless of the Panel's status. Interestingly enough, if the CU-22 was
    running off it's backup battery the "12 volt" bus was lower by enough so
    the transistor leakage wouldn't quite pull in that relay.

    I was lucky enough to be able to troubleshoot and repair that one easily
    enough, but it caused me to think about future service needs. I do have
    the Installer's Manual which came with the CU22, but I'd sure like to
    get a schematic of the whole pc board to tuck away for the next time I
    have to fix it. Schematics of the accessory units would also be nice to

    I haven't been successful Googling up anything much about those items,
    probably because they're all nearly 20 years old now. I can't even tell
    if Guardaware, Inc. is still in business.

    Cany anbody help with prints or leads to places where I can get them?

    Thanks guys,



    Jeff Wisnia (W1BSV + Brass Rat '57 EE)

    "If you can smile when things are going wrong, you've thought of someone
    to blame it on."
  2. Jeff Wisnia

    Jeff Wisnia Guest

    Thanks, and while it's not the first time I've encountered
    manufacturer's apparant paranoia over stuff like that, I've always felt
    it was pretty short sighted, since if another manufacturer really wanted
    to get the design, it'd take at most a couple of days to trace out the
    schematic from the circuit board (particularly a single sided board like
    the CU-22) and to get what you need, proving it correct with a
    breadboard. I've even seen manufacturers sanpaper the labeling off of
    integrated circuit chips for the same silly reason.

    The world of electronics has of course changed since my CU-22 was
    manufactured, and what I just said isn't as applicable to the current
    crop of solid state electronics with their integrated processors and
    such. Hell, most electronic components are so darned small now that you
    practically need a microscope to see them, so tiny that there's no room
    Well for me it'd be *three* keypads and the little bit of additional
    work swapping them in. I did have a look around the web in anticipation
    of not being able to fix the panel, and it appears there's not much
    current stuff out there that would be a quick swap for the CU-22 and be
    happy working with my three existing "dumb" keypads which just give a
    momentary contact closure to toggle the panel's arm/disarm and a couple
    of LEDs to indicate "loop closed" and "armed". But if I'm wrong about
    that, please clue me in.

    I totally agree with what you say, for anyone in the business or for
    someone whose every spare minute is worth money to them or even those
    who would rather play golf or do crossword puzzles than fix broken
    stuff. But what applies to folks still in the rat race doesn't
    neccessarily apply to those of us who have successfully made it into

    I'm one of those odd ducks who delights in a doing a successful fix of
    something that only needs the right 25 cent part replaced to make it
    good as new. And it's determining just which part that is that's the
    challenge. I get as much of a kick out of that as I would solving the
    whole New York Times crossword puzzle. (As if I ever could.<G>)




    Jeff Wisnia (W1BSV + Brass Rat '57 EE)

    "If you can smile when things are going wrong, you've thought of someone
    to blame it on."
  3. Aegis

    Aegis Guest

    Do you blame ADT for the same thing happening globally across most
    (non-alarm) technical industries too? You've got engineers and trained
    primates... No room for the tech anymore.
  4. Jeff,

    You sound like a Bostonian. Retired engineer from Raytheon maybe?

    I have a few CU22 panels, used, but functioning. May even have some
    keypads for it. Most of my Guardaware installs were CU66's and a few
    CU88's. I still have a few hundred CU66's still operating in the
    Greater Boston area.

    I also have some Corby pads.

    Guardaware, a company from Brockton Masachusetts area, was acquired by
    International Electronics Inc. (IEI) and the original design engineer,
    Chris, may still be there doing his thing. I always thought Chris's
    ideas were ahead of their time.

    I've saved a lot of "junk," aka antiques, from the 1960's and forward
    that will probably end up in the collection owned by Ralph
    Sevinor of Wayne Alarm in Lynn Massachusetts.

    I still have several customers with CU22's that were installed by
    other companies a long time ago.

    Reply here if I can be of any assistance.

    This thread has reminded me that J. R. requested that I send him
    copies of all the Guardaware documents that I have. Was supposed to
    do it several months ago. Where does the time go?

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day