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 outage
Location: Melbourne, Australia
Gender: Male
 |  | Odd electrical/telephony UE problem
< on 10/23/2003 9:11 AM >
|  | | | I recently got myself a menial job at the Defense Science and Technology Organisation at one of their laboratory complexes.
As part of my employment I have access to roam two buildings one of which is a semi-abandoned lab centre. This building is a total of seven stories high, five above ground level, and two below. The top four floors are still in use, as is half of the ground floor. The remaining half of the ground floor and both subterrainien levels are abandoned and have been locked down.
Naturally, I'm eager to explore. I've seen inside the abandoned sector once before and it looks extremely intresting in a foreboding way. Ever seen the TV show The Pretender? Remember SL27? Welcome to Building E. Intra-building security is basically non-existant, all security is concentrated at the complex perimeter. The only thing that stands in my way is an electronic lock, which my PIN code should open, but there lies the problem.
The site I've chosen or entry/exit to the abandoned sector is fitted with the same electronicly locked doors as the rest of the facility. This is an intresting telephone-based analog system I've never seen before. There's a 12 key keypad, plus an additional ACTIVATE button. To open the door, you hit ACTIVATE, this causes the keypad, which is connected to the complex's telephone system to dial a special extension (4799.) When the connection is established, the ACTIVATE button (which normally glows red) is extinguished and the other keys light up amber. You then key in your code which is transmitted down the phone lines and if all's well, the amber backlight turns to green and the door unlatches. The problem is this keypad doesn't work properly, likely as a result of being in a semi-abandoned sector of the building.
I found the problem, and it's in the keypad's connection to the telephone system. Said connection consists of a bunch of insulation-piercing spade/crimp lugs on the keypad's wires which connect to terminals in the phone box. The lugs and terminals both have oil all over them, and the lugs are coated in a patina of corrosion which distorts the audio signals and stops the keypad communicating with it's host properly. I've tried various methods of removing the grease and corrosion, but nothings worked very well. If the corrosion has worked it's way into where the spade lugs pierce the insulation of their host wire, I figure I might was well give up.
Anyway, the question at the end of this long winded prattling is can anyone think of an effective way to remove the corrosion and grease off the connectors to restore a static-free connection? I've been thinking of applying WD40 as I've heard that works for stripping off grease and corrosion, but I don't know. FWIW, the corroded lugs appear to be made of brass.
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NoSuchPerson
     
Stop, or I'll ask you again!
| | Re: Odd electrical/telephony UE problem
<Reply # 1 on 10/23/2003 1:16 PM >
| | | | Well, that's assuming the problem lies in these connectors.
Since it's only telephone voltages we're talking about here, you might be best to chop the connectors off and put new ones on.
But yes, WD-40 would work fine, just let it dry before you connect it again. You might also try fine-grit sandpaper.
You can also buy, from RadioShack or whatever you have over there, contact cleaner which is more or less made specifically for this kind of thing. It's not meant for large amounts of corrosion, but it could do the trick.
-Ex
Unit calling radio say again? |
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Chainsaw
This member has been banned. See the banlist for more information.
Location: Underground, Colorado
Gender: Male
| |  | Re: Odd electrical/telephony UE problem
<Reply # 2 on 10/23/2003 1:18 PM >
| | | | The connectors are cheap enough, just bring a wire cutter - cut off and remove the eroded connectors and either replace them or just wire directly to the terminals. WD40 is good for keeping corrosion from happening but not so good for removing it, try a little wire bristle tooth brush to clean up the terminals before you reattach the wires or new terms.
-Just in case you don't know - those phone lines carry a good amount of electrical current, please be careful if your pulling wires and reconnecting terminals.
[last edit 10/23/2003 5:50 PM by Chainsaw - edited 1 times]
Quid latine dictum sit, altum sonatur.
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DarkTreader
Gender: Male
| | Re: Odd electrical/telephony UE problem
<Reply # 3 on 10/23/2003 5:33 PM >
|  | | | Or if you'ev got time to work on it and want to make sure its all clean, put some coca-cola in a shot glass or some other small cup thing, put the connectors in it, and leave it there overnight. If the corrosion isn't off by then, its not coming off.
Hell, I figure if it works for spark plugs, it should work for this too.
footsteps light, flashlights bright
-~ DT
Losers go home... winners go home and fuck the prom queen |
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statik
Location: colorado
There has got to be more to life than just being really, really, really, ridiculously good-looking.
| | | Re: Odd electrical/telephony UE problem
<Reply # 4 on 10/24/2003 12:19 AM >
| | | | I'm probably way off base, but...
Why not bypass the keypad?
I'm thinking that if the door panel is wired directly to the phone system, it has to use DTMF tones to communicate with whatever system locks/unlocks the door.
Also, I'm assuming you already know the code
So, say the corrosion is so bad you can't get anything out of it:
Render the DTMF sequence with a sound editor like SoundForge, export to .MP3, and save it to an I-Pod or something.
Wire the headphone out to the main line behind the keypad, and play the .mp3 file.
The phone system shouldn't be able to tell the difference, and should unlock the door.
-Statik (purveyor of overly-complicated problem solutions since 1979)
None more black.. |
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Macsbug
Noble Donor
Location: St. Paul, MN
Gender: Male
Safety First!
| |  | Re: Odd electrical/telephony UE problem
<Reply # 5 on 10/24/2003 12:32 AM >
| | | | Posted by statik
Wire the headphone out to the main line behind the keypad, and play the .mp3 file.
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The keypad could be crap too, thats a good point.
Instead of spending time recording tones, you could also just bring a small phone with, and aligator clip it to the lines. (or a linemans handset if you have one)
"Believe those who are seeking the truth; doubt those who find it." |
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outage
Location: Melbourne, Australia
Gender: Male
| | Re: Odd electrical/telephony UE problem
<Reply # 6 on 10/24/2003 6:02 AM >
| | | | Thanks for all the suggestions.
My first thought was simply to replace the connectors, but they seem to be hard to source if you're not a contractor buying in bulk. That link I posted is the only retailer I know that carries then, and they might not actually have any in stock according to their website.
I've given a lot of thought to bypassing the keypad. I borrowed a test phone from the PABX room and listened in on a working 'pad's transmissions which is how I know the number it dials (the test phone has an inbuilt DTMF decoder). When ext. 4799 picks up, they squack at one another like modems, but only for a maybe one second. The keypad transmits a non-DTMF tone to x4799 for each key pressed, and the central computer answers with one aknowledgement tone per key pressed. The ACK tone differs depending on what number has been entered. After that they squack again, makes a faint 'pop' and the door unlatches. I was thinking I could record that last tone burst, and play it back to manually unlatch the door without the central computer ever knowing a thing.
I'll try cleaning the contacts again - I could probably soak it in coca-cola overnight without anyone being the wiser, and if that doesn't work I'll look into by passing the keypad. I think the simplest solution would be for me to go back to the PABX or maintenence room and try to find a spare, new keypad and plug that into the line. I've searched before I posted for the first time, but haven't found one yet.
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Ben
Noble Donor
Location: Mojave Desert
Gender: Male
| | | Re: Odd electrical/telephony UE problem
<Reply # 7 on 10/24/2003 11:59 PM >
| | | | I don't remember a whole lot from my phreaking days, but I do remember that a ring tone is about 100VAC, on hook is 50VDC and off hook is three or five VDC... or something like that.
Anyway, is it possible that the pop at the end is the computer changing the voltage, and it's just directly wired to a solenoid? I'm wondering if it's possible to just jump start the lock, with no need for a signal.
No matter what, it doesn't sound like a very secure system, unless there's more to the squawk than first appears.
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NotHere
Location: NorthSouth Ontario
Gender: Male
| | Re: Odd electrical/telephony UE problem
<Reply # 8 on 10/27/2003 12:47 AM >
| | | | Wait, so your bosses have no problem with you wandering about where you don't need to be? You're keying in your own ID number right? BTW, did you get through yet?
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outage
Location: Melbourne, Australia
Gender: Male
| | Re: Odd electrical/telephony UE problem
<Reply # 9 on 10/29/2003 6:37 AM >
| | | | Technically, it isn't a forbidden area, but I don't plan entry until the Christmas holidays when the place operates on a tiny skeleton staff.
I did soak the contacts in Coke. I filled the little bottle from one of those nasal sprays with the stuff and left it to soak overnight. It turned the corrosion a very intresting shade of pink, and lossened it so it came off easily with steel wool. Unfortunately, much of the inside of the connectors (where the electrical contact is actually made) was unaffected. I assume gas from the fizz pooled inside and stopped the liquid from penetrating. Anyway, it's still an improvement, and the pad now actually works one in five times. I've just had a little look in the immediate area on the other side, and it looks pretty promising.
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Mister Hobbs
| | Re: Odd electrical/telephony UE problem
<Reply # 10 on 10/29/2003 1:48 PM >
| | | | Caveat: It all depends on precisely what type of access control system it is, if it was properly installed to begin with and what purpose they wanted it to serve when they installed it. Removing the power from some of these strikes will open them because some of them are installed to automatically open in case of fire or power failure so people can exit. Others have the push bar override, etc.
If it is a low voltage strike controlling the door, you can usually remove whatever reader or keypad is involved and trace down to the power source for the strike. You can take a 12 - Volt NiCad battery that is properly charged and power the strike after checking polarity. Most readers / keypads on the outside of buildings have a spring tamper (microswitch and small coil spring or button) wired into the alarm system to prevent this. Some on the inside of buildings do as well. You won't know that unless you know how the system does or does not interact with the alarm system, assuming one exists at all. Couple screwdrivers, wire stripper, two wires with alligator clips and the aforementioned battery, small flashlight and perhaps an inspection mirror...a Multimeter would not be a bad idea either. You don't want to get a freak system that is running high voltage and find out the hard way.
This is just a way to get in, if the system is alarmed, you will find out quickly.
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tbone
Gender: Male
| | Re: Odd electrical/telephony UE problem
<Reply # 11 on 11/2/2003 2:09 AM >
| | | | wow, you actually solved the door problem ? my experience with things like that is you're always disapointed in the end
but it sounds like you've got it licked, good luck on the other side!
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