Interest Has Shown In How Older Alarms Were Repeaired Using Very Basic Kit
Entry posted by arfur mo
12,779 views
i have been around a long time in the security trade, some people have expressed interest in 'how it was back in the day' for installtions, fault tracing in repairs and so on.
this is a blog for me to take a walk back in time, hopefully of interest to others, and for the students perhaps to understand something of why and how alarms developed in the way they have.
i hope i can be considered as a valid reference on that time spanning now 43 years, having lived through many wiz-kid inventions that were though of as the next best thing only to fail for often the most obvious reasons, and the time spent to sort out what was wrong with them, and why the test bench s not always correct reflections in real life use.
a lot of info to come, i wil compose this off board and try to lay it in some logical sequence, but technlogy develop ment is not linier, so many devices happened along the way, which were sometimes a step forward but often a backward step.
========================
I did consider not bothering, several members having asked me to continue, the deal is this blogg is off limits, i.e. not open to the usual insulting comments or behaviour by some, if you don't beleive then your cordially invited to stay smugly SILENT!
i'm happy to discuss or explain further and will put up with some jokes, but if it gets out of order or nasty, i'll simply ask for it to be blitzed by the mod's. That will at others loss because i already know the facts.
i won't ever claim the following is a completed catalogue of all the kit i have ever worked on or seen. that would simply take far to long to write, even using dragon dictate. Some works is covered by Oficial Secrets Act, while other of little consquence today like murcury filled roller shutter contacts 
..
it attempts to cover i hope the more important, along with short observations taken from my experience.
please also remmember, some of this content is recalled from my distant memories of over 40 years, and kit that was lder than that at the time i dealt with it, i can't claim total accuracy - even for events last week 
.
The following is an insight into time spent in security systems and also I hope an interesting look how things moved on over these 43 years and perhaps why I sometimes seem intransient to some in my ways.
What I have wrote is not to show off or me to claim to be an authority, it is a complete history of every device, just some of it as it was and sometimes still is.
Many innovative wonderful items pushed as the ‘golden bullet’ I have seen an early end in the trash can, often after glaring oversights appeared. So while I do embrace new technology and idea’s, i also view with a very jaundiced eye. Where I can I’ll try out something at home or at understanding friends/clients who are the best aid to discovering such hidden unforeseen pitfalls before they are sold on.
I started my career on ‘special projects’, this department specialised in high value high risk works like banks, museums, art galleries, high end houses, I suppose would be grade 3 or 4 systems. The engineers were all indentured time served ex sparks. This was because banks required conduit work for cabling vaults, and mineral for the EWD (we called it the SAB then), so I was taught these ‘arts’ by some very good sparks attracted by rates higher than JIB.
I already knew how to read a meter, that’s due to my older brother (by six years), he was well into radio and Tv had taught me the basics on his highly prized AVO7 and AVO8 meters.
Back then, training on CHUBB was for a year at least, only then did you make it to Grade 3 (engineer under supervision of a Grade 2), your training engineer and supervisor had to recommend you, and then the manager reviewed it.
To then advance to Grade 2 was not given out with corn flakes, you took a very serious written and practical test running into 30 odd pages, and your quality of previous work was also looked at by your supervisor who had to put you up for it, so you fouled up it was on his plate.
The written part meant you had to know lock, stock and barrel every panel, every component and what it did or did not if it failed, from the current kit right back to year dot. The panels only had terminal numbers, something that only changed a year or so before I left. I was told this was considered security in case you were overlooked. Not sure I think that it was ever needed, we would not allow being over looked with the panel open by anyone, night have saved a few pcb’s from a fiery destruction while being changed when good engineers were out on their feet making unusual mistakes due to work load.
Grade 1 was not a reality, at my time I did not know of anyone getting it.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Burgot Panels.
Burgot panels were for the time I suppose very ‘revolutionary’, being double pole ‘feed & return’, this meant the circuit power was supplied (fed) from the panel, having gone around the protection ‘returned’ to the panel much as they are today.
The zone outputs were not fused, and often powered detectors like low voltage IR Rays from the zone ‘feed’. In those days it was nothing uncommon to have a couple of rays on the same zone as several door contacts, which made for some ‘fun’ fault finding, but that was accepted practice.
The box back hinged down after removing a single screw for servicing, all connections were on the back plate terminal blocks, it had a ‘G’ plunger contact as a tamper but that was only effective when armed.
Unlike just any other panel it’s cabinet had a hinged lid, these lids locked which was just a simple cupboard lock, and every panel had the same key. It also had no electrical connection, in fact the panel was operated simply by a big rotary switch in the middle, and toggle switches which acted as zone isolators, the locked lid then covered the switches and ‘prevented’ un-authorised operation, to day that would be seen as very naive.
The fact the lid had no tamper contact, but did have a lid contact which acted for if the lid was open to disabled the trigger to the ‘999’ transmitter (called imaginatively the ‘9’er’). The idea being, if the client turned the main rotary switch while system was in fault to ‘ON’, then it stopped a false 999 call, but not until very much later it was it also realised, if the client did not close the cabinet lid or the switch failed due to adjustment, that also stopped a real alarm being transmitted via the 9’er.
This design error was replicated even on Hi Security Bank Control Panels at the time, but I don’t know if any lose was ever sustained because of it.
Zones.
In these panels they used a simple self latching relay design, the current to the coils is passed through a set of the relay springs, remove current and relay deactivates, I zone closes the springs prevent that relay from puling up again maintaining the output to the bell until the rotary switch is returned to ‘off’.
on later panels there was an indicator light fitted to each zone so in effect this is a very early form of alarm ‘memory log’. When compared to today’s modern panels and the range of info gleaned while a very crude step forward, at the time this was of a massive benefit to fault finding.
Chubb Alarms Start Up.
I passed my Grade 2 test soon after Chubb bought Burgot and Rely-A-Bell to make Chubb Alarms, this meant we had to learn a whole new concept of alarm panels design, Rely-A-Bell in common with many other main players such as Brocks, AFA and I think Abel used the more traditional style panels (a design I believe originally by AFA) called rather charmingly a ‘lock block and coffin’.
The ‘coffin’ being the equivalent of today’s end station, and the ‘lock block’ = the remote keypad.
R-A-Bs ‘end of line’ all battery design.
In simple terms, the circuit batteries were electrically at the far end of the zone, usually located in the male toilets, or if in a dwelling in the cloak cupboard along with but not next to the panel. They were 3 x 1.5v very large ‘Q’ cells joined in series to make 4.5v, the control panel had 5 x 1.5v smaller ‘QS’ batteries also joined in series to make 7.5v. held in the ‘coffin’
The ‘Coffin’ had a removable plate, which had either 2 or 3 relays on it, the third relay was for ‘999’ transmitters.
The to main relays each had a slightly hooked lever attached to their armatures to act as an interlock, the circuit relay was 1k1 (11,100) ohms, this was to keep current consumption down.
When setting, user turned key switch which started bells or an agro buzzer, on closing the door and pressing an external button, this silenced the bells if all was well, the mechanical latch allowing second relay to drop, now if the zone is broken the circuit relay drops, with both dropped the bells ring.
On re-entering, bells sounded (if not already ringing), but the 999 is defeated by a Chubb Lock, then turn the key on lock block and press the lock block button, which pulled up the ‘second’ relay, allowing the latch to re-engage stopping the bells.
The older generation would say “I hear alarm bells wringing all the time in the high street, and nobody takes any notice” which was fairly true of there youth, and why it eventually it changed to silent set, for the benefit of many being less disturbed in there slumbers.
I’m sure some reading this will sneer, by today’s standards a very crude design, but then remember this design I started to work on them, 40 odd years ago, it was already in play for well over 50 years.
Protecting very high value sites and homes, earliest versions were actually made on side from scratch by the engineers, using fruit boxes and brass shim plate cut precisely to shape. The relays were hand constructed and wound on-site. Sheer quality all the way, even down to the varnish finish and the insignia penned into the wood by hand then lacquered, were simply in my mind works of industrial art to look at.
This was the sort of kit if you removed it for an upgrade then i got pangs of guilt for such an act of such desecration.
EWD’s were commonly a ‘straight ringer’ no backup pcb fitted, tamper was by a wire loop passed through the vents, knotted and then insulated with sleeving. They did have a ‘high security’ EWD, which worked SCB mode, having 5 QS cells in the back plate, these were the exception rather than the rule.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Record based 999 Transmitters.
For both companies earlier versions of these were based on modified clockwork record players, involving cam’s, cogs, pulleys and a battery operated valve amplifier. The more elaborate versions used a standard phone dial, with and an arm and peg that pulled it round to ‘9’, it then dropped the dial allowing the ‘9’ to dial out by it’s own spring to then jack it back up and repeat the process.
Resetting one was a tedious task if fascinating, having to re-wind the motor, line up several cam’s and levers, never felt being totally sure you had got it right.
Later versions were specially made, used pre-recorded 45 disk’s, machines were all 12 volt operated with electronic pulsed relay dialling. Some had line fault monitoring while others also had a delay based on the tone arm reaching the stop. These were easy to reset with a key, confirmed by a geen light.
Problems.
If the machine got a clump the tone arm could be knocked most way across, so no activation little or no voice message transmitted, so Emergency Services had to trace the call. Could be defeated by a thump on the side to send tone arm across record if you got to it quick enough (we often did this if you tripped it in error).
AES 999 8 Track Transmitter.
This was a very good unit, once tape machines arrived on the market recording a new message on change of client was achievable on site saving a lot of time. The 999 pulse was derived from the tape.
Problem
Very few, if anything the message was interrupted by the mechanism changing tracks.
AES Continuous Tape Loop 999.
As above advantages of tape and changing recordings,
Problems
Prone to drive belts snapping and tape cassette jams.
I worked for Combat Alarms, they had their own central station which was also where tapes were recorded. You had to ‘hand over’ the recording by testing with NSY. SO you’d listen in and hear -:
Police! Police! Police! This is a Combat automatic alarm system reporting from blah blah, this was repeated until the tape run out so about 15 times. Sometimes during the recording a system would signal resulting in half way through to Police Pol RING - OH SH!I – Police! Police! Or you’d here the guys telling rude stories in he back ground.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Mortise Locks
From before I started until I left employment to start my own business mortise locks were commonly installed, used early days as simple bridge across the final door or staff door contact/s needed to get in and out as ‘silent set’, later actually as the final set device. Timed exit entry with no lock came into fashion about 2 year approx before I started my own firm.
From initial employment I was taught how to fit mortise locks as we had at least one on each installation, and further training with Chubb Locksmiths. Over time i have serviced and fault found on countless Mortise locks of many types and design, mainly the Chubb 311G but also Ingersol and Brammah even ERA being most popular. Often we had to fit the contacts in the clients own lock to retain the keys already bought, this is where often your ingenuity was tested.
Problems – they caused to many to list, Some Chubb keys have long outer ‘fingers, these get easily bent if dropped, getting extra keys cut can be a pain as the key cutter often squares them instead or round profiling as the original. Door dropping or warping would make for difficult operation, someone would then squirt oil in often causing a complete lock up.
Seem people always had about 5lb in weight of other keys on the same keyring, the excessive friction this caused on the brass key guide against the harder steel quickly wore it away, so key alignment would be less than accurate – cue more oil.
On Chubb locks this key guide could be flicked out of position on key withdrawal, preventing the key being re-inserted next operation, simple enough to fix just getting client to do so not so simple to explain lol!
Another big problem on many calls, was the casing screws come loose, the springs would then slip out of position, resulting in the levers not being in the right place to align, not so bad if door is open but if shut and again if oiled then OMG! sometimes only way was knock out the hinge pins to get door open without damage as long as no hinge bolts fitted.
A smaller fault is build up of muck on the tongue, this could caused the lock to stick either in or out, when these locks were used as simple shunts, this muck if left would often cause the key holder to test try for the right key with the door open, resulting in an activation. With bell delay they were often not aware It had been tripped so left for home as normal only to be called back.
Brammar locks - were very secure, but the thin slots in the tubular key just invite tiny bits of grit and fluff, very few kept the nylon cap on, which helps stop that problem, also helps protect the key when dropped from closing those slots on impact.
Not sure if the right name, I know them as ‘Ronis Locks’, barrel lock used on many control panels, a little similar to Brammar in the sense the key was sa tubular shaft, but with indents instead of slots. Imo were a good lock but had a regular problem where the keyway slot would be out of align, the simple quick fix if you had no spares was to file off the location pip on the key, put the lock back in right place tell client use a ‘good’ key or issue new keys when available.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Door Contacts – well where do I start?.
At the time I joined them Burgot were still using Open Circuit door contacts (called ‘B’ Contacts) along with open circuit pressure pads. Burgot had really only just started changing over to Closed Circuit G contacts on domestics. These were flush mounted to the hinge side of the door in the jam, usually about 6” from the floor. They had a brass plate and a black plastic button sticking through it, closing the door simply pressed in the button with no adjustment catered for.
Problems
With both types wear on heavy use doors, and high resistances or intermittent operation in the internals caused many false alarms on the G contact, their usually low dawn location alo cause more dirt ingress.
Pye Micro.
As suggested these are a pye micro mounted on a metal plate flushed into the door frame on the hinged side. Possibly seen as a bit more difficult to overcome than the ‘G or B’ contacts above, having a spring loaded plunger which entered the plate holding the pye micro switch to depress the micro switch button.
Problems
Plunger would stick or get painted while open, often stopping the plunger entering far enough, and or busting the pye micro if jammed out. As the plunger shafts lubrication fails, just slamming the door could also crack the pye micro making it intermittent.
On earlier Rely-A-Bell systems the door contacts were hand made, the door having a wooden bar covered in copper on 2 sides, which when the door closed entered a large ‘kerry clip’ also made o copper. Current then passes through them. These had to be cleaned with emery cloth on every PPM to reduce intermittent connections.
Problems.
Obviously crude cleaning needs, but could also be bypassed with clipped on wires, but I’ve never seen it done though.
Roller Shutter Lever (Leaf) Contact.
These used to be a long arm attached to a plate, the arm would be so placed on the roller shutter roll at the top, as the shutter lifted it also rolled up the shutter, and so the lever would move until the micro switch was activated.
Problems
To be fair they were pretty reliable, in my opinion there are conflicting pro’s and cons when comparing advantages against magnetic contacts as fitted to the floor today. With magnetic it is possible to bust the shutter leaving the rail on the floor in place, water ingress has never been conquered properly, try all that with a ‘leaf’ roller shutter contact for reliability.
Pressure Pads.
Not that long ago these were still used widely, one of my worst hates as a service engineer. 3 types were in play.
Foil sheet – vinyl plastic envelope having 2 separate foil sheets, separated by a thin sheet of perforated foam, pressure would cause the foam to compress allowing the foil sheets to touch and create a short.
Problems.
Plastic envelope would deteriorate allowing damp ingress and earths, hoovers would pull the matt to be sucked along, often breaking the anchors, causing above more damage.
Client drops one of or a pack of pins, this works though the carpet, punctures the pad. Normal foot fall causes this pin/s to make an enlarged hole so it now intermittently shorts out.
Grid – Metal stripes crossing separated by foam material,
Problems
Much as above and lose effectiveness after shorter period.
Chubb had a capacitive balanced one (Closed Circuit), you could leave a chair on it and allow alarm to set, it would detect it being moved or pressure increased, decreased when set.
I Don’t know if they ever got it sorted, as you had to ‘balance’ the circuit. I think issues with changing humidity and temperature were a problem at my time.
Reed Magnetic Contact.
20 mm Flush Plastic. - Magnet section prone to separate from plate, depends on hole depth and position. if in top of door magnet drops or if happens on side locations simply rotates causing sporadic ‘can not set’ issues or false alarms.
25m Flush – Again mainly issues with the magnet, bolt or rivet comes loose and magnet rotates or falls inside door.
Susceptible to dropped doors, before drilling I check door for gap, then for play by lifting the leading edge, often the top hinge screws just needs a tweak, once done I check the door can be held closed properly, even adjust the latch if needed.
Some will feel that’s the clients responsibility and that’s very true, just I’d personally rather do what it takes especially if and only a few seconds involved, than be back in 3 months for CNS’s and arguing the toss.
With flush contacts on PPM I run a simple test with a screwdriver over the magnet, if I can here a heavy click or rattle I remove for inspection and any needed remedy.
Surface contacts – Have a more forgiving nature to warped, badly fitting or dropped doors, metal versions have less problems with water ingress, than plastic counterpart versions or concealed contacts.
I have posted about contacts in general the Grade 3, personally feel if the site warrants G3 then leaving a single door contact (of any sort) would be just madness no to fit a secondary motion sensor so In my opinion that makes the need for G3 contacts with such attributes meaningless.
Monoptic Rays
Amongst the earliest of electronic detectors, was mains operated ‘Mono optic Rays’ with a 1000 ft range, no battery back-up back then Guys. Rays of all sorts were often bounced by mirrors around a warehouse or large shop, one mirror gets a tap you could be ages on your own re aligning.
Problems – had to be careful about sighting, we used to quite often pass the beam through glass display cabinets, until cold weather would cause condensation of the glass and false alarms. Birds were a problem along with sunlight, so it became the ‘norm’ to fit 2 beams 18” apart transmitter and receiver each end t reduce false alarms.
Ultra sonic detection was very popular, easy to install as opposed to lace wiring.
Problems
telephone bells would set them off, you had to dull them with tape on the ringer, time clocks the same, also escaping air from compressors, you literally walked in to a job and listened for any causes – I still do this even today though I have not used them for over 25 years.
The earliest AES made ‘one bar fire’ was very good, let down by the rubber bands that suspended the ceramic transducers, Advisor brought out the Advisor 3 and Advisor 1, in my view amongst the best ever of the tech type, but the transducers were connected by push on plugs which was a real weakness.
Micro Wave Detectors
Also vied for our affections, while they ignored phone bells they had their own issues being as they could go through walls and see water in rain or W.C. pipes, not wonderfully stable possibly the best was made by PEAK.
I think I can lay a fair claim to have thought of and installed aversion of the 1st ever dual-tec at, Ratners Jewellers (remember him/them and tat!?). Shop was under the railway bridge in Southend High Street. Plagued from day one by false alarms from the detector in the ceiling, why it was ever there I don’t know, not many brave enough to dig through a mainline station track.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
So one night having been out twice in one night, i whacked in a suspected faulty ultra sonic in parallel with MWD, nervously (because never been done before) I thoroughly tested it for catch and all is ok, got a signature = silence for 4 weeks. But now I get pulled by my supervisor, bitching on about the extra expense of this detector, I get a royal rollocking and he insisted I go in and remove it.
I agree to go back and take it off – but he had to do all the attends. Took just a week for him to put it back, after the manager of shop steam roasted him for more false alarms, should have lodged the patent.
Vibro’s
Basic vibration sensor, often used glued onto glass windows. Shock would cause the spring weight to ‘pop up’.
Problems.
Sun would cause adhesive to deteriorate, often dislodged by window cleaners, crude adjustment.
Metal Foil.
Two main types, self adhesive tin and no self adhesive with more lead content. Either run like lace wire on plan glass, as a stripe around the edge or a strip 18” from lower window edge, covered in clear lacquer as insulator against moister shorts.
Problems.
Will often crack at any right angles so corners or onto foil blocks, prone to window cleaner damage, and condensation moisture especially during autumn to spring. Difficult to attach foil onto already damp windows. If lacquered while condensation was prevalent, lacquer would go milky white. Windows sometimes cracked under the foil without breaking it, have seen hole cut in plate glass bypassing the foil.
Inertia Sensors.
Used by the thousands, attached to walls, alarm bars, windows, door frames etc some were independently indicated others not.
Fine when they were reliable, pia when not. They worked by having a small gold plated ball, sitting on gold plate pins in a round housing. Rotating the casing altered the angle of the pins or weather Closed or Open circuit use and also the individual sensor sensitivity. Units wired were back to high speed interface and used an EOL.
Problems.
Influenced by action of fork lifts in adjacent buildings, or passing HGV’s, sensors would go high resistance.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Volurado Radar
This was hawked as the big labour saving device of the century, alarm equivalent to the cat’s eyes for roads, one box in the centre of a building, 2 aerials covered above and below – brilliant!
Er! actually No, due to its elliptical pattern, would be ok perhaps for a Wind mill or an old Oat House, but to get coverage to the ends of an oblong building would mean detection over spill at the narrowest points i.e. that’s often in the middle, going outside the protected building.
Once realised, installation engineers spent months fitting chicken wire to the inner walls as a shield, but eventually ripped it out in defeat and loud 
from all in the service department.
Systron Donnar.
Chubb bought into this French made kit real big time, after the joys of the above you think they might learn prudence. Placed one transmitter centrally and several receivers on the ceiling, these were cup shaped transducer (which was the basic down fall of the design).
Dust would enter the cup then gravitate to the middle, where it would then be compacted by the ultrasonic vibrations into tiny balls, rattle and altering the frequency.
Back then I could actually here if an ultrasonic detector was doing this due to the harmonics, but told clients I had a ‘gift’ akin to water divining .
I have avoided sensors I’ve used in high security sites as a matter of personal integrity, while many detectors I’ve seen seemed wonderful on paper and in theory, but most had hidden and some very serious gremlins, if you know of some ‘disaster kit’ please mention it, and if I know any history I’ll post it, an example follows -:
Capacitive Locker Alarm.
Never used it in anger, was I think of AFA origin but dug out of a junk box by my MD (ex AFA) and given the challenge. I managed to repair and installed it in Shields Training room as a demo. This kit was designed for golf and swimming clubs etc changing rooms, it used a wire attached to metal lockers which were placed on a rubber insulator matt, the idea being a human touching the locker altered the properties of the capacity in the immediate area, problem was, so will humidity, damp and ambient temperature.
Fault Finding ‘old school’.
I suggest a lot of the basic techniques still apply, I use many of the tests taught and also self devised along side new ones. To get a flavour, we did not have any fancy dan calibrated meters, Chubb issued a ‘minitest’ swing needle multi-meter, while having a massive maximum of one amp range for dc current. When I moved to other firms engineers supplied there own.
A scheme was started where capital tools were bought, you paid a 1/3 of pre vat cost, if/when you left the kit was yours. Imo a very good idea as this meant engineers had a vested interest so looked after it far better. you also chose kit you liked to use, which was often far better than the firms owned issued kit, and the firm did not loose all the capital investment when kit ‘walked’.
Lace wiring on ceilings walls even floors, and door contacts early on in my service life, were the main form of detection. Conscientious engineers tested for signs of faults every ppm. So apart from testing the batteries you looked for signs of damp, rodent infestation and so on, the ethos was a fault prevented is better than attending early hours.
Commercials often had many yards of lace wiring all under hardboard, also windows covered with tube and batten frames, so many faults were hidden from naked view. Sweat shops would often hang pattern’s or garments on the alarm bars, eventually breaking the wire and or tubes. Then try to avoid paying a service call, make what were tangled ‘fish hook’ connections. As I worked through my area I would replace damaged bars, this made it far easier to spot self repair potential faults, often without getting the meter out I’d point my accusing finger and rollock them, impressed they could not escape my all seeing eye - with a simple trick.
That repair may well work fine for a few months even a year, but it will gradually corrode and go intermittent, meanwhile it gets repeated elsewhere on the system. I think the record was 37 ‘fish hook’ repairs inside one t&b bar, it was simply a string of tangled knots. I like a quiet life at work, so I nailed down my area’s a.s.a.p. for my own benefit. On the smaller jobs when first taking over a new area, 1st visit rip it to bits, redo every connection I can find, get a nice steady meter reading.
Fault Finding pre-amble.
You get called to a reported false alarm, on arrival I will always question the client very closely about the event, go over it a couple of times to glean all the info, look at what they say and how they say it to compare what they state happened and what I know can actually happen. Early days this was the way it was done, you simply have to assess if fault is a client error, a system error or a design error, these days with the comprehensive logs available life is easier to detect the problem or if there Is not one, if read properly tells you more info than I ever had on past systems.
Unless you know the person well, I start from the point the Client will lie to some extent, either to avoid a charge, embarrassment, or if it is a servant/employee they may well be scared of a roasting or loosing their job. Some embellish so as not to look ‘thick’ to you, we all have a basic level of pride, so best let them feel more at ease. Don’t ever ridicule as they may then give up a vital bit more info - simple as.
Developing a line of gentle cross questioning is a technique that will help you sort the chaff from the wheat, can often save you a lot of wasted time looking for ‘red herrings’. Clients will learn after the 1st visit it’s far easier and cheaper to come clean, than try to ‘snow’ you, but some will always try whatever the approach used.
I’ve laboured the questioning area as it is one of your best fault finding tools.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Moving on to now with an ‘old style’ system.
Typical zone of the time has 10 8 x 4 panels of lace wiring under hardboard, 3 doors all wired under hardboard and the ceiling/s, remember this was all on one zone and some had far more than that. So “where the hell do you start?”, Is the first question off the trainee.
Always ‘WITH THE BASICS!’ Here I am talking old battery systems I dealt with same applies with a system installed an hour ago, after an alarm the zone now shows ‘clear’. Having checked the doors are secure, testing the zone batteries and connections was first action Make sure connections are tight in the panel. Remove the ‘return of circuit’ pair and test with meter on current. Current is used as your meter presents almost a dead short, the wiring and connections are then asked to pass far more current than normal. This results in any intermittent present or developing, showing up on the meter with far better tell tale deviations, than using just ohms or voltage.
You need at least a 100+ ma coming back for reliable operation, while the draw is only a few milliamps, available current should be well above that on smaller systems. Experience helps you guess approximately what to expect. If metering on Ohms, a rule of thumb was 5 ohms per 8 x 4 wired panel, 2/3 ohms per door contact, add in a little for cable run and so on.
As our meter of the time only reads up to one amp, if you get more back on a small zone, reduce buy cutting out one or even 2 batteries, now say you have 600ma at the panel, the amount of current is not so important here, it is a steady reading we need, so you looking for the needle wavering and you watch for at least 30 seconds, if it moves slightly it is a strong sign of an intermittent problem. On Burgot systems (and I think under BS.4737) the maximum allowed was 22 ohms per zone, minimum insulation resistance between poles or to earth was 1Mg,
Test each wire to an decent ‘earth’, your looking usually for staples which will rust, and if the cable insulation is damaged, sometimes the insulation is punctured when banging down the staple, wire would then be in contact with the galvanised staple, corrosion would mean the cable is parted but still keep contact via the staple due to dampness. Such ‘leakage’ being a very low level of current will show as a reading better on Volts than Ohms. Very important to clear this type of fault, as if you get a leakage serious enough on another zone, it can bypass the effected zones protection via the ‘earth’ supplying a false voltage.
While here, It was not always easy to find a good local earth point say on large windows, so connecting one pole to earth deliberately to measure against, then to clear the other ‘pole’ made life much easier.
Checking on voltage won’t load the wiring, so no pressure is applied forcing bad joints (rots) to break down, knowing the accurate voltage at the battery if, there is a major difference at the controls (wires removed) we could be looking for a partial short or another zone shorting onto the one under test.
<BR style="PAGE-BREAK-BEFORE: always; mso-special-character: line-break" clear=all>
Intermittent tracing (called rots).
With the meter attached and set on milliamps, a technique called ‘crashing out’ would commonly be used, ideally you would watch the meter while doing this, but sometimes the client was asked to watch it for you on larger circuits. The way it was done was with a pin hammer, using the handle to rap down the bars and bang on the panels, a sudden change in the meter as you hit the item, would indicate a local problem. Move meter to local test point J/B and zero in.
Don’t think door contacts can’t go intermittent or high resistance, while contact faults of this type are not so common, they are massed produced and can weaken or suffer a cracked reed capsule, when testing door contacts it is better to operate the contact several times, checking the reading on each operation, remains the same resistance each time.
Tasting.
Being brought up on 12 volts systems I would always use a meter, but engineers from RAB would often use ‘Tasting’, a couple of knives and some spare lace single attached, other ends bared and placed in the mouth on the tongue, any changed in current would tingle. Main reason I used a meter was after having watched a demo, in the COOP store at Southend one evening, the guy with me decides to use his knives above a window box. Got himself across some mains flex next I knew he is on the floor beside me.
When he had cut into the wires the other ends were not in his mouth but the shock to his hand threw him. Very easy mistake to make as alarm companies often used whit or brown plastic twisted twin flex, as did electricians of earlier days use for lighting lol. Fortunately he was not badly hurt, more his pride dented.
‘Juicing’ a Rot.
Method explained here is using a TMK 500vac battery operated mega, another method was used but some engineers got hurt by not understanding it, today unlikely to be used to there being little if any lace wiring, foil and t&b frames along with deol resistors, but if you do this don’t do so with door contacts in circuit as you could easily weld them closed circuit.
You detected an intermittent or h/r ‘rot’, so you make that zone into a ‘loop’ by shorting out the pair at the battery (or the feed in a feed and return panel), measure the resistance for later comparison, now turn on you mega so it tests into a short circuit formed by the zone. Ten seconds should be enough; the wine of the mega will tell you if it’s having any effect.
The idea is an intermittent connection will either blow and go open circuit making it easier and quicker to trace, or weld itself. This was usually a get out of jail quick for the weekend especially if a lot of calls were in, going back during normal time to look further.
Many engineers made up (ok, cobbled) ‘crashers’ often from old inertia sensor or otherfast response vibration type detector controller. In basic form this allowed a signal to be heard on a break or intermittent, handy when you had to ‘crashed out’ the job alone. I had got more interested in basic electronics above needed for the job, realising it was the way this trade was heading. Read up lot in ‘everyday and practical electronics mags, and books by B.Babanni.
The following is not to ‘show off’ but typical of what some engineers did to make life easier.
I had messed about with relays, switches and diodes as you do in the course of work, but the first electronic circuit I ever built was a single transistor oscillator, not that it was very complex I just caught the bug for electronics and experimenting big time when it worked. This interest was fired by need, I wanted better more convenient ‘crasher’ that reset itself without the need to return to the unit to press a button to silence as others crashers did.
I started off with a simple transistor Monastable, which was fine as it would as the others bleep for a few seconds on a ‘rot’ and go quiet, but if the circuit again like others if it had not restored the bleep would continue driving everyone potty. I added a bleep timer which solved that issue but did not show if the zone was set or not actually restored once the bleep stopped.
In a house for instance you did not know if a door had been left open by the daily moving about causing the bleep and also the timer out, if a wire had actually broken under a test, so I added an astable to give a ‘ping’ to indicate when not set. Eventually refined it so if an intermittent happened it would warble, if a door opened it gave a 3 second straight bleep then changed to the ping every 5 seconds. I refined the front end to be auto setting, no need to turn a pot for sensitivity. You could connect to a circuit that had power or to a loop and test, only switch on it turned it on or off.
This loop test facility was a surprise hidden treasure, often a call would be due to pressure matts, either F/A or CNS. Traditionally only way is to guess and lift carpets until you found the culprit, then 
with client who perhaps has had the offending chair there for several years.
With this box attached to an O/C zone in fault there is no escape, when you moved offending furniture and so the short, you immediately got the bleep, this proved point blank to the client it was their chair on that pad no argument.
Often you had several rooms to choose from, as this box was very fast, you treated a matt short like an intermittent, with the crasher attached you could go into each room and hunt about, sometimes walking near a pad would indicate or if wooden floor simply jump in the air (scarring to kack out of several clients), the vibration would ‘tickle’ the matt either way causing a ‘fault’ bleep when you were in the right room. That may seem small beer, try tracing a problem in a mansion full of antique furniture, by lifting carpets to look and you might start understand how helpful this crasher really was.
While not designed originally for this, the unit proved it was so sensitive it could detect the RFi from a kettle being switched on – so dead handy lol! This aspect also helped you to find electrically ‘noisy’ items like fridges etc. I’m not claiming brilliance, need is the mother of invention sand from a simple interest, grew this unit which through several stages of development taught me a lot and ended up saving service engineers frustrating tracing time, helping then fix faults first go they could otherwise easily miss. That directly made my life easier as they were fixing more faults, which meant less call outs to their area’s.
Another service ‘gadget’ I made was a ‘mini spider’, on long chains of wiring or windows, sometimes intermittent faults would happen days even weeks apart but engineers could for some reason not zero in on. This could be lack of access (or did not have a crasher). The original ‘spider’ idea came from Brocks/Modern alarms, basically a box with an electronic latch that was ‘set’, subsequently indicated after a fault. Placed several along the zone. Client watched every hour or so or when they opened up looking for a fault. When you got a red light you knew the fault was before it and the last one not indicating, a short would cause them all to come on, effectively it ‘zoned’ a zone (like with latching Vipers on one zone).
I made them as with the improved ‘crashers’ from CMOS IC’s so they could last a long time on a single PP3.
Earths.
These can more troublesome to find, juicing as above can make the ‘earth’ fault a lower resistance, so testing for earths after ‘juicing’ could make the job easier.
Once you have found earths exist, you have to break down the zone, isolate about half way and test each way. ‘divide and conquer’ is the attack method, so test and halve again, testing each way. Usually it’s a staple or staples perhaps a door contact with water in or a roller shutter contact.
Look for tell tale brown marks or discoloured/rusted staples caused by water, I have a long set of meter leads I’ve made up, to allow testing from the disconnected wire to each staple. Lift out those staples and watch the meter as you do, you know you are getting there when the meter drops but may be more than one staple at fault. When clear and repaired reconnect and test again for earths,
Having no reading indicating no earth is ideal, minimum of10 megs were ‘allowed’, if I had the time I’d have non of it, as a slight earth now usually only ever gets worse, so it just has to be cleared.
I hope this was enjoyed, if any item needs more information please ask and I’ll do my best. I have not covered every device, just many of the more important ones.
Arfur
-
1
10 Comments
Recommended Comments