Hi Guys,
First-time poster. Great forum! I've learned heaps from it already.
Posting in this forum as my 'issue' is similar to the OP - and desperately hoping for a swift reply.
ISSUE: -
I live in a block of 8 apartments that uses an old Intercom system.
- The Intercom system was about 30 years old, and literally falling apart.
- It never really worked well and was always working intermittently.
- In addition to the unit literally falling apart, the main issue was the fact that the caller couldn't hear the voice of the resident (using the handset in the apartment) while standing at the external Intercom (building entry door at street level). This issue increased the higher the apartments (the further away they were from the Intercom at street level).
= My goal (if possible) is to simply replace the old 8-way Intercom system with a new unit, using the existing 8 internal handsets, using the existing wiring, and using the existing latch/door-release.
ORIGINAL INTERCOM: -
I don't know the make of the old Intercom, but I can confirm the following:
- It was an 8-way intercom.
- It was fed by a nearby 12v transformer, which has an isolator switch.
- It had a speech unit (which allowed the 'resident' to hear the 'guest/visitor', and I assume the other way as well, perhaps?).
- It connects/opens the main door entry latch/lock.
- It had a timer for trades entry (ignore this though, as I've isolated the timer).
ORIGINAL/CURRENT HANDSETS: (See Picture)
I was hoping to retain the existing apartment handsets. They are very old (approx 30 years).
- The make is ACET.
- There are 2 wires (red & black) inside the handset from the external cable.
- The other coloured wires are present, but i now know that they feed the other apartments (see next point, Cabling).
- I should also point out the old handsets have an internal 'buzzer' within them, which buzzes when a visitor presses the Intercom.
ORIGINAL/ CURRENT CABLING: (Only discovered loop wiring after I bought new Intercom)
- Now that I've taken the old Intercom apart, and traced back (tidied and labelled) all the cables, I now know the full cabling set-up, which is as follows: -
> Apartment/Building Wiring
- The wiring is a 'loop' system feeding the left & right side of the building. (2 cables, 1 for either side)
- The cable used (for both sides of the building) is a 6 wire cable, which resembles the thickness and sheathing of a Cat5. The cable wires are sheathed & coloured (red/black/green /yellow/blue/blue&white) and are braided steel wire.
- The 'loop' system serves as a single cable supplying 4 apartments (4 apartments on the left side), and the same on the other (4 apartments on the right side).
-- This means that each apartment is only served by only 2 wires. 1 x common (red) + 1 x flat wire (black for my apartment). This is my big problem!
> 8-way Intercom Wiring
- 2 x aforementioned circuit cables (looping either side of apartment building), each side using 4 coloured wires (1 wire for each apartment) & common red.
- 1 cable feed from the 12v Transformer (uses 2 of 6 wires, red & black)
- 1 cable feeding the latch to unlock the main building door (uses 2 of 6 wires, red & black)
> Internal Apartment Handset Wiring
- 1 cable, using 2 of the 6 wires (red = common) & (black = my apartment).
- Note: within the cable, there is one unused wire (yellow I think), as there are only 4 apartments each side of the building & common (red). I mention this as it may come in handy?
NEW INTERCOM: - (See Picture)
So, before realising the wiring to my existing Intercom system was a 2 wire loop system, I recently purchased & installed a new Bell 8 Way Intercom system (SPA-08) & Speech Module (Bell 61).
- Now mounted outside our apartment, the new unit looks fantastic and was an excellent price (approx £150 including the speech module and some cat5 cable).
- Unfortunately, but unsurprisingly, the new unit didn't come with any wiring schematics - or indications that it required 4+1 wires.
However, upon installing it and trying to mimic the original wiring (from observing the original Intercom & speech module), it became clear that i needed more wires than i have (2 wires from each apartment) : (
HELP?
Cutting to the chase, I'm really stuck! I've spent 2 days getting to this point, and i need help!
- I know I need 4+1 wires (call/common/voice-out/voice-in/latch), but I can't run new cables!
- I'm unsure if I can modify the SPA-08 to work with 2 wires?
- I'm unsure if using the extra (unused) wire from the loop system would help me?
- I'm unsure if there are low-cost devices that can modify the cable from 2 wire to 4?
- I'm unsure if my existing (30-year-old) handsets are compatible with the SPA-08
- I want to use my existing latch/door release.
- Ideally, I would love 2-way voice coms (full-duplex)-and great signal in furthest apartment!
- The Intercom unit is surface mounted and needs to remain that way.
= My preference would be to modify the new Bell SPA-08, given that I've installed it and probably am outwith my return period. I probably should have got the version with an internal light, but hey - that's now the least of my problems.
This schematic image shows the SPA-08, with the 4 wire system, and I guess my question is = is there any way to modify this to use 2 wires (or 3 if I manage to leverage the unused wire in each apartment). And if so, what would the wiring configuration be? I've tried lots of combinations (testing with a single apartment, mine only, connected to the new intercom) - but I can't seem to get all the circuits working together i.e.
> from the intercom - I can make my apartment buzzer work;
> from the intercom - i can hear the resident answer (but they can't hear me);
> from my apartment handset - I can open the main door entry latch.
= This config is clearly 'almost right' but not perfect, so i haven't tested the config on the other apartments.
Please help!
Huge thanks in advance.
John
