"The phone is a remarkably complex, simple device, and very rarely ever needs repairs, once you fix them." - Dan/Panther
Started by escuta, July 28, 2017, 10:47:50 AM
Quote from: escuta on July 29, 2017, 04:17:21 PMNo, there is only one name plate which is on the inside of the door. Yes, I think there is space for two more cord circuits, one to the left and one to the right. Please see the attached photo.
Quote from: escuta on July 29, 2017, 09:46:14 AMLocated the Ericsson Review page on the Ericsson website. It's here: https://www.ericsson.com/en/about-us/history/sources/lme-reviewAnd found a closer match for my board, the ADE 1210 from 1953 which is identical, however mine has a jack socket between the "S" (splitting key) button and the "~" (pole changer key) on the vertical panel. Not sure what this would be for.
QuoteThe 1950 article OTOH talks about a 40 station + 6 exchange line capacity, making it unquestionably a PBX or "PMBX" as some call it (private manual branch exchange). Your photo shows a strip at the top with alternating light and dark lamp caps, suggesting probably exchange line jacks, and that yours is a PMBX.
Quote from: escuta on July 29, 2017, 05:41:47 PMOn this top strip there are 10 jacks but only five with lamps (or at least with light coloured caps). Above each of these is a label with what looks like a telephone number, the first of which is "222_5822". The rest all start with 222.
Quote from: unbeldi on July 29, 2017, 05:37:53 PMI would recommend to you to document your board by the components that are in fact installed, broken down to each functionality. Identify as many components as possible, for example I noticed the series of relays (RCA) used, etc. Relays are often subject to evolution of materials used. There is documentation available for many of the Ericsson parts. I think I have lists of relays with switch configurations and other components.
Quote from: Alex G. Bell on July 29, 2017, 05:49:02 PMWhen I change the gamma on your photo #17 to 2.5 I see only 5 pairs of equipment, so most likely alternate jack and lamp holes are not equipped with contacts. This is consistent with the E-R article stating a capacity of 6, though where the 6th would fit is TBD.
QuotePhoto #16 shows an R1 (functional designation) relay, one of 5, with the cover off, shown in #2 and #17 with the covers on.
QuoteThese are probably the 5 ringing detection relays for the 5 exchange lines. You could confirm this by tracing the wiring harnesses (bundled wires) to see whether there is a branch from these 5 relays to the top jack and lamp strip.
Quote from: escuta on August 01, 2017, 09:45:21 AMThe first task is to reconnect all remaining plugs to the cords. There are 8 plugs remaining but none was connected to any of the cords (they had been removed at some point and stuck back on for cosmetic reasons), so I do not know how to wire them. The cords are 3-core with yellow, black and red wires. Are you aware of any standard colour code used by Ericsson for wiring tip, rim and sleeve on the plugs?
QuoteThe hand-piece has its cord but has lost the plug that would have attached to the socket seen in photo #1 on the lower left-side of the unit. It has also lost its mic and speaker capsules, see photo #24 with the Bakelite caps removed. The hand-piece cord has three wire, however the socket has 4 terminals. Does this mean that the handpiece is not original? Quite possible, I suppose. Looking at the inside of the socket, one can see that from the left, the 1st, 2nd and 4th terminal are connected to an internal 3-core wire and that the 1st and 3rd terminal are connected by a jumper wire. Can anyone please offer suggestions on how I should go about wiring up replacement hand-piece capsules (I'll try to purchase these today) and connecting the cord to the 4-terminal socket? Would it be possible to find a replacement plug? I'll try using "banana" plugs for testing.
QuoteOnce these two tasks are done I'd like to try starting up the unit with DC power-supply. I understand that this should be a filtered 24V supply, however I plan to test with a 19V supply that I have handy from an old laptop.Also, I believe the plugs are 0.206" TRS plugs (photo #5), I have no calipers, but using a ruler it's a bit more than 5mm. Does 0.206" sound correct? They are certainly smaller than 1/4" and modern audio jack plugs are too large to enter the sockets. Would the following plugs make suitable replacements: http://www.markertek.com/product/np3cm-b/neutrik-np3cm-b-trs-206-inch-mil-b-gauge-phone-plug-black-brass
QuoteYet one more question: My unit has no weighted pulleys as shown in the ER articles. I was thinking of try to source something at a sailing/nautical supplies shop. Any suggestions on particular pulley types I should look for, or weights? Other suggestions?Thanks a lot!
QuoteFirst you will need to check continuity of any cord from each of the 3 plug elements (tip, ring and sleeve) to the 3 leads to determine which color is the tip, the ring and the sleeve, the descriptive and formal names of the 3 plug elements.
QuoteNext, with the DC power disconnected, the DC power input terminals short circuited together, and no TALK keys operated, you should find equal resistance between two of the plug cord terminals for any given cord circuit and the DC power input leads. These would be the T and R terminals since a talking circuit must be balanced electrically and therefore the T must have the same DC resistance to the (+) terminal of the power supply as the R has to the (-) terminal, therefore with the power input shorted the resistances will be equal.
QuoteYou will need to determine which terminal at the cord end of the handset is the common, the receiver and transmitter. Perhaps you will be able to determine some of this by visual inspection. Impossible to say without knowing the construction of the handset. If not by visual inspection you will need to perform continuity tests within the handset.
QuoteWhen power is applied to the switchboard there will be a DC voltage between one of the other jack contacts (2nd or 4th) and the 1st & 3rd. This jack contact is the transmitter lead. The remaining jack contact should not have DC on it and would be the receiver jack contact.
Quote from: escuta on August 07, 2017, 10:40:39 AMThanks very much for the detailed information Alex G. Bell and unbeldi, much appreciated. It took me a while to have a good look at the unit - comments follow below:None of the plugs were actually attached when the unit arrived. Most had been yanked off at some point and examining the cord ends, the longest wire in all cases was the black wire, followed by the yellow and then the red. Looking at #28, this suggests that they were connected to tip, ring and sleeve respectively.
QuoteExamining the other en of the cords each terminates with three terminal rings which allow the cords to be easily snapped into place (#26). The terminal at the tip corresponds to the black wire, the middle is the yellow and the terminal closest to my hand is the red. That seems to match nicely with the idea that black = tip, yellow = ring and red = sleeve. Please correct me if I'm wrong!
QuoteUnfortunately, when I tried this, I discovered that only 3 cord pairs (call and answer) out of the 8 gave any resistance reading at all. They were however consistent. The "black" terminal gave no measurement (ie. the meter stayed at 1), nor did any of the yellow terminals. The red terminals on the call and answer cords (of the 3 pairs that registered anything) all gave a resistance reading.
Quotere. the hand-piece:The hand-piece cord has three wires, red black and white. Black is the wire common to the mic (receiver? - sorry I'm new to telephones) and speaker.
QuoteUsing a 19V DC supply, unfortunately I could measure nothing across the terminals in #25Later, I'll attempt to trace how far the 19V gets in the switchboard.All the best