66 Block for Intercom? - Sundance Business VOIP Telephone Help

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I bought this 66 block off eBay today assuming it was for a 37 station intercom like the Melco KR-37. However, the last pair (H/INH) was throwing me a bit and after some Internet research I came across a Valcom product (V-136HRTF) which is a hands free, talk back intercom/paging system with speaker inhibit (INH, eh?).

But even then, nothing really lines up. I guess I'll just have to wait until it arrives to see how the Amphenols on the side are wired.

[img]https://lh3.googleusercontent.com/4...9mTXLvchWcfp48Y2Sffem1g-W=w1200-h1600-no[/img]

In the meantime, anyone seen/installed one of these before?

As I recall, the INH leads were a closure for accessing a PA system (cutting off Background Music). I think most of the Melco/Teltone/whatever intercoms had that setup. I'll have to look.

Sam

It depends upon the manufacturer. Some INH leads do what Sam describes, and some were used to force a 19-code unit to operate as a 9-code unit.

INH (Inhibit) leads were exclusively used on Valcom intercom units to cut off the hands-free signaling feature. In lieu of a buzzer, a 45 ohm speaker was installed within the set. They even made replacement face plates for 2830 sets with the speaker built-in.

This feature required an A lead for the intercom button. A resistor was installed in series with it to a common INH terminal on the intercom unit. Since this was a single-path intercom unit, two or more off-hook conditions via A lead would signal the unit to break the hands-free talk path to the speaker. The resistors offered enough of a readable difference in resistance as opposed to a short to ground with a typical A-Lead closure. Without the resistors, any set off-hook would create a short to ground, resulting in the hands-free intercom signaling feature to be, well... Inhibited.

In essence, one set off-hook with resistance was acceptable, but two resistors in parallel resulted in a full A lead closure, cancelling the hands-free speaker connection.

Oh, and yes: The Valcom intercom units came with a package of these resistors.

"INH (Inhibit) leads were exclusively used on Valcom intercom units..."

Ed, I'm afraid I have to disagree. The Teltone units also used INH terminals, to inhibit a two-digit situation and force the unit to be a single-digit one. Click this and scroll down to the third document:

https://www.telephonecollectors.inf...-19-t-19-c-19-key-system-intercoms-ocr-r

Bad wording on my part, Arthur. I even thought about that as I made my original post. What I meant to imply was that the INH lead on only Valcom units was used to cancel an HFAI call.

Good catch, though. Besides, you should never apologize for disagreeing with me. I'd be happy to know half of what you forgot.

OK, got it.

Cool, thanks for that. Hands free intercom would be pretty cool to have. Did any of these intercom units ship with a 66-block like the one I linked to?

All of the installation docs I've seen (Valcom, Melco, Teltone) show a standard arrangement on the block which is different than what I have above.

What you have there is a custom block designed for a particular system. The block connects to the Intercom via a 25 pair amphenoled cable. The exact layout of the block is predetermined by the wiring from the am phenol to the pins on the back of the block. If you plug that block into a different System then what it was designed for, then you may get some of the leads appearing in the "wrong" places.

Most of the Intercom units had ALMOST identical wiring layouts, but they all used a 25 pair cable. A T-10 and a KC-37 both used 25 pair cables but the layout was different. Sometimes it wouldn't matter and sometimes it mattered a lot.

You're going to have to test.

Sam

The test consists of watching to see if the magic smoke is released when you power up. While I used to share the enthusiasm of wild 'n' crazy youths like Sam, now that I am an old fart, I prefer to do it more scientifically, and safely. It's more satisfying just to take a standard 66 block and create the wiring yo' sef.

Rather than let the magic blue smoke out of my intercom, I decided to see how this thing was arranged. So, after a long evening with the multimeter, I've come to the conclusion (confusion?) that this isn't for Melco or Valcom; maybe Teltone, but not their 19 station units.

I guess it will go on the shelf of odd eBay things.

Anyway, for the curious, here's what I toned out. Where the pin is labeled XConn in the 66 block column, it doesn't appear on the block, but is connected to the other AMP on the pin(s) shown in the XConn column.

Code

AMP #1  66 Blk    Color   XConn         Melco    Teltone
26      T1-6      W-BL                  T        T
 1      R1-6      BL-W                  R        R
27      LBAT(1)   W-O                   LB       LB
 2      L1-L3     O-W                   L        L
28      H         W-G     28(2)         LG       H
 3      INH       G-W      3(2)         PC       INH
29      G/1       W-BR                  B0       B1
 4      XConn     B-W     29(2)         R0       R1
30      G/20      W-S                   B1       B2
 5      XConn     S-W      4(2)         R1       R2
31      Spare     R-BL                  B3       B3
 6      XConn     BL-R    26(2), 30(2)  R3       R3
32      Spare     R-O                   B4       B4
 7      XConn     O-R      1(2),  5(2)  R4       R4
33      G/5       R-G                   B5       B5
 8      XConn     G-R     31(2)         R5       R5
34      G/6       R-BR                  B6       B6
 9      XConn     BR-R     6(2)         R6       R6
35      G/7       R-S                   B7       B7
10      XConn     S-R     32(2)         R7       R7
36      G/8       BK-Y                  B8       B8
11      XConn     Y-BK     7(2)         R8       R8
37      G/9       BK-O                  B9       B9
12      XConn     O-BK    33(2)         R9       R9
38      G/0       BK-G                  B20      B0
13      XConn     G-BK     8(2)         R20      R0
39      G/21      BK-BR                 B21      B21
14      21        BR-BK                 R21      R21
40      G/22      BK-S                  B22      B22
15      22        S-BK                  R22      R22
41      G/23      Y-BL                  B23      B23
16      23        BL-Y                  R23      R23
42      G/24      Y-O                   B24      B24
17      24        O-Y                   R24      R24
43      G/25      Y-G                   B25      B25
18      25        G-Y                   R25      R25
44      G/26      Y-BR                  B26      B26
19      26        BR-Y                  R26      R26
45      G/27      Y-S                   B27      B27
20      27        S-Y                   R27      R27
46      G/28      V-BL                  B28      B28
21      28        BL-V                  R28      R28
47      G/29      V-O                   B29      B29
22      29        O-V                   R29      R29
48      G/30-49   V-G                   AUD GND  B20, AUD GND
23      20        G-V                   AUD SUP  R20
49      AUD       V-BR                  AGND     AUD SUP
24      BBAT      BR-V                  ABAT     BBAT
50      AGND      V-S                   BGND     AGND, BGND
25      ABAT      S-V                   BBAT     AGND

AMP #2  66 Blk    Color   XConn
26      XConn     W-BL     6(1)
 1      XConn     BL-W     7(1)
27      LBAT(2)   W-O
 2      L4-6      O-W
28      H         W-G     28(1)
 3      INH       G-W      3(1)
29      XConn     W-BR     4(1)
 4      XConn     BR-W     5(1)
30      XConn     W-S      6(1)
 5      XConn     S-W      7(1)
31      XConn     R-BL     8(1)
 6      XConn     BL-R     9(1)
32      Xconn     R-O     10(1)
 7      XConn     O-R     11(1)
33      Xconn     R-G     12(1)
 8      XConn     G-R     13(1)
34      1         R-BR
 9      Spare     BR-R
35      Spare     R-S
10      Spare     S-R
36      5         BK-BL
11      6         BL-BL
37      7         BK-O
12      8         O-BK
38      9         BK-G
13      0         G-BK
39      31        BK-BR
14      32        BR-BK
40      33        BK-S
15      34        S-BK
41      35        Y-BL
16      36        BL-Y
42      37        Y-O
17      38        O-Y
43      39        Y-G
18      30        G-Y
44      41        Y-BR
19      42        BR-Y
45      43        Y-S
20      44        S-Y
46      45        V-BL
21      46        BL-V
47      47        V-O
22      48        O-V
48      49        V-G
23      40        G-V
49      Spare     V-BR
24      BBAT      BR-V
50      BGND      V-S
25      Spare     S-V

        LGND(1)           LG1 - LG3
        LGND(2)           LG4 - LG6

That looks like it is for a Teltone M416-22 unit to me.