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Old 18th Aug 2020, 12:00 am   #1
Bodie158717
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Default Rewiring a Tribune

Hello,

After saving it from a bin at work, I have got myself a BT Tribune. It once was white and is the 9902 variant.

It's in generally good condition, the only problem is that the phone cable has been cut off.
It is a school, and I've only ever known it in this wireless state. I think it was used as a toy phone.

There is another 9902 in one of the other classrooms that is still in working order.

Having taken it apart and removed what was left of the old cable, I am struggling to find a suitable replacement.

The cable connection options are either the modern style plug or the older wiring were each individual wire was attached with a sort of little metal ring. Nowhere seems to sell the Tribunes style of connector. This is a JST 4-pin, 2mm I think.

Is there anywhere online that still sells these?

I can get the pins. If I can't get hold of a replacement cable, then my plan is to buy the pins and also buy a PSTN GPO 741 series cable. This has the little ring connectors. I would cut them off and join together the cable and JST connector.
Is the different series cable compatible with the Tribune?

If I do have to do the above, is there a better choice of cable that I could attach the JST connector to?

Thanks,

Jonathan
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Old 18th Aug 2020, 1:00 am   #2
Graham G3ZVT
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Default Re: Rewiring a Tribune

Hello Jonathan, and welcome.

What I would do is use a commonly available 431A to RJ11 lead, cut off & discard the RJ11, prepare the end and slip heat shrink sleeving on the conductors, then solder to the stump of cable left in the phone.
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Old 19th Aug 2020, 8:58 pm   #3
Bodie158717
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Default Re: Rewiring a Tribune

Thanks for the advise. Sadly I stupidly tried to see if the wires were slotted into the JST and thus able to remove and wires from the new cable could be plugged into it.

I stopped after two as it was now apparent to me that each wire was very much soldered in there and all I had succeeded in was ripping them out.

It is way beyond my capabilities to be able to reattach them.

Would a new JST soldered onto a 431A with the RJ11 discarded as you advised work?
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Old 20th Aug 2020, 7:57 am   #4
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Default Re: Rewiring a Tribune

I'd simply remove the socket and solder the wires direct to the PCB.

Looking at mine I think that Dupont connectors (those single-pole things that are popular with Arduino users) would do if you really want to keep the cord detachable.
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Old 30th Aug 2020, 9:57 pm   #5
Bodie158717
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Default Re: Rewiring a Tribune

Hi,

I received my 431A/RJ11 cable. Cut off the RJ11 end and wrapped the wires around the pins in the male JST connector.

There is power going to the phone but it's not behaving correctly.
With the handset in place, the phone rings continuously. As nice as it is to hear this phone ring for what probably is the first time in a very long time, it isn't an ideal situation.
If you take the handset off the hook switch it stops ringing but there is no dial tone. There is no sound when you press the keys either.
Ringing the phone from my mobile, I can get the recorded message we have. It doesn't give an indication that the phone is engaged. Despite that that's why I'm guessing the caller gets the recorded message. It thinks the phone is alway in use because its constant ringing.

Any help as to what could be causing this would be greatly appreciated

Thanks

Jonathan
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Old 30th Aug 2020, 10:38 pm   #6
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Default Re: Rewiring a Tribune

Try connecting the wires in the opposite order. In other words, take the 4 wires off, turn the cable over, and reconnect them like that.
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Old 30th Aug 2020, 10:45 pm   #7
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Default Re: Rewiring a Tribune

If you get no joy with Tony's suggestion try this.
Using the two outer wires in the cable and ignoring the two inner ones for now, see if you can find two pins that make it work as a phone, we'll deal with the ringer later.
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Old 1st Sep 2020, 9:41 pm   #8
Bodie158717
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Default Re: Rewiring a Tribune

I've tried the swapping round of the wires and have an improvement.
The phone still rings continuously when on the hook.
However now there is a dial tone when the handset is picked up.
I've tried making a call from the phone but nothing happens. The numerical keys still don't produce any sound through the handset. Some of the lettered keys do. Sort of electrical pulses.

It can receive calls though. You get two competing ringing sounds when the phone is dialled.
The sound of the caller is very faint but if your on the other end it's crystal clear. So no problem with outgoing sound but incoming is as I say faint.
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Old 2nd Sep 2020, 2:24 am   #9
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Default Re: Rewiring a Tribune

Leave the third "bell wire" where it is and swap over the other two, that should cure the continuous ringing whilst on-hook.

Sounds like it's set for pulse dialling. Do you get musical tones if you first press the * key?
There is a switch underneath to change the dialling mode between Pulse and Tone.

You also have a low volume in the earpiece The little holes in the the plastic aren't clogged up with earwax or furniture polish are they?

Gross I know, but I've seen it many times.
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Old 2nd Sep 2020, 1:31 pm   #10
Bodie158717
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Default Re: Rewiring a Tribune

Which is the third bell wire?

With the phone the right way up, minus the top cover the wires now read left to right - red, blue, green, white.

Which of these colours is the third bell wire and which are the other two bell wires I need to swap?

Sorry, I so use to tone dialling, I forgot back then there was pulse as well. My Tribune is solely pulse, there are no * or # keys.
So for all I know the keys could still work. Is there any sound made with pulse keys?
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Old 2nd Sep 2020, 4:25 pm   #11
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Default Re: Rewiring a Tribune

The Tribunes that I've worked on (9801, 9802) have the PCB mounted in the top cover. On those, the line cord is connected, starting from the pin nearest the handset rest linkage ; white, green, blue, red.

The line cord is of course the connector at the rear of the PCB. At the front are 2 connectors, a 4 pin one for the handset cord and a 2 pin one for the ringer.
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File Type: pdf Tribune_circuit.pdf (1.22 MB, 76 views)
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Old 2nd Sep 2020, 5:35 pm   #12
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Default Re: Rewiring a Tribune

Quote:
Originally Posted by Bodie158717 View Post
Which is the third bell wire?

With the phone the right way up, minus the top cover the wires now read left to right - red, blue, green, white.

Which of these colours is the third bell wire and which are the other two bell wires I need to swap?
You probably found that two wires made the phone work and a third wire allowed it to ring, the fourth wire does nothing useful.
Swap over the first two wires.
I am deliberately not referring to colours as they might be different in your line cord.
Quote:
Originally Posted by Bodie158717 View Post
Sorry, I so use to tone dialling, I forgot back then there was pulse as well. My Tribune is solely pulse, there are no * or # keys.
So for all I know the keys could still work. Is there any sound made with pulse keys?

OK understood. You won't hear any tones, but if you blow into the mouthpiece while dialling you should hear the phone mute for up to a second depending on which digit you press.

If you listen on a parallel extension while dialling on the tribune you should then hear loud pulses.
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