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Old 25th May 2020, 11:16 am   #1
Sparks
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Default Bellset 50B - terminals and switch wiring

I determined yesterday that in order to get this bellset off-hook, terminals T19 and T20 have to be shorted together. However, with a correctly wired hook switch in a Tele 713, placing the receiver off hook also shorts together T2 and T6. What purpose does shorting these two terminals serve if shorting T19 and T20 brings the set off-hook ? Also, to hang up, these four terminals are respectively disconnected but T6 shorts to T5. Again, what purpose does this serve ?

Many thanks again.
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Old 25th May 2020, 4:25 pm   #2
Pellseinydd
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Default Re: Bellset 50B - terminals and switch wiring

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Originally Posted by Sparks View Post
I determined yesterday that in order to get this bellset off-hook, terminals T19 and T20 have to be shorted together. However, with a correctly wired hook switch in a Tele 713, placing the receiver off hook also shorts together T2 and T6. What purpose does shorting these two terminals serve if shorting T19 and T20 brings the set off-hook ? Also, to hang up, these four terminals are respectively disconnected but T6 shorts to T5. Again, what purpose does this serve ?

Many thanks again.
What diagram are you connecting it up to?

A Tele 713 connected to a Bellset 50B is N813 upper circuit on page 2.. Note - without a dial - B9 is strapped to B10 but not shown on diagram - shorts out dial pulsing contacts.

A Tele 713 doesn't have T19 and T20 terminals ! And lifting the receiver on a Tele713 shorts out T1 and T2. T6 on a Tele 713 has no connection internally and isn't normally used.

Have you actually got a Tele N4455 ? It but looks just like a Tele 713 externally.

It has 'T' terminals up to T18 but no T19 and four separate sets of 'Make before Break' sets of contacts so is different internally
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Old 25th May 2020, 4:43 pm   #3
Sparks
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Default Re: Bellset 50B - terminals and switch wiring

Hello Pell and thanks for replying. The terminals I'm referring to are in the bellset, not the 713. Perhaps I should have described them as B19, B20 etc. The 713 isn't actually connected at all but, if it was, the hook switch wiring would be as I described.
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Old 26th May 2020, 9:31 pm   #4
Sparks
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Default Re: Bellset 50B - terminals and switch wiring

Anyone else ? I'm still no wiser as to why B2 and B6 are shorted together simultaneously with B19 and B20, when it's the latter that essentially 'switches on' the Bellset.
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Old 27th May 2020, 9:21 pm   #5
Pellseinydd
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Default Re: Bellset 50B - terminals and switch wiring

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Originally Posted by Sparks View Post
Anyone else ? I'm still no wiser as to why B2 and B6 are shorted together simultaneously with B19 and B20, when it's the latter that essentially 'switches on' the Bellset.
What diagram are you talking about?

The one I referred to earlier N813 top circuit 'direct exchange lines' on page 2 doesn't have B2 and B6 'shorted' except when the handset is lifted.

Without a dial, B8 and B10 should be strapped but everything as per the diagram but missing the dial/dial cord.
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Old 27th May 2020, 11:26 pm   #6
TonyDuell
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Default Re: Bellset 50B - terminals and switch wiring

I think he's asking why the second set of gravity switch contacts (the upper set in the diagram you refer to) are needed.
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Old 28th May 2020, 7:23 am   #7
Sparks
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Default Re: Bellset 50B - terminals and switch wiring

You're both right. The second set of gravity switches shorts B2 and B6 together when the handset is lifted. I'm just interested as to what purpose this serves. Thankyou both.
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Old 28th May 2020, 9:28 am   #8
Pellseinydd
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Default Re: Bellset 50B - terminals and switch wiring

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You're both right. The second set of gravity switches shorts B2 and B6 together when the handset is lifted. I'm just interested as to what purpose this serves. Thankyou both.
To disconnect the 'telephone' speech side completely from the 'line' when the handset is down and leave just the bell & capacitor in circuit.
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Old 28th May 2020, 11:01 am   #9
Sparks
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Default Re: Bellset 50B - terminals and switch wiring

Much obliged. Now I know, but there was no obvious (to me) function.
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