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Old 5th Nov 2011, 1:30 am   #21
siaynoq
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Default Re: GPO Telephone 328F.

Hello David I am sure we can track down your problem (Believe I have already spotted part of it)

By your own confession
"I must point out that some of the wiring that you see in the pic is not as per instructions (as mentioned in previous post), this after hours of trying to make the handset work. It will not work in its correct wiring, it will only work wired this way"

STOP! Take a deep breath and think logically. If it will not work wired the 'correct' way something is wrong! Re-routing the wiring haphazardly in an effort to try and make it work is a fatal mistake and you will learn nothing.

2nd..You really MUST learn to read a wiring diagram (you're getting there) AND use a basic multimeter &/or test lead.
Someone suggested testing for dial pulses with a meter or lead and you have not come back with the results of your findings?!
You ask what the component in the red boxes are? LOOK at the wiring diagram, check the colour of the wires shown to that in your phone, syou should be able to determine what part is what.

Think, what have you got wired to terms 4, 5 & 6 which must be "CORD, INST. No.3/63a"? So bottom left box you highlight must be.........yes, the handset! (R=Receiver M=Mike/transmitter MR=Common)
Above that box the next are "COND MC No97 The rating 0.1 uF/2uF gives this away as the dual 'Condenser(Capacitor)

The box bottom right....shows a 2 gang switch, something that lift up (up arrow) there is only one component that has those coloured wires going to it. Find it.....the "hook-switch".
Top right are the induction coils (4 in 1 unit)

Also compare this with the schematic ("EXPLANATORY") below the wiring diag, trace through the circuits and you will hopefully be on your way to getting your head around the system.
What will also help you is to print out a copy, enlarge if necessary, and cross out/draw in the alterations/new wiring so you can see what you are working with.


Back to your phone
A..Disconnect ALL the wiring.
B..Fit the links in the appropriate places INCLUDING a 3.3k resistor. It's not critical to dialling but necessary for correct ring functioning.
C..Use a standard BT Line cord. By the looks of things you have a non standard cord(s) What are they and why?
I would say you have an American? coded cord these often come supplied with/for modems, phones etc fitted with a BT431A/631A plug. They are NOT wired using the same colours! (At this point he says "DOH!" It's all becoming clear where I'm going wrong!)
The colouring goes as such
US style Black....OLD=Red....Later=White (+ve)
Red .....OLD=Blue....Later=Green (N/A)
Green...OLD=White..Later=Blue (Ring)
Yellow..OLD=Green..Later=Red (-ve)
The instructions you are following presume you are fitting a Later type line cord!

Things to check: There is a link between terms 2 & 3 on the DIAL terminal block, easily missed.
Using a multimeter (Needle type) or plain old test lamp (bulb and a battery) with the phone unplugged, leads on terms 1 & 9 of the phone, rotate the dial all the way and release. Does the needle or lamp pulse?
If not leaving one lead on term 9 circuit trace back ie test lead on wire from hookswitch (1) that goes to dial term 1. Blue wire leading to slate to dial(by-passing the hook switch).
All else fails replace the dial with your known working one (from the 700) confirm it's now working then compare the dials to locate fault
None of the parts you suggest replacing affect the dialling in anyway.

I know a little about these phones, do/check the things I and others have suggested and report back with your findings ie TEST.
Hope this helps a little.
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Old 22nd Nov 2011, 4:49 pm   #22
davidhood999
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Default Re: GPO Telephone 328F.

I thought I would update everyone and ask for some more advice. I got fed up of exploring every avenue trying to fix it so I decided to put it back together and just accept that it wasn't going to work unless I changed the capacitor (which would involve soldering, which I really did not want to do).

So I took it to a friends house to show him how I'd polished it up really nice and what a gem it looked, plugged it in to demonstrate it, dialled a random number to show how it doesn't dial out, and would you believe, it worked! It still will not work at our house though, and to add to the confusion, other dial phones that I have; a 706 and a 746 all work perfect.

Is this a common thing? Do 300 series dial out differently to 700 series? I'm very puzzled.

David.
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Old 23rd Nov 2011, 12:08 am   #23
BakeliteBear
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Default Re: GPO Telephone 328F.

You need to check the dial speed and make/break ratios on the dial. Your friend exchange might be more forgiving than the one you are on. The make/break really need kit to test, but you can test the dial speed by comparing with another dial phone that works on your line. Just dial ‘0’ on both phones and release them together. They should reach the stop at the same time, if they differ that might well be your problem.

I have never had a capacitor problem on any phone I have worked on, and I have done lots!
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Old 23rd Nov 2011, 9:33 am   #24
davidhood999
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Default Re: GPO Telephone 328F.

Right .... it does seem to dial slightly slower than my other two phones. How can I adjust the dial speed?
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Old 23rd Nov 2011, 12:32 pm   #25
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Default Re: GPO Telephone 328F.

Quote:
Originally Posted by davidhood999 View Post
How can I adjust the dial speed?
Very carefully.

Assuming your dial is clean and correctly lubricated, you'll need to take a pair of flat-bladed pliers and ever-so-carefully bend in the governor legs a wee bit. Best to check all other reasons for possible sluggishness first: governor cup alignment; dirt, etc...

Have a look here.
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Old 23rd Nov 2011, 12:40 pm   #26
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Default Re: GPO Telephone 328F.

Quote:
Originally Posted by BakeliteBear View Post
'The make/break really need kit to test...'
Can't you do it with an analogue multimeter either on 'Ohms' (AVO is best for clarity) or using a LV d.c. supply and variable PSU, with the meter set to FSD on a voltage range when the pulse contacts are closed? Connect your pulse contacts to the ohm-meter, or in series with your d.c. PSU and voltmeter, and compare the 'dwell angle' with a known working dial.

That should put you in the right parish.
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Old 23rd Nov 2011, 12:55 pm   #27
val33vo
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Default Re: GPO Telephone 328F.

As a previous post mentioned the quickest way to test your phone will be to disconnect it from the line and put an ohm meter on the lowest scale across the leads with the handset on hook all you should see is a bell circuit capacitor ( the meter will flick briefly every time you reverse the meter leads as its around 2uf )

Lifting off the handset you should now see a lowish resistance ( 100 ohms or so )

rotate the dial and the resistance should drop due to the dial off normal contacts shorting out the carbon microphone when you release the dial you should see the meter needle pulsing a number of times depending on what digit you dialled ie once for a one , two times for two and ironically ten times for a zero

It is really that simple all that a telephone dial is just a switch that disconnects the phone from the line according to what digit is dialled

If you want to be sure that the line itself is not faulty then hit the cradle hooks a few times and dial tone should dissapear as you will have dialled a digit as far as the exchange is concerned

Though being an ex GPO / telecom engineer I am not sure whether all modern exchanges support loop disconnect dialling now as their are so many competitors all with their own weird and wonderfull exchange equipment though I am pretty sure system X and Y should support loop disconnect unless the line card in the exchange is faulty , The british built system X is virtually bullet proof but the swedish Ericson system Y is now showing its age particularly with line card problems ( faulty relays )

regards

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