Author Topic: Ericsson 50 line PABX  (Read 1388 times)

Offline Keelan

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Ericsson 50 line PABX
« on: September 16, 2016, 09:48:44 PM »
Hey everybody... Some of you know that I have had an Ericsson 10+50 Strowger PABX (GPO 4000 series selectors) in storage for the last 16 years -- at the beginning of the summer I finally moved it in to my garage, and I've had the odd chance to fire it up here and there. I've filmed my exploits, and thrown them up on the youtubes:

Part 1 - Startup after being in storage, and moved to my house:

https://www.youtube.com/watch?v=FJ8CDuFN47w

Part 2 - Bit of electronics work to fix the Chinese switching power supply I bought to replace the giant/loud Northern Electric ferroresonant unit that the PABX came with (don't worry, I won't throw it out, but it'll be mostly for show now):

https://www.youtube.com/watch?v=QY2UrQYcOGk

Offline twocvbloke

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Re: Ericsson 50 line PABX
« Reply #1 on: September 17, 2016, 02:05:01 PM »
Very neat PABX (but I would say that, I'm British too!! ;D ), that chinese PSU though, yeah, not very well constructed at all, but it seems to do the job nicely after fixing it (something anyone buying mains-powered things from china should do before plugging it in!), even if the arc from tht capacitor made me jump when you shorted it or made contact or whatever it did then... ;D

Makes me want to have such a PABX, sounds so much more fun to listen to when dialling numbers... :)

Offline Keelan

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Re: Ericsson 50 line PABX
« Reply #2 on: September 19, 2016, 06:17:46 PM »
If you watch the earlier video, I power the PABX up with the Northern Electric unit, the sound really is quite horrible. It was too noisy for my little garage. The PABX draws very little current when it is idle, so the chinesium power supply is very minimally loaded. I left it on all day yesterday, and the power supply remained stone cold. One of the commentors posted a good analysis of the power supply -- he imaged it with a thermal camera and discovered out a few hot spots -- a few bleeder resistors on the capacitors, and resistor feeding the centre tap of one of the transformers. I plan on upgrading them to higher wattage resistors soon.

It scared the crap out of me too -- why do you think the video cuts right after the spark? :) The negative lead on the capacitor was barely connected, I completed the connection with the tip of the screwdriver.

unbeldi

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Re: Ericsson 50 line PABX
« Reply #3 on: September 19, 2016, 07:27:05 PM »
When was this system manufactured?
And where did they make these?

PS:
Another question:  Is this a No. 2 PABX, not sure of the dates, but early 60s perhaps?

How many connector circuits are there ?   Is it seven?
« Last Edit: September 19, 2016, 09:05:16 PM by unbeldi »

Offline twocvbloke

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Re: Ericsson 50 line PABX
« Reply #4 on: September 19, 2016, 11:38:53 PM »
If you watch the earlier video, I power the PABX up with the Northern Electric unit, the sound really is quite horrible.

Yeah, I watched them both in the order you had posted them, that original PSU, although nice to have to make it complete, is quite a noisy old thing, and I thought my Belkin UPS was a bit of a buzzbox when it was on battery power!!  ;D

It's actually rather surprising what a small box of tricks can power these days, like my aforementioned Belkin UPS, I used that to test my neighbour's old washing machine (still need to do something with that!) out in the back shed, and it worked, made the motor sound very unhappy due to the low-quality modified sinewave output, but power it up it did... :)

And just cos, the video I made of the UPS-powered washer:
https://www.youtube.com/watch?v=bZQ_AqegRgk

Offline Keelan

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Re: Ericsson 50 line PABX
« Reply #5 on: September 20, 2016, 04:47:30 PM »
The system appears to have been manufactured in 1971. It was made in Beeston, England by the British Ericsson Telephone Company. Of course they merged with Plessey 10 years prior, so many of my manuals have Plessey's logo on them instead of the Ericsson Telephones Limited 'ETL' logo.

This is a PABX 10+50 (No. N22845), not one of the numbered PABX designs.

It has 7 selectors, plus an additional two-motion switch for the callback feature.

unbeldi

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Re: Ericsson 50 line PABX
« Reply #6 on: September 20, 2016, 05:12:16 PM »
The system appears to have been manufactured in 1971. It was made in Beeston, England by the British Ericsson Telephone Company. Of course they merged with Plessey 10 years prior, so many of my manuals have Plessey's logo on them instead of the Ericsson Telephones Limited 'ETL' logo.

This is a PABX 10+50 (No. N22845), not one of the numbered PABX designs.

It has 7 selectors, plus an additional two-motion switch for the callback feature.

Ah, thanks a lot.  Yes, I know now which one this is.  It was reviewed (or introduced?)  in the Ericsson Bulletin, which was also published in Nottingham, I believe.
It could be equipped with either the 2000 or the 4000 series selectors, as desired. I will dig up the paper.

Offline twocvbloke

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Re: Ericsson 50 line PABX
« Reply #7 on: September 20, 2016, 05:20:47 PM »
Having a nosey about on the Bob Freshwater's site, there's some info on the PABX here:

http://britishtelephones.com/ericsson/n22845.htm

As standard it apparently came with the 4000 series selectors, with the 2000 as an option...

unbeldi

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Re: Ericsson 50 line PABX
« Reply #8 on: September 20, 2016, 07:49:07 PM »
Here is the article of 1960.

Do you have the attendant console too? Very cool looking.
« Last Edit: September 20, 2016, 07:51:46 PM by unbeldi »