UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Telephony and Telecomms

Notices

Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment

Closed Thread
 
Thread Tools
Old 23rd Jan 2019, 3:36 pm   #1
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default PBX survives power cuts but not the power being switched off?!

I'm really confused...my PBX (a BT Inspiration) has survived with its memory intact a couple of 2-3 hour long power cuts over the past few years, and it's survived being accidentally turned off at the wall quite happily a couple of times - but yesterday I switched off the power at the switched fused spur and that was it. All settings and time and date forgotten. Any ideas why?!
It has no internal backup battery fitted and never has.
boombox is offline  
Old 23rd Jan 2019, 3:44 pm   #2
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
Default Re: PBX survives power cuts but not the power being switched off?!

Were any exchange lines connected at the time the power was disconnected?
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments.
julie_m is offline  
Old 23rd Jan 2019, 3:49 pm   #3
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: PBX survives power cuts but not the power being switched off?!

Yep - but that's always the case - every time it's been disconnected from power - by whatever method
boombox is offline  
Old 23rd Jan 2019, 4:43 pm   #4
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: PBX survives power cuts but not the power being switched off?!

If it's been preserving the time and date over power loss, it must have a backup battery of some sort in there, even if it's not obviously visible. I don't know the BT Inspiration at all, but perhaps it contains one of the integrated battery-backed RAM and clock modules which were popular in the late 1980s-1990s. They look like an overgrown chip, and the most popular ones were made by Dallas semiconductor. These days they're at an age when the batteries are failing, giving the symptoms you describe. They're a common failure point in a lot of test equipment of that era.

Chris
__________________
What's going on in the workshop? http://martin-jones.com/
cmjones01 is offline  
Old 23rd Jan 2019, 6:03 pm   #5
JulietMike
Tetrode
 
JulietMike's Avatar
 
Join Date: Dec 2012
Location: Andover, Hampshire, UK.
Posts: 85
Default Re: PBX survives power cuts but not the power being switched off?!

The maintenance manual attached might help. It refers to a battery back-up on page 32.
Attached Files
File Type: pdf Instn&Mtce.pdf (1.89 MB, 129 views)
JulietMike is offline  
Old 23rd Jan 2019, 6:15 pm   #6
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: PBX survives power cuts but not the power being switched off?!

I think the battery backup is an optional lead acid battery to keep the phones powered.

The inspiration is vaguely similar to the old revelation, that used a supercap for power cuts.
__________________
Kevin
McMurdo is offline  
Old 23rd Jan 2019, 8:13 pm   #7
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: PBX survives power cuts but not the power being switched off?!

Interesting. I know there's no lead acid battery in there, so yes, a 'supercap' makes sense.

What doesn't make sense to me yet is why the 'supercap' discharged itself when the switched fused spur was switched off but doesn't seem to during powercuts EVEN when the powercuts go on for much longer than the few seconds I had the spur off for.

Thanks
boombox is offline  
Old 23rd Jan 2019, 11:01 pm   #8
JulietMike
Tetrode
 
JulietMike's Avatar
 
Join Date: Dec 2012
Location: Andover, Hampshire, UK.
Posts: 85
Default Re: PBX survives power cuts but not the power being switched off?!

Attached spec from the system handbook for BT Inspiration shows that a supercapacitor is used for memory backup. Perhaps it has now failed.

John
Attached Files
File Type: pdf BT Inspiration Spec.pdf (298.4 KB, 53 views)
JulietMike is offline  
Old 23rd Jan 2019, 11:02 pm   #9
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
Default Re: PBX survives power cuts but not the power being switched off?!

Boombox, you haven't said whether you have subsequently reprogrammed the unit and whether it now manages to retain its programming during power down.

Have you? Does it?

If all the settings are still lost / defaulted try reprogramming just one parameter or the minimum which will give some observable effect, and then power it off for a short time / a long time. Does it consistently lose the programming after either of those intervals?

If it does, whatever used to retain the programming during power down is no longer doing that.
SiriusHardware is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:29 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.