Exchange Line Simulator problems - UK Vintage Radio Repair and Restoration Discussion Forum

stuart_morgan_64 · 8th May 2016, 8:15 am

I am looking for advice or help. Circuit would be nice, but not sure if that's likely. I use this a lot, bought in the early 90s I think, we used to repair lots of cheap horrid answerphones. Now used with vintage phones.

It all works, except, there is no ringer voltage. I used to hear a relay clicking with the ring cadence, not anymore. The display is still showing it's ringing, also I can\did feel the ring voltage on the PCB around the coils.

Any advice, information or someone who can take a look at it.

Thanks

Biggles · 12th May 2016, 9:59 pm

It's probably worth checking those relays. Could be an open circuit coil, which you can prove with an ohm meter, or possibly the reverse blocking diode across the coil gone short circuit, or maybe a dry joint or relay driver transistor u/s. Start with the most obvious things first. Are the batteries in the battery pack still serviceable? If it's anything more complicated than that it could be very tricky to find, I can see a lot of ICs in there.
Alan.

stuart_morgan_64 · 13th May 2016, 9:52 am

Hi Alan, I was going to have another go, problem must be in a small area, not sure which relay is the ringer, but see if there is voltage on and off in line with the ring cadence. Put my patience cap on. There are a lot of ICs, but will have another go, ring voltage still there, I could feel it.

Thanks, Alan.

Biggles · 13th May 2016, 7:10 pm

I built a simple phone line simulator to quickly test phones at work. It produces line voltage, ringer voltage and tones but not dial tone. It decodes DTMF and has a level meter to check the phone mic sensitivity. It wasn't that hard to build so if all else fails you could maybe build your own, depending on how in depth your testing has to be.
Alan.

stuart_morgan_64 · 15th May 2016, 11:28 am

Sounds interesting, by the ringer not working on this it's not checking the REN level so you can ascertain if any mods are required. As soon as the bench is clear I will look at mine again. I do have a 4 way exchange which I uses to demonstrate phones, so do have the ability to ring a phone easily.

8th May 2016, 8:15 am	#1
stuart_morgan_64 Heptode Join Date: Aug 2004 Location: Woodbridge, Suffolk, UK. Posts: 501	Exchange Line Simulator problems I am looking for advice or help. Circuit would be nice, but not sure if that's likely. I use this a lot, bought in the early 90s I think, we used to repair lots of cheap horrid answerphones. Now used with vintage phones. It all works, except, there is no ringer voltage. I used to hear a relay clicking with the ring cadence, not anymore. The display is still showing it's ringing, also I can\did feel the ring voltage on the PCB around the coils. Any advice, information or someone who can take a look at it. Thanks Attached Thumbnails

12th May 2016, 9:59 pm	#2
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Exchange Line Simulator problems It's probably worth checking those relays. Could be an open circuit coil, which you can prove with an ohm meter, or possibly the reverse blocking diode across the coil gone short circuit, or maybe a dry joint or relay driver transistor u/s. Start with the most obvious things first. Are the batteries in the battery pack still serviceable? If it's anything more complicated than that it could be very tricky to find, I can see a lot of ICs in there. Alan.

13th May 2016, 9:52 am	#3
stuart_morgan_64 Heptode Join Date: Aug 2004 Location: Woodbridge, Suffolk, UK. Posts: 501	Re: Exchange Line Simulator problems Hi Alan, I was going to have another go, problem must be in a small area, not sure which relay is the ringer, but see if there is voltage on and off in line with the ring cadence. Put my patience cap on. There are a lot of ICs, but will have another go, ring voltage still there, I could feel it. Thanks, Alan.

13th May 2016, 7:10 pm	#4
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Exchange Line Simulator problems I built a simple phone line simulator to quickly test phones at work. It produces line voltage, ringer voltage and tones but not dial tone. It decodes DTMF and has a level meter to check the phone mic sensitivity. It wasn't that hard to build so if all else fails you could maybe build your own, depending on how in depth your testing has to be. Alan.

15th May 2016, 11:28 am	#5
stuart_morgan_64 Heptode Join Date: Aug 2004 Location: Woodbridge, Suffolk, UK. Posts: 501	Re: Exchange Line Simulator problems Sounds interesting, by the ringer not working on this it's not checking the REN level so you can ascertain if any mods are required. As soon as the bench is clear I will look at mine again. I do have a 4 way exchange which I uses to demonstrate phones, so do have the ability to ring a phone easily.