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Cortelco 2554 handset ADSL noise issues...

Started by twocvbloke, May 25, 2012, 09:55:43 AM

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twocvbloke

I finally got round to fitting the cable for the kitchen phone, the Cortelco 2554, and once wired in, I found it was playing ADSL signal noise through the receiver, I thought I'd mucked up the wiring, especially as there is a filter on the Master socket (meaning all extensions from it are filtered), and a long story short, the amplifier for the volume control in the handset was picking up and playing back the signals, even though they're not there on all the other phones that I plugged in to test for it... ???

For now I have stuck the red AT&T handset (from the red 2500) on there, as that does not play back the noises, but this is darned annoying as I was hoping to be able to use the volume control...  :-\

Any idea for a solution, or is it a case of not using the handset on an ADSL enabled (even if it's been filtered) line?  ???

EDIT:
Added a picture of the handset's innards...

Owain

check for any dry solder joints in the handset, they may be acting as a semiconductor and you have a crystal set in your handset.

twocvbloke

Quote from: Owain on May 25, 2012, 02:28:39 PM
check for any dry solder joints in the handset, they may be acting as a semiconductor and you have a crystal set in your handset.

That'll be fun, the PCB is stuck in place on a very very sticky foam pad....... :o

Still, it's worth a shot, plus I need to resolder the wires to the volume control cos one's snapped off and the other two are hanging on by a thread.....  ::)

Heatshrink tubing (which I will add myself) really helps prevent that sort of thing... :D

twocvbloke

I think I have narrowed down the problem, I removed the amplifier from the circuit altogether, tried the handset on the red 2500, and yup, noise was still there, so, took out the receiver, popped in a U1 type from the NE500, noise goes away, so, it's the receiver, and the amplifier is just amplifying what the receiver is picking up......... ::)

Just for the heck of it, I searched the forum for "receiver noise", and, well, whaddya know, a Cortelco which picks up filtered-out DSL signals:

http://www.classicrotaryphones.com/forum/index.php?topic=805.0

I think it must be a common fault with the receiver element if that's the case, something in that white plastic case is doing something it shouldn't, and there's been plenty of time for them to have come up with a fix(like, using the older style receivers!!), since (A)DSL has been around for a long time now... ::)

I should have got an original 2554.... :-\

twocvbloke

I give up, checked all the parts in the handset, they're all wired up correctly and solder joints are good, but the noise remains... ::)

So, the AT&T handset has officially replaced the Cortelco handset until I can get a matching plain G15 handset, it's got the Cortelco's transmitter, cup & RJ10 socket, but it's got the U3 receiver that was in there already, and no noise, so there's definitely something about their receiver/amp. that is what's mucking things up... ::)

Why couldn't they just stick to the original WE design?? :D

gpo706

Since we switched from BT ADSL to Virgin cable for the phone line, I still need ADSL filters for every extention from the Pana 616 on GPO/BT sets, no idea why?

WE sets just plug in the RJ11 outs and work fine.
"now this should take five minutes, where's me screwdriver went now..?"

twocvbloke

You sure it's Virgin Cable broadband and not Virgin ADSL (over a BT line) for those not in cabled areas?  ???

If the former, I'm intrigued, cos Virgin don't have ADSL equipment in their exchanges, as they pipe their internet over the cable TV network and use cable modems (see below), so why you'd need ADSL filters, I haven't a clue.... :o

This is our old cable modem (Ambit 256, used it before we moved last November, they may have changed them by now for something newer), can't do naff all with the thing now, no cable = no use, and they say "Just throw it in the bin, we can't re-use them", so I hung onto it, cos I don't know what to do with it (sell, throw, dismantle & re-appropriate, etc.).... ???

twocvbloke

Well, one good thing, the 12ft handset cable I ordered for it arrived just now, and it's perfect for comfortably stretching round the kitchen... ;D

gpo706

Quote from: twocvbloke on May 27, 2012, 01:57:40 AM
You sure it's Virgin Cable broadband and not Virgin ADSL (over a BT line) for those not in cabled areas?  ???

If the former, I'm intrigued, cos Virgin don't have ADSL equipment in their exchanges, as they pipe their internet over the cable TV network and use cable modems (see below), so why you'd need ADSL filters, I haven't a clue.... :o

This is our old cable modem (Ambit 256, used it before we moved last November, they may have changed them by now for something newer), can't do naff all with the thing now, no cable = no use, and they say "Just throw it in the bin, we can't re-use them", so I hung onto it, cos I don't know what to do with it (sell, throw, dismantle & re-appropriate, etc.).... ???

Sorry for the delay in getting back on-topic, Virgin used the ex-Telewest cable for BB, but still needed the BT copper pair for the phone, how does that work?

And that arsehole of a so-called "engineer" took out my extension out to the living room via my Pana 616 for his cable connection...

I haven't a clue!
"now this should take five minutes, where's me screwdriver went now..?"

twocvbloke

Quote from: gpo706 on June 01, 2012, 06:50:57 PMSorry for the delay in getting back on-topic, Virgin used the ex-Telewest cable for BB, but still needed the BT copper pair for the phone, how does that work?

Weird, all the other cable installations I've seen, they've used cable which has one side as the coaxial cable, and the other the telephone cable, so why they'd need to use BT's infrastructure, I don't know, unless it's a really old cable area that was installed before they started offering phone with the cable TV...  ???

QuoteAnd that arsehole of a so-called "engineer" took out my extension out to the living room via my Pana 616 for his cable connection...

I haven't a clue!

I remember that (cos I was reading the thread you mentioned it in earlier!!), there's a reason I prefer to do my own extension wiring, so they don't muck it up... ::)

gpo706

That dickhead was freaking out when I told him the Pana outputted 4 REN per extension, he assumed I said 4 REN IN!

Anyway, I've flogged the bloke enough on this forum...

"now this should take five minutes, where's me screwdriver went now..?"

twocvbloke

Well, some engineers think they know everything, until they're proved otherwise, which isn't hard to do with some... :D

twocvbloke

Well whoops, I pulled the Cortelco's receiver apart, and I managed to break the hearing aid loop (used with the aid in the T position) that was in there, the receiver still works after adjusting the wiring inside the receiver, it's just lost it's hearing aid compatibility... :D

Ah well... ::)

McHeath

Interesting.  My experience with Cortelco phones is that they have quirks like this due to cheaper parts and cost cutting.  Any way you can swap out a WE receiver into the Cortelco handset to get rid of the noise? 

twocvbloke

Yeah, I pulled the handset off my red ATTified NE2500 and connected it up on the cortelco, borrowing the transmitter and transmitter cup from the cortelco (which work fine, the AT&T cup's RJ10 socket was broken, and the transmitter pretty caked up with dirt which need a good cleaning out), so the phone is working, just not with the Cortelco handset with the amplifier... :)