atcomsystems.ca/forum Forums TDM Business Telephone Systems Nortel Telephones & Systems MOH crossed with Paging?

Customer has old 8x24 with DR5 or 5.1.

Music source is a receiver with output to the moh input of the 8x24, and input from the paging pins of the 8x24.

This whole setup has been in place for years and worked fine. Lately, the background music played through the page horns and set speakers has had a hum along with the music. Then they noticed that a caller on hold could hear the pages.

I pulled the bridging clips off the 8x24 moh input, and of course the caller on hold doesn't hear any pages (or music). Also, the hum is gone.

Is it possible that something is crossed inside the 8x24?

Any suggestions?
Thanks!

Jim

That sounds more like receiver problems. Lost the power ground of the receiver, failing power supply in the receiver are 2 possibilities. Of course, it could be that the receiver is off-station, or worse yet, set to an AM station. John C.

Pulling the clips off the moh input caused the music to clear up and sound better, at least as heard through my butt set on the 66 block.

1 of 2 possibilities. 1:Turn pair over, or 2: either the receiver or the KSU has a ground problem and I'd put my money on the receiver.

"Then they noticed that a caller on hold could hear the pages."

Oops, didn't catch that the first time around. And supposedly 'Nobody' has been working on the page/MOH? What is 'Nobodies' REAL name?

OR, it's always been that way so that the pages would come through the 'overhead' speakers AND the 'phone' speakers at the same time. Kinda 'cheesey', but one quick, dirty, and cheap way to do 1 page and hit ALL speakers, AND have BGM/MOH all over from 1 source. John C.

"OR, it's always been that way so that the pages would come through the 'overhead' speakers AND the 'phone' speakers at the same time. Kinda 'cheesey', but one quick, dirty, and cheap way to do 1 page and hit ALL speakers, AND have BGM/MOH all over from 1 source. John C."

Paging is set to page all overhead horns _and_ all set speakers. The receiver/amp has connections for both.

Callers on hold don't hear the music. The music is muted during a page. Callers on hold hear the page faintly, but well enough to tell what was said.

Jim

Paging and MOH are one unit? It's cross talk within the receiver or you've blown the MOH input of the KSU with to much volume.

I'll be on site late this afternoon. I'm bringing along another music source and will connect that, just to the moh input. Leaving the existing music source to feed only page horns for now. If there is still a problem, then I'll change the ksu.

(Customer does have an old 8x24 on the shelf for backup) I'll let you know more tomorrow.

Jim

I am with Marv on this one...

Related:
https://www.sundance-communications.com/cgi-bin/ultimatebb.cgi?/ubb/get_topic/f/8/t/003396.html

You need to make sure the KSU gets the right MOH input or damage will eventualy happen.

I did read your post before I submitted my original question. It has been ok for many years. Maybe it's finally gotten weak enough, or somebody cranked it up after work one Friday night???

I thought phone systems always wanted a 600 ohm connection to audio devices. The music source was connected with the 600 ohm terminals.

How do I make it a 3300 ohm connection? Put a 3300 ohm resistor in series with the music side of the pair? Across the pair?

Thanks.
Jim

Assuming, and we all know how dangerous that word is, your music source is 8 ohms, Radio Shack has an 8 ohm to 1000 ohm AUDIO TRANSFORMER. That has always worked well for 600 applications.

Since you say you have a receiver, could you not send one of the channels to the 8 ohm side of the AUDIO TRANSFORMER and the other 1000 ohm side to the MOH punch down on the station block so people hear clean MOH? But then I've usually been able to just plug 8 ohms to a Norstar and have it work.

Then for paging get a Radio Shack 12 volt DPDT relay and you probably have an old 12 volt DC wall transformer. Find the swing arm on the DPDT relay and follow the normally closed pins (not the swing arm pins) to their connection. Wire the second MOH to those pins. One is on EACH side.

Follow the normally open pins down to the connection and connect the paging output to them. One is on EACH side.

Follow the swing arm down and use that output to the input of the paging amp.

Now you hook one wire of your 12 volt transformer to one pin of the two pins that go to the coil. You run the other power wire up to the COMMON punch down pins for the Page, and run the N/O (Normally Open) punchdown to the other power pin of the coil.

In normal operation music goes out to the unpowered relay and passes from the normally closed contacts to the swing arm and out to the amplifier.

When they do an external page, power goes through the normally open and common punchdowns, the swing arm comes down and the paging voice goes from the normally open contacts to the swing arm and out to the amplifier.

If you want a diagram, PM me and I will fax it to you. Don't have a scanner to send it by email but you should be able to figure it out from the text.

This Burlington born gal is always happy to help out an Iowanian.