atcomsystems.ca/forum Forums TDM Business Telephone Systems Vodavi Telephones & Systems STSe Low Volume on L1 & 2, 4th KSU

Last August we replaced a 10 year old Vodavi Analog system (that had never been touched since we installed it) with an STSe. After a few months, the volume on Lines 1 & 2 gets so low that you can barely hear the caller. The problem is with the KSU. We've already replaced the KSU twice and I have to go tomorrow and replace it again because of the same problem. Line 3 never has a problem, just L1 & L2.

This customer is one block away from the CO. I've tested the loop current and it wasn't very high. I even had the CO tech check it for me and switch the circuit to a different card. Still, we have this problem.

The KSU has the same lightning protection that we put on every system we sell. We also have a customer with an STSe directly across the street from the same CO who has never had a problem in two years.

Somebody help me, please!!!

did you put some loop current regulators on the lines?

Also make sure the caller ID board is properly seated and check the loop length under Flash 41 you can change it from long to short.

I would bet that the loop current is the problem though. I had that same issue on a Panasonic system.

Did you happen to look at line 1/2 during a ring cycle?

You would think line1/2 would have more ringing activity on them pointing toward a ac ring cycle issue.

Ring generator in co could be spiking it.

This is a wild guess, but im lost as well Larry.
I have several ksu's less than a block from CO
with no issues.

This is just a stab in the dark from my end.
Wish you luck, and good hunting.

Gary, I have ordered the loop current regulators. Didn't put them on in the past because the current didn't measure high.

TJ, yes, I did try to measure the ring voltage. Even had the CO tech check it while I was standing next to him in the CO. It tested within range. He mentioned that if the ringing voltage was to high, half the town would have problems because the ring generator supplied half the CO circuits.

Sigh...

Still say even thought he checked it, doesn't mean it has gone crazy at times.

I don't buy the fact that it would put half the town out due to the issue.

They would "never" admit to a faulty ring generator issue, due to liability.

Yes, when he checked it it was OK im sure.
Heck, tie two boxes of inside wire on it in the attic and walk away from it.

Did he test both of them?

Im sure if one ring generator fails, it switches
to another, that use to be the design of central office way back then.

Shabby work, but you got to do something.
The regulators might work for you, but if the loop/ring tested ok, gee dont know.

If the loop current is above 35mA or the line voltage is above 52 VDC when idle, that might be your problem. CO line ports are built to compensate for long copper loop lengths, so the nominal 48 volts is typically "hot" when it leaves the CO. Being close to the CO is sometimes worse than being far from it.

I'm really not a big fan of grounding KSU's and providing additional surge protection devices for a standard system installation. In my experience, I have found that these actually "attract" problems.

How many times do you hear of a microwave oven getting fried in an office while the phone system, grounded three ways gets cooked? Multiple grounding of hardware isn't helping; it's actually asking for more exposure to the slightest ground or surge issue. Partner systems with the external ground connection made also have a higher than normal failure rate. People tend to think that extra grounding is their friend. In reality, it causes more issues due to differences in ground potential.

STSe line ports do appear to be very sensitive. I can't say that I have seen the failure rate that you are seeing, but I've certainly seen plenty of them where one port will do this for no apparent reason. Do I dare ask what Vertical's technical support has to say about this issue?

Bingo...... ED you win the prize.

"agree agree agree "

Ed, I agree with the mulitple grounding issue. We don't put a ground wire to the lug on the KSU. We always use Panamax/Surgegate/ITW/Whoevertheyarenow units on all of our systems. Except for this one location, I have never had to replace an STS KSU that we have installed with this arrangement. Have never even lost a LCOB or DTIB.

We have to install some protection on our systems because we are the lightning captial of the world.

I have never called tech-support for this. Why bother. They'll just tell me to replace the KSU.

TJ, he tested both lines for the ring voltage. I was there and saw the meter myself.

Other than adding the loop current regulators, I really don't know what else to do except put their old 308 back in and refund the money. This is very frustrating because we always do our installations the same and never have any problems to speak of. Just at this one site.

Well I hope it's not just because I've been lucky, but loop current around here is high and I've haven't seen this problem. I do use regulators on the fax detect circuits as they wouldn't work without them. As far as grounding the lug, I do, but I run a ground to the ground buss of the power panel, I only do this cause I don't always trust the 3rd prong ground provided.

Larry, I'm going to put on my electrician's hat for a minute on this one. There is a very good chance that the neutral on the customer's electrical service is failing. When this happens, the current that it can't carry ends up shifting to the ground in an effort to seek a return path. Sandy soil, as in your area, doesn't conduct electricity very well. In these situations, alternate paths are sought, likely back into the building. CO lines are grounded at the CO on the tip side, so that's a good place to start seeking a return path for "wayward" neutral current.

The fact that this issue is so concentrated on this site leads me to this conclusion. The only way to truly trust the stability of the electric service's neutral is to have it disconnected and tested properly by an electrical professional. NOT Joe Sparkie coming in with a voltage tester.....This kind of testing requires pros and a complete off-line battery of tests. That is expensive, but could save your customer from future problems.

If the electric service is underground, there is a good chance that the cable is aluminum. If it is overhead, I guarantee that it is aluminum. The hot conductors fail rapidly when they fail due to the high voltage differential to ground (soil). Failing neutrals often take years since there's essentially no difference in potential to ground. It is only chemical reactions that cause neutrals to fail. The degradation escalates and eventually the customer will start to notice flickering lights, etc. Until then, the KSU is the only indicator that they have with the exception of maybe a modem or fax machine.

Remember that the KSU is about the only piece of hardware that gets power from two different sources in the building. Any variances between the two are going to hit it first. Sorry to ramble on so much, but I figured this information might be something that you can share with an electrician who might care. You have my numbers, so if you get that far, I'd be happy to speak with them.