×
INTELLIGENT WORK FORUMS
FOR COMPUTER PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

noisy DID's

noisy DID's

noisy DID's

(OP)
Does anyone know of a good isolation transformer to block noise comming in on the AC? My DID's are so noisy you can't use them. When I run the IPK off of batterys it clears up nice. I even tried floating the ground with no luck. I tried UPS as well.

RE: noisy DID's

Sounds like you need line isolation transformers. Normally the line is balanced but a common problem with such things as lightning damage or other overvoltage damage is that the balancing circuit gets damaged. this results in the type of noise you are experiencing but the solution is expensive and often it is cheaper to replace the card with the problem. Try swapping cards to see if the problem moves. If it does then make the decision.

Commonly the cost of one transformer down here is $300-400 so if multiple ccts are damaged it can be cheaper to change the card.

RE: noisy DID's

(OP)
Cutting a strap on the card solved 75% of the problem.

RE: noisy DID's

Don't you hate it when you type a post and it disappears.

Which strap did you cut, and was it associated with the line balancing circuit.

I must have been a little inebriated when I first posted on this as they are not called line isolation transformers, they are called line balancing coils.

Analogue indial is still quite common down here, although currently being phased out, and this fault is quite common with this type of circuit. Changing the card or fitting the coils both of which is expensive are the only options I know of.

I was once told that if you return a card with this fault to NEC it would come back unrepaired as it wasn't a requirement for this type of circuit under our regs. I don't know how true that is though.

RE: noisy DID's

(OP)
This is an undocumented cure for AC leaks on DID card. The strap is S1 and located on the bottom edge of the face of the card. Some cards I have found do not have this strap. We cut the strap as well as put SNC chokes on the DID's and noise is considerably less, but still there. We are looking at conditioning the AC power as well.

RE: noisy DID's

When you said you floated the ground, did you actually unscrew the AC ground strap on the front of the elite?

RE: noisy DID's

(OP)
Yes. It didn't help. They work great running off the batteries. I have some SNC chokes on the lines too. They quieted them down even more. Still has some noise though. We are going to try to condition the AC with an isolation transformer.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login


Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close