Aggravated!

Status
Not open for further replies.
76nemo

76nemo

Senior Member
Location
Ogdensburg, NY
We have a problem with a test fixture at work with 120Hz on a 5V rail. We tried to rule it out by removing some of the systems cards, and there are many. All system cards seem to test fine.

Any idea where we are getting the clipped 120Hz from? We swapped the power supplies for sh*ts and giggles, same results.

Guess there is way too many details to post. This has proven to be a tuffy, one that has become very aggravating.

I shall post the results when we get to the botttom of it. We are down to the backplane which is so severely modified, it's a punch in the dark. Nothing easier than working on an intricate piece of test equipment with no schematics:confused:
 
76nemo said:
We have a problem with a test fixture at work with 120Hz on a 5V rail. We tried to rule it out by removing some of the systems cards, and there are many. All system cards seem to test fine.

Any idea where we are getting the clipped 120Hz from? We swapped the power supplies for sh*ts and giggles, same results.

Guess there is way too many details to post. This has proven to be a tuffy, one that has become very aggravating.

I shall post the results when we get to the botttom of it. We are down to the backplane which is so severely modified, it's a punch in the dark. Nothing easier than working on an intricate piece of test equipment with no schematics:confused:
Click to expand...

put a giant cap on it?
 
start with the bare box and add one group of components at a time until you find out what is clipping the power ?
 
We're thinking bad filtering caps, but the problem is so load dependent. We can't narrow it down to one card, or another/s, so it's load dependent. We tried a new PSU, yet no prevail. I thought about rectification problems, but that's not it.

It's a teaser with no schematics:-?:rolleyes:
 
Jraef has ruled out what seems to be the problem. We'll see tomorrow:wink: There's too many more details into the problem beyond my description, but again, I think Jraef has it nailed. I will post more after our conclusion.

No schematics is no fun:cool: Can't have it all,......eh????
 
120Hz noise is usually the result of bad filter caps after a full wave bridge. On older equipment they tend to dry out and slowly lose their effectiveness.
 
Status
Not open for further replies.
Top