HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comments
View Comments: Newest First|Oldest First|Threaded View
Page 1/3  >  >>
Critic
User Rank
Platinum
ESD!
Critic   5/6/2013 4:10:21 PM
NO RATINGS
ESD!

William K.
User Rank
Platinum
Bad parts right from new stock
William K.   5/4/2013 1:02:41 PM
NO RATINGS
Some of the mor4e frustrating repair projects come from assuming that a new part is good because it is new. Out of tolerance capacitors and wrong marked resistors can lead to an extended diagnostic chase, that is certain. Mismarked transistors also, particularly when a PNP is found marked as an NPN. So for some things that need to be correct the first time they are switched on, validating the "ggodness" of every part winds up being a real time saver. 

armorris
User Rank
Platinum
Re: Root Cause
armorris   5/3/2013 3:59:20 PM
NO RATINGS
It might be heat from the soldering iron. I remember those ceramic terminal strips, and several components might be soldered into those silver-plated notches. It might require a lot of heat to overcome that much thermal mass to melt the solder and replace the diode.

Rob Spiegel
User Rank
Blogger
Re: Quite a maddening problem
Rob Spiegel   5/2/2013 1:03:56 PM
NO RATINGS
BrainiacV -- from these comments, I get the feeling that this problem is not uncommon at all. I guess troubleshooting  should come without any assumptions, including the assumption that the parts -- even new ones -- are not faulty.

Rob Spiegel
User Rank
Blogger
Re: Quite a maddening problem
Rob Spiegel   5/2/2013 12:58:40 PM
NO RATINGS
Good point, Eric. So you would argue that Sherlockm shouldn't have been needed on this case. The problem should have been solved by quality control before the engineer began work on the project.

Eric Tucker
User Rank
Iron
Tek Models
Eric Tucker   5/2/2013 9:07:27 AM
NO RATINGS
Chiming in not as an expert but as an enthusiast of the classic 500-series Tek 'scopes: The Type 547 isn't a storage 'scope, perhaps the author meant the Type 564? I've owned both and still have the 564, which still stores a trace! Not bad for a 50-year-old instrument.

Rob Spiegel
User Rank
Blogger
Re: Quite a maddening problem
Rob Spiegel   5/1/2013 4:37:22 PM
NO RATINGS
That's right, Chuck. But until you actually experience this problem, it would be quite natural to discard the solution if the replacement part did not correct the problem.

Nancy Golden
User Rank
Platinum
Re: Quite a maddening problem
Nancy Golden   5/1/2013 11:11:49 AM
NO RATINGS
You make a great point, Eric - especially for a large company like Tektronix that has the resources to fully address these types of issues - they probably have a large stock of those diodes and they certainly have a QC department that can handle the testing. It may be faulty parts coming from a certain supplier and taking the time to find the root cause could possibly prevent not only QC failures at the factory but operating failures in the field, depending on the mortality rate of the part in question. In the case of the scopes - it is very frustrating when using a piece of test equipment and having it fail while testing or troubleshooting.

Nancy Golden
User Rank
Platinum
Re: Root Cause
Nancy Golden   5/1/2013 10:58:37 AM
NO RATINGS
Another variable to consider when seeking a root cause, Tekochip, is the source of your parts. I was building a microcontroller based wind rose for a project in college and I had an LED display that would light 4 different colors of LEDs to indicate 4 different ranges of wind speed, with the LEDS trailing within four circles to indicate wind direction. So...I had four circles of LEDs, each a different color. The smallest circle was yellow with a 0-5 mph range, the next circle was green...hopefully you get the idea. the outer circle was red and indicating over 20 mph. I etched my own circuit board, carefully drilled the holes - it was an intensive labor of love. I went to the local electronics store that all of us students bought our supplies at. After painstakingly soldering in all of my LEDs and beginning running tests - there was a huge variance in the color of my red LEDs - some showed up a very orangy-red which was very distracting to the balance of the display. I desoldered the ones that were orange and returned to the electronics store which often bought "surplus" parts. This time I brought a battery and tested the LEDs right at the shelf until I found enough red LEDs that were truly red, to complete my project. This taught me that when you buy at a store that carries surplus or nonstandard stock, to be especially careful to test the parts you are using to make sure they are operating within spec (or in the case of the red LED, what you expect).

tekochip
User Rank
Platinum
Re: QC May have been fine... But maybe NOT!
tekochip   4/30/2013 9:10:34 PM
NO RATINGS
Agreed, this is the type of fake I've seen. Maybe the die bonds are weak or the temp. specs. don't live up to the real part, but sitting on the bench in the lab they pass all the tests and make the purchasing guys happy.


Page 1/3  >  >>


Partner Zone
Latest Analysis
Advertised as the "Most Powerful Tablet Under $100," the Kindle Fire HD 6 was too tempting for the team at iFixit to pass up. Join us to find out if inexpensive means cheap, irreparable, or just down right economical. It's teardown time!
The first photos made with a 3D-printed telescope are here and they're not as fuzzy as you might expect. A team from the University of Sheffield beat NASA to the goal. The photos of the Moon were made with a reflecting telescope that cost the research team 100 to make (about $161 US).
At Medical Design & Manufacturing Midwest, Joe Wascow told Design News how Optimal Design prototyped a machine that captures the wing-beat of a duck.
The increased adoption of wireless technology for mission-critical applications has revved up the global market for dynamic electronic general purpose (GP) test equipment. As the link between cloud networks and devices -- smartphones, tablets, and notebooks -- results in more complex devices under test, the demand for radio frequency test equipment is starting to intensify.
Much of the research on lithium-ion batteries is focused on how to make the batteries charge more quickly and last longer than they currently do, work that would significantly improve the experience of mobile device users, as well EV and hybrid car drivers. Researchers in Singapore have come up with what seems like the best solution so far -- a battery that can recharge itself in mere minutes and has a potential lifespan of 20 years.
More:Blogs|News
Design News Webinar Series
10/7/2014 8:00 a.m. California / 11:00 a.m. New York
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 20 - 24, How to Design & Build an Embedded Web Server: An Embedded TCP/IP Tutorial
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: 10/28-10/30 11:00 AM
Sponsored by Stratasys
Next Class: 10/28-10/30 2:00 PM
Sponsored by Gates Corporation
Next Class: 11/11-11/13 2:00 PM
Sponsored by Littelfuse
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service