Video Teardown and Repair of an Agilent 86120B Multi-Wavelength Meter - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 31, 2014, 03:09:21 am
content: In this episode Shahriar repairs an Agilent 86120B Multi-Wavelength Meter. The instrument reports “E14 Data Acquisition Problem” which corresponds to a potential internal HeNe reference laser failure. After the instrument disassembly, the old HeNe laser is removed and its optical power is compared to that of a new laser. The measurements confirm that the old laser has significantly deteriorated in output light intensity. The new laser is fitted inside the unit and the error message is eliminated. The free-space optic portion of the instrument is revealed and the principle operation is reviewed. Various components of the Michelson Interferometer is examined.To test the correct operation of the instrument, a single tone semiconductor laser is applied to the unit and the result is compared to a different wavelength meter. The concept behind the operation of a Fabry-Perot laser is also presented before the signal is applied to the wavelength meter.You can view the video at: [42 Minutes]http://thesignalpath.com/blogs/2014/03/31/teardown-repair-and-experiments-of-an-agilent-86120b-multi-wavelength-meter/Direct YouTube Link:

author: echen1024
author_rank: Super Contributor
timestamp: March 31, 2014, 03:27:12 am
content: Just started watching. Delightful video as always, Shariar! Keep up the good work.

author: Vgkid
author_rank: Super Contributor
timestamp: March 31, 2014, 04:10:27 am
content: Good job with the teardown, and subsequent laser replacement. That machined laser case is beautiul on the inside.

author: daqq
author_rank: Super Contributor
timestamp: March 31, 2014, 11:46:21 am
content: Thanks! It's really great to be able to see what's inside some of the more exotic tech!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 01, 2014, 02:55:06 am
content: Quote from: AhhhChoo on March 31, 2014, 08:34:55 amYes, I agree. The amount of unnecessary waste is staggering.

author: alex.forencich
author_rank: Frequent Contributor
timestamp: April 01, 2014, 03:27:57 am
content: Quote from: Hugoneus on April 01, 2014, 02:55:06 amThat's really one of the unfortunate downsides of the incredibly high level of integration of most products today. They're very cheap to produce, but impossible to cheaply repair - the 'smallest replaceable unit' has become the entire device, or what might as well be the entire device. And the really unfortunate part is that this is not limited to consumer electronics. Many of the modern digital scope designs are based around one single board. Anything fails on the board, and the swap the entire board. Such a waste. And it also means that the resale value of broken modern equipment is practically zero, because it is not feasible to repair it. My MSO7104A has an issue in one of the converters that prevents the self cal from running (init for talon cal failed on chan1). The fix is a mainboard swap, and they're asking about $6k, which is more than I paid for the unit in the first place. Go figure.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 01, 2014, 03:36:21 am
content: Quote from: alex.forencich on April 01, 2014, 03:27:57 amHP/Agilent used to have a component level diagnosis/repair strategy. Now they have a module/board replacement strategy. This shift is the result of what you speak of along with the fact that component level diagnosis is now more expensive than just changing the entire board.

author: han
author_rank: Frequent Contributor
timestamp: April 01, 2014, 03:52:03 am
content: Great video, i find your video always very educating..It's a long time since the high frequency oscilloscope video.it's very amazing that they can precisely measure up to PM resolution.From your video, the wavelength meter can plot like OSA, and since OSA typicaly using grating and servo controled, Is there any pros and con between each technique?And why they didn't integrated PMD measurement into the product, since the component required only broadband LED and de/polarizator?

author: vaualbus
author_rank: Frequent Contributor
timestamp: April 01, 2014, 08:44:27 pm
content: Ya since HP become agilent they almost no more release schematics.(And now that will became Keysight technology who know what will happen!)An example could be the schematics of the DSA that dave tried to repair. (also because the unit is still in production.)Probably this strategy of assembly repair is more easy to menage from agilent also because nowdays agilent used a lot of hybrid and asic that are not so interesting on a schematics side.By they way how much cost the laser source you replace in the instrument?

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 01, 2014, 11:10:32 pm
content: Quote from: vaualbus on April 01, 2014, 08:44:27 pmI paid $50 including shipping for the laser replacement from eBay.

author: vaualbus
author_rank: Frequent Contributor
timestamp: April 02, 2014, 05:14:51 am
content: Thank for the info.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: April 02, 2014, 02:12:07 pm
content: Quote from: han on April 01, 2014, 03:52:03 amProbably because they have other products to cover that. Although, Agilent doesn't make OSA's anymore. It is a shame. They lost that market to the Japanese.