Category Archives: Best of Site

Longer articles featuring the best of SBE36.org. Biographies of local engineers, news event coverage, and “Making Waves” commentary.

Best of Site, Commentary

Making Waves Commentary: The Shotgun Approach

A little over two years ago, Fox 6 photojournalists were showing up at our service shop with odd, seemingly unrelated problems with their camcorders. The symptoms involved anything from servos to color encoding to erratic controls. We learned that the solutions, however, were almost always the same–change out a group of surface-mounted electrolytic capacitors or replace the entire circuit board. The DVCPRO camera or studio deck always went away working again until another, unrelated, failure occurred. Repair veterans like Greg Capalbo of GRC Electronics were warning us that the failed capacitor scenario was an epidemic, especially with Panasonic gear, but also to a lesser extent with Sony and other brands. And Panasonic was not supporting out-of-warranty fixes with either parts or labor.

As we saw more electronics come in with bad capacitors, it became increasingly clear that the future duties of our ENG specialist Ladd Prier might involve an endless, daunting series of tracing erratic component behavior to a circuit, then buying new caps, awaiting their arrival, then swapping them out and hoping the bad behavior would disappear. We visualized the coming stack of broken equipment and unhappy users. There had to be a better way.

Ladd and I come from a time when a technician took pride in tracing an obvious equipment failure to one or more components directly responsible. When an RCA TR-3 2″ videotape player headwheel wouldn’t spin up, I would get the four-inch thick manual, an extender, and Tektronix 545 oscilloscope and through a series of calculated guesses, eventually find the open or shorted germanium transistor or diode, then replace it and check a couple of waveforms before pronouncing the monster ready for duty.

Fast forward 25 years. Today’s equipment contains little undocumented black boxes. When the servo fails, you change out the servo board. But what if all boards fail on all news equipment? We were looking at a potential of essentially having to replace part-by-part all of our five-year-old Panasonic equipment.

A Better Way

On a whim, I called our temporary agency, TLC Staffing, and asked if they had any registered rework specialists. In manufacturing, these are the people who take circuit boards with errors on them, either by design or by manufacturing defect, and change out components as ordered to resurrect those boards. {mosimage}They are skilled at performing Lilliputian surface-mount technology soldering, and with incredibly tedious repetition.

TLC sent us Vu Le, who appeared businesslike, cheerful, and ready for action. Over the next ten weeks, he replaced nearly every surface-mounted capacitor in every Panasonic DVCPRO deck, both from the field and from inside the plant. He changed up to 400 caps a day for a total of nearly 20,000. Total cost: nearly $16,000 including parts. Every VTR and camcorder finished worked like new, especially when heads were changed at the same time. There were no more mysterious misbehaviors, a fraction of the downtime, and Ladd was now free to take care of the more normal maladies of ENG.

Months after Vu went on to other work, we noticed more equipment failures that seemed as though they could be capacitor related. Modules in our Wheatstone TV-80 mixer started having problems with bandpass and open circuits. Our digital Hitachi studio cameras had assorted color problems.

This time we didn’t hesitate. We hired temp Daniel Yanez to swap out all the electrolytics in those devices, though less careful to estimate the extent of the project. Now some 10 weeks later, Daniel is still slaving away, module after module. He began filling a three-gallon plastic jar with the tiny devices, and now it’s nearly a third full.

Obviously, if we knew the more about the exact nature of the failures, we could be more selective about the replacement. Were some of the caps higher grade? Which values really fail? If temperature is a factor, couldn’t we perform an IR scan to find the hotspots? Since we didn’t have a good composite history of the mixer and cameras across their user base, we didn’t have the knowledge to pick and choose what devices to replace, so we replaced them all. The basis for doing so was 100% empirical and 0% scientific.

Epilogue

Industry experts continue studying the science behind the SMT chip capacitor failures. It surprises me to learn that they blame not just chip chemistry, but physical conditions during manufacturing and board assembly. It appears as though bad things are happening to good companies with respect to their products not living as long as expected.

We bought replacement capacitors that were labeled as having a long expected life, but there’s no assurance that we’ll even double their life. In fact, we’ve replaced the camcorders in a surprise blast of capital funding. I expect the 7-year-old standard definition cameras and analog audio mixer can’t be far behind.

Daniel is looking for his next gig. Got bad stuff?

Comments

Courtesy CGC Communicator

The capacitor saga dates back to about 1998 and the wide use of surface mounted electrolytics. Those parts have a time and temperature rating. The ones supplied in most gear do not have the most generous ratings. While we deal with Sony, Panasonic, JVC, etc., their original board assembly may all be
done at one outside vendor. Thus, plenty of gear was built with marginal capacitors.  I first ran into this with Panasonic DVC-Pro recorders.  One audio card that was troublesome had 50 of the beasts on it.

The best way to test for bad capacitors is with a Capacitor Wizard that uses a high frequency to measure reactance. It works fine testing caps with no need to unsolder.

Roy Trumbull, roy547 (at) msn.com

 

 

The Panasonic DVC-Pros are the first and worst detected.

We tried Panasonic replacement kits and they didn’t fix all symptoms. I decided not to test the capacitors, figuring that we would have too many iterations of failure/remove/disassemble/test/replace/reassemble/return. Our rework guy could replace 400 caps per day, so I just said to heck with testing –replace them all!

It’s been my experience that measuring in-circuit reveals the problems in only one point in time and doesn’t address future cap failures. In our case, we haven’t had any symptoms in our DVCPRO decks since the mass replacement of capacitors.

Gary Stigall

URLs FOR ELECTROLYTIC PROBLEMS

Scroll down to the Great Capacitor Scare:
http://catless.ncl.ac.uk/Risks/22.73.html#subj9

This article discusses acidic leakage damaging circuit boards in mobile radios:
http://www.repeater-builder.com/motorola/spectra/spectra-caps.html

While this article is oriented towards PC board mounted caps, the cause is the same – bad electrolyte:
http://en.wikipedia.org/wiki/Capacitor_plague

And more links yet:
http://www.ttiinc.com/object/ME_Zogbi_20050919.html
http://www.badcaps.net/
http://www.theinquirer.net/default.aspx?article=24596 (re Dell)

All in all, it looks like bad electrolyte is the root cause.
In some cases it causes a reduction in capacitance value (which
changes circuit performance), in others it blows the tops off the
caps, in others the electrolyte eats its way out of the cap and
eats up the board.

Mike Morris, WA6ILQ

Best of Site, Local News

KSDS Gets FCC OK to Raise Power

(Disclosure: The author is employed by Bay City Television, San Diego-based programming, advertising, and marketing arm of XETV Tijuana)

The FCC issued on October 31 a construction permit for KSDS (FM), 88.3 MHz, to increase power from their current 3 kW vertical to 22 kW ERP vertical, upgrading the facility from class A to class B1. The station, operated from the campus of City College downtown, but transmitting from a tower at Mesa College in Linda Vista, has been operating since 2002 with 3 kW ERP vertical polarization after a compromise worked out with Fox Television affiliate XETV, channel 6 in Tijuana.

The latest CP approval comes as a surprise to XETV, which has fought the increase in power since 1995 on grounds that it creates a substantial interference zone since the stations are only separated by a minimum of 200 kHz between allotments, or 550 kHz between carrier centers. The stations represent a unique situation in the U.S., where a border non-commercial FM had protected a channel 6 TV signal broadcasting in English-language from Mexico. The new construction permit appears to change the crossborder relationship by declaring previous protections null and void.

The new FCC ruling says that previous international broadcast treaties do not specifically deal with the TV-FM interference issue, so the XETV signal has no rights to protection from U.S. non-commerical FM stations after all. At the same time, the order gave recognition to XETV public service efforts and ordered that KSDS broadcast its increased power in vertical polarization only. KSDS must provide a shallow null to the southeast, and they must remediate any known interference and report unsolved cases to local FCC inspectors.

KSDS intends to have its facilities ready for increased power by spring 2007.

Best of Site, Commentary

Making Waves: BPL Comes Home

What happens when you suddenly find your dipoles surrounded by BPL couplers? I’m about to find out.

The Broadband over Power Line (BPL) pilot project continues in San Diego. The test observation committee set-up by SDG&E power systems engineer Terry Snow, of which I am the token broadcasting representative, met last during the recent NAB Convention, but Terry was kind enough to forward a copy of the meeting minutes. 

{mosimage}So imagine my surprise when I looked at an enclosed map to see that the third vendor pilot would surround my University City home. The system power-up is scheduled for this week, and the amount of activity in the neighborhood has been very high. Truck crews have been installing wireless receive antennas and data couplers on poles and electricians have put data modems in a test  home…which happens to be a next-door neighbor.

I won’t comment much on the BPL pilots to date except to say we haven’t found any measurable interference to the broadcast bands that you care about. I’ve agreed with SDG&E to patiently await results of spectrum analysis tests before drawing any conclusions. There is something a bit childish about berating a scientist as he’s performing his experiments, whether you agree with the science or not.

It appears as though Terry and his co-workers are genuinely interested in getting feedback on interference caused by their BPL pilots, and they are studying similar pilots around the country for experiences with interference. In fact, they added a vendor to their pilot series that was known for reduced interference. There are at least three of us on the committee who are licensed ham radio operators. Whether the board at Sempra Energy takes their, or our, final recommendations to heart is another matter.

I have to believe that my neighborhood was chosen because it was one of the last with overhead electrical lines, and due to the lack of CC&R’s, it has has a higher incidence of ham radio operators than later built neighborhoods. If Terry chose specifically to surround my house, that’s very funny Terry. Very funny.

As a ham radio licensee for 35 years, I haven’t been very active for the past few years. I have enjoyed 6 meter E-skip operations from time to time, but that’s about it. I have a dual 10 meter/40 meter dipole and a decent collection of 40-year-old Drake equipment, so I’ll be firing that up to make sure there the HF interference characteristics haven’t changed. It’s been amazingly quiet here considering the urban nature of the neighborhood. I hope it remains that way, but the future’s not bright. 

One of the surprising findings on a previous pilot project site test was that the primary radiators in the fake home office was a plasma TV generating a big, raspy signal on the upper portion of the AM broadcast band. When we turned that off, we found another device radiating in the middle frequencies of AM–this was the power supply of the BPL modem, not the power lines themselves. We saw a heterodyne on channel 6, but turning off the BPL system made no difference. 

Ever played Whac-a-mole at Chuck E Cheese?

Best of Site, Commentary, National

Making Waves Commentary: Gonsett Fights Satellite Receiver Makers

(Commentary) The popular industry email bulletin CGC Communicator published by Communications General Corporation consulting engineer Robert Gonsett ran a series of summary articles this year on the emissions of what he terms “mini-transmitters” used for getting audio from satellite receivers to automobile FM radios. At question was the power and frequencies chosen for the job.

Sometimes taking on entrenched forces of big business and big government becomes a hopeless morass of stonewalling and legal manuevering; the one with the most expensive den of attorneys wins. At other times, the system works. Follow along as we piece together the story of how one person can shed enough light on foul activity to make a difference.

This story began nearly two years ago, shortly after I took the job as Chief Engineer at the XETV Fox 6 studio in San Diego. Disclosure: XETV retains well-known consulting engineer Robert Gonsett specifically to deal with matters of interference, be they intentional or incidental. The actions taken by Bob were largely done by his own initiative, though I am left personally grateful and somewhat astonished from the lesson of power in process and persistence.

The Punching Bag of TV Spectrum

Pity the poor channel 6 over-the-air viewer in San Diego. First of all, the signal’s low band VHF, which means viewers must contend with urban electrical noise and the visual blight of a large antenna, if they bother at all. Then there’s the distance from the transmitter in Mexico to viewers north of Mission Valley. Add that the XETV’s power is split between horizontal and vertical polarization so that unless you have a special circular polarization receive antenna, you can’t receive the full signal. And then we deal with the adjacent band noncommercial FM broadcasters who want nothing worse than to improve coverage for their deserving listeners. The latest assault, however, comes from the proliferation of little FM modulators people use to transfer without wires the audio from their file players and various satellite receivers to a stock automobile FM stereo radio.

Those FM modulators are termed by the FCC “intentional radiators,” which means that their radiation is intended, in contrast to the unintended radiation from, say, your computer’s switching power supply. Under FCC regulation 15.209(a), such intentional radiators must have a fundamental signal within the FM band measured at no more than 150 uV/m at 3 meters distance, and they’re just plain not allowed on TV channels 5 and 6.

The  Journal

2005 – I begin receiving occasional calls from viewers who say that they are watching us when the colors  flash and they can hear music or voices unrelated to the video emanating from their TV speakers. Their interference comes and goes as do their neighbors. Obviously, this must be occurring with other channel 6 outlets around the country.

December 2005 – Gonsett’s newsletter, the CGC Communicator, relays a report from an LA radio chief engineer that a pirate broadcaster he picks up on his car radio is actually an XM satellite receiver FM modulator. “It amazed me how far I could hear the FM modulator….at least 250 feet if not further. This is the second time that this has happened to me while driving around…I strongly question whether these XM modulators are Part 15 compliant because they are able to radiate signals over 250 feet….”

March 11, 2006 – The Philadelphia Inquirer runs a story about the interference to non-commercial FM stations caused by satellite radio receivers. By this time, it is common knowledge that the default frequency on many of those receiver modulators is 88.1 MHz, much to the dismay of stations like KKJZ in Long Beach. Mike Starling, NPR Director of Engineering and Operations in Washington, promotes using 87.9 MHz as a default frequency—understandable in light of the fact that many, if not most, of these mini-transmitters come equipped to transmit only on non-commercial frequencies at the lower end of the FM band.

March 29, 2006 – Bob Gonsett writes a detailed letter to Sirius Radio Public Relations officers, with copies sent to various FCC contacts. In it, he asks that the satellite radio companies provide proof that they have received from the FCC a specific waiver that allows them to market satellite radios with FM modulators, “intentional radiators,” operating outside the FM broadcast band on 87.7 and 87.9 MHz.

March 30, 2006 – TV Technology magazine, in Doug Lung’s RF Report, highlights the FM modulator issue as a result of correspondence with Fred Lass, director of engineering at WRGB channel 6 in Schenectady, N.Y. Doug names the names of several modulator manufacturers that advertise illegal modulators and clarifies the FCC rules regarding continuous intentional radiation either misunderstood or ignored by those manufacturers. Doug reveals that Lass has notified the FCC Office of Technology about these transmitters. Lass tells Lung, “All that is required to find [illegal transmitters] is to do a Google search of ‘87.9 MHz’ to get a list of manufacturers and retailers selling these devices in the U.S.”

April 8, 2006 – Bob Gonsett “gets the ball rolling” by filing a complaint with the FCC in Washington against Sirius Satellite for incorporating 87.7 and 87.9 MHz into the intentional radiator mini-transmitters that are built into many Sirius consumer satellite receivers. He chooses to focus the filing on a single high profile case in order to simplify the process, shed light on the problem, and hope that the FCC would itself broaden the investigation.

April 27, 2006 – XM Radio files an 8-K form with the SEC in which it reveals to investors that it has received an inquiry received from the FCC OET on April 25 regarding the emissions of the Delphi SkyFi2 radio. The company states that it is making an internal review and anticipates “responding to the letter shortly and cooperating fully.”

May 8, 2006 – Bob Gonsett posts on his CGC Communicator an anonymous comment from a Los Angeles FM broadcast engineer favoring modulators operating below the FM band. “My feeling on any small transmitter for an XM, Sirius, HD or MP3 players is that they SHOULD use these out of band frequencies. Currently, FCC Rules do not allow this, but the situation deserves careful examination and consideration. Given the interference these devices cause to mobile on-channel reception of legitimate stations, we should give them out of band authorization (but not above 107.9 MHz). As a user, I cannot find a clean channel to use in Los Angeles for my XM receiver. As a licensee, I would not want them on my channel.” A sort of spectral NIMBY statement, but who wants mass transmitters on his frequency?

May 16, 2006 – Reuters reports that Audiovox Corp. suspends shipments of its Xpress Model XMCK10 XM satellite radio receiver after the FCC says the unit “did not comply with either operating bandwidth or related emission specifications.”

May 30, 2006 – XM Radio files another Form 8-K with the SEC in which it reveals to investors that it has suspended marketing of radios made by Delphi and Audiovox in order to comply with an inquiry received from the FCC on April 25. XM says it will modify the radios in question and submit them for Part 15 compliance testing. “We plan to have modified devices shipping to retailers in the near term.”

May 31, 2006 – Orbitcast.com quotes Sirius Radio EVP/CFO David Frear as saying that “all SIRIUS Satellite Radio receivers are in full FCC compliance. Some letters were sent regarding some Sirius devices that were out of spec. Frear stated that they then went to the receiver manufacturers and took care of the problem a while ago. All SIRIUS Radios are in full FCC compliance. Case closed.” Phewww.

Like the Whac-a-mole amusement at your local Chuck E Cheese, getting a couple of vendors to change their ways through FCC inquiries will inevitably result in another vendor producing a replacement product. After all, consumers demand a convenient way to transfer audio without wires. And none of this activity has yet dealt with the multitude of transmitters out there designed to transmit Apple iPod audio over FM. Some of those mini-transmitters are reported to put out suspiciously high signal levels. The work continues.

Best of Site, Local News

FCC Cites San Diego Radio Pirate…Again

FCC inspectors recently revisited the Golden Hill pirate station calling itself Free Radio San Diego at 96.9 MHz. An FCC Notice of Unlicensed Operation document signed by Bill Zears of the San Diego field office details an April 3 trip to the new 33rd Street transmitter site that found field strengths measuring over a thousand times Part 15 allowances. Station equipment, including the transmitter, was confiscated last summer in an FCC raid. Apparently this latest notice means that enforcement processes have started anew.

The website normally associated with the pirate station is down. The station normally plays a variety of free form music not heard on local commercial outlets, as well as community information and political talk.

We posted an interview with the station manager known only as Bob Ugly in July 2005.