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The Voltair

I have put off writing anything about this for several reasons. First of all, there is a lot of secrecy surrounding the use of the Voltair magic machine. No one will admit to it, however, I have had several off the record conversations with various engineers.  All of this is hush-hush, unofficially off the record and on the QT, so no names, call letters or cities of license can be disclosed.

The general gist of these conversations is this; the Voltair seems to be increasing ratings in some cases and but not others.  It is sometimes too early to tell whether the increased ratings are a one time anomaly or something more permanent.  In one case, an AC station saw 30% increase in numbers, while a certain talk station saw next to nothing.  Results are mixed.

In the credit where credit is due department; the Telos Marketing campaign is has been effective.  Again, from a variety of different sources; Program Directors, Market Managers and Sales Managers are “beside themselves,” or “giddy”  when the UPS truck delivers the Voltair to the front door.  In one case, requiring that “I (the market engineer) drop everything” to get it installed as quickly as possible and “acting like it is God’s gift to radio.”  It looks like all those trade publication ads are paying off, $15,000 at a time.

Voltair PPM encoder enhancing device, in the wild

Voltair PPM encoder enhancing device, in the wild

One interesting thing about the Voltair, you can program simulated listening environments such as sporting events, restaurants, kitchens, vehicles, etc.  This allows the user to see how their program material is being decoded by a PPM survey device in those types of environments.  For example, if you are a sports station, having your program material decode well at sporting events or restaurants and bars might be important.

Of course, we have all seen the confidence display:

Voltair PPM encoder enhancer "confidence display"

Voltair PPM encoder enhancer “confidence display”

So, what does this mean?  Perhaps there is an inherent flaw in the Nielsen PPM encoding technology?  In the past, PPM has been blamed for the demise of the Smooth Jazz format.  I always had the notion that Smooth Jazz was responsible for the demise of the Smooth Jazz format.  However, if PPM is indeed causing certain program material to disappear from the airwaves, then it would be a case of the tail wagging the dog.  If PPM requires that station owner’s purchase a $15,000 in order to get credit for their TSL and cume, then there is a pretty big problem with the technical aspects of the system.

Of course, there are others that say there is no “Voltair effect.”  The Voltair machine is simply a fancy and expensive gizmo that looks good but does not really do anything.

Nielson Audio is having a Webinar on July 21 to address some of the questions regarding the Voltair and PPM encoding for subscribers only.  It will be interesting to see what the outcome is.

Cost saving measures

Excerpt of a memo from a few years ago, during the great recession:

(Redacted) has implemented a consumables reduction program.  All consumables; copy paper, toner, note pads, pens, pencils, paper towels, garbage bags, paper plates, plastic flatware, toilet paper, and so forth must be reduced by 25%.  (Redacted) is spending far to much on such material which is impacting our financial performance.

The Management

My contribution to the effort:

new consumable reduction program

new consumable reduction program

I wouldn’t want the CEO to miss his bonus this year…

Night of nights, 2015

Every year, the Maritime Radio Historical Society celebrates the closing of the last commercial Morse code radio station, which happened at 0001 UTC, July 13, 1999.  They do this by re-manning the watch for a few hours in honor of all those who so diligently listened for distress signals on 500 KHz and other frequencies continuously for over 90 years.  Your humble author was one of those, who in the late 1980’s and early 1990’s strained to hear, through the static crashes and OTHR, the simple, yet effective combination of SOS sent in Morse code.

Fortunately, after the closure of KPH, the National Parks Service took over the land and preserved the buildings and antenna fields intact.  Today, a dedicated group of volunteers maintain these facilities as a working museum.  This is the earliest history of radio technology and from this, sprang Amateur Radio, then Broadcast Radio services.

So, if you have the opportunity on July 12 (Sunday, starting at 8 pm, EDT), tune around to some of the frequencies listed below and see how ship to shore communications was handled:

KPH KFS KSM WLO KLB NMC NMW Ship transmit
426 426 488 472 448 425, 454, 468,480,512
500 500 500 500 500 500
2055.5
4247 4343 4184
6477.5 6383 6276
8642 8438.3 8658 8582.5 8574 8368
12808.5 12695.5 12993 12992 12552
17016.8 17026 16914 16968.5 17220.5 16736
22477 22280.5

These are duplex frequencies, meaning; the ship transmits on one frequency and listens on to the shore station on another and vice versa.

Those medium frequencies do not carry that far during daylight, however the high frequencies should be heard across the world.

In addition to that, there are youtube videos to watch:

There are more videos on youtube, if one is so inclined.

Those old RCA transmitter look like they are in excellent condition. Somebody has spent a lot of time restoring those units.

Hopefully, one of these years, I will get a chance to head out to San Fransisco during the middle of July and see this in person. It would be nice for my children to see what their old man used to do in what seems like a different lifetime.

The Emergency FM Replacement Antenna

Hurricane season is here. This time of year makes me fondly remember hurricanes of the past and the things we had to do to get stations back on the air; walking a mile down a sandy spit of land, wading through swamp water to get to the transmitter shack, being threatened with arrest by the Connecticut National Guard, blow drying RF modules with a hair dryer, sleeping in a camper for a week…  Ahhhh, good times, great times!

The one thing that I did learn, if the disaster is big enough, expect none of the normal services to be functioning.  That includes things like gas stations, fuel delivery, grocery stores, restaurants, hotels, UPS, roads, bridges, telephone service, internet service, etc.

It is not a far fetched scenario for the main FM transmitter site to be out of commission and will not be available or accessible for some prolonged period of time.  There might also be mitigating circumstances such as catastrophic tower failure, destruction of transmitter building, flooding, or other major infrastructure disruptions.  In those situations, calling the broadcast supply vendor of choice for a replacement might not be an option.

It has happened before…

All of these things got me to thinking about how to fabricate a reliable FM broadcast antenna from simple materials available on hand.  The FCC allows for temporary operation with an emergency antenna in part 73.1680, which reads:

(a) An emergency antenna is one that is erected for temporary use after the authorized main and auxiliary antennas are damaged and cannot be used.

(b) Prior authority from the FCC is not required by licensees and permittees to erect and commence operations using an emergency antenna to restore program service to the public. However, an informal letter request to continue operation with the emergency antenna must be made within 24 hours to the FCC in Washington, DC, Attention: Audio Division (radio) or Video Division (television), Media Bureau, within 24 hours after commencement of its use. The request is to include a description of the damage to the authorized antenna, a description of the emergency antenna, and the station operating power with the emergency antenna.

(1) AM stations. AM stations may use a horizontal or vertical wire or a nondirectional vertical element of a directional antenna as an emergency antenna. AM stations using an emergency nondirectional antenna or a horizontal or vertical wire pursuant to this section, in lieu or authorized directional facilities, shall operate with power reduced to 25% or less of the nominal licensed power, or, a higher power, not exceeding licensed power, while insuring that the radiated filed strength does not exceed that authorized in any given azimuth for the corresponding hours of directional operation.

(2) FM, TV and Class A TV stations. FM, TV and Class A TV stations may erect any suitable radiator, or use operable sections of the authorized antenna(s) as an emergency antenna.

(c) The FCC may prescribe the output power, radiation limits, or other operating conditions when using an emergency antenna, and emergency antenna authorizations may be modified or terminated in the event harmful interference is caused to other stations or services by the use of an emergency antenna.

In this situation, making a circularly polarized antenna would be overly complicated, so either a horizontally or vertically polarized antenna would be the most likely scenario.  There are a few antenna types that readily lend themselves to field expedient fabrication.

These are, in no particular order:

Of these, the 1/2 wave wire dipole is the easiest to construct.  Cut two wires, length (in feet) determined by the formula 234/Frequency (Mhz).  Attach one wire to the center conductor and one to the shield, stretch to the wires out and tune for minimum SWR by cutting or adding small lengths to the ends.  The total length for such an antenna would be approximately five feet and it could be mounted horizontally or vertically.  The issue with a wire dipole would be bandwidth and power handling capability.

A 1/2 wave dipole made from tubing would have better bandwidth and power handling, but tubing is a little harder to work with when it comes to tuning the antenna.

Frankly, if one is going to go through the trouble of using tubing to create an emergency antenna, the the J-Pole (end fed antenna with a 1/4 wave matching section) is probably the best.  This antenna is easier to tune, does not need to work against a ground plain, has good bandwidth and a low take off angle, meaning more power is radiated out toward the horizon, giving it a good deal of gain over both a ground plane or dipole antenna.  Additionally, when using standard RG-8, RG-214, LMR-400 or other similar transmission line, a well matched antenna might be able to accept about 1 KW of input power, which would net approximately 4.4 KW ERP.  Not an insignificant sum, especially in an emergency situation.

Vertical radiation pattern for J-pole (1/2 wave end fed) antenna

Vertical radiation pattern for J-pole (1/2 wave end fed) antenna

1/4 wave ground plane vertical radiation pattern

1/4 wave ground plane vertical radiation pattern

There are many J-Pole antenna calculators available on line, but many of them include a 20 inch or so section of tubing below the tuning stub that can be electrically coupled to the supporting structure.  This configuration defeats the main advantage of the antenna, creating a good deal of upward radiation.  It is a better idea to use a non-conductive support piece and keep any conductive materials at least 1/2 wave length or greater from the radiating portion of the antenna.

The basic j-pole antenna looks like this:

J Pole (1/2 wave vertical antenna) diagram

J Pole (1/2 wave vertical antenna) diagram

The radiating part of the antenna starts above the tuning stub.  Basically, the 1/4 wave stub is shorted at the bottom, the feed point is adjusted away from the shorted end until a 50 ohm impedance point is found.  The center conductor of the coax is attached to the 3/4 wavelength section, while the shield is connected to the stub. The critical distances are the tuning stub length and the distance of the feed point from the shorting section.  I created an excel spreadsheet (.xls) that can be used to create all the lengths required to fabricate one of these antennas.  That spreadsheet can be had here: J Pole Calculator

Having a few moments of time to spare, I thought it would be fun to build one of these and put the analyzer to it.  I think testing things in the real world is a good exercise and I always enjoy working with antennas anyway.  Looking in the basement, I found some 3/4 inch copper tubing, a tee, an elbow and a few end caps.  The complete list of parts is thus:

Part Amount Use
¾ copper tubing 78-96 inches (196-244 cm) (frequency dependent) Main section
¾ copper tubing 26-32 inches (66-82 cm) (frequency dependent) Tuning stub
¾ copper tubing 2.5-3 inches (6.35-7.62 cm) (frequency dependent) Tuning stub short
¾ copper tubing 2 inches (5.08 cm) Mounting section, bottom of T to MIP threaded adaptor
¾ copper T section 1 each T section for joining main section to tuning stub
¾ copper 90 elbow 1 each Elbow
¾ copper end cap 2 each End cap on tubing
¾ to 1 inch copper MIP threaded adaptor 1 each Antenna Mounting
1 inch PVC FPT threaded adaptor 1 each Insulating mounting connection
1 inch PVC Approximately 20-25 inches (50-65 cm) Insulating mounting material
1 inch stainless steel hose clamps 2 each Attaching the coax to the antenna feed point
RG-8, RG-214, LMR-400 or other transmission line As needed, including 5-6 turns, six inches in diameter to form RF choke at feedpoint RF choke needed to keep RF off of coax shield

One important detail to remember when using the above spreadsheet, the measurements are to the closest side and not the center.  Thus, if something measures 2.5 inches, it is metal to metal.  Some basic soldering skills are required, but assembly is relatively straight forward.  In a pinch, almost any conductive material could be used including aluminum, brass, steel, EMT, rigid conduit, or even iron pipe.

Parts cut to size for j-pole antenna on 87.9 MHz

Parts cut to size for J-pole antenna on 87.9 MHz

j-pole antenna assembled

J-pole antenna assembled

J-pole antenna on the antenna testing range

J-pole antenna on the antenna testing range

I made this particular J-pole antenna on 87.9 MHz because I didn’t feel like chopping up all my 3/4 inch tubing.  Cutting and soldering the tubing took about a half an hour.  Designing and fabricating the feed point system another half an hour.  I’ll throw another hour in for rounding up the parts, tools, etc.  Thus, entire antenna was constructed in about two hours.  I used my AIM 4170D to find the proper feed point.  If I were going to actually use this antenna, it would then be a matter of finding a mounting location and running the transmission line.

J-pole antenna analysis results

J-pole antenna analysis results

Actually, I was less than happy with this. While the antenna is nice and broad across several channels, there is 16 ohms inductive reactance that is impossible to get rid of. That gives an SWR of 1.4:1, which is not great.  With that kind of load, I would be reluctant to run more than a couple of hundred watts into this antenna. The interesting thing is, that graph is the first one, with everything set as calculated in the spreadsheet.  After that, I could make the impedance and reactance worse, but not better.

Still, in a pinch, I would use this antenna until something better could be found.

Update:

As promised, a picture of the feed point:

J-pole feed point connections

J-pole feed point connections

The hose clamps are not optimum, I am sure a better way to attach the feed line to the antenna can be fabricated, but again, I was thinking of an emergency situation and the parts which may be available from local sources.

Pittsfield Massachusetts’ newest “Metro-Station” 103.3, W277CJ

We have been poking away at this one for the last year or so.  It seems that the previous owners of Berkshire Broadcasting had filed for a translator to rebroadcast WNMB, (100.1 WUPE-FM) North Adams in downtown Pittsfield, during the great translator rush of 2003.  When the CP showed up in the mail last March, the current owners were quite surprised.

After looking at the Construction Permit, we made some modifications;

  • Moved the transmitter location from 100 North Street to 1 West Street (Crowne Plaza Hotel) which is the tallest building in Pittsfield.  Antenna AGL is 44 meters (145 feet).
  • Changed the rebroadcasting station from WUPE-FM, North Adams to WUPE-AM Pittsfield
  • Changed the antenna to non-directional
  • Changed the ERP from 48 watts to 100 watts

We were able to make those antenna and power changes because we changed the parent station to the local AM station, WUPE, 1,110 KHz.  The previous power/pattern was submitted to keep the translator signal within the 60 dBu contour of the FM station in North Adams.

This, I feel, is the best use for an AM to FM translator.  WUPE-AM is a class D station with no night time service.  Adding a night time service greatly increases the station’s value to the community.  While the 100 Watt translator does not cover near as much as the 5,000 watt AM station, the transmitter location is right in the center of Pittsfield, so coverage of the population center is excellent.

The view from the top of the Crowne Plaza is quite spectacular.  I am pretty sure I will have a lot of transmitter maintenance to do right about the middle of October.

W277CJ 60 dBu contour

W277CJ 60 dBu contour

The installation is fairly straight forward:

W277CJ installation, roof of Crowne Plaza, Pittsfield, MA

W277CJ installation, roof of Crowne Plaza, Pittsfield, MA

W277CJ transmitter in outdoor enclosure

W277CJ transmitter in outdoor enclosure

The outdoor enclosure is a DDB POD-16DXC which is rather nice, it comes with rack rails and a thermostatic controlled fan.

W277CJ Shively 6812B antenna

W277CJ Shively 6812B antenna

The antenna is a Shively 6812B with RADOMES. The transmitter is a BW Broadcast TX600v2.  I really like these transmitters, they are well designed and rugged.  We have yet to have a single failure of one of these units in the field.

The station ERP is 100 watts, so a small bit of calculating is required to arrive at the proper station TPO.  I find it easier to make all these calculations in the decibels per milliwatt (dBm) unit domain, then convert back to watts.  Thus, the ERP is 100 watts, or 50 dBm.  The antenna has a gain of -3.4 dBm.  We used 25 feet of LMR-400, which at 103.3 MHz, has a loss of -0.26 dBm.  The total losses are -3.66 dBm, making the necessary TPO 53.66 dBm, 232.27 watts or rounding down to 232 watts.

Six years

That is how long it has been since I started this blog. Six years and 727 posts later, I find myself wondering how much longer I can continue this.  I have not been posting too much lately because I seem to have run out of things to say.  Posting just for the sake of posting seems to dilute the good material with mediocre stuff that has to be deleted later.

The radio business has changed little in the last six years; fewer owners, AM is still plagued with technical issues and poor programming, the FM band is getting jam packed with translators and the occasional LPFM, HD Radio is, well HD Radio.

My situation changed as well with the change in jobs, a new degree, more family responsibilities, etc.

I was thinking about ways to make this more interesting and perhaps doing more with my under utilized youtube channel would be fun.  I was called an “old timer” a few months ago as a compliment and I am not sure how I feel about that.  After a bit of reflection, I realize there is some truth to it and there are fewer and fewer of us out there that can do what we do.  Perhaps some informational things on how to trouble shoot and find problems, what a day in the life of a radio engineer is actually like, radio station people, etc.   I know that good trouble shooting is an art form.

I would need a tripod and a better camera.

In the mean time, here are a few statistics from the last six years:

  1. I have typed a total of 812 posts, of which 727 are public and there are about 30 drafts on various subjects hanging out, waiting to be finished and posted. Out date material is usually deleted when I get around to it.
  2. The blog has a decent following, with an average of 700 page views a day, approximately 120 regular readers and 185 RSS subscribers.
  3. There are 3,494 comments and the spam filter has eliminate 1,102,631 useless, fake, ridiculous or otherwise stupid machine generated garbage.
  4. There is also an international readership, with approximately 40% of visitors coming from outside of the US. According to my flag counter, these are the countries that have not visited yet:
    • British Indian Ocean Territory
    • Central African Republic
    • Christmas Island
    • Comoros
    • Guinea-Bissau
    • Mayotte
    • Nauru
    • Niue
    • Norfolk Island
    • North Korea
    • Saint Barthelemy
    • Svalbard
    • Timor-Leste
    • Tokelau
    • Tuvalu

    Everyone else has made at least one appearance.  I am a little bit disappointed that no one from North Korea has graced our presence.

  5. Top six non-US countries are Canada, UK, India, China, Germany and France.
  6. There are approximately 1,380 images of various interesting things. Most of them are my own, some are borrowed from other sites or the public domain.

I hope that I can continue this thing in some way or format.  I have certainly enjoyed meeting many people, reading comments, replies, off line emails and such.  It has been an overall positive experience and I value everyone’s input.

The old school marketing campaign

I found these old drawings in the filing cabinet and thought they were kind of cool. They look like they were drawn sometime in the 50’s for the WPTR studio at 1860 Central Avenue in the Town of Colonie.

WPTR-billboard

It looks like there was a lot of Neon, including a speller, which I take to mean the sign would spell “W-P-T-R 1540″ then turn off again.

This was the sign for the entrance to the studio building

WPTR sign for front of old studio building at 1860 Central Avenue

WPTR sign for front of old studio building at 1860 Central Avenue

I think this is a take off on the old KHJ sign in Los Angeles.

Shielded Category Cable

There is some disagreement in the organization that I work with regarding the use of Shielded Cat 5e cable. Is it needed and if so, when and where?  Category cables commonly used in Ethernet computer networks and also used for analog audio and other data applications come in a variety of flavors.  Shielded (Shielded Twisted Pair or STP) and unshielded (Unshielded Twisted Pair or UTP) Cat 5, 5e and 6 are the most common in radio broadcast facilities.

The main purpose for using UTP and STP for high speed data transmission is common-mode rejection.  Cables that are installed in office buildings are subject to various electric and electronic noise sources.  Properly installed UTP works to reject these unwanted signals by using differential signaling, which is balanced.  Differential signaling can best be described as transmitting information using two complimentary signals that are opposite from one and other.

Noise rejection, differential signaling.  "DiffSignaling" by Linear77 - Own work. Licensed under CC BY 3.0 via Wikimedia

Noise rejection, differential signaling. “DiffSignaling” by Linear77 – Own work. Licensed under CC BY 3.0 via Wikimedia

The key performance measurement in category cable is Common Mode rejection.  Outside noise will introduce a common mode signal on the cable which will be cancelled out by the differential amplifier on the receiving end of the circuit.  Proper terminations and good wiring techniques are very important for proper performance.

Using the correct patch panel termination, terminating block or RJ-45 (8P8C) connectors are required to maintain the advertized bandwidth of the cable.  There is also a difference in connector and terminating block designs for solid versus stranded cables.  Using improper connectors for the type of cable installed can cause dropouts and loss of data.

When installing category cable, care must be taken not to kink the cable, not to exceed the recommended minimum bending radius or exceed the maximum pulling force. Each of these will degrade the cable performance by changing the physical characteristics of the cable. Each pair of wires in category cable has a different twist. Altering these twist ratios by stretching the cable or bending it too sharply will increase the NEXT (Near End Cross Talk) and FEXT (far end cross talk) between pairs. In Gigabit networks, this will degrade throughput and create bottlenecks.

Generally speaking, the minimum bending radius is four times the cable diameter, or approximately one inch for Category 6 cable.  The maximum pulling tension is not more than 25 ft/lbs or 110 Newtons.

Category 6, Shielded Twisted Pair

Category 6, Shielded Twisted Pair

In high EMF environments, shielded cable (STP) can be beneficial in mitigating high electrical noise along with proper installations techniques noted above.  Signaling levels on 100BaseT are +1, 0 and -1 volt (MLT-3 Encoding).  On Gigabit Ethernet, the levels are +1, +0.5, 0, −0.5 and −1 Volt (PAM-5 Encoding).  Induced voltages on in cables from external sources can degrade network performance and create bottlenecks.  High EMF environments would include places like transmitter sites and anything on a tower or rooftop.  Properly terminated shielded cable is necessary for EMP protection from lightning strikes or other sources.  STP has special shielded metal connectors which each category cable class.  These connectors supply the path to ground through the RJ-45 jack.

Ungrounded shields are useless.

RJ-45 or 8P8C shielded plug for Category 6 STP

RJ-45 or 8P8C shielded plug for Category 6 STP

There are also other cable characteristics to consider such as UV resistant jacking for outdoor installations or gel filled (AKA “flooded”) cable for wet locations.  Fortunately, there are plenty of sources for these types of cables and they are not terribly expensive.

To answer the question at the beginning of the post; STP can be beneficial at high EMI/EMF or RF sites to mitigate induced voltages on the cable from external sources provided it is properly terminated.  In office and studio locations which are not at or next to a transmitter site, UTP is more than adequate provided it is properly installed and terminated.

Be careful where you put your hands!

So, I was working at one of our FM clients in Albany when I decided I had a few moments of spare time, I could neaten up the remote control rack.  I opened the rack door and was staring intently at the remote control interface panel, when out of the corner of my eye, I saw something move.

Now, the top of the rack is a little bit dark and I was not sure what I was looking at.  At first I though somebody had stuffed a rag in the top of the rack.  But, I could not figure out why anyone would do such a thing.  Then I thought it was some cardboard.  I almost reached up and grabbed it, but something was amiss.  Then I saw the tough flick out and smell the air:

Transmitter room denizen

Transmitter room denizen

At this point, I think I may have said something like “Oh, shit!” and took several steps back. Those colors and pattern have two possibilities; Copperhead or Grey ratsnake. Since I could not really get a good look at its head, I could not tell which it was. I went and got a work light to see better with.

Grey rat snake

Grey rat snake

A copperhead is a pit viper, which has a triangular shaped head and a small indentation or pit under each eye.  This snake has neither, so it is fairly harmless.   Actually, the ratsnakes are beneficial because they eat the mice and other pests around the transmitter building.  There are several versions of these in the northeast, including a black ratsnake which happens to look just like a piece of 7/8 coax laying across the pathway to the door, until it moves that is…

This species can get to be about 6 feet long (1.8 meters) and the larger ones can draw blood when they bite.  Even though he looked to be on the small side (approximately 30 inches or 76 cm), I decided that discretion is the better part of valor, closed the door on the rack and did something else for a while.

The Sportable 3306LED02 Baseball Scoreboard

This post has nothing to do with radio engineering, but is full of geeky goodness, nonetheless. My son is playing Little League again this year. This is his first year in the majors division, and I have to say, I have been thoroughly enjoying watching his games. There is, of course, one minor glitch in the matrix; the scoreboard, which occasionally looks like this:

Little League Scoreboard, missing LED segments

Little League Scoreboard, missing LED segments.

Now, that is more of an annoyance than anything else. I know what inning it is and what the score is. Truth be told, most of the time the scoreboard is being run by one of the parents (read: a mom) and they can become distracted at times. Very often, the ball/strike/out count is not correct, which in turn causes the home plate umpire to angrily stare up and the scorekeeper’s window.

Anyway…

As I was saying, more of an annoyance…

Regardless, I thought to myself; jeez, I fix things, perhaps I should have a go at that sign. So I spoke to one of the Little League board members who was more than grateful for any assistance I could render.

Thus, one afternoon, after work, I got the ladder out and started poking around to see what I could learn.  These signs are relatively simple.  Each digit on the sign has one circuit board.  Each circuit board has seven segments.  Each segment has fourteen LEDs in series.  There is a Toshiba ULN2803APG, which is a 16 pin darlington driver, a LM 317 voltage regulator which is fixed with a 62 ohm resistor.

Scoreboard single digit circuit board

Scoreboard single digit circuit board

Approximate schematic scoreboard circuit board segment

Approximate schematic scoreboard circuit board segment

After poking around with the DVM for a while, I determined that the bad segments were due to open LEDs.  I measured the working LED’s and determined that each LED was dropping about 1.7 volts.  I took a board home with me and rummaged around in the parts bin until I found some orange 5MM LEDs that matched the voltage drop of the ones on the board. I confirmed my ladder top troubleshooting findings on the work bench using the DVM in diode mode.  I also noticed that the Fluke DVM had enough current to light the LED, thus making troubleshooting much easier.  There were three bad circuit boards with various segments out.

Scoreboard LED voltage drop

Scoreboard LED voltage drop

Scoreboard individual LED testing good

Scoreboard individual LED testing good

A few minutes with the soldering iron and presto:

Scoreboard, repaired

Scoreboard, repaired

Sign repaired.  I little further research and I found that an Everlight MV8104 LED (Mouser part number 638-MV8104) is a near perfect replacement.  Literally, a 23.3 cent (US) part.

In all fairness to the company that  makes the scoreboard, this unit was new in 2003 or 2004.  It has spent at least 11 years outside in upstate NY, which is not a tender climate.  They will replace the digit circuit boards for 175.00 each, plus $25.00 shipping.  My repair work used 9 LEDs ($2.10) plus about two hours troubleshooting and repairing vs. $600.00 plus perhaps an hour to replace the boards.