These were all the rage when they came out some 23 years ago or so. They were specifically made for DJs who were used to shuffling carts in and out of cart machines. The idea was to use familiar motions and procedures so DJs could easily perform their shifts using CDs without relearning studio dynamics. The only downside, a DJ could remove the CD that was playing by accident whereas pulling a playing cart out of a cart machine is difficult to do. Later Denon versions made it more difficult to remove playing CDs.
This is a promotions photo circa 1987.
This machine is still in use 22 years after its manufacture date. Over the years the top cover has been removed countless times, no doubt to replace the KSS-210A optics and bearings or to periodically clean them. The Phillips head screws are so worn a screw extractor is nearly required.
They are located under a circuit board, which has to be removed. Again, the DN-951 series CD players did away with this, making maintenance easier. These CD players could and often were affected by RF especially when the studios were co-located with an AM transmitter site. One such symptom was randomly speeding up and slowing down while playing. It made for some interesting-sounding songs and even more interesting commentary by the morning show.
Every time the optics and bearing were replaced, there was a pretty involved alignment procedure that took some time to get right. I remember some funny Japanese-to-English translations in the service manual.
Of course, nowadays if there are any issues, you just chuck the computer and get a new one.
Almost all radio stations use a tower of some sort to support their transmitting antennas. These towers need maintenance from time to time and only qualified people should perform maintenance on towers. Hence, the tower company is formed.
Over my years of experience, I have dealt with many different tower companies, from one-man operations to big corporations that have multiple crews out in the field on any given day. I have discovered that not all tower companies are created equal. Not only do tower climbers need to be in good physical shape and be trained correctly in all tower climbing safety procedures, they also need to be good mechanics so they can actually repair things on the tower. Climbing a 470-foot tower to repair a strobe light is all well and good. Once the climber gets to the strobe light, he needs to be able to disassemble it without dropping parts or breaking things, troubleshoot if needed, install new parts, and re-assemble the unit, again without dropping or breaking anything.
Applying RF connectors, installing an FM antenna or STL antenna, and repairing light fixtures or conduit all require some amount of manual dexterity and concentration. Assembling high-powered antennas requires close attention to detail. Any pinched O rings, cross-threaded bolts, bent bullets, and the antenna will have problems, likely at the worst possible time.
The sign of a bad tower company is if its climbers cannot carry out those tasks with one or at most two climbs. I have a situation on a tower where our FM station is a tenant. The tower has a strobe light failure near the top of the tower where our FM antenna is located. They have climbed the tower no less than four times to repair this, and it is still not fixed yet. Each time they climb, the station has to reduce power to protect the tower climbers from excessive RF exposure. Each climb it takes them several hours longer than anticipated to finish their work.
A good rule of thumb, If the defective part cannot be fixed in the first two climbs, then the entire strobe unit should be replaced on the third climb. Even though the strobe units are expensive, by the time they get done paying for all this tower work, they could have bought two new strobes. Today will be the fifth climb and there is no guarantee that it will be fixed.
I advised the tower owner that they should be looking around for another tower company because these guys aren’t exactly setting the world on fire.
Gone is the day when the radio station engineer had to troubleshoot down to the component level, often crawling in and out of transmitters to get at the suspected part. I for one, spent many a long night at a transmitter site chasing some weird combination of symptoms down to the $0.34 1N914 diode in the directional coupler (see previous post about the MW-50).
It is a skill set now mostly confined to manufacturers’ repair departments, for which they charge a pretty penny. Nowadays, the technician simply slides out one module or circuit card and slides in another. If that doesn’t fix it, panic ensues. I know of several class C FM radio stations that are now relying on the computer guy to fix transmitters, because, you know, it’s cheaper.
To be fair, most engineers are contractors and many of those simply do not have the time to troubleshoot to the component level. So, they ship everything back to the factory and then pass the cost on to their client.
Then of course, most circuit boards these days are surface mount systems, which are hard to work on if you don’t have the right tools. Normally an expensive temperature-controlled soldering station is required, as well as a magnifying glass.
All of these things combine to make circuit board work something to be outsourced. Unfortunately, a night spent troubleshooting was often a great learning experience. I have done some of my best work when my back was up against a wall and I was out of options.
I make the attempt to fix things locally unless the transmitter or other item is under warranty or not having a spare/attempting to troubleshoot will take the station off the air. I think it is important to keep abreast of technology and keep my troubleshooting skills up to par. Besides, I find it gratifying that at least I can still fix things.