Hi Gene, > And yes that supply s/b installed so it can be swapped out for a fresh > one easily, the capacitors WILL die, sometimes a horribly messy death. > Least dependable part in any system. We need to invent something more > dependable for use as a large capacitance, but alu foil, kraft paper, > and a cc or less of technical grade ethylene glycol is 100 years later, > still the cheapest farad you can buy by several magnitudes.
I used the highest hour rated, highest temperature and 4x the needed value for the simple linear DC power supplies in this project. http://www.autoartisans.com/LGB/Lions%20Gate%20Bridge%20Pano1.jpg This summer it will have been running for 10 years without (AFAIK) any failures. Granted the power factor sucked but a more complicated supply that would move the PF up to close to 100% would have added a major potential single point failure to 6 LED modules in each lamp. I'm also a > Certified Electronics Technician, now long since retired after spending > nearly 50 years keeping some tv station on the air. Spent a year as a disk jockey at CJOI 1440. Evenings for the first 2.25 hours were boring playing religious "send me your money" tapes. After that it was rock music till 1AM. I had the job because the automation system (International Good Music IGM) was flakey and would play run the card reader empty and then just play the backup music tape and no commercials. Since I had two hours every night where all I had to do was queue tapes and keep the volume high enough to determine it was working I'd play with the automation system. All RTL logic. Two of the 4 fans in the cabinet were toast. I replaced those. (I had a high school diploma in Electronics Technology). Here's how the system worked. A punched card reader. An IBM Selectric 735 computer controlled typewriter. Two reel-reel tape machines with music. Two large cartridge machines (like 8 track but huge) one with odd minute messages and one with even minute messages. Each message was about 8 seconds long. Then a series of rotary carousels with cartridges holding the commercials and promos. Like 8 track but the pin roller was part of the player and not inside the cartridge. It could take up to 25 seconds to rotate around and find the cartridge and cue it. So a punch card would have and ID in the first 3 columns like E21 or B12 for the cartridge carousels. A T00 for a Time Card and a L00 or L01 for the reel to reel machines. The program director would organize the music, commercials and time announcements The rest of the punch card had information like client or song or whatever. The card reader would index through the first three columns of the card and that would then select the carousel or tape machine getting it ready for the end of the previous selection. Once the music or commercial started the card would be read at the speed of the Selectric which printed out the 3 digit number, and the rest of the text on the card onto the log printout. Then the 3 columns of the next card would be read and the corresponding hardware would be queued. Finding that next selection took 25 seconds and didn't matter because the music and commercials were at least 30 seconds long. The problem was the time announcements. At about 8 seconds they'd be done before the next commercial was queued. So the electronics (micro-processors didn't exist yet) would read the T00 time card, latch that a time announcement was needed. Either ODD or EVEN, and then eject the T00 card and read the 3 columns of the next card. And there was the problem. Once it hit a time card, it would read it, eject it and then eject the entire pile in the reader too. All the commercials were gone. With an empty card reader the music tape would default and play with a few seconds gap between songs. And when it ran out, dead air. Replacing the fans didn't really do anything. But when one of the boards was on an extender card out in free air suddenly the system worked and sounded different. A bit of time with a scope and freeze spray and I found the offending chip. Once replaced the 3 column punch card read which had taken about 1/4 second suddenly sounded like it was a single column read it was so fast. Kind of a blurp rather than a tick tick tick. There was another timer circuit. If took too long to read a card and the T column latched an EJECT signal for the card out went all of them. Once the new RTL chip was installed the read was so fast the timeout never happened. All discovered because a slight change in temperature with the card out in ambient air on the extender card made the card reader sound ever so slightly different which set me onto the path with freeze spray. And I'm willing to bet everyone on this list running CNC can 'feel' and 'hear' when something isn't quite right. It's so subtle and often even difficult to explain to someone without experience. But it's there. > > Its been quite a ride since I fixed my first tv in 1948, at 14 years old. > Yup, I was a geek before the word was invented. But now I've had a > couple health accidents that have slowed the thinker a bit. Most > recently a pacemaker, I was getting dizzy in between heartbeats. > Figured I had better get that fixed as I have a fading wife to care for. Do take care of yourself. And I'm still waiting for pictures... <GRIN> John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
