Gingy would like to remind you every time is the right time for petting your feline assistants.
The cool looking radar is sadly no longer in use. Anyway, as for the title, we’d been having issues with the big transmitter here for months and it just wouldn’t run on all three cabinets. Its intermediate power amp had been giving issues on one cabinet and our other engineers had been over the manual and talking with tech support for months, it just wouldn’t make wattage.
Finally the solution was to not trust the manual. It said the arbitrary “IPA Gain” number was supposed to be between 100 and 450. It was set on 100 and that led to only 9 watts drive to the IOT tube — 150 was needed. The solution in the end was … set the gain to about 520 or so. Amusingly, it only raised up from 9 watts once I went past 420.
420 blaze it
One of the other engineers had this Printrbot Simple Metal that he hadn’t gotten working so I took it back to play with it through the boring Thanksgiving morning shift. Despite it being a SOLID chonker, the carriage plate was bent up causing the hotend to hang at a weird angle, and some screws were loose or incorrect, so I fixed that and got it extruding. The only thing I wasn’t able to do which bugs me was to get a bootloader onto the Printrboard in there and load it with a newer version of Marlin supporting mesh bed leveling. This one is old and appears to take no parameters to G29 – it probes only three points. Weird. I couldn’t get Atmel’s FLIP utility to work and had issues with building Marlin for that particular cpu — it seems like you either have to use the toolchain for the Teensyduino++ or use PlatformIO, neither of which wanted to cooperate. Thus, it remains on old firmware.
A while back I noticed, hey, we’re actually using a…. plurality…. of 2000 watt halogen Fresnel fixtures in our studio. I brought up to the network’s one lighting guy that I’d found this cool (literally!) VisionSmith ReLamp System that includes a 275 watt tungsten lamp colored drop-in replacement for the CYX lightbulb… and can apparently also let you use acrylic Fresnel lenses which increase the fixture’s output even farther. He gave me this look like I’d just waved a dead skunk in his face, so I dropped the subject on the spot. Oh well, someday we’ll be able to explore MODERN technology 😉
So I’d mentioned this to someone in a thread on Facebook who got sticker shock seeing that the LED CYX replacement costs $945.25 from one vendor. The halogen CYX costs $30 (surprisingly, that’s a little less than the common HPL bulb used for Source Four lamps). I immediately thought to myself the total cost of operation must be VERY VERY much lower so I ran some back of the napkin numbers on it. These do not include the cost of air conditioning to remove the waste heat from the space as I don’t know how to calculate that off the top of my head. This is just for the bulb cost and electricity cost:
Average US electricity cost: 13.19 cents/KwH.
Rated life of the VisionSmith module: 50K hours
Rated life of the CYX halogen: 300 hours
Cost of electric power to run CYX bulbs for 50K hours: $13,190
Cost of 167 bulbs (!): $5010 Total cost of operation: $18,200
Cost of electric power to run the VisionSmith for 50K: $1814
Cost of one module: $945.25 Total cost of operation: $2759.25
Yeah—- I’m pretty sure which one I’m gonna go with.
I feel spoiled. I use DV video tape equipment sometimes and none of my stuff ever gives any issues. It just works. My stuff is Sony, Ikegami, and a couple of consumer grade mini dv camcorders. Every camera’s tape works in every other deck, dropouts are minimal and usually happen in the first second or two of rolling so if you preroll for “speed” it’s fine. My Sony DSR-1500A will even read DVCPRO media, though I’ve never tried it. Maybe I should?
Our station used to have a bureau down south in another city. This station had a 3-deck a/b roll editing system using DVCPRO. This was in service until about 2008 when everything was switched to HD when the network bought it and actually spent money on the station, unlike Shitclair which owned it in the past. Anyway, they had over 300 tapes of file footage there which were mostly dubbed on this one deck. The time finally came to get this footage transferred to the current digital archive system in use.
I’d been warned that DVCPRO tended to have alignment and timing drift issues that cause tapes to not interchange freely between equipment unless it’s all been field aligned to work together. So, thus, I tried the deck they were recorded on. First thing I found was a filthy transport, so I cleaned it up and replaced the little roller that cleans the video heads on load/eject. Please note in the picture above that there are two heads on the drum – the small interconnect boards just link the two heads to the rotary transformers.
Failure. The deck had severe picture breakup trying to play anything back.
I talked to one of my more experienced coworkers who told me to stop there and use a better deck. See, this 450 series, these were the cheap seats in the DVCPRO bowl. It didn’t even dawn on me until then that the 2-head deck is just not common! My consumer grade DVCAM stuff tends to have four or even six. I opened up one of the nicer decks and found four – it uses a finer pitch head for playback, making it even compatible with the narrower tracks of consumer DV! Also, uh, my decks are in good condition and not packed with 12+years of dust.
Ok, time to get serious about reviving some old forgotten crap.
These decks were known for having terribly bad capacitors; before the great Capacitor Plague and Samsung’s current habit of putting out lots of home electronics with crap caps, Panasonic put out a lot of gear that needed dozens of crappy smt electrolytics changed….. some on boards like this
I’m gonna go hide now ok
Finally… After hours of work I got three decks up and running and they all read the tapes from the other bureau fine! I did wind up having to revise the cabinet using brute force and power tools though because the Evertz Video Passport turns out to double as a nice space heater and almost roasted itself once I started rolling video from the 3/4″ deck through it. It needed lots and lots of ventilation. The DVCPRO decks aren’t much better about that but at least they have forced front to back airflow.
The most perplexing moment of all this was when I had one deck working great then I ejected the tape and looked back inside and found the pinch roller lying in the bottom! What the heck? I just replaced it. I don’t know.
The thing around my hair is not a ferrite core. It’s more like a slap bracelet and it’s awesome. It keeps the tail from just lying on the back of my neck.
The big hoop is an old TV/monitor degaussing coil and the box is what it came in. Don’t confuse this Jif with that other Jif. I don’t think either rhymes with Gif. Also, one of my coworkers gave me that beautiful blue hair dye, it’s from the Manic Panic line and I love it.
Thankfully I don’t have to really do any major overhaul work on these — we have the tooling in house to do it, including PCs loaded with custom software to perform certain adjustments (yikes!) and these decks don’t even speak plain English to you like my Sony DVCAM stuff does… you have to have The Fine Manual in front of you because everything is just by numbers with no text labels in any of the menus! Hurrrrrrrrrrrrrrrrrrrrrrrrrr
The transmitter…. Harris Broadcast PowerCD, a funky Inductive Output Tube based system with modular architecture supporting multiple cabinets.
The silliness: much. Much, much silliness. So here’s a hilarious one: this board is right at the power input to each cabinet and watches for power supply phase loss and provides voltage metering outputs. Power in this case is 480v 3 phase delta and the metering circuits on this card measure the voltage between A and B, B and C, and C and A. The measurement circuit is uhhhh the CACA type. 😉
So, here’s what you’re looking at. The three resistors are 15K ohm 3 watt and are wired in series with R27 (a PTC 0.15 amp polyfuse device) and the sensor coil inside that LEM current sensor.
The LEM LV25-P sensor is a Hall effect current sensor with galvanic isolation. It accepts 0-10mA and puts out a sense voltage proportional to the current input.
The resistors are dissipating 3.84 watts total on each phase, well within their rating. However, this rating was not assuming they’d be piled up like this and crammed on a board stuffed in an unventilated space in the cabinet!
The end result of this was that one of the voltage readings constantly jumped around and caused false alarms to fill the alarm log…. while we were trying to diagnose another issue.
I’m entirely confused as to why such a roundabout approach was taken to this when a set of isolation amplifiers with one side being powered off a voltage divider or even a small transformer on each phase would have worked with less bill of materials cost and less heat, but uh