Tilt-A-Whirl Video Heads.

I was digging around in the… uh… museum… here at work and found a whole box of worn out video head drums. Some of them had a very interesting feature to them— piezoelectric tracking.

The head can be shifted up and down on a piezo bender.

Why is this here, you may ask? Well, here’s the reason—

Normally, when you play a tape in a helical scan transport like this, the video heads trace an arc across the tape as the drum spins. This arc more or less perfectly matches the way the video frames/fields are recorded across the tape *as it moves* at normal operating speed.

Purpose of the fixed heads and other gribbles on this drum will be read out of a dusty old service manual some day when I’m not fighting the migraine from hell.

But what about when you are NOT at normal operating speed? The tracking angle will not be correct, and the picture “tears” as the head runs across the boundaries between fields.

Enter the piezoelectric tracking mechanism. By applying a sawtooth waveform synchronized with the head drum’s rotation, Sony was able to cause the head to perfectly track a video field beyond angle differences caused by different tape speeds. Thus, when you grab the jog/shuttle dial on one of the decks employing this system and start moving around, or settle down on a still frame (don’t do this too long!), the picture remains clear.

The Sony J-1 Betacam/SX compact player I use at my desk doesn’t have this, and the picture tears when you mess with the speed or pause on Betacam SP (analog) tapes. On BetaSeX tapes, as my coworker calls them, the digitized frame data seems to land in a RAM buffer somewhere and you can still frame or slow down. The tape transport speed and drum rotation speed in Betacam SX mode are much different, and the angle error doesn’t cause as much of an impairment.

I recall seeing a high voltage warning on or near the head drum inside these decks. Not just for show. It’s about 200 volts!
A much more thoughtful description of the dynamic tracking system and better view of the heads and benders may be found here:

http://dexterslab2013.blogspot.com/2016/05/sony-betacam-dynamic-tracking.html

Just Big and Lousy

Today’s— uh, victim— JBL LSR2325P active studio monitor. It’s a nice sounding biamplified monitor with an active crossover system and suspicious “Imagine” brand capacitors. Hmmmmm. 😉

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Our music producer came to me with this loudspeaker he uses to play his creations for our news director, among other things, because it was crackling and popping ferociously when the input gain knob was touched. I found the input gain knob loose on the rear panel and guessed I’d also find cracked solder joints. But where?

Input gain control is below the inverted plastic bathtub under that board. So how do you remove this plastic bathtub? Desolder the shitty thermoplastic power switch—- which will melt and eject its metal parts. WTF??!!

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You can see the switch on the panel here – it’s a snap in flange mount – the only way to get around doing this would be to cut away the plastic flange and back it out, I guess. The tub it’s in is sealed so this wouldn’t create an air leak. But still— AARGH!!! Also, WHY THERMOPLASTIC? I have a problem with this. See, if the switch starts warming up, the plastic will soften, removing pressure from the contacts, creating more heat. Eventually the fault will only clear when the switch either totally loses contact or the thermoplastic erupts into flames.

Proper electronic assemblies use thermoSETTING resins. Glass reinforced polyesters/epoxies are nice. These are resins that set either when two parts (a resin and a hardener) are mixed, or enough heat+pressure are applied to kick over a curing reaction. This reaction is a one way process and the resulting product WILL NOT MELT and soften. It may eventually be flammable, but most thermosetting resins, especially glass fibre filled ones, have a very good track record of self extinguishing.

Phenolics are very common in solderable connectors. You can always tell when you’re dealing with a phenolic resin because it will not soften and allow the connector to deform with extended heating during soldering. These resins are often colored teal blue/green, or a tan color on Amphenol products. Ever wondered what the name “Amphenol” is about? 😉

Wikipedia article on thermosetting polymers

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I don’t even want to think too hard about what that AC power inlet fixture is made of, all things considered.

The header pins leading to both the boards inside this tub were also graced with total shit-grade soldering and I reworked them. There’s one board below with the three jacks and one board above with the amplitude pad and the HF/LF trim filters. I resoldered the input pot and tightened the nut around it with some Loctite purple on it. In theory, I probably should have used blue, but I can’t find the blue, and red is right out of the question. Whatever works, right? I’ve had just as good luck with things like this using nail polish on them.

 

That’s the fate that befalls any nail polish I buy that looked GREAT in the store but when I put it upon my claws it turned out all watery looking or otherwise unsatisfying. (“NYC Color”, this means you. Well– some of their shades. Some of their newer ones are actually formulated with, well, color, in them.)

After this– I can’t wait for my assistant here to show up so I can run my fingers through his thermal insulation and hear him make silly happy squeaky meows.

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How to achieve silly smiles… 🐱

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Paranormal transmitter site adventures

I figured now that I wrote all this up I should copy it here finally.

Believe in what you will, or what you won’t, but there are things that lurk in the airwaves aside from our electromagnetic waves.

There’s a radio tower southwest of Miami in the middle of nowhere. Well, kinda not exactly middle of nowhere as McMansions are encroaching on it and it’s next to a country club, but still. It used to be the broadcast tower for Channel 6 before the digital transition. Due to the fact that there was another 6 in Orlando, they had to stick this one waaaay south of Miami to “protect” from co-channel interference between the two destroying the signals of both.

There was an old engineer there, Richard Van Hook, who absolutely loved his job. He was in charge of maintaining the transmitter at the site and the associated equipment. As he got on in years he was fighting cancer but continued going to work there every day until about a week before he passed away. The next day, after he passed, he went right back to work. The security guard at the site (it used to be manned 24/7/365) saw the door open, heard footsteps down the hall.. but…. there was no physical body there anymore 😉

Shortly afterwards they put another engineer down there to watch the site until the analog was switched off for the DTV conversion which put their transmitter at another site about 40 miles north. He was always a little creeped out by the site but refused to believe there was a ghost there.

I was working for a radio station whose transmitter was there at the time. The tower had been sold from NBC to a total smeghead management company, Richland Tower, who laid off the guard and left the site unmanned and unmaintained. I’d often be down there doing maintenance and hear doors opening and closing and footsteps in the hallway, but there was nobody else there in this little tiny building in the middle of a field miles from anything other than a berry farm.

Richland refused to negotiate on a new lease with the university who owned that radio station so we had to abruptly remove all our equipment… then put it back! The transmitters* didn’t survive the moves out and back so I was left to assemble a good one out of the guts of two dead ones.

It was like 3 in the morning and I was sitting on a paint bucket with transmitter parts everywhere when the door opened to the room I was in and closed again. Across the room from me was a small Crown Broadcast transmitter that was keeping the station alive for the time being, connected to an Optimod 2200 processor to handle audio levels and compression.

The Optimod’s front panel lit up like someone had turned the adjustment knob or pushed a button. I looked over just in time to see the display change from MODE -> OPERATE to MODE -> TEST. A test tone started screeching out of the radio across the room (as it did over the airwaves).

I looked over and said “Stop that!”.

The processor turned back to OPERATE mode, the station went back to normal operations, the door opened and closed again and I heard footsteps down the steel staircase fading into the distance.

I fell on the floor laughing, it was the most hilarious thing I’d seen ALL FREAKING YEAR.

 

There were another couple of times I went to try to contact spirits in haunted buildings. One was in the Biltmore Hotel in Coral Gables. I was there with some of my friends from the station and we were walking down a stairwell in the tower next to where Al Capone used to have a suite and we all heard a whisper “hello!”. One of my classmates had a portable Minidisc recorder running on him with a funky field mic that looked like a pair of earbuds in reverse. We’d tested it prior to going in but now… it was recording *dead silence*. Testing it afterwards showed the equipment was working perfectly fine. Trolled again, but that’s not ALL we we were gonna get. We found access to the rooftop which was via two staircases and an equipment room and were walking around up there when we all heard, very clearly, a toilet flush.

There was no toilet on the roof. The nearest toilet was two floors below us. The only thing above us was a weird architectural dome full atop a ladder that’s potentially made of solid pigeon shit that also housed the 147.150 Mhz amateur radio repeater…

We all just couldn’t stop laughing at this point.

We later went back there with an Ouija board and the first thing that came out of it was my ham radio callsign KG4CYX. I guess they’d heard me use the repeater at some point in time. We asked the spirits there if they or their friends ever hung out on campus, and someone did reply that they often visited one of the older buildings there.

I had been reading about the “Spiricom” experiments and decided to try replicating that, first off because I’m freaking obsessed with electronics and radio, but also because I’d hoped to actually get a recording like they did out of that project. Instead of using a bunch of discrete tone generators to create the voice band audio frequencies, I just synthesized them in Audacity and played the result on loop. As I was messing with the janky little iPod transmitter and receiver I had up there, I heard a voice from behind me (seemingly out of the solid plaster wall) say “Shut up!”. It caught me by surprise and I tried to play back the recording in Audacity—-

You guessed it, DEAD SILENCE. I mean, the least significant bit of the analog to digital conversion didn’t even change (meaning, there was literally, absolutely, no sound there.)

 

Ridiculous pranksters, they are.

 

Say, wouldn’t this make a fairly good Creepypasta? Dunno, since it’s not a work of fiction……..

How to tell you’ve entered clickbait hell

Boy, the clickbait “news” sites are thick as a brick nowadays. So you see a link, or maybe even clicked it – how can you tell if it’s clickbait garbage or not?

First off, take a look for the story they’re talking about by searching via Google News. Look to see if the same subject comes up in a well established source such as the New York Times, Reuters, Washington Post, etc. Huffington Post kinda doesn’t count that much anymore, sadly.

But second, well, visit the link with uBlock Origin installed and active on your browser and see what happens. Do you get bombarded with prompts asking you to disable ad blocking and/or turn on desktop notifications for that site? Yeeeah—- chances are good you’ve found bullshit clickbait. Well, unless you’ve gone to Forbes, but that’s malware spewing bullshit of a different stench. Actually, I primarily run uBlock to protect against malvertising– I don’t really mind ads so much as long as they don’t block the page content or require interaction to get them out of the way first, but the ad networks have allowed sponsors to abuse the privilege of injecting active content for years. Oh how great were the days when ads could only be a 468×60 pixel jpeg or gif??

Look at the article. Sometimes you can actually, once in a blue moon, find a good reliable source cited in clickbait, then sometimes laugh as it contradicts the clickbait article you found it from. More often than not it’ll just lead you to some cesspool like Alternet though.

And then other times you’ll find something that looks so bloody insane that you think it HAS to be clickbait and then you find it proven true by Reuters, BBC, NPR, PBS, NBC, Fox, CBS, CNN, and official White House press releases, and you lose a good chunk of your faith in humanity…. oh wait, that’s just the last week or so… and the next four years… nevermind

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