Test Equipment Anonymous (TEA) group therapy thread

[Kosmic]

Some advice or restraint needed guys.
A friend of mine offered me a DSO81304B 13ghz oscilloscope, (2) 13ghz active probes and 4 passive probes for $5500. I've been eyeing a debugging setup for USB3.0 and displayplayport 1.3/1.4 for some time now but they are super expensive. The DSO80000 series looks pretty sweet, but I know it's on the older side. I believe the 13ghz is software emulated/extrapolated on the 80000 series and the hardware is natively 12ghz.
You think this oldie is a goodie? I'm waiting back from the guy to see if he has any cal records.
I could rent something newer, but I love having my own gear on hand.
So tempting. The probes alone are super pricey.
I may need some holding back guys.....

My limit for a single TEA item is 999.99$. and even at that price I normally know I can flip it twice that price. 5500$ is definitely in the no go zone for me.

[tggzzz]

Today's "disappointment guaranteed" fleabay sale: https://www.ebay.co.uk/itm/Tektronix-Oscilloscope-High-Voltage-Probe-P6015/114353264295

Listed as "used" and " 100% Working", but can you spot two or more reasons that ain't so?

Likely has zero freon left, like the two I have. Only mine are in much better shape and can still be used at the stated deratings for no dialectric fluid.

Mine contains visible fluid, which I presume is freon.

Mine also has an earth strap, now that I've taken one off my P6013. Fortunately earth straps are trivial to make, if you have a little phosphor bronze sheet available.

Hopefully! If you have visible fluid, you're good to go as the vapor pressure of freon provides the right concentration in a sealed environment. I'm still look around for the slim possibility I might find some to fill mine with. BTW for those playing along at home, DO NOT get any bright ideas and try to fill a P6015 with a modern refrigerant. The probe case is designed for the vapor pressure of freon, which is much lower than most of the common refrigerants nowadays.

Just so!

Realistically I wouldn't want to trust my life to equipment with an unknown provenance. Fortunately even without freon it is OK to 12kV.

The max I can imagine using it for is 3kV on a CRT cathode and grid. I do have a 40kV voltmeter and a Testec HV DMM probe should I ever want to look at, say, 20kV acceleration voltages.

[BU508A]

CRTs of colour TV sets are usually going up to 27kV, eventually 30kV. Haven't seen anything higher than that.

[tonyalbus]

Found a way to save a few pennies and most of all heat... and you have a nice view on the two Kethley's new to my collection.

[mnementh]

On the Bench Tonight...



So... on the way back from taking a load to the storage unit, I spotted this just hanging out on the curb with somebody's recycles.   GLOMM!!!   Along with a couple bundles of nice big cardboard boxes. 

   
   

Got it home and after clearing off the bench... THIS is what I found broken. This one little cut wire on one of the speakers. Patched that up, tested it... everything works, even the cassette deck has decent belts; not in the least bit marshmallowy.  Of course I went through and cleaned the CD and cassette decks, blew it all out with compressed air. The sound from this thing is actually pretty freaking awesome for a bookshelf unit; I'd guess a honest 15-20 watts per side. Bi-amped speakers make so much difference in the sound reproduction, even at this size. 




Other than that, the only thing I found wrong at all was poked tweeter domes... which I know how to fix. Normally, my first line of attack for this would be a vacuum cleaner to pop them back out; however, the design of this speaker makes disassembly quite difficult without doing permanent damage. We're gonna have to get medieval on its arse.




First, we need a small hot air gun we can set on LOW. This one cycles between 250-325°F. Perfect.




Next we need to make a puller to do this; think auto body work, only smaller scale. You'll need something with a rounded end, approx the same diameter as the poke in the dome. Next, cut a piece of the black foam mounting tape used for car emblems and the like. It needs to be a little smaller than the poke in the dome.

Now we make our tool: first, wrap some masking tape with sticky side OUT across the end of your tool (I used a Sharpie here); then fold it over itself and use another bit of tape to fasten this sticky tube to the body of the tool, leaving the end 13mm or so as exposed masking tape stickum. The reason for doing this is we need to make sure this side sticks better to the foam tape than the side that will get stuck to the dome. When you're done applying the foam tape to the end of the tool, it will look like this.




Now to make the pull; you'll insert the tool such that the shank is as close to 90° from the center plane of the poke in the dome as you can manage. Place the end with foam tape against the dome and press gently; be very careful. You want to be centered in the poke as much as possible, and not press hard enough to make the poke in the dome any deeper. Twisting gently sometimes helps make a good bond.

Once you can feel that you have a good bond, pull out quickly in a straight line; again, at 90° to the centerplane of the poke. The curve of the end of the tool will force the dome to pull back out; the adhesive sortof rolls free of its surface.

Or, every once in a while, it pulls the dome clean off of the speaker.  Then it becomes just a matter of straightening it out from the back side and gluing it back it in place.




This is what a successful pull will look like. Not perfect, but we're not done yet. This is why we need the hot air gun. If it doesn't go the first time, you may need to apply a new bit of foam mounting tape; the first try gets rid of the dust & accumulated smoke, etc, leaving you a nice clean spot for the second attempt. Be patient, be brave! 




This part requires care and finesse. You need to make sure you have really good lighting so you can see the instant the dome reforms and pull the heat away; usually a circular motion is best, starting from ~150mm away and working closer in steps 20-30mm per. But because this plastic is in the way and I really can't disassemble the speaker, I'm doing a little back & forth in this crescent slot, then the same action in the top slot.




The money shot - an almost PERFECTLY restored dome. This technique will also work on silvered/chromed mylar domes as well, however you do run a risk of peeling the shiny coating off. Even if you do it still looks better than a poked dome, however.

Now that this beast is 100%, I can give it to my wife to use at her new job at a local music school... after I finish modding it for her iPod. But that is a project which requires some 3DP, and I have some connectors on the way from Amazon for that part of the project.

See you in a bit when that all arrives!

mnem
 

[med6753]

Some of those old Ghetto blasters do sound quite good as long as you don't crank the volume to max and then force them to play rap crap. 

[bd139]

Perhaps that’s what the audiophiles are doing; trying to find something rap sounds good on.

[med6753]

Your dumpster diving reminds me. As a teen this was the best dumpster dive. ChannelMaster AM radio. The only thing wrong with it was a broken handle. And it had amazing sound for an AM radio and excellent sensitivity. I don't recall as to what happen to it. I think one of my brothers got it and then after that probably back into a dumpster. 

 

[med6753]

Perhaps that’s what the audiophiles are doing; trying to find something rap sounds good on.

Maybe at the bottom of the ocean driven by a sonar unit. But the fish may object. 

[Saskia]

why should we audiophiles listen to some stuff out of a burning trash can ?

[mnementh]

Some of those old Ghetto blasters do sound quite good as long as you don't crank the volume to max and then force them to play rap crap. 

Hey! I was one of those kids... 

Okay, never could stand cRap music; but I sure did like to play it loud. For a while I had a old Sony monster boombox that was 60% empty space inside; I replaced the speakers with some decent JBL component tweet/driver and then cut a 40W/CH Xplod 7-band booster/EQ into the back with a 7AH lead-acid battery inside. Thing weighed a legit 20 lbs, but whenever those D-bags would play their shit on the courtside while we were hangin' or shootin', I'd just push the button and blast their heads off with some AC/DC or Deep Purple.




I know it wasn't anywhere near this... but it sure felt that way. 

mnem
*visceral*

[Saskia]

watching spare pre amp on fleabay ...
and received some copper strips from my mentor for trace repair for my Sony TA-E 86B

[Saskia]

grocery and pharmacy shopping tomorrow. furthermore, need to get the AC in place.

[Specmaster]

@mnementh, bloody hell do you live in a relatively wealthy area or what? I mean you are always pulling out something from dumpsters, thrift stores or curb finds. I never come across anything remotely like that in my area 

[med6753]

Some of those old Ghetto blasters do sound quite good as long as you don't crank the volume to max and then force them to play rap crap. 

Hey! I was one of those kids... 

Okay, never could stand cRap music; but I sure did like to play it loud. For a while I had a old Sony monster boombox that was 60% empty space inside; I replaced the speakers with some decent JBL component tweet/driver and then cut a 40W/CH Xplod 7-band booster/EQ into the back with a 7AH lead-acid battery inside. Thing weighed a legit 20 lbs, but whenever those D-bags would play their shit on the courtside while we were hangin' or shootin', I'd just push the button and blast their heads off with some AC/DC or Deep Purple.




I know it wasn't anywhere near this... but it sure felt that way. 

mnem
*visceral*

There's absolutely nothing wrong with playing it loud. As long as it remotely sounds like music. Rap does not qualify.

[med6753]

@mnementh, bloody hell do you live in a relatively wealthy area or what? I mean you are always pulling out something from dumpsters, thrift stores or curb finds. I never come across anything remotely like that in my area 

You are not alone. Neither do I. 

[Cerebus]

why should we audiophiles listen to some stuff out of a burning trash can ?

Burning Trash Can? I remember them. Seventy six or seventy seven when they broke up wasn't it? 

[mnementh]

Sorry... thought y'all were talking aboot the White House and just tuned out... 

mnem
Whuu-we-talkin'-aboot...?

[mnementh]

@mnementh, bloody hell do you live in a relatively wealthy area or what? I mean you are always pulling out something from dumpsters, thrift stores or curb finds. I never come across anything remotely like that in my area 

You are not alone. Neither do I. 

Honestly, yeah... Definitely upscale; this neighborhood has amazing curb scores. I can't remember the last time I found crap like I find here; probably was when I worked lawn care as a "yewt" in Shaker Heights (yuppie 'burb of Cleveland) & surrounds.

mnem

[mansaxel]

Perhaps that’s what the audiophiles are doing; trying to find something rap sounds good on.

Not that it is rap, not the least, but Sonic Youth are known for being a loud and pretty noisy band. The first time I saw them live it was on a large outdoor stage with a very well tuned L-Acoustics line array system. That was impressive. Crystal clear. Loud as fuck too.

In my not so humble opinion the largest problem with sound quality in hip hop is the rappers. The mindbogglingly stupid idea of cupping mikes and expecting loud monitors simultaneously...

[nixiefreqq]

Some of those old Ghetto blasters do sound quite good as long as you don't crank the volume to max and then force them to play rap crap. 

Hey! I was one of those kids... 

Okay, never could stand cRap music; but I sure did like to play it loud. For a while I had a old Sony monster boombox that was 60% empty space inside; I replaced the speakers with some decent JBL component tweet/driver and then cut a 40W/CH Xplod 7-band booster/EQ into the back with a 7AH lead-acid battery inside. Thing weighed a legit 20 lbs, but whenever those D-bags would play their shit on the courtside while we were hangin' or shootin', I'd just push the button and blast their heads off with some AC/DC or Deep Purple.



I know it wasn't anywhere near this... but it sure felt that way. 

mnem
*visceral*

There's absolutely nothing wrong with playing it loud. As long as it remotely sounds like music. Rap does not qualify.

neither does this:

[med6753]

neither does this:

No? Perhaps some Ozzy then. 

[nixiefreqq]

no problem with ozzie.

but i still prefer the classics:

[bd139]

And now for some chill out music

https://youtu.be/oLdUdnk5za8

[med6753]

No argument from me. Floyd is my favorite group.