Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

@mnem: screw those huntron prices. You could get a better engineer for that much more cash.  BTW you got me started on STM32 now. After much googleage I found this: http://kevincuzner.com/2016/05/22/dev-boards-where-were-going-we-wont-need-dev-boards/ ... and they have 12 bit ADCs which solves a bit of a problem I have at the moment.

Don't expect too much from those ADCs. While I have no experience with STMs, I'm happy when I get 10 usable bits from my RX ADCs (they're also 12 bit). The lower bits are fine for gathering entropy, though. 

Oversample all the problems away 

I’ve got some 12 bit microchip ADCs which aren’t as noisy. I was going to use one of them before. I’ve looked at ST but I still can’t be arsed. I can do it with an AVR with virtually zero toolchain or further knowledge investment. AVR will talk to the ADC and go to sleep until the ADC is ready.

I’ve got 0.1dB resolution over a dynamic range of 70dB so 10 bits is probably fine TBH.

Yup. This is a known issue with the ADCs in pretty much all general purpose microprocessors; the noise inherent in being made on the same die as the working horsepower, especially on GPIO format ports. As bd sez... oversample the hell out of it, narrow the bandwidth to just what you absolutely need, and live with 8-10 bits of actual resolution from a "12-bit" ADC. If you need more, go external ADC over SPI bus. But then you get into crazy filtering code and shit, where your "signal" can be as much artifact as real ADC. 

mnem
No... not I₂C... just think of the bits... all the poor little bits.

[med6753]

Construction on that appears very similar in concept to the 2230. If so, the top board is the acquisition/memory board, and the one on the side will be raster/vector character generation. I've read that the 2230 will operate as an analog scope without the acquisition board ev3n in place.

If it's made like the 2230, that acquisition board will be on a hinge, and even has a plastic "prop rod" to hold it up so it doesn't slam shut while you're in there working. Look out for .0100" MOLEX and ribbon connectors that need to be unplugged before you can swing the board up; sometimes they aren't obvious. If you feel ANY resistance when trying to lift the board, look again.

Good hunting!

mnem

Yea, thanks. I'm going to spend the rest of the day RTFM'ing first before I try ripping the supply out. And I think you can operate the power supply outside the chassis and on the bench but I have to confirm that. This guy is so much different from the 2465's that I'm used to poking around in.   

[worsthorse]

So I was sitting here, writing an "advice asking" post about my relative level of repair inexperience vs the 2216 sitting on my bench right now when I took a break to look at CL and I found this:

>https://portland.craigslist.org/clc/ele/d/canby-tektronix-equipment/6836176599.html

The seller is asking $195 for the whole pile. He claims some of it actually still works. I don't know what I would do with any of it but I hate to see it go to the dump. Am I crazy?

Oh hell....BUY IT!  If it were close to me I would.

I’d buy that!

I still may but for now the lack of storage will keep me from doing so. Unfortunately, I don't think that pile of gear is going anywhere and my resistance will weaken with time.

Besides, Today I pick up two HP meters and a power supply (HP 3478A, HP6237B), which will keep my addiction in abeyance for a couple of day, and I need to finish rebuilding the TM500 plug-ins sitting on my bench already, along with finally getting up the nerve to rehab the 475A which I have been using as-is (grime included) since I bought it at a hamfest more than a year ago. 

[bd139]

Good hardware. 6236b and 475a here 

[ArthurDent]

"I still may but for now the lack of storage will keep me from doing so. Unfortunately, I don't think that pile of gear is going anywhere and my resistance will weaken with time."

The posting has been deleted by the author. You missed it.

[mnementh]

Time is an illusion. Online time, doubly so.  

mnem
*agitating-ily*

[med6753]

Started tearing down the 2430 to get to the power supply. This scope is a packaging nightmare. I got the top board tilted up as shown and there's another board attached to it's backside. This appears to be the processor board and in the far left lower corner is a lithium battery (yellow object) for NVRAM cal data. It's probably dead but not worried about it right now.



Down there, buried, is the power supply. There was a cover on it which came off easily. Tomorrow gonna start probing. The manual recommends putting the scope on an isolation transformer for troubleshooting which I have and will follow that advice. And once I figure out the bad components the REAL fun will getting that supply out to change the parts. 



 

[bitseeker]

Ero-Shan's got a magic eye watching us, now.

Sorting through a box of old tubes and stumbled on one I have.
Anyone want it for a project ?

Ordinarily i'd be tempted to say "ME!" but i'm too busy working on my novel or working myself half to death for profit.

Magic eyes are so cool, but I had to resist as well. Too much in the queue! *sigh*

[worsthorse]

The fact you're even LOOKING at that pile of hollow-state goodness means you're absolutely batshit crazy. Welcome to the asylum. 

Here's a thread to shove you over the edge give you some idea what to expect: https://www.eevblog.com/forum/testgear/vintage-tek-restoration-pictures-by-martin/

mnem
"Very helpful... very helpful indeed..." Chibila thought to himself.

Oh man, that is some amazing restoration work. And, frankly, seeing it makes me feel better because I can tell myself, however crazy I am, it ain't that crazy, right?   

and yes, around here, sometimes fire does accidentally come out.

[0culus]

A very heavy pair of boxes arrived today...8566A spectrum analyzer in very nice shape. Plan is to track down the parts to convert to an 8566B eventually.

[mnementh]

The fact you're even LOOKING at that pile of hollow-state goodness means you're absolutely batshit crazy. Welcome to the asylum. 

Here's a thread to shove you over the edge give you some idea what to expect: https://www.eevblog.com/forum/testgear/vintage-tek-restoration-pictures-by-martin/

mnem
"Very helpful... very helpful indeed..." Chibila thought to himself.

Oh man, that is some amazing restoration work. And, frankly, seeing it makes me feel better because I can tell myself, however crazy I am, it ain't that crazy, right?   

and yes, around here, sometimes fire does accidentally come out.

When you start grading your crazy, you know you're over the edge. Fortunately, we have a 12-Step Program right on the first page, so you DO have a roadmap. 

mnem
When the fire accidentally comes out... those are the FUN times.   

[Kosmic]

A very heavy pair of boxes arrived today...8566A spectrum analyzer in very nice shape. Plan is to track down the parts to convert to an 8566B eventually.

Woahh 22Ghz! 

Looking good, congrats with your new acquisition.

[Kosmic]

A very heavy pair of boxes arrived today...8566A spectrum analyzer in very nice shape. Plan is to track down the parts to convert to an 8566B eventually.

What's the difference between the A and B version ?

[0culus]

A very heavy pair of boxes arrived today...8566A spectrum analyzer in very nice shape. Plan is to track down the parts to convert to an 8566B eventually.

What's the difference between the A and B version ?

It's mostly entirely confined to the digital parts of the RF section. The display section is the same, as is all the analog stuff (LO, PLLs, etc). The upgrade was sold as a kit, but you could also send them back to the factory to be retrofitted. My working 8568B is one of those units. The B revision added quite a few more capabilities as far as automatic measurements, also more RAM. I believe it even added a rudimentary FFT (not real time though). Basically, taking advantage of the faster Motorola 68k processor.

[beanflying]

Morning all, unsupervised overnight artwork completed, lid is on the printer. Now for todays 3D Printed TEA D&C My pair of HP 5000 based counters had a few broken clips that hold the halves together so Coffee first then Fusion time.

Also I will start a thread for these sorts of bits as a resource, first post as a updated master list with links by brand to a forum post or elsewhere on the net. 'Replacement Knobs, Feet and Fittings for Test Equipment' maybe?

[bitseeker]

Sounds good to me!

[tautech]

Ero-Shan's got a magic eye watching us, now.

Sorting through a box of old tubes and stumbled on one I have.
Anyone want it for a project ?

Ordinarily i'd be tempted to say "ME!" but i'm too busy working on my novel or working myself half to death for profit.

Magic eyes are so cool, but I had to resist as well. Too much in the queue! *sigh*

Just for neo, an RCA 6U5 plus base and ~300mm leads



Pulled from a then very old valve receiver.....decades ago.
Glass envelope slightly loose in base.
Filament checks OK @ 5.7 ohms

[mnementh]

LifeHack # 1723...

   med, this butt-ugly hack is just for you. I figure it's at least 25% Doc Brown.    Short version: The BluRay player I got for the kids' bedroom doesn't have a rear USB; I wasn't willing to put up with the cable to the HDD sticking out the front just waiting to get broken off, so I added a port. Or three. 

     After trying three different ones, I found a hub that the OS hidden under the Java UI would recognize. A little Dremel abuse on the PCB to get rid of the superfluous 4th port, and then some sheetmetal nibbler abuse on the back panel and we were in business.  Some LVDS cable from an old monitor to connect things, and voila.

   The Payoff!

Here's something the hosers who made this thing never meant for it to do. 

mnem
*Data abuse*

[med6753]

6U5 "Magic Eye" tubes are rare and hard to find. The more common version was the 6E5. They are pin for pin equivalent but have sightly different characteristics. In some instances a 6E5 can be subbed for a 6U5 but not always.

[med6753]

LifeHack # 1723...

   med, this butt-ugly hack is just for you. I figure it's at least 25% Doc Brown.    Short version: The BluRay player I got for the kids' bedroom doesn't have a rear USB; I wasn't willing to put up with the cable to the HDD sticking out the front just waiting to get broken off, so I added a port. Or three. 

     After trying three different ones, I found a hub that the OS hidden under the Java UI would recognize. A little Dremel abuse on the PCB to get rid of the unneeded 4th port, and then some sheetmetal nibbler abuse on the back panel and we were in business.  Some LVDS cable from an old monitor to connect things, and voila.

   The Payoff!

Here's something the hosers who made this thing never meant for it to do. 

mnem
*Data abuse*

I guess I'm a bad influence aren't I? Welcome to the dark side. 

[bitseeker]

6U5 "Magic Eye" tubes are rare and hard to find. The more common version was the 6E5. They are pin for pin equivalent but have sightly different characteristics. In some instances a 6E5 can be subbed for a 6U5 but not always.

I shall vicariously enjoy someone's 6U5 project. Be sure to post pics!

[tautech]

6U5 "Magic Eye" tubes are rare and hard to find. The more common version was the 6E5. They are pin for pin equivalent but have sightly different characteristics. In some instances a 6E5 can be subbed for a 6U5 but not always.

My old RCA valve book has 6U5 and 6G5 listed as equivalents and can be used to replace 6H5 and 6T5.
6E5 is listed as a sharp cut-off triode while 6U5 is remote cut-off.....whatever that means. 

[0culus]

A very heavy pair of boxes arrived today...8566A spectrum analyzer in very nice shape. Plan is to track down the parts to convert to an 8566B eventually.

What's the difference between the A and B version ?

The parts touched by the retrofit are listed in the retrofit kit manual: https://www.keysight.com/upload/cmc_upload/All/08566-90151.pdf

It's not quite as simple as I said; the retrofit also replaced the front panel keyboard and a handful of passive components. I believe it also replaced the rear panel of the RF unit.

[ArthurDent]

After reading about the magic eye tubes I had to go out to storage to plug in my old ESI 250-DA RLC bridge that I haven't powered up in years. It still works and the 6E5 tube is strong and doesn't exhibit fading as well used weaker tubes do.

I also have an RCA Chanalyst like the one shown in the photo that used 4 of the magic eye tubes.

[mnementh]

LifeHack # 1723...

   med, this butt-ugly hack is just for you. I figure it's at least 25% Doc Brown.    Short version: The BluRay player I got for the kids' bedroom doesn't have a rear USB; I wasn't willing to put up with the cable to the HDD sticking out the front just waiting to get broken off, so I added a port. Or three.  (SNIP)

I guess I'm a bad influence aren't I? Welcome to the dark side. 

Dude... I grew up on a farm.  "Ugly but it works" was a way of life; there were days I made 3 impossible cobbles before breakfast.

mnem