Test Equipment Anonymous (TEA) group therapy thread

[factory]

Part two of the hp Dymec 2590A microwave frequency converter teardown.

Cover removed from the RS Electronics Corporation I.F. strip, it needs a repair to one of the pillars for the cover screws.





Underneath the largest cover of the two die cast assemblies, I did a quick check of the Sprague axial capacitors and nearly all of the ones with the white seal are knackered, from past experience these are worse than the later ones with the black seal.



And finally underneath the smaller cover, for the mixer oscillator assembly?




David

[cyclin_al]

There is a nice Sony TA-D88 in ebay classifieds. For those unfamiliar with it, it is a hifi crossover for up to 4 channels.
Seller wants 1500 for it, I would be offering 600 - 800, so we won't be closing a deal.

This is a nice crossover though, and if I did not already have a high end crossover, I might be tempted.

btw most addictive game for me was Civilization II. I did play Ultima 1-5 and Wing Commander, though.

Similar here ... Civilization, Ultima 1-6.  Also discovered Castle Wolfenstein just before exams ... 

[Robert763]

Had a quick look at the Shuttle DS81.
All working fine. Has CentOS (redhat linux) on it. Password protected, but that didn't take long to sort even for a non-linux user like me.
Not a huge spec, i3 4150 3.5GHz 4GB ram and 320GB HDD. I might keep it to play with linux but seeing what they sell for on ebay (>£150) I might flip it. I paid £5 for it and a NIB greenpar interseries attenuator with BNC ends. I'd have paid that for either
1653B next.

[factory]

Hmm, you didn't see the Tek 585A with scope mobile and multiple plug-ins including SA nd test? Only £85 ONO?
I would have loved to rescue it but literally don't have anywhere to put it. It also ads nothing to my capability.
I bought  bunch of kit including:
HP 1653B LA with 'scope option
HP 33335A Synth with OCXO and printed manual
HP 5090A
HP 5090B
Shuttle DS81 micro PC
Pico ADC 12 interface (12 bit logger / scope adaptor)
Olsen IEC power  strip new C/W plugs.
Sony Video Walkman + 3 non display portable recorder and box of bits.
Greenpar interseries abaptor and attenuator (NIB)
Various other bits.
Total spend including entry fee £55 

I'm curious, have either the hp 5090A/B been modified to work with 198kHz LW (from the original 200kHz)? If they have, will you be keeping them?

Neither of mine have, I did buy some bits for converting the 5090B, but since I've tried & failed to create a board layout with various CAD programs, the project has stalled. 

Note: only the 5090A manual is online, no 5090B manuals exist as far as I know (apart from a mention on an old defunct website). Look for the Radcom November 1989 pdf* for conversion info and note the hp uses negative PSU rails, I was going to use a separate transformer for this, as a previous owner has already had a PSU burn out with some kind of mod (not the Radcom one).


David

Neither have been converted AFAIK. The B is pretty rough. I don't think I'll convert the A. It is still useful as a phase comparator for 1 and 5 MHz even unlocked. I could also divide the 800kHz from one of the Marconi Rb's by 4 and lock it to that......
I only paid £1 each for them.

Your 5090B is probably in much better condition than mine. The fuzzy marks of the front panel of mine are actually corrosion.
I'm guessing the screws need tightening up for the recorder output panel on yours and the meter sorting out. 
£1 each was an absolute bargain.

David

[Robert763]

First look at the 1653B is OK-ish. It has an original HP floppy in it and boots from it. But, it's a 1650/51/54B disk so does not have the 'scope function  However that proves that the unit and drive both work so it's worth spending the time making a 1652/53B disk. Files are available thanks to KO4BB and "Brent".
I paid £5 for it and a single woven ribbon cable. The seller is local and say he has the other cable, pods and grabbers nd will call me when he finds them. That would be nice, but even without them £5 for a 100MHz 400Ms/s 'scope is pretty good.
So I'm off to get my WIN 98 /  DOS laptop out and find a DD 3.5" floppy.

[Cerebus]

I bought a Keithley 197A off of Craigslist. It's in excellent physical condition. Date codes on ICs are 1996. Came with folding bale and original IEC cord. Everything seems to work OK on it. Best part: I paid USD20. 

Green backlight is pretty dim. Probably just right for working in a coal mine on a clear, moonless night. It has a "regular" fuse in a panel mount holder in the front. What's up with the funny fuse with the resistor on the PCB?

You'll just have to take my word on the voltage comparison side-by-side. I couldn't be arsed to Dig the GW Instek out of the shelf. Keithley had no warm-up.

Had to use the cell phone for the main PCB shot.      I need to get some more dang lights.

Did you take off the shielding can for that photo, or does the 197A not have one (the 197 definately does), or it is missing in action?

BTW, watch out for the top right corner - very exposed mains. I got bitten by my 197 and some momentary inattention.

[tggzzz]

I paid £5 for it and a single woven ribbon cable. The seller is local and say he has the other cable, pods and grabbers nd will call me when he finds them.

Definitely get those! The grabbers are ~£1 each on the open market

[med6753]

7A24 plug-in repair.

I was pleased to discover that the custom IC's are plugged onto the 485 vertical board rather than soldered. Tek used the same individual sockets as typically used for transistors. So it was easy removal. HOWEVER, lining up 16 pins on the IC with 16 individual sockets on the 7A24 plug-in board was a real chore. It's very easy to bend a pin or two. Ask me, I know. 

Should I try to sell then for $40 USD a pop like that idiot on Ebay? 



Anyway, the 7A24 is fixed. Displaying a 50MHz Sine from the Type 191 Signal Generator. Piece of cake for this plug-in since it's spec'ed to 400MHz.

[Cubdriver]

Mike, those look like a bear to plug in, but even worse to get OUT without mangling the pins.  From the original pics you posted, I figured they were flat leads and soldered in like RF transistors usually are.

Nice to see things working!

-Pat

[med6753]

Mike, those look like a bear to plug in, but even worse to get OUT without mangling the pins.  From the original pics you posted, I figured they were flat leads and soldered in like RF transistors usually are.

Nice to see things working!

-Pat

Pat, prying them out is not bad at all. Just go evenly and carefully so pins aren't bent. But yes, plugging them is MUCH worse with trying to line up all the pins and pushing it in without bending a pin. I would assume the Tek Ladies had some sort of plugging fixture to assist them.

[mnementh]

Yeah, perish the thought that they might actually test something before they release it...   Hell, even console games effectively ship in open beta these days.   

I dunno that I'd characterize this as a design flaw; I'm definitely abusing any browser the way I use it. I mean, if I had to personally keep track of 75-150 tabs in my head, I would have memory leaks too.

mnem
Actually, now I think of it... I do have memory leaks all the time, and my own mental loading is much less than that.

[bd139]

I just keep opening the fuckers all day here. 150 is amateur territory.

The work machine has 64Gb of ram for the tabs and electron apps.

[med6753]

I just keep opening the fuckers all day here. 150 is amateur territory.

The work machine has 64Gb of ram for the tabs and electron apps.

Well call me a total neophyte. I rarely have more than 3 tabs open. 

[bd139]

You need to be in the "problem solving mode" to open that many.

1. Find problem.
2. Google how to fix it.
3. Fix it and forget to close the tab.
4. Celebrate prematurely.
5. Goto 1

[Specmaster]

I just keep opening the fuckers all day here. 150 is amateur territory.

The work machine has 64Gb of ram for the tabs and electron apps.

Well call me a total neophyte. I rarely have more than 3 tabs open. 

Same here, I don't see how you can keep a track on them all, or know where one you want is 

[duckduck]

I bought a Keithley 197A off of Craigslist. It's in excellent physical condition. Date codes on ICs are 1996. Came with folding bale and original IEC cord. Everything seems to work OK on it. Best part: I paid USD20. 

Green backlight is pretty dim. Probably just right for working in a coal mine on a clear, moonless night. It has a "regular" fuse in a panel mount holder in the front. What's up with the funny fuse with the resistor on the PCB?

You'll just have to take my word on the voltage comparison side-by-side. I couldn't be arsed to Dig the GW Instek out of the shelf. Keithley had no warm-up.

Had to use the cell phone for the main PCB shot.      I need to get some more dang lights.

Did you take off the shielding can for that photo, or does the 197A not have one (the 197 definately does), or it is missing in action?

BTW, watch out for the top right corner - very exposed mains. I got bitten by my 197 and some momentary inattention.

Oh, in the rare cases when I have to probe a powered-up DUT I go into paranoid mode. I shocked myself (120VAC mains) taking apart a plugged-in chirping-bird Xmas ornament when I was a child and it made a powerful impression on me. I removed the shield on the 197A for my photo because I know what the people on this thread like.

[bd139]

I just keep opening the fuckers all day here. 150 is amateur territory.

The work machine has 64Gb of ram for the tabs and electron apps.

Well call me a total neophyte. I rarely have more than 3 tabs open. 

Same here, I don't see how you can keep a track on them all, or know where one you want is 

Mostly lots of red bull, coffee and practice.

[med6753]

Mostly lots of red bull.....snip

How can you drink that shit? It's fucking gross. 

[bd139]

Tastes different in UK. US red bull is vile.

Some progress with the curve tracer finally. Managed to design a working source-sink channel with 200V 500mA compliance (yes 100 watts!) in LTspice. I am now trying to reduce this in cost as the MOSFETs are 15 quid a pop  . My initial failure was expecting to drive an analogue scope from the output which required a high voltage slew. This is not required now as sampling interface is ADCs. Also that allows shorter pulse measurements to be made (within the slew rate limit of the amplifier) 

[Cerebus]

Oh, in the rare cases when I have to probe a powered-up DUT I go into paranoid mode. I shocked myself (120VAC mains) taking apart a plugged-in chirping-bird Xmas ornament when I was a child and it made a powerful impression on me. I removed the shield on the 197A for my photo because I know what the people on this thread like.

I mentioned it because I have received two avoidable electric shocks, one before I was 10 years old dismantling an in-line light switch out of curiosity, and one from my 197 a couple of years back. I reckoned if it managed to bite ultra-cautious me, then it was likely to get anybody.

[bd139]

I tend to hook these shitty old DMMs up to a bench power supply to work on. Much safer. E3630A is glorious for that sort of stuff.

Saves a lot of room compared to the old solution! (yes I know there's a 6236b in there but that came along last for this test)

[Cerebus]

Tastes different in UK. US red bull is vile.

It's 'cause they use salty tea in the US version

[Vince]

No no, Firefox doesn't need 10Gb, it is much less as this test here shows, much the same is required for all of the top three browsers, with Edge just a fraction  less than both Firefox and Chrome.

Yes it does  ! 

I don't know about tests and other browsers. The only test that's worth something as far as I am concerned, is using FF on my machine, for many years now,  and seeing what happens. It happens that it can takes 10GB no problem, with only 60 tabs and 3 windows opened and just a few weeks or months running ! 

I did notice though that it depends heavily on how many tabs are open and what's in them. The biggest memory hog seems to be Youtube pages. I tend to have lots of YT videos/pages open, and I noticed that FF roughly uses 100MB or so of memory for each and everyone of them ! I don't know if it's FF or the crappy "Flash" plugins that it uses to read the videos, but it doens't matter sin one does not go without the other...

So to try to stay out of trouble, avoid running out of RAM and swap and having the computer freeze on me.... I try to discipline myself and not open too many tabs. Also, restarting FF after a few weeks helps a bit, I guess it clears some junk from memory.

Right now it pretty reasonable. Takes "only" 3.8GB spread over 9 different threads, for 22 open tabs including 5 Youtube pages.

Can't fight that, it's just the way it is. I hate it. I don't find it acceptable technically, but that's how it is so... unless I keep restricting myself to a small number of tabs, which I can't do, then the only option is to give FF what it wants : lots of GB of RAM, and unfortunately for me that means a brand new machine as it's 15 years old/obsolete so I can't upgrade any individual component, the entire thing needs to be replaced.

I am not crying, 15 years is pretty good life expectancy, much better than an Ipad or fancy modern Smarthphone ! 

HP Laserjet 6P at 24 years now and still going strong !!  I am sure it can manage 30 years, let's see ! 
Regardless, think I would buy a new printer. Would like a colour printer ! .... but no inket jet. A decent A4 laser colour, SOHO type, not the crappy consumer style built to a price with proprietary language, that fall apart after 6 months and small capacity toners that do very little pages and cost an arm per page.
Needs to be Linux friendly too, or else I cant use it.
I find it's still too expensive for me.. also would like an old / affordable A3 B&W printer, or better yet a little tracer, so I can print fold out schematics from service manuals, when I need to trouble shoot some my old Tek scoep typically...

[Specmaster]

I tend to hook these shitty old DMMs up to a bench power supply to work on. Much safer. E3630A is glorious for that sort of stuff.

Saves a lot of room compared to the old solution! (yes I know there's a 6236b in there but that came along last for this test)

Hey, thats a HP 1740 power board unless I'm mistaken 

[bd139]

Correct. Well spotted.

HP power supplies repairing an HP power supply 

Thread here from the distant past: https://www.eevblog.com/forum/testgear/hp-1740a-power-supply-burn-up/

this was one of my favourite repairs as it required some board rework and I found the culprit: a burned out bond wire in an LM723 (pictures in thread).