Test Equipment Anonymous (TEA) group therapy thread

[Ice-Tea]

If I buy from France I pay their VAT.
If I buy from outside I pay our VAT.

That is actually no longer true, at least not when the rules are followed correctly. If I sell something to a Fin, I have to charge the Finish VAT rate. That VAT is then forwarded to the Finish tax services. This is the "OSS".

[m k]

Since 1-Sep our VAT is 25.5%, old one was 24, before that 23, 22 and so on.

1-Oct-91 our VAT changed its direction.
Before it was down from BTO, now up from NTO.

When that direction change happened old systems were obviously still in place and actual counting continued old way.
New VAT was 22%, so 18.03% old way, nobody was arguing against the complexity.

And as you can guess, now papers are telling how companies are whining that their pos-systems can't handle VAT fractions.

[Ice-Tea]

Just modified my POS system 

[m k]

After some Metrix tests the thing is not outputting anymore if loaded, somewhere is a contact problem.
Gently poking different parts is difficult, fingers are burning, must find a small wooden stick, maybe I go to the woods with a knife.

I think I'll leave the hybrid desoldered for the next guy.
+/-V filter caps (5+5) are also off and nuts and bolt will secure the hybrid.
813 816 ely 100uF/50V
821 822 tan 2.2uF
807 810 pol 1uF
806 809 cer 100nF
818 819 cer 1nF

Pictured two left hybrids are correctly positioned, pin 1 is up left.
Low left of the board is RF out, next relay is its enabler, other relay is for internal terminator, its parallel resistors beside it.
Top left diode is +V reverse polarity protection, resistor next down is 10k to feedback.

Pin 13 from right hybrid is out, so two inputs to the golden one, golden pins to nowhere are +/-15V supply (2+2) and GND (5x), right hybrid pins 1 and 11 are also GND.
R818 between golden input and output is stamped under it on the other side, took a moment to realize, first I thought it's a capacitor, but it's two resistors stacked, around 3k5.

Other green of top left of right hybrid is insulation.

Gently poking the right hybrid almost anywhere with a wooden cocktail pick created severe output disturbances.
Bushing socket under it is not a socket but two separated bars and plenty of space.
I'll leave the reseating to the next guy.

For overloading,
first I thought it's a simple thing since the output was completely negative, now after some poking the output is completely positive.
Selected output is +/-2.5V all the time, so overheating is actually a feed driver trying to meet its deeds.
Slow slope problem seems to be also disappeared, very funny, maybe it's because filter caps are off, earlier mentioned BE is still shorted.
The machine is also sending sync pulses and receives external trigger, and had an intact cal seal, so pretty original, or something.

--[whitespace]

Then something completely different,
how to evolve with this "my prospects to our gold" system.
Now it's quite limited, first the target must be interested, then part that is leaving behind must be valued correctly and then what if the result is not what it was meant to be.

Maybe next level could be something where the whole bad batch is the original pool.
Then possible resource base could be wider, but it probably would also be more time consuming all the way.

For Ice-Tea's situation, actually for many others also, I'm practically behind the sea.
Closer resource would probably have more options.

Then the semimandatory BTW,
old rule of bad subcontractor, what if the new one is even worse.
So even if you are a bad subcontractor, don't give up, you don't know how bad the other guy is.
For face to face situations, stay at least a broom length away, just in case the other guy is actually pretty good.

Other BTW,
my 465 lost its A channel, dang, only one channel is actually quite limiting.
It's also a bit hard to measure if you forget to swap and the other end of the probe is still resting at trigger input.
I think I'll check if I can remember how the 2215A is broken, it's at least sort of a single board thing.
Maybe I'll finally get that real DSO.

[onsokumaru]

I was testing another piece of the recent loot, this Tektronix TDS 524A and I noticed this weird effect in the display. Looks like a layer in between the outer glass and the CRT, maybe a coating or who knows. I think it could be removed, but, anyone knows about this issue?
Appart from that, this scope is a beautiful machine  . The floppy drive is nice, but it has an vga output on the back which is going to be very handy I think. Don0t know in which condition are the acquisition stages, but at least is working, appart from the screen defect.

[TERRA Operative]

Yeah, that's a known issue. There is a gel between the LCD shutter assembly and the CRT.

You can CAREFULLY cut the shutter assembly away (it's held on with silastic), being VERY careful not to slice the wires for the LCD shutters that are embedded in the silastic, then super carefully remove the LCD panel. It will be stuck on with the 'suction' of the gel, so be careful not to crack the LCD panel. Did I mention you need to be careful?

Then it's a matter of the messy job of cleaning out all the gel, and finally sticking the LCD shutter back on to the CRT with some more silastic.


There are guides around the place about it.

Here's one link to get you started: https://jvgavila.com/tds524a.htm

[onsokumaru]

Thanks, I can see the process is very delicate but doable. I like the vga out, so if I don't want to take the risk of tearing it out I can always use an external monitor, I have many old ones around. Do you guys know whats the function of that gel? My first thoughts were about an optical interface between the crt and the polarizers, like to keep an specific refraction index, so I thought once you remove the gel the screen was not going to work ok, like loosing the color effect or having some kind of chromatic aberrations. In the link you posted everything looks good after the gel removal, so I'm really wondering what was its original purpose 

Yeah, that's a known issue. There is a gel between the LCD shutter assembly and the CRT.

You can CAREFULLY cut the shutter assembly away (it's held on with silastic), being VERY careful not to slice the wires for the LCD shutters that are embedded in the silastic, then super carefully remove the LCD panel. It will be stuck on with the 'suction' of the gel, so be careful not to crack the LCD panel. Did I mention you need to be careful?

Then it's a matter of the messy job of cleaning out all the gel, and finally sticking the LCD shutter back on to the CRT with some more silastic.


There are guides around the place about it.

Here's one link to get you started: https://jvgavila.com/tds524a.htm

[m k]

Viewing distance, the closer you are the better you see.
Other thing is that human vision is very good at making shapes to where there are none.
See it once and it's always there doesn't help either.

It's actually very difficult to get dry surfaces together properly and completely.
You can of course make jigs, but air has still few tricks.

Shop window decorators use soap water.
Gel is sort of a sophisticated version of that.

[AVGresponding]

I like the vga out, so if I don't want to take the risk of tearing it out I can always use an external monitor

It's not uncommon to completely remove the CRT and LCD shutter and fit an appropriately sized LCD screen plugged into the VGA

[TERRA Operative]

I'm currently working on an LCD replacement for these TDS500/600/700 series scopes. Just gotta get my boss to get around to writing the VHDL for the FPGA we have yet to choose (Probably an iCE40 or something), I have no expertise in that area so I'm useless there... I do have most of the mechanical design done for a direct drop-in LCD panel/bracket assembly though. But it'll be open sourced once done. It'll use the common trick of piggybacking off the video DAC chip.

As for the gel, it's to provide an optical coupling between the LCD shutter and CRT to help prevent reflections etc, and prevent dust and moisture ingress and the like.

[Ice-Tea]

Folks, I'm experimenting with a webshop on my site. Could you guys have a look? Looking for feedback.  Would you consider buying? How does it compare to eBay? What can I improve? Stuff like that... Any input greatly appreciated.

https://ftrnf.com/equipment

[tggzzz]

Folks, I'm experimenting with a webshop on my site. Could you guys have a look? Looking for feedback.  Would you consider buying? How does it compare to eBay? What can I improve? Stuff like that... Any input greatly appreciated.

https://ftrnf.com/equipment

General points...

I dislike fleabay stores since my eye-brain combination finds it easiest to speed read vertical lists i.e. the fleabay search results. The grid presentation in stores is "complex/slow" to scan and doesn't present enough information without having to select a grid entry.

Fleabay stores also make "successive refinement" of searches a pain.

[m k]

Consider leaving partial scrolling parts off.

Scrolling a whole page is fast and easy, other variations not so much.

[onsokumaru]

This 8860A Multimeter from the loot is also working, although the reading drifts a bit, I have to test it a little more. The power button gets stucked and you have to pull it out to turn it off, but I think that's an easy fix. Looks super retro, and is not a monster like most of the other gear. If it's in working condition it may be an useful device. Maybe a good candidate to use the calibrator?

[timeandfrequency]

Hi TEA team,

Just scored at a ham radio flea market last saturday a Metrix MX52 multimeter for mind-boggling two bucks.
Still bang on when measuring 10 VDC.
However, some display digits are weak/ghosted and I noticed some false contacts in the banana posts.
Will certainly need some love this winter : recapping, reflow solder joints, tighten the banana posts nuts + verification/calibration.

This french forum post suggest a deep dive in an ultrasonic bath to revert the damage of the years.
Any advice/experience on that subject for this range of multimeters ?

[AVGresponding]

Hi TEA team,

Just scored at a ham radio flea market last saturday a Metrix MX52 multimeter for mind-boggling two bucks.
Still bang on when measuring 10 VDC.
However, some display digits are weak/ghosted and I noticed some false contacts in the banana posts.
Will certainly need some love this winter : recapping, reflow solder joints, tighten the banana posts nuts + verification/calibration.

This french forum post suggest a deep dive in an ultrasonic bath to revert the damage of the years.
Any advice/experience on that subject for this range of multimeters ?

Nice, and what a bargain! I love my MX-series, great little meters.

No advice specific to Metrix MX meters, but, generally, remove fuses and displays, they don't like ultrasonic cleaning. Observe the rotary switch before you clean it; if it's greased, re-grease it afterwards, if it's ungreased, don't put any on it.

Let us know how it goes!

[TERRA Operative]

I have a habit of throwing entire circuitboards into the dishwasher when my wife isn't looking.

Remove batteries first, and a bit of strategically placed kapton tape on buzzers and DIP switches etc will protect them.

I've done piles of boards and haven't killed one yet. Just make sure you blow them dry (softly with compressed air, or use a hairdryer) and let them dry in a warm place for a couple days.

[Ice-Tea]

I need the help of you Gurus. I'm new to this so I'm not sure. Is this bad?



(This is actually after I unplugged it and opened the window. A lot worse before when I was looking up error codes )

[onsokumaru]

That looks like Hot-Tea    (sorry for the very bad dad joke). Does it smells like a fried capacitor ? I think the dishwasher trick can't help here...

I need the help of you Gurus. I'm new to this so I'm not sure. Is this bad?



(This is actually after I unplugged it and opened the window. A lot worse before when I was looking up error codes )

[m k]

Quite clear ghost operators.

This 8860A Multimeter from the loot is also working

What kind of a bottom MCU it has?

You see it when you remove the inner cover plate.

[TERRA Operative]

I need the help of you Gurus. I'm new to this so I'm not sure. Is this bad?



(This is actually after I unplugged it and opened the window. A lot worse before when I was looking up error codes )

That's not Rifa madness is it?

[wkb]

I need the help of you Gurus. I'm new to this so I'm not sure. Is this bad?



(This is actually after I unplugged it and opened the window. A lot worse before when I was looking up error codes )

That's not Rifa madness is it?

If it is, the missus will have your head if you sneak the PCBs into the dish washer...

[Ice-Tea]

Came from this board... Some yellow, some orange and some black tants. No RIFAs (actually there was one in the linefilter, already replaced that...)



...

Black?

...

Yes, black.

[factory]

I need the help of you Gurus. I'm new to this so I'm not sure. Is this bad?



(This is actually after I unplugged it and opened the window. A lot worse before when I was looking up error codes )

To quote something off the TV the other day...           
                                                                                                                                     
...which family are going to remind me of constantly.

"Nothing is easy with a Hewlett Packard"

 

David

[factory]

For 50Hz operation I have changed the crystal from 120.000 KC to 100 kHz, quite surprized I actually had one, almost all the others in the selection were 120kHz.



The mystery device seems quite uncommon, searching the web I could only find one picture of another.

David

For those who are not familiar, size of those crystals can be misleading.
They are bit bigger than usual Arduino stuff, I think.

It's been a while since I started work on this device, had different health malfunction and spent two weeks in Crewe hospital, humanoid TE was something labelled Dynascope in the A&E department and the annoyingly loud Mindray things going off at 5.30 to 6am, needed the earplugs most nights, now need a rage-room filled with old Braun IV pumps (the alarm noise they make was pissing a few of us off). Also noticed Samsung & Philips both using Canon Xray parts.

Anyway back to the uncommon Keithley, the crystal is indeed a bit larger in size to modern ones.





Before the hospital stay I had powered it up with the lamp limiter and determined one of the Mallory capacitors was open, both by measuring AC ripple & using the Peak ESR, today I got round to replacing it and the other plastic cased Mallory caps & another from Richey Electronics (none of these tested bad).
I'm not happy with the condition of the 15uF 300V Mallory cap for the display supply, but haven't got anything suitable in stock ATM. Need some dry weather to deal with the foam dust that is showing in the picture, after changing the caps.

I now have a dead tree edition of the manual, serial no. of the one in the manual picture is one less than my ex-demo one. 



David