Test Equipment Anonymous (TEA) group therapy thread

[Cerebus]

The "acetone slump" isn't quite that bad, usually less than 0.25mm. What can cause problems is that it rounds off all sharp corners and small details. For PLA you can get a similar effect using Ethyl Acetate, but beware, it's seriously nasty stuff and you should only use it outdoors if you want to survive the process!

McBryce.

Nothing nasty about Ethyl Acetate, it's used to flavour confectionery, as a solvent in nail polish, for decaffeinating coffee and lots of other things. Has low toxicity (Rat, oral, 5620 mg/kg*) and even smells pleasant (somewhere at the intersection of pears, apples, bananas and pineapple).

*Ethanol for comparison is 7060 mg/kg, people happily drink 40% ethanol for fun.

[Zucca]

RE: 3DP PLA polishing... In this video he does a good job with some sort of superglue I think.

Another whole level of insanity to take your 3D printing further 

[Cerebus]

Has anybody an idea, what this could be and where it is used?

This is an adhesive strip, about 30cm long and on one side there are two metallised strips of an unknown material.

Looks like a glass break sensor for a burglar alarm. Tape it to window glass, if the glass breaks so does the conductivity.

[Robert763]

R&S ZVH4 cable and antenna analyser on ebay UK.
Seems to have the Spectrum analyser option and is clean which make it look a bit of a bargain. Seller knows nothing about it.

www.ebay.co.uk/itm/373851304724

[ch_scr]

Has anybody an idea, what this could be and where it is used?

This is an adhesive strip, about 30cm long and on one side there are two metallised strips of an unknown material.

I think if you glue it around the outside of a flower pot in a circle and connect a 9V battery, snails will not cross it.
With higher voltage it maybe even banishes ants?

[Kosmic]

Has anybody an idea, what this could be and where it is used?

This is an adhesive strip, about 30cm long and on one side there are two metallised strips of an unknown material.

Wrap multiple layers around your head and it will protect you from 5G.

[factory]

: when the picture turns to B&W... I notice that I can make it go back to colour if I fast forward just a few seconds. Then I fast rewind a few seconds to go back to the part of the movie that was previously B&W and now... oh magic it's in coiour now !  So that means the tape itself is not the problem I guess.... must be the VCR doing something funny.

I am pretty sure it is false triggering on turning the color decoder on when you wiggle it that way. If you look at the color picture you attached, it is evident the colors are wrong and color interferrence can be seen in form of a mesh, also visible on top of the black frame bars.

I don't understand any of what you say, I don't kn,ow my VCR stuff 

But do I sense that you agree that the problem might that the tape is not guided and/tensionned properly ? After wigglijg it a bit using Fast forward/rewind, I had no more B&W ruin my viewing for the entire movie !   
So I guess the tape was not properly positioned on the drum, and wiggling it brought it back where it should be.
I guess when in playback mode, it's a bit loose and wanders about. Might also (?) explain another issue I am witnessing : very blurry/fuzzy picture, like it's way out of "focus", say. Also very unstable, it's moving up and down all the time, randomly, but incessantly.

I guess could be worse playing with the mechanical adjustments responsible for positioning and tensioning (is that a new word ? Firefox chokes on it...) the tape ? Don't don't how to do that, need to do some reading...

I did watch a few VCR repair/service videos on " 12votlvids " YT channel. Will watch his VCR vids again to refresh my memory....

The blurry/fuzzy picture is probably due to the limitations of the consumer/home VHS machines, if I remember correctly from the TV programme "Secret Life of Machines" you only got about half the quality of a live TV broadcast from a VHS tape, as only half the information (lines) are recorded, commercial video recorders must have been different.
Also older LCD TV's tend to make standard definition analogue content look even worse, even digital TV looked blocky & crap of the last dumpster find TV I had.



David

This post was "recorded on sticky tap & rust". 

[mnementh]

   https://kano.tech/us/original   On The Bench Today: Kano Touch LCD/Digitizer

So... after inspecting reflections in the surface of the glass, it was pretty clear that it wasn't the part that was warped. This means I need to take things apart and try to unwarp the plastic frame and back of the LCD itself.



Okay... here we go. I've started heating the circumference of the digitizer glass and working it loose; I'm at the second corner and it's a little reluctant to let go, so I use a guitar pick to very gently twist and separate the two layers. This technique helps keep the mounting foam intact.




 Well, fudge... looks like I guessed wrong and started on the wrong side.




Here I'm starting on the opposite side, with a couple of spudgers in place to hold the already loosened side apart.




And here it is, fully separated. Since I got lucky and was able to keep the mounting foam intact, I've applied strips of release sheet from one of my daughter's sticker books to preserve the adhesive. 




Here I'm heating the back of the LCD (as I expected it is bonded directly to the digitizer glass, Apple/Samsung style); I am working around the outer circumference, but not heating the center where the compression spot is...




...and now, while holding the sides of the digitizer glass down under a heavy lamp and the heel of my palm, I pull upward in the center and hold it under tension until the metal cools. It's hard to tell from the pic, but there is a good 3-4mm of deflection here. Very promising; the spot is gone from the front, and while I can make it return by pressing in on the back of the LCD, I have to press fairly hard and it immediately goes away when I release pressure. Temporarily powering it up shows no visible faults anymore in the LCD. w00t!   

Inspecting the plastic frame with a straightedge and laying on a sheet of glass showed it was slightly warped and the center area was convex against the LCD by 2-3mm; time to make it so my fix to the LCD stays...




"The Universal Warrior uses all tools at his disposal."   Here I'm using a drawer of my desk as it is just the right size to provide even support on 3 sides of the plastic frame, so I can apply heat and then press the center area so it cools slightly concave where it faces the LCD. This took several tries of applying heat and pressure, and rotating the frame to get both the concave shape and restore the warped outer bezel area where the digitizer glass adheres.




Here I've reinstalled the clear trim/protector ring and started the foam mounting tape on one side. As you can see, I've pulled the release strips out the sides, and will work the adhesive down about 30-40mm at a time, making sure as I go that the glass is correctly centered in the bezel/trim ring. Still looking promising!



Okay... time to populate the thing with all the workity bits so we can see how much better it really is...




The money shot!

Awesome! Not only is the contact distortion gone, but also the very prominent "golden halo" discoloration visible when it was powered up on my first inspection after discovering the compression fault is completely gone. I was afraid it might require heating the front of the LCD directly to get rid of it, but I got lucky. Now to disassemble and put it all back in the box so my son can build it!

mnem

[Neper]

Awesome! Not only is the contact distortion gone, but also the very prominent "golden halo" discoloration visible when it was powered up on my first inspection after discovering the compression fault is completely gone.

You may now give yourself a pat on the back. 

[mnementh]

Yeah, I was really afraid it was permanent, caused by bleeding LCD syndrome from long-term pressure. I totes got lucky; I was not looking forward to the thought of trying to replace that LCD bonded directly to the digitizer; not even sure if I could source a replacement.

mnem
 

[tautech]

Yeah, I was really afraid it was permanent, caused by bleeding LCD syndrome from long-term pressure. I totes got lucky; I was not looking forward to the thought of trying to replace that LCD bonded directly to the digitizer.

mnem
 

Great fix mnem, I learnt something today. 

Now if you have any tips on fixing a 6S that went under a tractor wheel I'd be mighty pleased. 

[factory]

A couple of parcels were waiting when I returned from work, first was some TI 74LS160AN IC's for the 5340A repair, from what I've read on here & elsewhere the original 1820-0986 ICs are a common failure.


The second parcel was the HP 432B I've been waiting for, here are a couple of pics, testing will have to wait till the weekend.



I've never heard of Gralex before, I was expecting an Analogic DPM inside.




David

[Neper]

Now if you have any tips on fixing a 6S that went under a tractor wheel I'd be mighty pleased.

Show pics.

[mnementh]

Yeah, I was really afraid it was permanent, caused by bleeding LCD syndrome from long-term pressure. I totes got lucky; I was not looking forward to the thought of trying to replace that LCD bonded directly to the digitizer.

mnem
 

Great fix mnem, I learnt something today. 

Now if you have any tips on fixing a 6S that went under a tractor wheel I'd be mighty pleased. 

What, that actually KILLED a 6S...? I'm honestly a bit surprised; they have a rep for being nigh nuke-proof.

mnem

[factory]

Yeah, I was really afraid it was permanent, caused by bleeding LCD syndrome from long-term pressure. I totes got lucky; I was not looking forward to the thought of trying to replace that LCD bonded directly to the digitizer.

mnem
 

Great fix mnem, I learnt something today. 

Now if you have any tips on fixing a 6S that went under a tractor wheel I'd be mighty pleased. 

A good sledgehammer should work fine, mine fixed this Babyliss hairdrier at the weekend.   


David

[tautech]

Now if you have any tips on fixing a 6S that went under a tractor wheel I'd be mighty pleased.

Show pics.

Slightly crunchy banana form 
See attachments.
Screen shagged which until swapped out restricts lots of functionality like getting it backed up on iTunes. 
Can power it ON and OFF just as the top of the display still sorta works.
I have another that was the son's to rebuild this one as it's a 128G model with a very new battery but for now I'm getting by with a tired 7 gifted from a friend.

[mansaxel]

This post was "recorded on sticky tape & rust". 

Wonderful video. Thanks.

(although nothing in it will sway me from my tape hate  )

[mnementh]

The "acetone slump" isn't quite that bad, usually less than 0.25mm. What can cause problems is that it rounds off all sharp corners and small details. For PLA you can get a similar effect using Ethyl Acetate, but beware, it's seriously nasty stuff and you should only use it outdoors if you want to survive the process!

McBryce.

Nothing nasty about Ethyl Acetate, it's used to flavour confectionery, as a solvent in nail polish, for decaffeinating coffee and lots of other things. Has low toxicity (Rat, oral, 5620 mg/kg*) and even smells pleasant (somewhere at the intersection of pears, apples, bananas and pineapple).

*Ethanol for comparison is 7060 mg/kg, people happily drink 40% ethanol for fun.

https://www.ehs.com/2015/04/ethyl-acetate-a-sweet-smelling-safety-hazard/

Yes, it is a byproduct and component of winemaking and natural fermentation, so would seem "more or less harmless".

However as produced for use as a solvent, it is considered highly flammable, a potent skin irritant, a safety hazard if inhaled and neurotoxic if ingested.

I'm not sure if overall it is more or less dangerous than methyl hydrate, but I certainly received plenty of flak for suggesting that as a substitute for IPA, so I'm not exactly sanguine about suggesting that ethyl acetate is "not nasty".   

mnem
 

[Neper]

although nothing in it will sway me from my tape hate

Nothing wrong with good old audio tape. Not that I'd want it back, but it was quite practical and easy to work with.

The misery really began with the advent of the rotating head drum. That should never have been invented.

[mnementh]

RE: 3DP PLA polishing... In this video it does a good job with some sort of superglue I think.

Another whole level of insanity to take your 3D printing further 

I puttered around a bit at my local MakerSpace in Tejas with lost PLA casting; made a couple promotional widgets in aluminum but never got around to my own projects due to "shifting gears for the move".



mnem
 

[mansaxel]

Awesome! Not only is the contact distortion gone, but also the very prominent "golden halo" discoloration visible when it was powered up on my first inspection after discovering the compression fault is completely gone.

You may now give yourself a pat on the back. 

I concur. Well done.

[Vince]

Say hi to my new friend ! 

It's nice collecting all glowing Tek scopes, but I also would like to find some period accessories to go with them. Cool plugins or some stand alone piece of TE like here.
Makes the collection richer, more interesting, more diverse, and adds features to my scopes, making them more useful / usable, which is cool 

So I got lucky and found this little guy ! Love this small TE of the period. Looks just like a glowing Tek, just as cute, yet much smaller, so more manageable !

No, no fast pulser for me, unlike one of our friends recently... but I found this type 1121 ! It's a pre-amp. Amplifies the signal by 100, fixed gain. Has also an attenuator as well but I don't see the logic in attenuating a tiny signal that your are trying to amplify, but it's just me I guess...

I already have my type 502 and 502A which can measure tiny signal, up to 100uV / cm sensitivity. However this comes at the price of a ridiculously low B/W : a few tens of kHz IIRC. The advantage of this pre-amp is that coupled with a "regular" 500 scope, it can achieve similar sensitivity, but while giving you about 15MHz B/W !!! So a lot more useful in practice ! 

So that's how I justify this purchase. But the only reason really is that it's cute and will be a great addition to keep company to my scope collection. That's all...

I am really lucky I found it, because it should have escaped my radar ! It did not show up with my usual / Daily search terms : "Tektronix", "Oscilloscope", "Metrix"...
BUT I found it anyway because... same guy was selling a piece of Metrix TE that caught my attention, and noticed the guy had no less than 174 other items for sale ! So I though hey may be he has some other cool stuff.... so I spent some time skimming his 174 ads. Turned out 95% of it had nothing to do with electronics at all, but it was worth making the effort to go through all of his ads because yeah he had this cutie for sale as well !!! 
Looked decent on the outside, only 50 Euros, willing to ship, and I didn't have to twist his arm to get additional pics to see the interior, and it looked great inside as well (and complete). So I just could not find any good reason NOT to buy it !

This type of Tek TE is ultra rare here, first I see in years of looking for Tek stuff. So knowing it would probably my first and last of this kind, I had to get it, so that I have at least one to play with.

So I just received it this evening. Some piccies below.

Condition :

1) cosmetics : on the outside, rusty screws on the handle bar and bottom cover, easy enough to replace. Inside, really clean, minor amounts of dust. Only thing to report would be a crusty TO3 package transistor. I gave it the usual quick 30 minute clean in the kitchen. I am surprised at how good it came out. Was crusty as hell, but it's amazing what a bit of spit and polish can achieve. UHF connectors and bright work and face plate look very decent now, quite pleasing to look at. Not NIB of course, but for a thing of this age it looks very nice, no show stoppers.

2) Electrical : guy told me there was a gassy tube, as he could see one that had white sutff at its top. Said it was a 6DE7 type tube. Looked it up in the schematics, it's part of the PSU so quite needed...   Never heard of this tube model before, none of my numerous Tek scopes have any. Searched ebay, seems fairly common and dirt cheap in the US, but not so over here. In Europe ebay found me on ly 3 Of them ! One in France, NOS/NIB for 20/25 Euros shipped. Another one in Spain, again NOS, same priced. Last one was cheaper but used, and located in some Eastern European country, think it was Lituania or something...
Went for the French one, easier to sue him in case something goes wrong, and the fastest shipping time of all 3 of course, which I wanted.
I received the tube yesterday, just before the pre-amp, great. So I was able to replace that gassy 6DE7 this evening, great.
Pulled the old one... no wonder it's "gassy" : glass is broken !  What's weird is that it broke extremely cleaning, one single piece, no debris, and it's still attached to the bottom of the tube. Strange... it's like someone took a laser cutter and cleanly cut a piece of the glass.. see pic.

Attenuator : it's the dreaded " Turret " style monolithic assembly, that I read about on Tekwiki....  First time I have one... let's hope it works or else it's a lost cause. Luckily since it's a pre-amp, the attenuator is not needed at all for proper operation. It's just there as an extra feature should you want one... so worse case, if it's fucked, it can remain fucked and I can still use this pre-amp just fine    Obviously would be cool if it worked and this TE was fully operational... that goes without saying.

3) Mechanical : that's the main area of work to restore this thing. Needs some work... it clearly got dropped. Its four little plastic feet underneath, got pushed in and bent the front and back panel of the chassis, as well as bending the bottom cover of course... which is easy to see on the pictures as the edge of the cover does not line up at all with the side panels. Not the end of the world to fix, but needs to be done with care and accuracy, with proper tools. Not something I can tackle at the moment, but surely will later.


It powers up. Fan rattles a bit as always, blades need adjusting, routine stuff.
Too late to embark into testing / assessing it properly, plus I want to do it, for the first time, nicely.. with proper coax cables and adapters, not with a shoe string as I have always been doing so far. So as soon as I get my Farnell order which carries coax cables and various adapters, I will be able to play with this pre-amp like a pro 

Enough talking, we want piccies !! 

[tggzzz]

I never heard you lecture anyone on how to spell tggzzz which nobody can get right. Neither did I of course, but I was so tired of not knowing how to spell it that I eventually tried and found a way to remember it, in case it helps others... The repetition rate of the letters increases by one with each passing letter. So " T " is written only once, then the second letter " G " is written twice, and third letter " Z " is written 3 times. 1-2-3 times TGZ = TGGZZZ.   

Yup; it has a low probability of a name collision, unlike my legal name.

I've always said I don't mind what people call me, so long as they do it to my face and not behind my back

[Vince]

Pics of the damage on the underside, chassis and bottom panel.

Pics of the turret attenuator too, and the crusty TO3.

[mnementh]

I never heard you lecture anyone on how to spell tggzzz which nobody can get right. Neither did I of course, but I was so tired of not knowing how to spell it that I eventually tried and found a way to remember it, in case it helps others... The repetition rate of the letters increases by one with each passing letter. So " T " is written only once, then the second letter " G " is written twice, and third letter " Z " is written 3 times. 1-2-3 times TGZ = TGGZZZ.   

Yup; it has a low probability of a name collision, unlike my legal name.

I've always said I don't mind what people call me, so long as they do it to my face and not behind my back

I never noticed that "nobody can get it right"... I thought the mnemonic for it was pretty obvious: tigger sleeping.



mnem
t(silent i) double guh-zzz...