Test Equipment Anonymous (TEA) group therapy thread

[Kosmic]

I was wondering why my cheap Chinese probe (P6500) was not working anymore. I opened up the base of the probe and found this:



Look like the core is not attached to the dielectric and it's actually moving around when you move the cable.



I was trying to save a bit of money on those cheap 500Mhz probes and was hopping they would be noname version of the branded one. Look like they are really not the same  after all. Probably going to stick with branded one from now one.

[beanflying]

Seems @Brumby has a new toy and by some evilbay sleuthing may have bid on another item of TEA too You cannot hide ...... 

[Brumby]

Hey @Brumby want to raise the blood pressure of SHMBO 'some more' 

Needs some love but if it was closer I would find a place for it in the toy collection  eBay auction: #193188410543

(Added to my Watch list.   )



   

Well ... what did you expect would happen?

Going on a little trip tomorrow afternoon to pick up this and another acquisition (a 2ch 20MHz scope) - and SWMBO only knows about the scope.

Now ... where to put it!!

[Brumby]

Seems @Brumby has a new toy and by some evilbay sleuthing may have bid on another item of TEA too You cannot hide ...... 

^ ^ ^  Guess who's to blame thank .... ^ ^ ^

[mnementh]

Just in time...      should I do something on that exposed copper? Epoxy?   

With rotten shellac on still-good copper like that (all those "dark" areas of Shellac over copper are "rotten"), leaving it will just result in the rot spreading; but you have to balance the need to repair against the possibility of damaging a trace. Correct solution is to mask off the edges of the trace with something like Kapton tape to protect the substrate, use fine steel wool to scrub all rotten shellac off a section of trace leaving shiny copper, then remove the masking and move to the next area of trace until it is all either clear shellac or shiny copper.

After that, clean with IPA and paint with new shellac or clear fingernail polish. Epoxy is also perfectly fine, I've used it in a pinch; just be sure to make a thin coating using a flattened & cut-off Q-Tip stick or coffee stirrer as a squeegee.

If i have any doubts as to whether the thickness of the trace has been compromised by acid etching, I consider reinforcing with wire or tinning the trace. This is best done by applying rosin to the shiny cleaned copper trace, then starting at a solder pad and adding a fair blob of solder, then dragging the iron across the bare copper through the flux. Work a little hot & as fast as you can to avoid lumps and to avoid damaging the trace/substrate bond. This requires a fair amount of practice and soldering skill; you need to practice a lot on junk boards to get your technique down pat. After the trace is tinned, clean up the solder pad areas where you started tinning from and paint the trace as above.

mnem
moo...?

[AVGresponding]

Mmmmmmm LEDs... snagged a Solartron/Schlumberger 7065 in the early hours of the morning (late for work as a result
    ) for £62 shipped, also a pair of Minimus 11 speakers to go with my very old but very loved Minimus 7s.

I'm seriously considering buying a 3D printer (you lot are a terrible influence!), and am soliciting opinions on the merits of UV vs FDP, given that I'd like the best precision I can get when making potentially very small parts.

[beanflying]

Mmmmmmm LEDs... snagged a Solartron/Schlumberger 7065 in the early hours of the morning (late for work as a result
    ) for £62 shipped, also a pair of Minimus 11 speakers to go with my very old but very loved Minimus 7s.

I'm seriously considering buying a 3D printer (you lot are a terrible influence!), and am soliciting opinions on the merits of UV vs FDP, given that I'd like the best precision I can get when making potentially very small parts.

Random but I typed this elsewhere earlier in the day 

The results I have seem coming from them look great but like all SLA/Resin type printers the cleanup and post curing sucks to a greater or lesser degree depending on your usage.

If you want to load up to produce a 'single' widget say 20x20x50 you still need to load the tank and after the print clean the tank and printer totally. Add to that post cleaning and curing of the print. Meanwhile allowing for the reduction in surface finish the FDM printer is likely done several hours before and the print in use.

If you want to run the 'same' resin and produce several widgets back to back then the cleanup time and post processing time will reduce so it will have less of an impact.

By products of SLA and disposal. Contaminated IPA that really shouldn't be reused with different resins and even then it will contain residue from past use if you try to reuse it sometime later. Contaminated gloves and wasted resin to little to use for another print. Take the view of bury or burn it and it is someone elses problem :evil: or consider what cost or inconvienience it is to get rid of these items.

Will I maybe get an SLA printer - maybe to unlikely. They do have a place but go in with your eyes open.

[AVGresponding]

That seems like a ton of hassle if you aren't making efficient use of it.

I guess I'll shop around for a higher resolution FDP...

[beanflying]

Most of the FDM printers can get to similar resolution. Standard is 0.4mm nozzles and 0.2mm layers. 0.1mm Layer is fairly easy to go and dropping the nozzle size to 0.3 works and you can get 0.2 (tough to get it working well)

All of my Creality printers get used at a mix of 0.2 and 0.1mm layers and do it well. The exception to this initially was the magnetic bed on the Ender but changing to a Glass bed fixed that.

Have a look at the following youtubers for some real world unbiased opinions. Some of the others are straight up bs for freebies printers and commission from the usual suspects. https://www.youtube.com/channel/UCiczXOhGpvoQGhOL16EZiTg  https://www.youtube.com/channel/UCb8Rde3uRL1ohROUVg46h1A  https://www.youtube.com/channel/UCxQbYGpbdrh-b2ND-AfIybg just search for 'resin' or 'sla' should get you some to look at.

[xrunner]

I'm seriously considering buying a 3D printer (you lot are a terrible influence!), and am soliciting opinions on the merits of UV vs FDP, given that I'd like the best precision I can get when making potentially very small parts.[/b]

Propane tanks for an N scale model railroad, 0.4mm nozzle.

[bd139]

It's antenna day here. I put the soaked coax on the NanoVNA and unfortuntely it wasn't very interesting at all. Literally high VSWR down the entire line.

This time I'm not screwing it up so I have put together a new head for it which is a bit better designed than the original i.e. it has the coax entry pointing down, is shrinked properly and then coated in liquid tape just to make sure.



Please excuse the pikey current balun. They are cheap and work! (Fair-rite 5943003801 - Amidon can fuck off with their markup!)

Edit: the wire is sotabeams stuff which is awesome. It doesn't stretch at all https://www.sotabeams.co.uk/antenna-wire-lightweight-100m/

Also the moment I decided to go out and set it up it started pissing it down. 

[med6753]

I'm seriously considering buying a 3D printer (you lot are a terrible influence!), and am soliciting opinions on the merits of UV vs FDP, given that I'd like the best precision I can get when making potentially very small parts.[/b]

Propane tanks for an N scale model railroad, 0.4mm nozzle.

(Attachment Link)

Keep them away from bd139. He'll use them as bombs. 

[bd139]

3D printed bombs. Now there’s an idea 

[Zucca]

Just in time...      should I do something on that exposed copper? Epoxy?   

With rotten shellac on still-good copper like that (all those "dark" areas of Shellac over copper are "rotten"), leaving it will just result in the rot spreading; but you have to balance the need to repair against the possibility of damaging a trace. Correct solution is to mask off the edges of the trace with something like Kapton tape to protect the substrate, use fine steel wool to scrub all rotten shellac off a section of trace leaving shiny copper, then remove the masking and move to the next area of trace until it is all either clear shellac or shiny copper.

After that, clean with IPA and paint with new shellac or clear fingernail polish. Epoxy is also perfectly fine, I've used it in a pinch; just be sure to make a thin coating using a flattened & cut-off Q-Tip stick or coffee stirrer as a squeegee.

If i have any doubts as to whether the thickness of the trace has been compromised by acid etching, I consider reinforcing with wire or tinning the trace. This is best done by applying rosin to the shiny cleaned copper trace, then starting at a solder pad and adding a fair blob of solder, then dragging the iron across the bare copper through the flux. Work a little hot & as fast as you can to avoid lumps and to avoid damaging the trace/substrate bond. This requires a fair amount of practice and soldering skill; you need to practice a lot on junk boards to get your technique down pat. After the trace is tinned, clean up the solder pad areas where you started tinning from and paint the trace as above.

mnem
moo...?

Thanks mnem, crazy idea don't spit me in the face, would a sharpie ink be sufficient to protect the substrate?
It would be so much quicker and precise.

[GreyWoolfe]

From the "Perversity of the Universe Tends to the Maximum" Dept...



It just sits there, mocking me...

It mocks me; and I am mocked. 

Decades I've had that Minimus-7 speaker in my possession... so many moves, and over a decade I've been looking for a mate to it, figuring that when Ifni deigned for it to be so, one would manifest in a thrift or flea market at a price I couldn't refuse.

Until a couple months ago... when I gave up and sent it to med in a "care package". Flash forward to now... and what should mystically appear on my thrift RADAR...?

Yup. Even better condition, and CAD$3.99... 

mnem
Okay, okay... Ifni has spoken. I shall have one Minimus-7 speaker; no more, no less. 

Mnem, I shall keep the balance in the universe for you.  I have 4, 2 currently in use and 2 packed away.  I have had mine since the early 90's when I worked for Rat Shack for a time.  I actually got mine for free.  The manager and I were cleaning out a back room of the store and these were there, too scratched to sell but worked perfectly.  Got them for free along with anything else I wanted out of the piles.  The speakers are all I have left from those days.

[Cerebus]

3D printed bombs. Now there’s an idea 

Whoops, bd139 just found himself on another watchlist.

[bd139]

I'm probably on a few 

Well this antenna business is going pretty well and the NanoVNA is amazing still. For once I cut the antenna waaaay too long instead of too short.

Lowest VSWR is supposed to be around 7.05 MHz.



Will fix that tomorrow. Had enough of outside for the day now!  . Will load it up with an ATU. I've made contacts on half a broken antenna before

Edit: K2 ATU FTW. 2w out on badly tuned antenna. Spot on Austria straight away 

[xrunner]

For once I cut the antenna waaaay too long instead of too short.

Right! 

[Specmaster]

3D printed bombs. Now there’s an idea 

Whoops, bd139 just found himself on another watchlist.

Hey, welcome back Cerebus, looks like you've been lurking in the background reading the posts but not actually contributing all that much and then when you do, you nail it just like that  .

[McBryce]

the different from a museum to a well cared collection is: The most old instruments in a museum are clean, inside dirty, and of coarse not working. This is a problem.

I have saved a wonderful old computersystem, and changed there for a lot of money elkos to make it running again. Now, the Maya have started allready, but the WAF (womens acceptance factor) for a multiprozessor Unix mashine is smaller then zero, so I asked some museum if the are interested. But not one of them want to give me the pay for the spares I have used to make it running. It is complete, including document, licences for the OS and the May and so on, and not a penny, this is our time. I will find a way to put the little ONYX2 also in this work room, to play with the amazing grafix ("reality engine"). Not museum.

I'm stuck in a similar conundrum with one of these:       A Heath-Zenith Z-120 (only with working 5GB Winchester drive) that has been in my possession for 15 years. I had it working 100% about 10 years ago; however the usual "dried-out caps" failure mode has claimed it as another victim, and I just couldn't make it to the top of my repair que in all that time due to assache factor and cost of parts...

I've seen oodles of articles where a collector or small museum space has spent the time & money to buy and restore one of these seminal works of computer history... but every time I try, I simply cannot find ANY ONE OF THEM willing to even pay the cost of shipping. So yet again, it goes into storage to be dealt with on another day...

mnem
*mocked*

A 5GB Winchester drive!!!  That must be worth a fortune! 

McBryce.

[tggzzz]

Most of the FDM printers can get to similar resolution. Standard is 0.4mm nozzles and 0.2mm layers. 0.1mm Layer is fairly easy to go and dropping the nozzle size to 0.3 works and you can get 0.2 (tough to get it working well)

Here are some examples of the same components made in three different materials

• white: DirtyPCBs' SLA
• purple: Shapeways' strong and flexible nylon
• red: Prusa printer's PLA, 0.4mm nozzle, 0.15mm step, 100% infill

In the pictures below, the surface finish of the PLA and nylon is easy to see, but that of the SLA is so smooth the part appears to be out of focus!

The first component is a scope probe tip designed to (successfully) minimise the inductance of a ground lead. The dimensions and finish are non-critical, and the internal nibs are an interference fit over the probe.

The nylon is the best material since the outer walls deform when the probe is inserted, gripping well but allowing the probe tip to be easily removed without damage to the probe. The PLA works, but requires careful reaming out for it to be an interference fit, and its hardness an roughness damages the probe. The SLA is intermediate. Overall the PLA is sufficient to prove the concept, but it unsatisfactory otherwise.





The second component is a handle for a Tek P6013 HT probe. The key design feature is that the 2mm pitch thread which screws into the HT part of the probe.

The SLA variant works perfectly, inparticular the thread works surprisingly well. The PLA variant is a failure: the thread doesn't screw in, and the slicer automatically modified the shoulder's overhang.



The final component is a collet for a Tek 24x5 squirrel cage cooling fan. The design points are the compression of the collet inside the fan, by being pulled to the left with a screw.

Lightly compressing the PLA variant with fingertips caused it to fracture along a layer boundary, so it is unlikely it could survive the tension exerted by the screw. That's not entirely surprising, PLA (and similar materials/depositions) was never going to be a good material for this task. The SLA variant works well, and will probably be OK in the medium term: the SLA scope probe handle is fine after 4 years, and the collet won't get very warm.

[Cerebus]

3D printed bombs. Now there’s an idea 

Whoops, bd139 just found himself on another watchlist.

Hey, welcome back Cerebus, looks like you've been lurking in the background reading the posts but not actually contributing all that much and then when you do, you nail it just like that  .

Biding my time dear boy, biding my time...

No, not really. The contract I was on for the last year kept me busy, and moreover kept me busy at a screen and keyboard all day so that I wasn't really in the mood for using the same for social and entertainment reasons. I was sticking my head around the corner now and then and trying to catch up on here, but when you're reading twenty pages behind the rest of the world you don't bother to comment because it's more than likely that someone else will have said exactly what you're about to somewhere in the next 19 pages. Lord knows that I am a fool, but I'm not going to make it quite so publicly obvious by autonomously re-hashing someone else's comments like that.

I've had a break now and am feeling more myself, and I'm sufficiently up to date here to get back into the swing of things. I spent the last few weeks since that contract ended just kicking back and failing to catch up with all the jobs around the house (both necessary jobs and self-entertainment like TEA and electronics) that I'd promised myself that I would once I had some time on my hands. I did have another contract lined up that would have me scrabbling off to the Middle East this weekend for a kickstart meeting on Monday, but that fell through. Perhaps a blessing in disguise as I'm getting too fricking old for rushing around the world but it does leave me twiddling my thumbs and wondering what to do next. So while I do that I'm free as a lark to totter in here and instruct as many youngsters as I can find exactly in what fashion, and with precisely described timing, how to get off my lawn.

I see that, in my temporary absence, Med has gone from a quite understandable obsession with Tek blue to a worrying one with Smurfette blue. One shudders to think where this may end up. It's the sort of think that can lead to dressing up in furry costumes and meeting with like minded people in smoky dive bars or seedy hotel rooms. Marginally acceptable as a detour in the young when they're at that "finding themselves" stage, but distinctly unnatural in men of our age unless they are judges, politicians or any of the occupations where the holder went to a certain class of school, one of a particular set of universities and had a nanny.

[med6753]

Look what followed me home. Yep, the seller and I struck a deal. RCA Institutes 3 inch AC coupled scope. The model number tag is missing so I'm going to have to do some Google sniffing to figure out the model number and find a schematic/manual. Not surprisingly it's all hollow state considering where it came from.



The tube complement is 6X4 B+ rectifier (that 6X5 written on the chassis is wrong), 6D10 “compactron” triple triode, two 12AU7's duo triodes, 6BL8 combo pentode/triode, and 1V2 HV rectifier.




The underside. Shows lots of evidence of past Gorillas/monkeys being in here. At the very least a recap is in order.



It does work. A decent trace but the longer it's on the more noise appears on the trace. And the Horizontal gain is fixed. The control has no effect. More evidence of Gorilla activity. The cabinet is gray and in decent shape so believe or not I probably won't respray it. 

[med6753]

I see that, in my temporary absence, Med has gone from a quite understandable obsession with Tek blue to a worrying one with Smurfette blue. One shudders to think where this may end up. It's the sort of think that can lead to dressing up in furry costumes and meeting with like minded people in smoky dive bars or seedy hotel rooms. Marginally acceptable as a detour in the young when they're at that "finding themselves" stage, but distinctly unnatural in men of our age unless they are judges, politicians or any of the occupations where the holder went to a certain class of school, one of a particular set of universities and had a nanny.

How did I manage to become so (in)famous??? 

[Cerebus]

How did I manage to become so (in)famous??? 

I think it might be all the piss taking concerned comments from your friends on here.