Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 14559131 times)

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Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15100 on: August 23, 2018, 02:25:50 am »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.
I've used Goo Gone for decades on every kind of plastic you can imagine. They used to advertise "100% oranges for a natural clean" or somesuch crap. It is DESIGNED for getting sticky stuff off of plastic, and recommended usage is to soak stubborn labels off with it. I spent most of a decade in the recycled electronics trade where I went through a bottle or more a week, and never had a single casualty due to the stuff. The same cannot be said of alcohol or WD40, which will peel up applied vinyl coatings commonly used on steel & aluminum equipment covers.

WD-40 used to be mostly benign a Pat says; but it has become somewhat malodorous in recent years, just like Goo Gone. I suspect the original formula has been similarly supplanted due to the artificially low cost of many petroleum products right now. Again, you have to be prepared to wash it right off to get rid of the stink.

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Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15101 on: August 23, 2018, 02:38:29 am »
(SNIP)

Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?
The 73 is a good beataround meter to keep in your box, or as a 2nd meter when you need to measure voltage & current at the same time. $35 is pretty good, actually; and the iffy display is usually due to a problem with the zebra strip on the LCD just like the 87 suffered. Similarly, cleaning the strip/contact areas of the PCB & LCD with alcohol and/or flipping the zebra strip over will often resolve the problem for months or years at a time.

I'd gladly buy one in the condition you describe for that price, and I'm a cheap bastahd.

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Offline GregDunn

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15102 on: August 23, 2018, 03:08:26 am »
(SNIP)

Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?
The 73 is a good beataround meter to keep in your box, or as a 2nd meter when you need to measure voltage & current at the same time. $35 is pretty good, actually; and the iffy display is usually due to a problem with the zebra strip on the LCD just like the 87 suffered. Similarly, cleaning the strip/contact areas of the PCB & LCD with alcohol and/or flipping the zebra strip over will often resolve the problem for months or years at a time.

I'd gladly buy one in the condition you describe for that price, and I'm a cheap bastahd.

Awesome.  I plan to be in the area again tomorrow, so I'll drop in and see if it's still there.

It's somewhat amusing to note that the associate pulled all the Fluke items out of the case instead of just the two I indicated; there were a couple of NCV meters, which I wasn't really interested in.  He casually mentioned that Fluke stuff tended to get snapped up quickly; however, I noted that the stickers (some pawn shops do this) had a list of dates and markdown prices.  The idea is that the longer something sits on the shelf, the lower the price drops.  Both the 179 and the 73 III had been sitting there since January.   >:D 

Oh, as a followup, I did a set of tests on the 179 once I got it cleaned up.  It tracked my 8600 (and by implication, the 115) closely on every test: DCV, ACV, mA, A, and R.  I also got accurate frequency readings at a couple of spot check points.  I'd say it's good to go. :-+
 

Offline bitseekerTopic starter

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15103 on: August 23, 2018, 04:00:00 am »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.

Goo Gone is good stuff, but I've experienced some bad reactions, so testing it is definitely advisable. In one case, some Goo Gone leaked onto a plastic bottle of degreaser and melted a big hole in the side of it. :o

With some clear plastics that go hazy, you can restore clarity with a heat gun. Of course, don't get carried away or you'll melt that, too.
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Offline bitseekerTopic starter

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15104 on: August 23, 2018, 04:03:23 am »
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New one for the POI's, bitseeker.

Sure. Linked to factory's post since his quoting of Alan's Tek 576 video makes it a two-fer POI.
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Offline bitseekerTopic starter

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15105 on: August 23, 2018, 04:07:04 am »
Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?

Typically, that's just the zebra strip in need of some cleaning with IPA. Simple fix, if it's the problem (not sure about that model, specifically). If not, you might need to get a replacement LCD panel. Check out Mr. Modemhead's blog for those subjects and more about Fluke DMMs, including cleaning tips.
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Offline bitseekerTopic starter

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15106 on: August 23, 2018, 04:12:22 am »
wow.  that guy jim Williams was right.

you really can make a sub nanosecond pulse generator with parts from the junk box.

Wow, that's pretty cool. Now, I don't have to buy a pulse gen.

Quote
ok ok.  should have used a real power supply instead of the leakage test voltage from an antique cap/res bridge. 

but it was close to hand.  and i like tuning eyes.

Haha, I was just thinking about that the other day looking at the Sprague TO-6 I got this summer. They are just adjustable power supplies at heart. But, yeah, the magic eye is a weird and wonderful thing. One day, I should look into exactly how they work.
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Offline GregDunn

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15107 on: August 23, 2018, 04:30:05 am »
Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?

Typically, that's just the zebra strip in need of some cleaning with IPA. Simple fix, if it's the problem (not sure about that model, specifically). If not, you might need to get a replacement LCD panel. Check out Mr. Modemhead's blog for those subjects and more about Fluke DMMs, including cleaning tips.

I'm in the process of replacing the LCD on my 8020A so I've read his blog.  But I'll check out the parts about cleaning...
 

Offline neo

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« Reply #15108 on: August 23, 2018, 04:42:01 am »
wow.  that guy jim Williams was right.

you really can make a sub nanosecond pulse generator with parts from the junk box.

Wow, that's pretty cool. Now, I don't have to buy a pulse gen.

Quote
ok ok.  should have used a real power supply instead of the leakage test voltage from an antique cap/res bridge. 

but it was close to hand.  and i like tuning eyes.

Haha, I was just thinking about that the other day looking at the Sprague TO-6 I got this summer. They are just adjustable power supplies at heart. But, yeah, the magic eye is a weird and wonderful thing. One day, I should look into exactly how they work.


http://www.rfcafe.com/references/popular-electronics/the-tuning-eye-how-it-works-jan-1955-popular-electronics.htm
 
Really are neat things as i understand it there exists voltage difference between center and start. The closing of the eye is caused by a voltage shift which in itself is caused by an amplified signal.
« Last Edit: August 23, 2018, 04:58:37 am by neo »
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Offline bitseekerTopic starter

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15109 on: August 23, 2018, 05:32:38 am »
Cool, thanks neo! The ray control electrode was the missing piece to my understanding. That's the bit that, when more negative than the target, causes the shadow that "opens" the eye.
« Last Edit: August 23, 2018, 05:40:16 am by bitseeker »
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15110 on: August 23, 2018, 06:36:26 am »
Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?

Typically, that's just the zebra strip in need of some cleaning with IPA. Simple fix, if it's the problem (not sure about that model, specifically). If not, you might need to get a replacement LCD panel. Check out Mr. Modemhead's blog for those subjects and more about Fluke DMMs, including cleaning tips.

I'm in the process of replacing the LCD on my 8020A so I've read his blog.  But I'll check out the parts about cleaning...
Not a certainty though, I had a 25 that was doing the same thing but it was the display. After cleaning both the zebra strip and the contacts it was the same. Swapped display with another one that was working and it worked just fine. As a double check, popped the flickering one into the other one and it flickered.
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Offline tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15111 on: August 23, 2018, 07:17:09 am »
wow.  that guy jim Williams was right.

you really can make a sub nanosecond pulse generator with parts from the junk box.

transistor - 2n3904
bias resistor - 1 Megohm
relaxation cap - 3 ea 12 pf 50 V in series
avalanche voltage - 120-135V

how much narrower is the pulse than the 870ps shown?  impossible to know with a 400 Mhz scope. (but this sure is one of those applications where equivalent time sampling works great)

Yup, that's the problem. Since you don't know the amplitude, you can't derive the risetime.

I prefer using 3*(74lvc1g14+143ohms) in parallel to give a very clean sub-ns step. Make sure you decouple them very well! I'm not sure of the exact risetime; indirect measurements indicate ~600ps, but a quick test by somebody else on their scope showed 300ps.

Alternatively a Tek1502 has a tunnel diode ~50ps generator.
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Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15112 on: August 23, 2018, 08:20:53 am »
I'm using the "original" LT1073 boost converter plus a random Central Semi 2n2369 for that job. It worked nicely. However no idea of the actual rise time as I have nothing fast enough to measure it. Also I nicked the LT1073 out to use in another converter so it's not working now anyway. I did buy a 74LVC14 to make another one with but haven't got around to it. Much simpler really.
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15113 on: August 23, 2018, 12:02:38 pm »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.
I've used Goo Gone for decades on every kind of plastic you can imagine. They used to advertise "100% oranges for a natural clean" or somesuch crap. It is DESIGNED for getting sticky stuff off of plastic, and recommended usage is to soak stubborn labels off with it. I spent most of a decade in the recycled electronics trade where I went through a bottle or more a week, and never had a single casualty due to the stuff. The same cannot be said of alcohol or WD40, which will peel up applied vinyl coatings commonly used on steel & aluminum equipment covers.

WD-40 used to be mostly benign a Pat says; but it has become somewhat malodorous in recent years, just like Goo Gone. I suspect the original formula has been similarly supplanted due to the artificially low cost of many petroleum products right now. Again, you have to be prepared to wash it right off to get rid of the stink.

mnem
*Not yet ready for Prime Time*

And this stuff is DESIGNED to solvent weld polystyrene:



I don't wish to get into a battle with you about this, but at the same time I would feel remiss in letting you leave an impression that something orange oil based is harmless to all plastics.

You may have been lucky over the years but anything that is principally orange oil is principally (>90%) limonene and it is well known, and well documented, as an effective solvent for a range of common plastics and is also used as the basis for a number of paint strippers. There are many plastics that are tolerant (polyethylene) to highly tolerant (nylon) of limonene but there are many that aren't, polystyrene, acrylic and ABS being the commonest. Using a limonene based product indiscriminately can and most likely will lead to grief.

I am not saying don't use limonene or limonene based products; I keep it as part of my own collection of problem solver solvents:



I'm just saying that understanding and caution are required in using it.
« Last Edit: August 23, 2018, 12:04:34 pm by Cerebus »
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Offline Discotech

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15114 on: August 23, 2018, 12:24:23 pm »
I got a little carried away but at least I'm ready to test some LED's I think   :-/O

The PSU is the only thing I paid full price for despite them all being brand new, total was around £800
 

Offline bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15115 on: August 23, 2018, 12:44:37 pm »
You did good there. That GDM-8342 is made by GW Instek and is a damn good meter. I owned the GDM-8341 for a bit. See: https://www.eevblog.com/forum/testgear/quick-gw-instek-gdm-8341-bench-dmm-teardown-review/

Just sold my old car for way more than I was expecting assuming the dude turns up. Hopefully some more TEA budget for the weekend. Unless the event gets rained out :(
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15116 on: August 23, 2018, 01:07:38 pm »
I'm using the "original" LT1073 boost converter plus a random Central Semi 2n2369 for that job. It worked nicely. However no idea of the actual rise time as I have nothing fast enough to measure it. Also I nicked the LT1073 out to use in another converter so it's not working now anyway. I did buy a 74LVC14 to make another one with but haven't got around to it. Much simpler really.

wanted to try a jw pulser just because it was easy and quick. (and fun)  was very happy with the results.

gotta admit though that this sn74ac14n doodad is perfectly fine for testing random hunks of coax.  it's rise time does not appear to be as fast by my measurements, but it is a whole lot more convenient, and by focusing on the ringing peak it has no trouble resolving 4 inches of coax added to or removed from the end of a longer run. 

https://www.ebay.com/itm/TDR-Time-Domain-Reflectometer-Fast-Clock-Version-Detect-cable-faults-More/152587007700?hash=item2386e4f6d4:g:fKMAAOSwXXxZQqx-:sc:USPSFirstClass!52402!US!-1


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Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15117 on: August 23, 2018, 01:16:12 pm »
Just sold my old car for way more than I was expecting assuming the dude turns up. Hopefully some more TEA budget for the weekend. Unless the event gets rained out :(

[Fx: Monty Burns] Excellent! [/Fx]

We seem to have a lot of the UK guys synchronised on MOT timing. Mine went in for the usual annual "Oh god I hope they don't find anything wrong" test yesterday. I was a little nervous as it's been a little crackly on the overrun recently and I thought I might be up for an emissions test failure. Nope, 6ppm hydrocarbons (against a 200 ppm limit) and 0.01% CO (against a 0.2% limit). Not bad for a P reg (1997) car!
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Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15118 on: August 23, 2018, 01:18:38 pm »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.
I've used Goo Gone for decades on every kind of plastic you can imagine. They used to advertise "100% oranges for a natural clean" or somesuch crap. It is DESIGNED for getting sticky stuff off of plastic, and recommended usage is to soak stubborn labels off with it. I spent most of a decade in the recycled electronics trade where I went through a bottle or more a week, and never had a single casualty due to the stuff. The same cannot be said of alcohol or WD40, which will peel up applied vinyl coatings commonly used on steel & aluminum equipment covers.

WD-40 used to be mostly benign a Pat says; but it has become somewhat malodorous in recent years, just like Goo Gone. I suspect the original formula has been similarly supplanted due to the artificially low cost of many petroleum products right now. Again, you have to be prepared to wash it right off to get rid of the stink.

mnem
*Not yet ready for Prime Time*

And this stuff is DESIGNED to solvent weld polystyrene:



I don't wish to get into a battle with you about this, but at the same time I would feel remiss in letting you leave an impression that something orange oil based is harmless to all plastics.

You may have been lucky over the years but anything that is principally orange oil is principally (>90%) limonene and it is well known, and well documented, as an effective solvent for a range of common plastics and is also used as the basis for a number of paint strippers. There are many plastics that are tolerant (polyethylene) to highly tolerant (nylon) of limonene but there are many that aren't, polystyrene, acrylic and ABS being the commonest. Using a limonene based product indiscriminately can and most likely will lead to grief.

I am not saying don't use limonene or limonene based products; I keep it as part of my own collection of problem solver solvents:



I'm just saying that understanding and caution are required in using it.

Clearly, the product is designed for use on plastics, particularly the kinds of plastic used on electronic equipment. Therefore, it is your understanding of the product that is at question here. You ASSUME it is full of limonene, therefore you assume it is hazardous to plastics. You ASSUME that the manufacturer has somehow formulated a product for use on plastic without neutralizing it to be a safe product for use on plastic.

Now which is really more likely here; that your understanding of the product is faulty, or that it is dissolving people's electronics all over the world ever since it was introduced and hasn't been pulled from the market?

I am fully aware of the chemistry you speak of; I am NOT ignorant. I'm telling you that decades of use on all manner of plastic cabinetry, most of which is  in a production environment is valid empirical evidence that in this case, you don't know what you're talking about as well as you think you do.

In general, Goo Gone is safer to use for cleaning than IPA, which will remove and smear many types of coatings and paints commonly in use today on electronics; Goo Gone just makes  them shiny. I used to use IPA to clean up after Goo Gone; then we started getting gear with micro-rubberized coating that IPA just turns into a flaky mess. Even that is unaffected by Goo Gone unless it's already turned marshmallowy; but by then there's no saving that stuff. The only solution there is to strip it all off, and IPA is good for that, IF it doesn't turn the base plastic hazy.

Yes, of COURSE there will always be the exception to the rule. Yes, you should ALWAYS test on an inconspicuous area FIRST.

But consider this... due to my extensive EXPERIENCE with the product, I am confident enough in the safety of Goo Gone IN GENERAL that I didn't hesitate to smear it all over the lens of my just-acquired Fluke 189 to make SURE before recommending it to Greg.


mnem
mmmm.... solvent....
« Last Edit: August 23, 2018, 01:38:39 pm by mnementh »
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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15119 on: August 23, 2018, 01:28:24 pm »
Just sold my old car for way more than I was expecting assuming the dude turns up. Hopefully some more TEA budget for the weekend. Unless the event gets rained out :(

[Fx: Monty Burns] Excellent! [/Fx]

We seem to have a lot of the UK guys synchronised on MOT timing. Mine went in for the usual annual "Oh god I hope they don't find anything wrong" test yesterday. I was a little nervous as it's been a little crackly on the overrun recently and I thought I might be up for an emissions test failure. Nope, 6ppm hydrocarbons (against a 200 ppm limit) and 0.01% CO (against a 0.2% limit). Not bad for a P reg (1997) car!
Haha my 2013 had its 3rd annual test today, passed without even an advisory warning of things to be watched. That set of a wave of expense though, road tax, just paid, next week insurance would have made another hole in my TEA budget were it not for the cull I'm having on older and duplicated gear, thanks to which I have a fat wad waiting for right thing at the right time. I'm like a  coiled spring waiting to pounce on something not sure yet what but when it comes WHAM I'm in. [emoji41][emoji41][emoji41]
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline Discotech

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15120 on: August 23, 2018, 01:29:45 pm »
You did good there. That GDM-8342 is made by GW Instek and is a damn good meter. I owned the GDM-8341 for a bit. See: https://www.eevblog.com/forum/testgear/quick-gw-instek-gdm-8341-bench-dmm-teardown-review/

Just sold my old car for way more than I was expecting assuming the dude turns up. Hopefully some more TEA budget for the weekend. Unless the event gets rained out :(

Yep the scopes are rebranded GW-Instek versions too and I believe the DMM is an appa 505, it's no fluke but for the price I paid it's worth to have a more reliable DMM compared to my cheaper A8008 style ones
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15121 on: August 23, 2018, 01:31:57 pm »
Cool, thanks neo! The ray control electrode was the missing piece to my understanding. That's the bit that, when more negative than the target, causes the shadow that "opens" the eye.
It's actually a pretty amazing functionality; the cone behind the phosphor lumina is charged opposite the inverted cone in the center. This produces a field of static charge across the surface of the lumina, exciting it. What I still find amazing is how the ray-control electrode creates such a crisp, clean line in the separation of the static field... it shouldn't be so; that covalent area should be a lot more random than it is.

Damned electrons... just when you think you understand them...  >:D


mnem
...or maybe damned fool engineers & physicists, thinking we can understand EVERYTHING. Remember, we made this thing work back when we were exactly wrong about the direction of electron flow.  :-DD
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Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15122 on: August 23, 2018, 01:45:55 pm »
Clearly, the product is designed for use on plastics, particularly the kinds of plastic used on electronic equipment. Therefore, it is your understanding of the product that is at question here. You ASSUME it is full of limonene, therefore you assume it is hazardous to plastics. You ASSUME that the manufacturer has somehow formulated a product for use on plastic without neutralizing it to be a safe product for use on plastic.

I'm not assuming, I'm trusting you to be correct in what you said: "They used to advertise "100% oranges for a natural clean" - which implies a highly significant limonene content in the original formulation (>90% if it was indeed 100% oranges [oil ASSUMED, as juice would be farcical]) and reasonably implies a significant concentration in more recent formulations. As it is, a check of the MSDS shows the current formulation to be 1-5% d-Limonene. Still enough to be a concern if left in contact for a significant time.

I am not aware of any mechanism by which a solvent's solving ability can be "neutralized", let alone doing so and it still contributing an ability to dissolve certain things which is surely the whole point of it being in there in the first place (label glue for instance). I'll readily admit that physical chemistry is not my thing so if you know better then please enlighten me as to the mechanism of this neutralization. I mean that seriously, I'm always more than willing to have my ignorance replaced by knowledge.

FFS man, I'm just saying "be cautious if it's got limonene in". It definitely has, so one should definitely be cautious.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
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Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15123 on: August 23, 2018, 01:46:30 pm »
I'm using the "original" LT1073 boost converter plus a random Central Semi 2n2369 for that job. It worked nicely. However no idea of the actual rise time as I have nothing fast enough to measure it. Also I nicked the LT1073 out to use in another converter so it's not working now anyway. I did buy a 74LVC14 to make another one with but haven't got around to it. Much simpler really.

wanted to try a jw pulser just because it was easy and quick. (and fun)  was very happy with the results.

gotta admit though that this sn74ac14n doodad is perfectly fine for testing random hunks of coax.  it's rise time does not appear to be as fast by my measurements, but it is a whole lot more convenient, and by focusing on the ringing peak it has no trouble resolving 4 inches of coax added to or removed from the end of a longer run. 

https://www.ebay.com/itm/TDR-Time-Domain-Reflectometer-Fast-Clock-Version-Detect-cable-faults-More/152587007700?hash=item2386e4f6d4:g:fKMAAOSwXXxZQqx-:sc:USPSFirstClass!52402!US!-1
Souvacrap... that IS a nifty solution! *Adds to watch list for later* Elegant in its simplicity, pretty hard to eff up. Brilliant!


mnem
Everything is a learning experience.



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Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15124 on: August 23, 2018, 01:50:42 pm »
Haha my 2013 had its 3rd annual test today, passed without even an advisory warning of things to be watched. That set of a wave of expense though, road tax, just paid, next week insurance would have made another hole in my TEA budget were it not for the cull I'm having on older and duplicated gear, thanks to which I have a fat wad waiting for right thing at the right time. I'm like a  coiled spring waiting to pounce on something not sure yet what but when it comes WHAM I'm in. [emoji41][emoji41][emoji41]

I went through a process a few years back of doing some things early so that my MOT, road tax, and insurance all got separated in time. So the MOT was yesterday, tax is October and insurance December. Makes the whole process a little less daunting not having them all pile on top of one another to make for a very expensive month.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 


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