Test Equipment Anonymous (TEA) group therapy thread

[0culus]

So that beefy HP power supply I got, intending to use it to power a radio? Line fuse absolutely vaporized when when I tried to draw real current from it. 

[0culus]

Here's a real boat anchor....I wonder if any of these have survived intact.


https://www.radiomuseum.org/r/dumont_la_giant_screen_oscillograp.html

[beanflying]

IMNSHO, 3d printers are like solderless breadboards. You spend as much time fettling as printing.

If your mode of thinking is like machining, i.e. adding and removing parameterised component shapes, then OpenSCAD is a good starting point. There are free standalone versions, and browser/web version.

This collet, one threaded, one not, took me a couple of hours to knock together.

  You have uttered this crap once to often and it just doesn't hold up with decent quality modern printers!

It is based on observation of the old and new printer at the local hackspace; the latter is a "Original Prusa i3 MK3".

The local "how to" manual lists many ways in which prints can go wrong and twiddles that can and must be made. It appears there is quite a lot of "suck it and see" involved, which I regard as fettling.

There may be fewer issues if only one person ever uses the machine with only one material, but since I use a variety of materials, I'm never going to own a machine. Hence any prints I make personally will have to be on that shared machine.

Used by non owners and the unwashed masses is not any basis for reality!

It is the basis for one valid version of reality. I accept you may live in a different, equally valid, version.

You have made this same sweeping generalization which doesn't apply to 90-95%+ of the one user printers based on this now explanation.

You are making equally sweeping generalisations for the 90-95% of people that use shared printers. (But it is a bit difficult to understand exactly what your sentence is trying to convey)

YOUR decision to only use a service to print items and never own a printer and I assume never use the shared one you have access to is YOUR option. It follows that then in no way make you a competent or practiced user of a well setup 3D printer and reading some 'manual' doesn't make you practiced or more competent in your use of one.

A well setup printer with a tweaked profile or two makes it a walk up insert card and print not the fiddle you keep go on with. Your version of your truth has no basis in fact with modern printers and the truth but you tried to justify it with a narrow case of a shared one as evidence that is likely poorly maintained caked with crud in the nozzle etc.

So stop attempting to be both an expert at setting up and using a printer when you apparently have little to no experience in doing so while dumping on personal ownership and use of one.

[Neomys Sapiens]

Here's a real boat anchor....I wonder if any of these have survived intact.


https://www.radiomuseum.org/r/dumont_la_giant_screen_oscillograp.html

No. This is a ship's anchor. Anything called a 'boat' would surely be dragged into the ocean's depths by it.

[0culus]

Touché. 

[0culus]

Got my hands on some 2 pF ceramic caps, so I gave the avalanche pulser another go, this time using Manhattan style construction. It works! There's still some optimizations to be done, such as getting some high quality 50 ohm resistors instead of paralleling a pair of 100 ohm resistors, and shortening leads some more. Then make it fit into a BNC project box. But, I'm happy with this prototype! [edit] yes, I'm aware that the 7A29 loses some bandwidth with the variable control engaged, but it was the only way to make it fit for a risetime measurement using the graticule.

[ArthurDent]

Just to prove I didn't skip any posts while trying to catch up, some slide rule pron

So I'm not the only one who collects slide rules...

[beanflying]

This one is still in my pencil/drafting box from secondary school. Never used in anger even when we were taught about Log tables briefly in year 10 pure and applied maths. At that same time we were 'allowed' to use scientific calculators in tests so it became a curio and conversion reference.

[Carl_Smith]

Something in my 7854 has decided to take an occasional dump to ground, and I've only managed to notice because the case shocked me earlier. As far as I can tell, there's no other faults occurring when this happens. It's only a mild shock as one would expect from an otherwise functioning device.  The fault exists regardless of what plugins I've got installed, so it's definitely in the mainframe itself. It does take around 30 minutes of operation before the fault manifests itself, and it's doing so fairly consistently.

I've never had to track down a "mild" fault such as this.  Anyone have any suggestions on how to tackle tracking down the bugger?

The power supply voltages and ripple were good last I checked, but I'll be checking them again at startup and once the fault manifests.

As for tracking down the fault to a particular board, I'm considering using a 7A22 in another mainframe with the negative input probe attached to the ground at the mains input and move the positive input probe around each board's ground test points to narrow the fault down to the board, then continue from there to find the bastard.

Does anyone have any ideas?

Am I reading this right? You're getting a shock off a supposedly grounded chassis? Correct??   

If yes you need to determine why your scope isn't grounded. Is there a problem chassis to ground prong on the power plug? Or do you have bigger problems with the lack of a ground on your mains wiring? You need to figure this out first.

I think, but not sure, that the EMI filter has capacitors in it tied between hot and ground. If you don't have the chassis grounded these caps could cause the chassis to elevate to a fairly high potential, sometimes as high as 80 to 90 volts. The current is real small but you might feel it. And if the caps are going leaky then the current will go up. And also this leakage current could damage other equipment.

Be safe. If you are getting a shock off the chassis of your equipment something is seriously wrong and you need to shut it down and determine ASAP what's going on. 

This reminds me of the time many years ago when I found a way to get the cable TV company repairman to your house in a matter of minutes.  I was doing something with my mom's VCR that required disconnecting the coax.  Because of the setup, I laid my arm across the top of the VCR to reach the coax and unscrewed the connector, and when it disconnected but I was still holding the connector, I got a bad shock. Went and got the multimeter and I measured something like 80V between the VCR and the cable company coax.

I called them up and told them what happened and they said "Don't touch anything, we will come out and check out the problem."   Cable guy showed up in like 15 minutes.     Turns out the connection to the ground rod outside had come loose... 

[mnementh]

The Type 114 is done. All cleaned up, cabinet repainted, switches deoxit'ed. Now going through a mandatory burn-in of several hours.      

Too shiny! *crosses arms with a scowl* Harrumph!

mnem
Whaddayouget when you cross arms with a scowl...?

I dunno, but it can't carry Jack shit!

How about if I drop my shorts and moon you. Is that too shiny too?? 

Edit....better still...I'll drop my shorts and you can kiss my ass. 

Not with rented lips.

mnem
”That’s no space station; it’s a MOON!!!”

[worsthorse]

For the first time in a month, I had three solid hours at the bench tonight, which was enough time to work my way through the 114 testing and calibration. Here it is after I cleaned the case, which was covered with the names of several owners in various types of permanent marker:



Here's what comes out of it now,
a 1us square wave: A 100ns pulse train:

A 100ns pulse: A 100ns inverted pulse: 

Rise time under 10ns: 

After adjusting the power rails and running through the calibration procedure, it is better than specification on all counts.  It helps to have test equipment from the 90s when you are calibrating test equipment from the 60s.     There's still some ringing, but it meets spec, and may be a result of my test setup.

Cosmetically, its an eight: the paint is not in great shape, the Tek logo is mostly worn off the handle and I need to replace some screws (someone had the case apart and used the wrong hardware to re-assemble it).  Specification-wise it is a ten.   

All in all, a good night's work.

[mnementh]

 

mnem
*toddles off to ded*

[mansaxel]

This was first electric calculator.

FACIT AB, Åtvidaberg!

I use to say that my (maternal) grandfather was the first IT person in my family; he repaired FACIT, Addo, and Odhner calculators and typewriters his entire life, and rose to the rank of workshop manager (Verkmästare) in the branch office where he worked. I still have a suitcase typewriter he serviced and sold to my (paternal) grandmother who used it to write travel diaries on. I have a bunch of the electromechanical calculators too, and also inherited his special and ordinary tools, several of which have permanent residence in my tool cases and boxes.

[mansaxel]

On to the next fad, after RPN that is. I now own a 3d printer  . Managed to snag a cheap Creality Ender 3 from their official eBay drop shipping outfit. Got 10% off due to ebay promo as well. The things are selling second hand for that so worst case it's a zero sum game 

But where is the 427A? 

[beanflying]

On to the next fad, after RPN that is. I now own a 3d printer  . Managed to snag a cheap Creality Ender 3 from their official eBay drop shipping outfit. Got 10% off due to ebay promo as well. The things are selling second hand for that so worst case it's a zero sum game 

But where is the 427A? 

At least he will be able to make new feet for it 'when' he gets one 

[Martin.M]

is that true, 2% ?

[beanflying]

It's 2% at FSD

[Martin.M]

ok. I have not understand how to adjust there the exactly reference voltage for a ± Diff.
My Oldie is there different in handling

[tggzzz]

IMNSHO, 3d printers are like solderless breadboards. You spend as much time fettling as printing.

If your mode of thinking is like machining, i.e. adding and removing parameterised component shapes, then OpenSCAD is a good starting point. There are free standalone versions, and browser/web version.

This collet, one threaded, one not, took me a couple of hours to knock together.

  You have uttered this crap once to often and it just doesn't hold up with decent quality modern printers!

It is based on observation of the old and new printer at the local hackspace; the latter is a "Original Prusa i3 MK3".

The local "how to" manual lists many ways in which prints can go wrong and twiddles that can and must be made. It appears there is quite a lot of "suck it and see" involved, which I regard as fettling.

There may be fewer issues if only one person ever uses the machine with only one material, but since I use a variety of materials, I'm never going to own a machine. Hence any prints I make personally will have to be on that shared machine.

Used by non owners and the unwashed masses is not any basis for reality!

It is the basis for one valid version of reality. I accept you may live in a different, equally valid, version.

You have made this same sweeping generalization which doesn't apply to 90-95%+ of the one user printers based on this now explanation.

You are making equally sweeping generalisations for the 90-95% of people that use shared printers. (But it is a bit difficult to understand exactly what your sentence is trying to convey)

YOUR decision to only use a service to print items and never own a printer and I assume never use the shared one you have access to is YOUR option. It follows that then in no way make you a competent or practiced user of a well setup 3D printer and reading some 'manual' doesn't make you practiced or more competent in your use of one.

A well setup printer with a tweaked profile or two makes it a walk up insert card and print not the fiddle you keep go on with. Your version of your truth has no basis in fact with modern printers and the truth but you tried to justify it with a narrow case of a shared one as evidence that is likely poorly maintained caked with crud in the nozzle etc.

So stop attempting to be both an expert at setting up and using a printer when you apparently have little to no experience in doing so while dumping on personal ownership and use of one.

It is clear that I don't own one (and therefore have not twiddled configs); until very recently the only one I had access to was a joke suitable only for demonstrating principle. Hence I have made zero pretence to be an expert, and I resent your false statement to that effect.

However, your phrase "A well setup printer with a tweaked profile or two" reveals that fettling is indeed required. The next question is how much fettling? There I have to rely on watching experienced users of the local machine, and the amount of fettling the have to do to ensure it makes acceptable prints - and it is non-trivial. I have also seen many anecdotes to the effect that users of other machines do recognise that fettling is an issue.

I'm happy that you have found a printer that is suitable for your purposes. It could never be useful for my purposes, since I have found it necessary to use four radically different materials: brass, PLA, nylon, SLA.

Now, while I dearly like my vintage scopes and use them daily, I wouldn't recommend them to an infrequent user that doesn't want to spend time keeping them working - because too much fettling time is required. Similar considerations apply to 3d printer.

YMMV, of course. And that's just fine.

[tggzzz]

Got my hands on some 2 pF ceramic caps, so I gave the avalanche pulser another go, this time using Manhattan style construction. It works! There's still some optimizations to be done, such as getting some high quality 50 ohm resistors instead of paralleling a pair of 100 ohm resistors, and shortening leads some more. Then make it fit into a BNC project box. But, I'm happy with this prototype! [edit] yes, I'm aware that the 7A29 loses some bandwidth with the variable control engaged, but it was the only way to make it fit for a risetime measurement using the graticule.

Be aware that in order to use an impulse to measure risetime, you have to know the impulse's characteristics. Knowing that, you can use deconvolution to work out the scopes' impulse response.

If the pulse is much shorter than the scope's response time, then the scope shows the integration of the area under the impulse. That's the principle that we used in school physics lessons to measure charge with a current meter. There you rapidly discharge the capacitor into a slow acting ballistic galvanometer, and measure the needle's peak deflection which occurs around a second later.

Informally, and in a hand-waving fashion, your scope would show the same response to a 1ps 10V impulse and a 0.1ps 100V impulse.

If, however, you can add a transmission line stub to your impulse generator, then the resulting step will be helpful in measuring the scope's risetime.

I occasionally wonder about buying a ballistic galvanometer "for old time's sake". Then I come to my senses and realise it would be a poor use of floorspace and my time.

[tggzzz]

is that true, 2% ?

That's standard for moving coil meters, unless you create a scale for each meter.

[VK5RC]

Martin. M  Those null meters are very difficult to use, around the null they approach terra ohms input impedance. The manual describes the check and set up protocols. Some have an early type of chopper amp using neons and plastic tubing - mine has had that replaced with the modification. Once it settles at a null, a warm breath on the connector pegs the meter to one side.
Use the set up tests to confirm that the chopper circuit is happy.
There is an AC version as well!

[beanflying]

ok. I have not understand how to adjust there the exactly reference voltage for a ± Diff.
My Oldie is there different in handling

(Attachment Link)

My 895A was around the corner  Still needs a little loving on the dials as they are a bit sticky.

[beanflying]

IMNSHO, 3d printers are like solderless breadboards. You spend as much time fettling as printing.

If your mode of thinking is like machining, i.e. adding and removing parameterised component shapes, then OpenSCAD is a good starting point. There are free standalone versions, and browser/web version.

This collet, one threaded, one not, took me a couple of hours to knock together.

  You have uttered this crap once to often and it just doesn't hold up with decent quality modern printers!

It is based on observation of the old and new printer at the local hackspace; the latter is a "Original Prusa i3 MK3".

The local "how to" manual lists many ways in which prints can go wrong and twiddles that can and must be made. It appears there is quite a lot of "suck it and see" involved, which I regard as fettling.

There may be fewer issues if only one person ever uses the machine with only one material, but since I use a variety of materials, I'm never going to own a machine. Hence any prints I make personally will have to be on that shared machine.

Used by non owners and the unwashed masses is not any basis for reality!

It is the basis for one valid version of reality. I accept you may live in a different, equally valid, version.

You have made this same sweeping generalization which doesn't apply to 90-95%+ of the one user printers based on this now explanation.

You are making equally sweeping generalisations for the 90-95% of people that use shared printers. (But it is a bit difficult to understand exactly what your sentence is trying to convey)

YOUR decision to only use a service to print items and never own a printer and I assume never use the shared one you have access to is YOUR option. It follows that then in no way make you a competent or practiced user of a well setup 3D printer and reading some 'manual' doesn't make you practiced or more competent in your use of one.

A well setup printer with a tweaked profile or two makes it a walk up insert card and print not the fiddle you keep go on with. Your version of your truth has no basis in fact with modern printers and the truth but you tried to justify it with a narrow case of a shared one as evidence that is likely poorly maintained caked with crud in the nozzle etc.

So stop attempting to be both an expert at setting up and using a printer when you apparently have little to no experience in doing so while dumping on personal ownership and use of one.

It is clear that I don't own one (and therefore have not twiddled configs); until very recently the only one I had access to was a joke suitable only for demonstrating principle. Hence I have made zero pretence to be an expert, and I resent your false statement to that effect.

However, your phrase "A well setup printer with a tweaked profile or two" reveals that fettling is indeed required. The next question is how much fettling? There I have to rely on watching experienced users of the local machine, and the amount of fettling the have to do to ensure it makes acceptable prints - and it is non-trivial. I have also seen many anecdotes to the effect that users of other machines do recognise that fettling is an issue.

I'm happy that you have found a printer that is suitable for your purposes. It could never be useful for my purposes, since I have found it necessary to use four radically different materials: brass, PLA, nylon, SLA.

Now, while I dearly like my vintage scopes and use them daily, I wouldn't recommend them to an infrequent user that doesn't want to spend time keeping them working - because too much fettling time is required. Similar considerations apply to 3d printer.

YMMV, of course. And that's just fine.

I resent that you claiming much if any knowledge of the process of driving one. YOU clearly made an OVERSTATED and  claim "You spend as much time fettling as printing."

As such I called it for what it is 

With the profiles on my printers it is TRIVIAL to tweak them if needed for a given print or material and noy 'fettling'. Get some actual hands on experience and stop trying to defend your lack of it!

[tggzzz]

IMNSHO, 3d printers are like solderless breadboards. You spend as much time fettling as printing.

If your mode of thinking is like machining, i.e. adding and removing parameterised component shapes, then OpenSCAD is a good starting point. There are free standalone versions, and browser/web version.

This collet, one threaded, one not, took me a couple of hours to knock together.

  You have uttered this crap once to often and it just doesn't hold up with decent quality modern printers!

It is based on observation of the old and new printer at the local hackspace; the latter is a "Original Prusa i3 MK3".

The local "how to" manual lists many ways in which prints can go wrong and twiddles that can and must be made. It appears there is quite a lot of "suck it and see" involved, which I regard as fettling.

There may be fewer issues if only one person ever uses the machine with only one material, but since I use a variety of materials, I'm never going to own a machine. Hence any prints I make personally will have to be on that shared machine.

Used by non owners and the unwashed masses is not any basis for reality!

It is the basis for one valid version of reality. I accept you may live in a different, equally valid, version.

You have made this same sweeping generalization which doesn't apply to 90-95%+ of the one user printers based on this now explanation.

You are making equally sweeping generalisations for the 90-95% of people that use shared printers. (But it is a bit difficult to understand exactly what your sentence is trying to convey)

YOUR decision to only use a service to print items and never own a printer and I assume never use the shared one you have access to is YOUR option. It follows that then in no way make you a competent or practiced user of a well setup 3D printer and reading some 'manual' doesn't make you practiced or more competent in your use of one.

A well setup printer with a tweaked profile or two makes it a walk up insert card and print not the fiddle you keep go on with. Your version of your truth has no basis in fact with modern printers and the truth but you tried to justify it with a narrow case of a shared one as evidence that is likely poorly maintained caked with crud in the nozzle etc.

So stop attempting to be both an expert at setting up and using a printer when you apparently have little to no experience in doing so while dumping on personal ownership and use of one.

It is clear that I don't own one (and therefore have not twiddled configs); until very recently the only one I had access to was a joke suitable only for demonstrating principle. Hence I have made zero pretence to be an expert, and I resent your false statement to that effect.

However, your phrase "A well setup printer with a tweaked profile or two" reveals that fettling is indeed required. The next question is how much fettling? There I have to rely on watching experienced users of the local machine, and the amount of fettling the have to do to ensure it makes acceptable prints - and it is non-trivial. I have also seen many anecdotes to the effect that users of other machines do recognise that fettling is an issue.

I'm happy that you have found a printer that is suitable for your purposes. It could never be useful for my purposes, since I have found it necessary to use four radically different materials: brass, PLA, nylon, SLA.

Now, while I dearly like my vintage scopes and use them daily, I wouldn't recommend them to an infrequent user that doesn't want to spend time keeping them working - because too much fettling time is required. Similar considerations apply to 3d printer.

YMMV, of course. And that's just fine.

I resent that you claiming much if any knowledge of the process of driving one. YOU clearly made an OVERSTATED and  claim "You spend as much time fettling as printing."

As such I called it for what it is 

With the profiles on my printers it is TRIVIAL to tweak them if needed for a given print or material and noy 'fettling'. Get some actual hands on experience and stop trying to defend your lack of it!

At this point it is best if I channel HAL.