Test Equipment Anonymous (TEA) group therapy thread

[tggzzz]

Small difference; lowly DSO vs TOL professional CRO, fair comparison do you think ? 

That's only one comparison, and not a very enlightening one.

Another, arguably more useful, is to compare what you can get for a fixed price - in this case a couple of hundred pounds or so.

The last 4 CRO's I've acquired I got for nicks and my time like anyone else's need be factored into the real cost of getting a CRO and fixing it or keeping it going. ...

The "cost of your time" depends on the individual. Some are cash-rich time-poor, some are time-rich cash-poor.

The cost can also be negative, e.g. if repairing something allows you to learn something that is later valued by, say, a potential employer.

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

[Mr. Scram]

The "cost of your time" depends on the individual. Some are cash-rich time-poor, some are time-rich cash-poor.

The cost can also be negative, e.g. if repairing something allows you to learn something that is later valued by, say, a potential employer.

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

In what regard are CROs better and why aren't companies capitalizing on that?

[Specmaster]

The "cost of your time" depends on the individual. Some are cash-rich time-poor, some are time-rich cash-poor.

The cost can also be negative, e.g. if repairing something allows you to learn something that is later valued by, say, a potential employer.

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

In what regard are CROs better and why aren't companies capitalizing on that?

I don't think that anyone is claiming CROs are better, both CROs and DSOs have advantages over each other. Apart the obvious like the higher cost of a DSO over a 2nd hand CRO, and the size and weight differences, there are differences in the way that they work, screen size etc.

DSOs are good at capturing signals, storing them and allowing them to be displayed /examined in many ways which most CROs cannot. CROs in the main are live only devices with smaller screens and earlier ones do not have screen cursors and wealth of information they can provide unlike DSOs which all have them.

Fact is however that a CRO is more likely the way that beginners will be learning their scope manship on purely on the grounds of cost alone. What makes transistion to DSOs harder is that the interface is so vastly difference with many functions tucked away behind many levels of a menu system requiring multiple pushes of a button to reach.

Fact is that in reality a good electronics bench really needs both of them to accomplish different tasks.

I just wonder if the DSOs of today will still be around on say 20 let alone 40 like so many of the CROs are?

From mobile device so predictive text might have struck again [emoji83]

[Berni]

Im guessing they wont be around after 40 years. Most modern scopes keep there firmware in flash memory, it has a data retention life time. To make it even worse the modern flash is ever crappier as they are primarily optimizing it for more memory density rather than reliability.

We already seen this happen where the Keysight X2000 and X3000 scopes would fail to boot due to flash corruption. It was apparently a issue that the bootloader did not use ECC checks and eventually over time a bit got flipped inside the bootloader in a small number of these scopes, but in enough of them for Keysight to recognize it as a issue and offer free repair for them.

Its actually common practice for the last 15 years that NAND flash memory has ECC codes in it. This high density type of flash memory was known to be unreliable so ECC was introduced as a standard feature in NAND flash. Each page of memory page is slightly larger than a power of two number, the extra bytes being used to store a ECC code for the rest of the page. On each read operation the ECC code is checked by the flash controller and in the case of an error the code is used to correct the flipped bit and the corrected data is written back to the page to fix it before being checked again to make sure the fix worked. Additionally there is an area where even newly manufactured chips contain a table of bad pages, the table is meant to also be updated by the memory controller if it finds any new stuck bits. So as long as flash is constantly being used it does tend to self heal itself even if its being read from, but obviously as the specified data retention time comes closer and closer its going to start getting worse and worse until too many bits flip and the ECC code can't recover them anymore.

If this was not bad enough the smart engineers at memory manufacturers realized that you don't have to fill a flash memory cell up all the way, you could have various levels of "fullness". So if you store 4 different analog levels in a cell you can store 2 bits per cell, turning a 8GB chip into a 16GB one. This is called MLC flash and as you might imagine its even worse in terms of reliability as it takes less of a drift in the cell to flip a bit. Yet due to the density benefits this kind of flash is ever more popular.

So yes my MSO6000 scope will probably be dead in the year 2050 while your dual trace 20MHz Tek is still going.

There might be some hope for the MSO9000 scope. It has a PC inside of it so most of its firmware is on a hard drive. While the acquisition board is running all FPGAs that tend to have firmware stored in offboard low density NOR flash chips that are much more reliable. It won't be fun finding a replacement motherboard for it tho as anythyng made in 2050 will likely not be compatible, or i likely would not be able to install Windows 7 on it.

[bd139]

I don’t expect a DS1054Z to last more than about 3 years. Anything after that is a bonus.

Then again if we divide the initial cost including inflation of some of the analogue scopes over the lifespan, the rigol works out cheaper if you have to replace it every three years anyway. 7603 with two verticals and a delayed timebase wasn’t cheap! Over $18,000 in 2015 prices according to w140.com

[Specmaster]

That sucks the life out of the second hand market then

[med6753]

Some vintage pron. Tek 465 Vertical Board. It has to come out to diagnose and fix issues with the Channel 2 attenuator deck switch. According to bd139 it's not too bad to pull. In comparison to what? A root canal? Not sure what I'm facing but I'm going in. Not sure when or if I'll return. And of course this delicate surgery demands a good assortment of high quality tools. So full (careful) speed ahead.

[tggzzz]

The "cost of your time" depends on the individual. Some are cash-rich time-poor, some are time-rich cash-poor.

The cost can also be negative, e.g. if repairing something allows you to learn something that is later valued by, say, a potential employer.

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

In what regard are CROs better and why aren't companies capitalizing on that?

1) for relative advantages and disadvantages, see elsewhere - ad nauseam

2) cost of new equipment, plus the rapid advancement of fast ADCs over the last decade has made them practical, plus the problems of using CRTs with multi-GHz signals.

None of that affects the statement I made in any way.

[bd139]

That sucks the life out of the second hand market then

Second hand market is getting a bit weird anyway at the moment I've noticed. Prior to manf about 1990 there's plenty of kit. Between about 1990-2010 there's bugger all and then everything after that is way too expensive. I think a lot of people are renting then it gets disposed of. Our TF930s were a rare disposal leak.

Some vintage pron. Tek 465 Vertical Board. It has to come out to diagnose and fix issues with the Channel 2 attenuator deck switch. According to bd139 it's not too bad to pull. In comparison to what? A root canal? Not sure what I'm facing but I'm going in. Not sure when or if I'll return. And of course this delicate surgery demands a good assortment of high quality tools. So full (careful) speed ahead.

That's an early rev one. Same as mine. Most of the coax connectors just pull out, pot shafts disconnect etc. Only desoldering is the front end cap and possibly the delay line.

Compared to the D83 power supply transplant that's easy money

[tggzzz]

I just wonder if the DSOs of today will still be around on say 20 let alone 40 like so many of the CROs are?

The DSOs of 20/30 years ago should be jettisoned ASAP (except for sentimental reasons). They were grim compared with their contemporary CROs, but rapidly replaced  ASOs, which were even grimmer!

It is only in the past decade that ADCs (and DACs) have improved rapidly.

[bd139]

That might actually explain the gap in kit from 1990-2005

[tggzzz]

Some vintage pron. Tek 465 Vertical Board. It has to come out to diagnose and fix issues with the Channel 2 attenuator deck switch. According to bd139 it's not too bad to pull. In comparison to what? A root canal? Not sure what I'm facing but I'm going in. Not sure when or if I'll return. And of course this delicate surgery demands a good assortment of high quality tools. So full (careful) speed ahead.

... and it has a DM44 in the way as well. Oh joy.

Your most important tools are:

• patience
• paper, pencil, and a digital camera - to record what each stage looks like, and where connections/screws go, just before you destroy take it apart
• small ziplock bags, to keep the screws etc from each stage of disassembly
• the right manual

[bd139]

+ coffee

When dismantling stuff I label all wires with tags made from cut off paper address label. These stay on until it’s working again.

[tggzzz]

That might actually explain the gap in kit from 1990-2005

Don't take the times too literally; date/performance boundaries are always fuzzy and moving.

But one example: a high-end HP DSO (HP54100 introduced in 1986) was a two man lift, had 7-bit 40MS/s DACs, but a 1GHz bandwidth.

[med6753]

Some vintage pron. Tek 465 Vertical Board. It has to come out to diagnose and fix issues with the Channel 2 attenuator deck switch. According to bd139 it's not too bad to pull. In comparison to what? A root canal? Not sure what I'm facing but I'm going in. Not sure when or if I'll return. And of course this delicate surgery demands a good assortment of high quality tools. So full (careful) speed ahead.

... and it has a DM44 in the way as well. Oh joy.

Your most important tools are:

• patience
• paper, pencil, and a digital camera - to record what each stage looks like, and where connections/screws go, just before you destroy take it apart
• small ziplock bags, to keep the screws etc from each stage of disassembly
• the right manual

Taking a break. Slow and steady progress. Yep, the DM44 was in the way and had to come out. Lots of pictures. So far I've left all the coax towards the back in place. I want to get the board itself totally free first.

[nixiefreqq]

bill and daves last cro……….and why it stays on the bench.

although my 54502a is on the bench too...….and gets more everyday use.

[BravoV]

Folks, as I'm a noob when it comes to RF cable,  this should be decent right ?

Just bought 50 meters of RG8 equivalent, coaxial for my GPSDO antenna, Leoni brand.

[BravoV]

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

Well, I'm also get irritated by people who always suggesting a 1st time scope buyer that they already admitted they're practically a beginner, to buy an used analog scope, even already stated they can afford the budget for a "new" entry DSO.

[Specmaster]

Well the point is that if you can get a working CRO for a few quids, then thats the way to learn surely and then if they ultimately fuck it up, its just a few quid down the drain rather a few hundred. Better to make your noob mistakes on a cheap piece of equipment rather than making those mistakes become expensive ones. Once your relatively with an old CRO, upgrade to a DSO entry level one or maybe slightly better when you have a better appreciation of what they are and how to use them correctly.

[bd139]

Folks, as I'm a noob when it comes to RF cable,  this should be decent right ?

Just bought 50 meters of RG8 equivalent, coaxial for my GPSDO antenna, Leoni brand.

Should be fine. RG8 is usually specified up to about 2.2GHz. It will have loss and this is significant at 1.5GHz so keep the run as short as possible. Sod terminating RG8 like that on anything other than N/PL259 though. I’d probably have used RG174 and lost a few dB to be lazy

While I advise beginners against trying to repair scopes, I get irritated by people that claim that only DSOs should be considered and/or that DSOs are better in all respects. Neither is true.

Well, I'm also get irritated by people who always suggesting a 1st time scope buyer that they already admitted they're practically a beginner, to buy an used analog scope, even already stated they can afford the budget for a "new" entry DSO.

I’d go as far to say that as a beginner you are doing yourself an ill if you don’t have something known in hand. Known usually means new.

Well the point is that if you can get a working CRO for a few quids, then thats the way to learn surely and then if they ultimately fuck it up, its just a few quid down the drain rather a few hundred. Better to make your noob mistakes on a cheap piece of equipment rather than making those mistakes become expensive ones. Once your relatively with an old CRO, upgrade to a DSO entry level one or maybe slightly better when you have a better appreciation of what they are and how to use them correctly.

Only if you know it works. Most of the scopes I’ve sold so far have gone to beginners who want something that works correctly and has some after care. It’s quite difficult to find a trustworthy analogue scope.

[BravoV]

Well the point is that if you can get a working CRO for a few quids, then thats the way to learn surely and then if they ultimately fuck it up, its just a few quid down the drain rather a few hundred. Better to make your noob mistakes on a cheap piece of equipment rather than making those mistakes become expensive ones. Once your relatively with an old CRO, upgrade to a DSO entry level one or maybe slightly better when you have a better appreciation of what they are and how to use them correctly.

The reason is always they're dirt cheap ... yeah , but you will have to wait, lurk, stalk for good deal, maybe days, weeks or even months.

Also ALWAYS judging that every beginners will 100% and definitely screwed & toasted their 1st scope, and better buy cheap sacrificial one is not a strong argument, c'mon, you have to admit this one is pretty weak.

[Specmaster]

Only if you know it works. Most of the scopes I’ve sold so far have gone to beginners who want something that works correctly and has some after care. It’s quite difficult to find a trustworthy analogue scope.

Same here, most experienced and more involved users would want something a bit better than what I'd call a beginners scope, in fact I'm on the point of selling one of mine to a beginner now and it has the good attributes for a beginner even if it should fail, its still available to buy new so spares are available and it has a linear power supply so its easier to repair. 

I'm already eyeing up a replacement for it, Philips 33xx series.

[BravoV]

Folks, as I'm a noob when it comes to RF cable,  this should be decent right ?

Just bought 50 meters of RG8 equivalent, coaxial for my GPSDO antenna, Leoni brand.

Should be fine. RG8 is usually specified up to about 2.2GHz. It will have loss and this is significant at 1.5GHz so keep the run as short as possible. Sod terminating RG8 like that on anything other than N/PL259 though. I’d probably have used RG174 and lost a few dB to be lazy

Thanks, according to the datasheet, at GPS L1 freq return loss is about 20 dB, and with attenuation max at GPS frequency is 20dB/100 meter, my installation probably only needs about 30 meters or maybe less.

Also the antenna LNA gain is about 40 dB for the GPS signal.

[med6753]

I've worked on this for several hours and I find myself getting a little aggravated so it's time to stop and pick up on it later. I had to pull the DM44 to get it out of the way. The Vertical Board itself is free in the back and I'm slowly working towards the front. I will be pulling and labeling all the coax. And there's at least two other wires that will have to be unsoldered in addition to the delay line. On the front panel I have everything pulled except the shaft for the Channel 2 variable pot. The allen key isn't long enough to reach down to the set screw so I'll have to be real careful when I pull the board out so as to not break that shaft. I have a few questions....

Do the BNC's pull WITH the board or will I have to unsolder them?

I assume the Vertical Mode switch board behind this board pull as one unit, correct?

Right now I think it's 50/50 that I'll ever get this back together in one piece. But I'm not giving up.

[Specmaster]

Well the point is that if you can get a working CRO for a few quids, then thats the way to learn surely and then if they ultimately fuck it up, its just a few quid down the drain rather a few hundred. Better to make your noob mistakes on a cheap piece of equipment rather than making those mistakes become expensive ones. Once your relatively with an old CRO, upgrade to a DSO entry level one or maybe slightly better when you have a better appreciation of what they are and how to use them correctly.

The reason is always they're dirt cheap ... yeah , but you will have to wait, lurk, stalk for good deal, maybe days, weeks or even months.

Also ALWAYS judging that every beginners will 100% and definitely screwed & toasted their 1st scope, and better buy cheap sacrificial one is not a strong argument, c'mon, you have to admit this one is pretty weak.

Totally disagree, its not a weak argument, so your saying that Dave's advice is also flawed in the same way, he has done a series of scope videos showing how to connect them without blowing the arse out of them which is a typically a thing a beginner might do. I'm not saying that someone a bit more experienced wouldn't to, hell we can all screw up from time to time.

I liken it to just passing your driving test and we all know that does not mean that your a safe driver at all, just means that on the day you reached the required standard for a pass. Once passed would rush off out and secure your that Aston Martin DB8 and probably kill yourself (assuming an insurance company would take you on with such little experience, or buy something more suitable first to gain experience and demonstrate to everyone that you can actually handle a car correctly and not be a hazard to others? That's probably not the best example but you should see the logic in it.

Clearly it would be nonsensical to suggest to somelike bd139 to buy themselves a cheap CRO first when he clearly understands what he is doing, although he has been known to blow things up occasionally