DSO Reliability

[David Hess]

with modern designs moving more and more towards very advanced SMPS, and ditching the traditional LDO and linear regulators, it's very hard to gain insight from an analog scope these days.  Scopes have sort of transcended their traditional uses and limitations.

What did you have in mind?  Analog oscilloscopes work fine for measuring various switching and recovery waveforms, checking transient response, and measuring RMS and peak to peak noise.  DSOs can do these things as well except maybe for RMS noise.  DSOs are exceedingly useful for measuring startup and shutdown behavior where a pretrigger record is needed; this can be done on an analog oscilloscope but it is much easier on a DSO and is one of the more common things I use DSOs for.  DSOs are also better when waveform math is needed to measure quantities like power although I have done this with difficulty on analog oscilloscopes.

I don't think there is any real compromise in quality in Rigol PSU's.  They are as good as anything out there.

I doubt they compromise either although they did have a recent problem with their DP832 power supplies.  If their power supplies are just as good as everybody else's though, this could be damning with faint praise if everything else out there is designed as I described.

On the front of reliability, an older scope is going to be impossible to repair (in some situations).  The only reason I can see for using anything (other than a good modern DSO/MSO) is for characterizing noise in highly critical power supplies.

I would consider any modern DSO to be an Apple like product after the warranty expires.  If it breaks in a significant way except maybe for dried out aluminum electrolytic capacitors, then throw it away and buy a new one.

At least the older oscilloscopes have detailed service documentation which gives you a fighting chance at repairing them.  Of course that would not help at all if one has to deal with complex parts using surface mount construction.  On old oscilloscopes it is very difficult to repair hybrids although some people do it.

In a production environment, I just don't see how it's possible to spend the time to maintain old dinosaurs.

This is usually going to be the case with specific exceptions like when new instruments are not available which have old capabilities.  If this happens then at some point the production process needs to be changed to accommodate new test equipment.

This is probably how I got my sampling oscilloscope in such good condition.  Apparently it sat in a closet for 10+ years because nobody could figure out its simple failure or wanted to pay to have it repaired and was considered too expensive to throw away even if it was useless.

[nctnico]

At least the older oscilloscopes have detailed service documentation which gives you a fighting chance at repairing them.  Of course that would not help at all if one has to deal with complex parts using surface mount construction.  On old oscilloscopes it is very difficult to repair hybrids although some people do it.

The low end analog scopes may be easy to repair but the higher end ones (even from the early 70's) are filled with obsolete / proprietary chips and transistors. OTOH it is very easy to work on surface mount components with a simple hot-air station. If I look at the teardowns of Chinese equipment you often find commercially available chips. Replacing the ADC on a Tektronix TDS500 series is a no go because it is a proprietary part. On a Rigol oscilloscope you can buy a new one and just solder it in.

[TunerSandwich]

What did you have in mind?  Analog oscilloscopes work fine for measuring various switching and recovery waveforms, checking transient response, and measuring RMS and peak to peak noise.  DSOs can do these things as well except maybe for RMS noise.  DSOs are exceedingly useful for measuring startup and shutdown behavior where a pretrigger record is needed; this can be done on an analog oscilloscope but it is much easier on a DSO and is one of the more common things I use DSOs for.  DSOs are also better when waveform math is needed to measure quantities like power although I have done this with difficulty on analog oscilloscopes.


I doubt they compromise either although they did have a recent problem with their DP832 power supplies.  If their power supplies are just as good as everybody else's though, this could be damning with faint praise if everything else out there is designed as I described.


I would consider any modern DSO to be an Apple like product after the warranty expires.  If it breaks in a significant way except maybe for dried out aluminum electrolytic capacitors, then throw it away and buy a new one.

At least the older oscilloscopes have detailed service documentation which gives you a fighting chance at repairing them.  Of course that would not help at all if one has to deal with complex parts using surface mount construction.  On old oscilloscopes it is very difficult to repair hybrids although some people do it.


This is usually going to be the case with specific exceptions like when new instruments are not available which have old capabilities.  If this happens then at some point the production process needs to be changed to accommodate new test equipment.

This is probably how I got my sampling oscilloscope in such good condition.  Apparently it sat in a closet for 10+ years because nobody could figure out its simple failure or wanted to pay to have it repaired and was considered too expensive to throw away even if it was useless.

This was kind of my point about modern SMPS.  Very often we are employing controllers for tracking and interleaving and other real-time data intensive control and monitoring.  Not being able to grab time correlated metrics on an analog unit, and do pass fail masking throws the analog beasts under the bus.  Although I do still employ my old Tek and a differential pre-amp/probes for characterizing overall noise.  That is something I highly doubt DSO's will ever replace.  When the Tek finally dies and can't be obtained (in another decade or so) then we will have a real problem.  Again a lot of the issue comes from the current pace we are required to work at.  Our development and implementation life spans have gone from years to months.  This is where the analog beasts just can't meet demands.  Like I said, I certainly don't like this trend, but it's reality.  I miss pen and paper and the good ole' applied physics routine.  In this day and age though, there is more math to be done in a modern power delivery system, than one could hope to do in their lifetime.  Having the ability to track results in realtime and capture/log and then disassemble is paramount.  Almost impossible to innovate in small form factor SoC designs, because of cost.  Equally impossible to use discreet components, because of cost to consumer and overall thermal/size constraints.  Modern DSO's, IMO, have added to this insane pace.  Like I said I don't like it, but it is reality....a sad one....but none the less....

Again on the issue of disposable gear....I fully agree.  It does however mirror the consumer marketplace.  People don't bother to repair their computers or cars anymore....throw it away and buy another.  It's appalling, but once again....reality 

here is an example of a topology, where an analog scope simply won't do the necessary functions to complete the design, in a timely way....this general topology is the standard in any modern system....with half way decent power management

[David Hess]

At least the older oscilloscopes have detailed service documentation which gives you a fighting chance at repairing them.  Of course that would not help at all if one has to deal with complex parts using surface mount construction.  On old oscilloscopes it is very difficult to repair hybrids although some people do it.

The low end analog scopes may be easy to repair but the higher end ones (even from the early 70's) are filled with obsolete / proprietary chips and transistors.

I think people make too big a deal about this although there are exceptions.  I have several of these oscilloscopes and the custom ICs and hybrids are the most reliable part.  The exceptions are known and besides some tunnel diodes, transformers, and those stupid Mostek mask ROMS include the later 2465 series oscilloscopes which use parts like the z-axis and horizontal amplifiers which came from Maxim after Tektronix sold them their semiconductor processing division although there were some dodgy aspects to the 2465 design which I believe contributed to the problem.

OTOH it is very easy to work on surface mount components with a simple hot-air station. If I look at the teardowns of Chinese equipment you often find commercially available chips. Replacing the ADC on a Tektronix TDS500 series is a no go because it is a proprietary part. On a Rigol oscilloscope you can buy a new one and just solder it in.

I will have to defer to you on this since I have not had to work with BGA and leadless parts.  I miss PLCCs.

[G0HZU]

One aspect of scope design that is common to both types is the ruggedness of the user interface. Back in the 1960s and 70s the designers knew that a scope would see a lot of use and the switches and controls were big and solid and well engineered.

But over time this has changed. I'd certainly question how long the buttons and controls will last on a modern scope and how well it would survive a drop. Maybe they will be very reliable but back in the 1980s a lot of test gear proved very fragile and unreliable in this respect. Especially from HP.

I expect the modern design driver for a low cost DSO is to make something that is rugged enough to last for a few years' regular use before it gets upgraded. A bit like a laptop PC.

[David Hess]

This was kind of my point about modern SMPS.  Very often we are employing controllers for tracking and interleaving and other real-time data intensive control and monitoring.  Not being able to grab time correlated metrics on an analog unit, and do pass fail masking throws the analog beasts under the bus.

...

here is an example of a topology, where an analog scope simply won't do the necessary functions to complete the design, in a timely way....this general topology is the standard in any modern system....with half way decent power management

If I was doing development work involving digital power management controllers like the DM7332, then I would expect to be using a modern high end DSO as well like a Tektronix MSO2000 or MSO3000. 

Is it my imagination or is the MSO3000 series discontinued with the MDO3000 replacing them?  I guess I would settle for one of them.

[TunerSandwich]

One aspect of scope design that is common to both types is the ruggedness of the user interface. Back in the 1960s and 70s the designers knew that a scope would see a lot of use and the switches and controls were big and solid and well engineered.

But over time this has changed. I'd certainly question how long the buttons and controls will last on a modern scope and how well it would survive a drop. Maybe they will be very reliable but back in the 1980s a lot of test gear proved very fragile and unreliable in this respect. Especially from HP.

I expect the modern design driver for a low cost DSO is to make something that is rugged enough to last for a few years' regular use before it gets upgraded. A bit like a laptop PC.

.....BUT you are replacing things like resistive switching networks, and carnhill style switches (which all have contact wear and decay over time) with rotary encoders....I imagine the modern rotary encoder will FAR outlast old, clunking, switches and trimmers....they certainly don't feel as good though....in a perfect world carnhill dual concentric and chicken head knobs would be fun, but the world is so far from perfect.....

[TunerSandwich]

This was kind of my point about modern SMPS.  Very often we are employing controllers for tracking and interleaving and other real-time data intensive control and monitoring.  Not being able to grab time correlated metrics on an analog unit, and do pass fail masking throws the analog beasts under the bus.

...

here is an example of a topology, where an analog scope simply won't do the necessary functions to complete the design, in a timely way....this general topology is the standard in any modern system....with half way decent power management

If I was doing development work involving digital power management controllers like the DM7332, then I would expect to be using a modern high end DSO as well like a Tektronix MSO2000 or MSO3000. 

Is it my imagination or is the MSO3000 series discontinued with the MDO3000 replacing them?  I guess I would settle for one of them.

with electronics entering daily use items, at an ever increasing and feverish pace....I don't think we will see anything less than power management and highly advanced SMPS designs.....we are all eventually (regardless of discipline) going to have to come to terms with the modern design pace and constraints.....

in another decade I think the only use of the analog scopes will be for nostalgia and characterizing the most basic of properties....I don't like that idea and I will miss the smells of old electronics....it is however a fast emerging scenario

MDO's and vast time correlated domain analysis will be required, for even the simplest of competitive designs....in this day and age we need to see power, spectral, data all at the same time and fully "deskewed"....I think the modern engineer, has become more of an equipment operator and less of a thinker.....it seems the trend is to just cobble together existing technology.....stack bloat on bloat and package it.....I don't like it

At the same time it is fun to lust after an age gone by.....I do miss that smell

[G0HZU]

One aspect of scope design that is common to both types is the ruggedness of the user interface. Back in the 1960s and 70s the designers knew that a scope would see a lot of use and the switches and controls were big and solid and well engineered.

But over time this has changed. I'd certainly question how long the buttons and controls will last on a modern scope and how well it would survive a drop. Maybe they will be very reliable but back in the 1980s a lot of test gear proved very fragile and unreliable in this respect. Especially from HP.

I expect the modern design driver for a low cost DSO is to make something that is rugged enough to last for a few years' regular use before it gets upgraded. A bit like a laptop PC.

.....BUT you are replacing things like resistive switching networks, and carnhill style switches (which all have contact wear and decay over time) with rotary encoders....I imagine the modern rotary encoder will FAR outlast old, clunking, switches and trimmers....they certainly don't feel as good though....in a perfect world carnhill dual concentric and chicken head knobs would be fun, but the world is so far from perfect.....

I was also considering the quality of the push switches. I don't know what technology is used in modern chinese DSOs but there's plenty of HP and Marconi/IFR test gear out there that use lightweight (membrane?) switches that don't withstand much in the way of heavy use before they become intermittent.
Hopefully lessons have been learned and the switches on modern gear will be more rugged.

[TunerSandwich]

One aspect of scope design that is common to both types is the ruggedness of the user interface. Back in the 1960s and 70s the designers knew that a scope would see a lot of use and the switches and controls were big and solid and well engineered.

But over time this has changed. I'd certainly question how long the buttons and controls will last on a modern scope and how well it would survive a drop. Maybe they will be very reliable but back in the 1980s a lot of test gear proved very fragile and unreliable in this respect. Especially from HP.

I expect the modern design driver for a low cost DSO is to make something that is rugged enough to last for a few years' regular use before it gets upgraded. A bit like a laptop PC.

.....BUT you are replacing things like resistive switching networks, and carnhill style switches (which all have contact wear and decay over time) with rotary encoders....I imagine the modern rotary encoder will FAR outlast old, clunking, switches and trimmers....they certainly don't feel as good though....in a perfect world carnhill dual concentric and chicken head knobs would be fun, but the world is so far from perfect.....

I was also considering the quality of the push switches. I don't know what technology is used in modern chinese DSOs but there's plenty of HP and Marconi/IFR test gear out there that use lightweight (membrane?) switches that don't withstand much in the way of heavy use before they become intermittent.
Hopefully lessons have been learned and the switches on modern gear will be more rugged.

considering the infancy of development of encoders and tactile switches in prior decades, I think we have overcome those potential issues.  modern tactile domes have astounding cycle ratings.....I think they will far outlast old contact closure style and mechanical style devices.....fingers crossed on that though.....reworking a modern surface mount switch sounds like a real nightmare.  I suppose it's a double edged sword.  The older stuff was very easy to service and replace.....I can't imagine arcing/zapping a modern capacitive node and having any luck repairing it....

I think the list of good will easily exceed the list of bad....especially in the coming years.....also with advancements in 3dprinting and small cnc systems, it might even be possible in the coming years to completely replace surface mount and imbedded devices on demand. 

If you look at the pace of advancement in the current age, it vastly exceeds the pace of decades gone by.  Moores law will assure us that our "modern" DSO/MSO will be obsolete and useless for design, before anything breaks    (on a side note as long as the gear does what it does and fits the need, it can always be re-purposed for end of line QC/QA). 

[coppice]

One aspect of scope design that is common to both types is the ruggedness of the user interface. Back in the 1960s and 70s the designers knew that a scope would see a lot of use and the switches and controls were big and solid and well engineered.

This is looking at the past through rose tinted glasses. Much of the older high end equipment was notorious for crazy user interface design, where huge amounts were spent crafting highly customised actuators, putting many functions on a single spindle, while the actual switches being actuated were the cheapest and nastiest garbage around. The Tektronix 7000 scopes were probably the worst offenders. Their elaborate actutators pushed the nastiest of slide switches from cheap transistor radios, which were regularly ripped off the board by normal use. Many an engineer or technician has spent an afternoon going through every 7000 series plugin in the building, trying to find a set of amps and timebase which were actually usable, and sending a large stack away to have the switches repaired. Frequently they'd end up breaking the calibration seals, and fixing the switches themselves, just to have something to work with.

[G0HZU]

This is looking at the past through rose tinted glasses.

Maybe, but my old Tek 585 from the 1960s has some pretty big and solid switches and controls on it. The 465 is reasonably rugged too.

Much of the older high end equipment was notorious for crazy user interface design

I certainly agree in the case of the 7000 series One look at a 7000 series scope is enough for me to walk away. The 7000 series gives plenty of its admirers a hard on but I just see a crap and fussy user interface with dinky controls that would seriously piss me off each time I used it

[coppice]

My old Tek 585 from the 1960s has some pretty big and solid switches and controls on it. The 465 is reasonably rugged too.

The 465 was a real solid workhorse. Tektronix's budget Telequipment range also had solid controls. It seems like the more expensive the model, the flakier its controls.

[TunerSandwich]

The 465 was a real solid workhorse. Tektronix's budget Telequipment range also had solid controls. It seems like the more expensive the model, the flakier its controls.
[/quote]

complex problems = complex solutions

that formula also works in reverse 

[coppice]

The 465 was a real solid workhorse. Tektronix's budget Telequipment range also had solid controls. It seems like the more expensive the model, the flakier its controls.

complex problems = complex solutions

that formula also works in reverse 

So, you think its appropriate to put the cheapest and crappiest components into the most complex and expensive equipment?

[David Hess]

The Tektronix 7000 scopes were probably the worst offenders. Their elaborate actutators pushed the nastiest of slide switches from cheap transistor radios, which were regularly ripped off the board by normal use. Many an engineer or technician has spent an afternoon going through every 7000 series plugin in the building, trying to find a set of amps and timebase which were actually usable, and sending a large stack away to have the switches repaired. Frequently they'd end up breaking the calibration seals, and fixing the switches themselves, just to have something to work with.

I have very rarely had any problems with any of the 7000 switches although the potentiometers usually need cleaning.  I have one plug-in from 1969 which required an easy switch rebuild and one other where the slope switch is intermittent but not annoying enough to pull apart and fix.

Much of the older high end equipment was notorious for crazy user interface design

I certainly agree in the case of the 7000 series One look at a 7000 series scope is enough for me to walk away. The 7000 series gives plenty of its admirers a hard on but I just see a crap and fussy user interface with dinky controls that would seriously piss me off each time I used it

I agree they are complicated but that comes from supporting so many sweep and trigger configurations and how many oscilloscopes support independent chopped or alternated triggered sweeps?  I keep hoping to find a DSO which does short of using two separate ones.

[coppice]

The Tektronix 7000 scopes were probably the worst offenders. Their elaborate actutators pushed the nastiest of slide switches from cheap transistor radios, which were regularly ripped off the board by normal use. Many an engineer or technician has spent an afternoon going through every 7000 series plugin in the building, trying to find a set of amps and timebase which were actually usable, and sending a large stack away to have the switches repaired. Frequently they'd end up breaking the calibration seals, and fixing the switches themselves, just to have something to work with.

I have very rarely had any problems with any of the 7000 switches although the potentiometers usually need cleaning.  I have one plug-in from 1969 which required an easy switch rebuild and one other where the slope switch is intermittent but not annoying enough to pull apart and fix.

Maybe only the tougher examples have even survived until now. 
The last time I used a 7000 series was in the early 80s. Things like the pots hadn't started to give trouble at that stage. The problems were mostly broken 1 cent switches on 10 dollar hand turned actuator shafts.

[David Hess]

Maybe only the tougher examples have even survived until now. 

I included this thought in my post but edited it out.

The last time I used a 7000 series was in the early 80s. Things like the pots hadn't started to give trouble at that stage. The problems were mostly broken 1 cent switches on 10 dollar hand turned actuator shafts.

I have gotten good at rebuilding the mechanical aspects.  None of my 7000 series have suffered major electronic faults so I am missing out on that fun.  I have a couple of power supplies which need to be refurbished including replacement of their aluminum electrolytic capacitors.  They still work but occasionally restart.

Not counting sampling plug-ins, these are my fastest oscilloscopes with a current bandwidth of 350 MHz which would be 400 or 500 MHz if I picked up a different set of vertical amplifier plug-ins.  Considering how much it would cost me to duplicate this with a new oscilloscope, they were a bargain.

[TunerSandwich]

The 465 was a real solid workhorse. Tektronix's budget Telequipment range also had solid controls. It seems like the more expensive the model, the flakier its controls.

complex problems = complex solutions

that formula also works in reverse 

So, you think its appropriate to put the cheapest and crappiest components into the most complex and expensive equipment?

complex solutions = complex problems 

which is why I said that formula works forwards or in reverse.....

[AndyC_772]

I'm talking about your standard benchtop 100MHz or so DSO not $12k 500MHz equipment.

Compare equal bandwidths and the price difference isn't quite so great; a DSO-X3014A is £2600, and a Rigol DS4014 is £1700. Not quite such a big jump.

I guess to some extent it comes down to your idea of a 'standard' bench scope. Rigol and other Far Eastern manufacturers have created a whole new market for scopes that offer tremendous capability at a consumer price point, which I couldn't have dreamed about when I was learning electronics and doing it as a hobby. But they're not really up to the job of being an 'every day' scope in a working laboratory, not because of their spec sheets, but because they don't have the ease of use and reliability necessary. The tools themselves must never distract from the task in hand, and that's really hard to achieve, and worth paying for IMHO.

I should add that I've seriously considered buying a DS1054Z... fantastic capability for less than the price of a new phone. Madness.

[rf-loop]

  None of my 7000 series have suffered major electronic faults so I am missing out on that fun.

I have 3 nice (and some basic) Tek 7000 series mainframes and of course some plug ins. Years after years these works. (im happy I have not get these units what some "service" workers have destroyed with wrong service methods)

These mainframes are (old) oscilloscopes "Rolls-Royces". (and when they was new, price label was "nice")


7854 with waveform calculator keyboard and 1k waveform memory (ana/digi from beginning of 80's )

7834 ("fast" storage) but still perhaps HP1727A storage writing speed is better.

7844 real dual beam scope (tube have two independed electron beams)

No failures. (exept one fan need perhaps oil)

[coppice]

I guess to some extent it comes down to your idea of a 'standard' bench scope. Rigol and other Far Eastern manufacturers have created a whole new market for scopes that offer tremendous capability at a consumer price point, which I couldn't have dreamed about when I was learning electronics and doing it as a hobby. But they're not really up to the job of being an 'every day' scope in a working laboratory, not because of their spec sheets, but because they don't have the ease of use and reliability necessary.

I've been using low end Chinese DSOs as everyday scopes for professional work for years. I can't remember one ever failing, and I only rarely need to reach for a high end scope because the cheap one isn't up to the job. Most lab work is really pretty undemanding of an oscilloscope, unless you are in one of a few niche activities. Most really serious work is done with more specialised tools, like spectrum analysers or precision measuring instruments.

[coppice]

7834 ("fast" storage) but still perhaps HP1727A storage writing speed is better.

When those things were in their prime the failure rate of the storage tubes was horrible. The HP storage tubes worked a lot better than the Tektronix ones, but they were just as bad for early failures. Warranty on a new scope in those days was 90 days, and Tek and HP replaced a lot of tubes under warranty. If a tube lasted through warranty it tended to go on for quite a while, unless the user insisted on always turning up the brightness to full. Failures outside warranty were really bad news, as a new tube was a large part of the price of a new scope. However, it seemed like if you got a good sample of tube it went on and on working nicely. Maybe all the machines still in existence have those golden samples of tube in them.

The large Tektronix storage tubes, which were the mainstay of the early CAD industry, had a far more predictable life, but it wasn't that long. A well used terminal needed a new tube in less than 2 years.

[David Hess]

When those things were in their prime the failure rate of the storage tubes was horrible. The HP storage tubes worked a lot better than the Tektronix ones, but they were just as bad for early failures. Warranty on a new scope in those days was 90 days, and Tek and HP replaced a lot of tubes under warranty. If a tube lasted through warranty it tended to go on for quite a while, unless the user insisted on always turning up the brightness to full. Failures outside warranty were really bad news, as a new tube was a large part of the price of a new scope. However, it seemed like if you got a good sample of tube it went on and on working nicely. Maybe all the machines still in existence have those golden samples of tube in them.

I have never understood the bistable storage mode on the 7834.  It works but the contrast is so low that it is very easy to turn the intensity up and burn the phosphor.  Was this part of the high tube replacement rate?

A fair number of 7834s discussed on the TekScopes@yahoogroups.com email list had their high voltage transformers fail.  One of mine has a geometry problem with the CRT which I suspect was caused by UPS dropping it.

I would never recommend the 7854 to anybody unless they had a very specific need because its complexity leads to complex failures.

All of the things I might use a dual beam 7844 for are covered by DSOs so I have never felt the need to acquire one.

I mostly use a 100 MHz 7603 for its large screen but increasingly like the faster mainframes because their CRTs are incredibly bright and sharp.

Despite their flaws I still recommend the current crop of low cost graded intensity graded DSOs when asked for general purpose work as long as their feature set include peak detection.

[coppice]

I have never understood the bistable storage mode on the 7834.  It works but the contrast is so low that it is very easy to turn the intensity up and burn the phosphor.  Was this part of the high tube replacement rate?

What is there to understand? If you want to catch a rare event, the practical solutions were to leave one of these scopes in bistable mode, or leave a polaroid camera in front of a conventional scope until the event occured. Most scopes wouldn't let you exclude light well enough for the polaroid approach to be very effective, so a storage tube in bistable mode was the key option. Turning the brightness to maximum certainly increases the wear and tear a lot, but I don't think it contributes to complete failures

A fair number of 7834s discussed on the TekScopes@yahoogroups.com email list had their high voltage transformers fail.  One of mine has a geometry problem with the CRT which I suspect was caused by UPS dropping it.

I think the storage tubes use a much higher voltage that normal scope tubes. Extra stress certainly doesn't help with long term reliability. I don't remember power supplies being a big issue when these scopes were young.

I would never recommend the 7854 to anybody unless they had a very specific need because its complexity leads to complex failures.

I wouldn't recommend an analogue storage scope to anyone for anything. Their time passed long ago.

All of the things I might use a dual beam 7844 for are covered by DSOs so I have never felt the need to acquire one.

I assume these are rare now, because they were rare in the 70s. Few people could justify the extra cost.

I mostly use a 100 MHz 7603 for its large screen but increasingly like the faster mainframes because their CRTs are incredibly bright and sharp.

Despite their flaws I still recommend the current crop of low cost graded intensity graded DSOs when asked for general purpose work as long as their feature set include peak detection.

That's the best choice for most people.