Confusing, Stupid,  And Wrong Equipment Manual Entries - Post Yours Here - Page 1
Forum section: electronics / general

author: SgtRock
author_rank: Unknown
timestamp: February 18, 2012, 12:48:27 am
content: Greetings EEVBees:--King.oslo's post (see below) about reading the accuracy specs in a manual for and LCR meter, put me in mind of some of the really stupid things that have been written in DMM User Manuals. So I decided to start a new thread where people can post pictures of stupid things written in User Manuals.https://www.eevblog.com/forum/general-chat/question-about-a-datasheet/?topicseen--It seems clear to me that these DMM companies (no matter how mighty), at the last minute, always find the stupidest miserable pud knocker on the premises to write the user manual in a dashed hurry, preferably someone whose first language is not the one they are writing in. Case in point; the Fluke 87 User Manual which you can download today from their site. I submit for your perusal. See picture below as well as link where you may download the Fluke 87 PDF Manual.http://assets.fluke.com/manuals/87______umeng0800.pdf--Arrrrg!! Where do I begin? Lets take the first line of text, which I quote:"Accuracy is given as±([% of reading] +  + [number of lease significant digits])..."--This is complete gibberish. Newton, Einstein and Feynman could not compute this. Also notice the spelling of "least". The writer should have said:"Accuracy is given as ±([% of reading] + [specified number of counts])--Reading down to about the middle, and I quote:" ** Below 10% of range, add 16 counts.*** Below 10% of range, add 6 digits"--So apparently for one function you are supposed add counts and for another function you are supposed to add digits. Now digits are not the same thing as numerals, numbers or counts, and cannot be used interchangeably. A six digit number is a number that requires numerals (0,1,2,3,4,5,6,7,8,9) to be written in six places to represent it. Feh! In the meanwhile, least is still being misspelled. And finally:"The meter will display a reading (typically <25 digits)"--"< 25 digits", I.E. 1.0000000000000000000000000, one would hope it is less that 25 digits, else the meter would be 2 feet wide. Oh well the writer must have meant to say:"The meter will display a reading of (typically <25 counts)"--Or even better, would be."Typically the meter will display a reading of 25 or less"--Now these are just some of the mistakes on page 36 of a 53 page User Manual by the company considered by many to be the foremost maker of DMM,s in the world. I rest my yellow rubber sleeve protected case.He was born ignorant, and has been losing ground ever since."Fred Allen 1894 1956Best RegardsClear Ether

author: vk6zgo
author_rank: Super Contributor
timestamp: February 18, 2012, 03:08:17 am
content: It's a Multimeter for Pete's sake!You just pick the the thing up & use it.This navel gazing about accuracy,no matter how you read it, is a waste of time.In most applications,5% is about all you need.There!,I've upset all the fanboys,so I'll go & put on my flameproof suit

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: February 28, 2012, 02:51:26 am
content: My horror story:I made a PCB according to the component footprint found in a company's datasheet.I emailed them when I was debugging, after assembly, because the chip wasn't working.They changed the footprint on their datasheet after I mentioned the problem.They said I had used thewrongfootprint. Yes, it was; the documentation was wrong! This particular chip was $27.

author: Noize
author_rank: Regular Contributor
timestamp: March 01, 2012, 07:35:30 pm
content: Quote from: ErikTheNorwegian on March 01, 2012, 06:04:31 pmIts a english expression you can use instead of "for f$$$$ sake"

author: olsenn
author_rank: Frequent Contributor
timestamp: March 01, 2012, 07:44:58 pm
content: My favourite instruction manual of all time is from the SNES game for Tool Time, which was a one page leaflet that says "Real men don't need instructions"

author: SgtRock
author_rank: Unknown
timestamp: March 01, 2012, 08:03:27 pm
content: Dear Vk6gko:--You stated:"It's a Multimeter for Pete's sake!You just pick the the thing up & use it.This navel gazing about accuracy,no matter how you read it, is a waste of time.In most applications,5% is about all you need.There!,I've upset all the fanboys,so I'll go & put on my flameproof suit"--I rather feel like someone just told me; "Get away from that wheelbarrow, Gomer, you don't know anything about machinery" Oh well, in any case, I just thought I would point out to you that, being curious about whether your equipment meets its published specifications or not, is not always a pursuit for supercilious namby-pambies, and can indeed have implications which are of a practical nature. Now while the "Harbor Freight School" of measurement and the "Plug er in, and see if she smokes" school of repair certainly have their uses in the real world, sometimes a more demanding standard is required.--A few of cases in point: 1) One is trying to diagnose a problem in a circuit containing a 1% resistor. 2) One is trying to sell a piece of equipment and the potential buyer asks if is meets its specs, and is not going for the "For Pete's sake its just a widget speech." 3) If I measure a 5% resistor with my 5% meter and the reading is within 5% of the resistors nominal value, what degree of confidence can I have that the resistor is within specification as per the schematic? I could mention many others, but I do trust that most of the members of this blog understand that circuit specifications are often designed to assure that a piece of equipment will continue to function 2 years from now in a different environment with different daily, and seasonal temperature and humidity curves. Hence many repairmen have an interest in how long the equipment is likely to continue to function, out it the field, and often the best way to assure this is to make sure the equipment meets its original specifications and or calibration requirements.--Indeed why does DJ do all those videos about precision, characterization, and confidence intervals ,and who are those navel gazing dolts who watch him?"Measure twice. Cut once"Norm Abram 1950 -Best RegardsClear Ether

author: vk6zgo
author_rank: Super Contributor
timestamp: March 01, 2012, 11:37:33 pm
content: Sarge,I'm sorry if I upset you.It was a bit "Tongue in Cheek",but it is close enough to real life,that"they could kiss without sin".Most well designed circuitry does not rely on component values having accuracy down to 1% or less,in fact that was for many years,a cornerstone of design philosophy.When 5% resistors,for instance,were standard,many devices were designed which would have worked as well with 10% or 20% resistors,but 5% were commonly available,so they were used.If someone made the same device today,they would use 1% resistors because they are commonly available.The circuit is still capable of working well within specifications with the earlier tolerance components,& in fact,that is why theydohave long operating lives----changes in component values with aging do not effect the operation of the device.In Broadcasting,it is common for equipment to stay in service for over20years (that knocks your 2 years into a cocked hat!),so"critical" component values are avoided to allow for component aging.Things like Electrolytic capacitors change value radically over time,but I have tested some of these devices which read down to less than a quarter of their original value,while the equipment concerned is still in spec!OK! There are circuits which rely on precise values of components,but they are the exception rather than the rule.--Indeed why does DJ do all those videos about precision, characterization, and confidence intervals ,and who are those navel gazing dolts who watch him?--indeed,why?

author: SgtRock
author_rank: Unknown
timestamp: March 02, 2012, 05:41:19 am
content: Dear Vz6kgo:--I do not know a lot about broadcasting equipment, but formerly my understanding was that the frequency specifications, for unmodulated carrier waves were to accuracies greater than 5 %. I did not know there was so much play allowed in these things. Who knew? Receivers must then have even looser specs. You learn something knew every day. Receivers must then have even looser specs."You should never bet against anything in science at odds of more than about 1012 to 1."Ernest Rutherford 1871 1937Best RegardsClear Ether

author: vk6zgo
author_rank: Super Contributor
timestamp: March 02, 2012, 07:51:27 am
content: Dear Clear Ether,I think you misunderstood me.I am not saying that accuracy is unnecessary,I am simply saying that extreme accuracy of measurement,in many cases is not required.Your understanding of the frequency spec for Broadcasting is not correct,5% at 720 kHz, the frequency of 6WF, the Station I used to work at ,would be 36KHz.It is a long time ago,but I think the spec for MF AM stations for the unmodulated carrier was of the order of 100s of Hz.The frequency of 6WF,was determined by a Quartz crystal oscillator,which is probably the most common method.The Quartz crystal is the dominant component in determining the frequency of the oscillator.Variations from marked value in other components have a vanishingly small effect on the frequency of oscillation.Where they may have some small effect is in the amplitude of the oscillator output.A similar situation exists with other equipment used in this field.For instance,an audio line amp if designed without Negative Feedback,would have characteristics heavily dependent upon the actual values of the components used in its construction.With Negative Feedback,the amplifier characteristics become very much less dependent upon these values.The history of analog Electronic circuit design has seen a constant striving to produce designs which give repeatable results with the least possible reliance upon precise component values.

author: G7PSK
author_rank: Super Contributor
timestamp: March 02, 2012, 08:08:28 am
content: The difference between yesteryear and today is trim pots. Many pieces of modern equipment have very few or even no trim pots.you go back 40 years and the inside was stuffed with them and 80 years ago the trim pots had external knobs as drift was such that the user had to constantly make adjustment as the equipment (very often radios) drifted of tune.I guess what I have just said here is stability is more important than precision but it takes precision to measure stability.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 02, 2012, 09:47:28 am
content: Older equipment used large numbers of general purpose discrete components,so trimpots were a cost effective answer to mass production of equipment.They could have been designed to not need them,but they would have cost more!Techs didn't spend every waking hour tweaking these pots,many,once set at the factory,did not need adjustment for the life of the equipment.Modern equipment uses ICs which are purpose-designed to be "building blocks" of the ultimate radio,TV,or whatever,so we have,for instance, IF stage/Detector/AGC ICs.These devices are again,designed to minimise the effect of internal tolerance variations upon their ultimate performance .They normally don't need trimpots.Latterly,we may use Digital Signal Processing,so that any adjustments will be in software,again no trimpots.Whether a 1k Ohm resistor in an unrelated section of a piece of equipment is actually 1050 Ohms or 950 Ohms,or even 1200 Ohms,or 800 Ohms, is extremely unlikely to have any effect on the frequency stability of the equipment.Over the years,I have seen countless manhours wasted by people searching for,& obtaining with great difficulty, extremely close tolerance components to replace supposedly"not good enough"ones,only to find that they have no effect on whatever problem they are chasing,when some of that time could have been spent finding the real answer.In one classic case,production was delayed for a day,waiting to obtain 1.1K resistors for integrating networks on one PCB,when the other component was an Electrolytic capacitor with a specified tolerance range of +or- 20%.Suggestions that they use 1k or 1.2k resistors fell on deaf ears!

author: Unknown
author_rank: Unknown
timestamp: March 02, 2012, 10:03:15 am
content: Quote from: G7PSK on March 02, 2012, 08:08:28 amThe problem with trim pots is they were invariably adjusted by knobs, whether they were fitted with a knob or not. I'll wager adjustment by knobs caused as many problems as tolerance drift.Tolerance and accuracy are important but no to the point where pursuit of them ignores practicality.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 02, 2012, 11:42:24 am
content: G'Day,Unc,nice to hear from you!

author: Neilm
author_rank: Super Contributor
timestamp: March 02, 2012, 06:08:59 pm
content: Quote from: Uncle Vernon on March 02, 2012, 10:03:15 amIn a well built instrument, the trim pots should have been adjusted until correct then locked in place with a bit of varnish to prevent them from moving.Neil

author: Unknown
author_rank: Unknown
timestamp: March 02, 2012, 10:00:57 pm
content: Quote from: Neilm on March 02, 2012, 06:08:59 pmA well built user/technician/consumer would know not to tamper with factory calibrations. Sadly many users, technicians, consumers etc are not so well built, which has them seeing themselves knowing best with all kinds of stuff! So many claim expertise with antennas systems, carburetters, electronic calibration, and yet so few of these experts ever deliver great results.Varnish tagging of trimmers and other adjustments never stopped the fiddlers it merely offered recourse when said knob fiddler later claimed for warranty.

author: G7PSK
author_rank: Super Contributor
timestamp: March 02, 2012, 10:30:09 pm
content: The early radios were built with the trimmers and tuners adjustable on the front due to things like battery voltage falling tuning and wandering this was particularly prevalent with the regenerative units all the knobs would need turning just to change stations even the grid bias was switchable on some units.

author: SgtRock
author_rank: Unknown
timestamp: March 03, 2012, 12:36:36 am
content: Dear Vk6zgo:--Sorry to have misunderstood your post. As always your post about radio are interesting and informative. So to measure transmitter output frequencies, one must needs use measuring equipment of an accuracy greater than 5 %, if I read you correctly.--Perhaps I should have explained myself better, in my initial post, so that you would not think that I was a pusillanimous namby pamby in search of accuracy for no reason what so ever. I buy a lot of used equipment, some of it I sell on, and some of it I keep. Unfortunately, in order to sell this stuff at its true value, an honest appraisal of it condition is necessary, and one often needs to find out if this used equipment meet its original specs and if not, then at least a rough idea of how badly it is out is needed. To do this I often need another piece of equipment with as good as or even better specs.--My experience with various and sundry Fluke meters is that they are dern near bullet proof. But I did find that the specifications in Fluke 87 manual, to be written in gibberish, which was exasperating."I were better to be eaten to death with a rust than to be scoured to nothing with perpetual motion."William Shakespeare 1564 1616Best RegardsClear Ether

author: vk6zgo
author_rank: Super Contributor
timestamp: March 03, 2012, 01:10:27 am
content: Quote from: G7PSK on March 02, 2012, 10:30:09 pmA lot of early stuff allowed a large amount of adjustment because the pioneers were determined to get the absolute best they could out of the (then) rare & expensive valves/tubes,so allowed for many different "tweaks".Old "bright emitter"directly heated tubes had a DC voltage drop from one end of the filament to the other,which affected the overallDC voltage on the filament,& hence interacted with the grid bias.(The directly heated PA tubes in AM Broadcast Transmitters used centre tapped filament transformers to correct for the same effect.)The filament & bias controls were used to optimise these parameters.(Sometimes,in Audio stages,the filaments were adjusted as a crude volume control).In receivers,the advent of indirectly heated tubes removed the necessity for front panel adjustment of filaments & bias,but still leftin straight TRFs, the requirement for tuning two RF stages,& in single stage Regenerative sets,one tuning,& one "reaction"(Regen) control,plus a volume control ( If it is a TRF with Regen,add one more control).Early Superheterodynes used one knob for the RF tuning ,& one for the Local Oscillator,but the introduction of ganged variable capacitors reduced the tuning knobs to one,in both Superhets & TRFs.(Again,some TRFs still had Regen).Another change which contributed greatly to the stability of early radios was the advent of metal chassis & (particularly),front panels.This reduced the previously intractable problem of "hand-capacitance" to a manageable level,particularly with Regenerative sets.When I built a 3 valve Regen radio in the late'50s,it had 3 controls--Tuning,Regeneration,& Volume.It wasn't that brilliant,but it was sufficiently stable,that it could be used for general listening purposes.It wasn't anywhere near as good as a Superhet!On HF,over a period of 10 to 15minutes ,it would drift & need re-tweaking,but I wasn't constantly retuning,on MF it was quite a lot better.I'd like to build it again,to see if ,in the light of later experience,I could make a better job

author: vk6zgo
author_rank: Super Contributor
timestamp: March 03, 2012, 01:40:45 am
content: Quote from: SgtRock on March 03, 2012, 12:36:36 amDear Clear Ether/Sarge/GomerYes,I get your point,& again I never thought you were a "pusillanimous namby pamby" (What a magnificent phrase!)I think you were the unlucky recipient of my pent up bile from reading untold postings by people trying to test the limits of their test equipment with various "Rube Goldberg/Heath-Robinson" bodge-ups,& then grizzling on this forum that they couldn't get the results they wanted.As in:-"I made up this cruddy squarewave generator with a few CMOS chips,but my One Hung Low/Rigol/Agilent/Tektronix Oscilloscope doesn't seem to have the claimed risetime!"The other thing that gripes me is when they start to obsess about the value of some random component which has no effect on circuit operation:-"Oh my goodness! they say,"My 1% resistor reads as 1.002% out on my OHL ( note politically correct use of Acronym),DMM---"It is in series between a 9 volt battery & an LED .Will it affect the operation of the LED in this circuit?"Cheers,Bryan/VK6ZGO/Grumpy Old SodPS: About the Frequency measurements--even the cheapest of Chinese Frequency Counters will have more than enough accuracy for all but the most critical use.Old HP stuff will be better for accuracy,but usually doesn't have quite as good a frequency range.