The title for this blog started back in the early 70's with an article in Audio magazine about an amplifier made by the Lirpa company. The frequency response of the amplifier was listed as "DC to Daylight". I am, by nature an analog geek, and i seem to collect lots of random bits of information on anything analog, quite literally from DC to Daylight. If i don't have it, i have probably seen it somewhere, and give me enough time and i can usually retrieve it. I have a few focused interests, such as audio amplifier design and RF design. So this blog will sometimes contain something random, but hopefully useful.
Rtfm
Posted 22nd July 2009 at 03:06 AM by unclejed613
everybody should know what this means...... if not here's a linux page with a description of this command and it's usage.........
http://www.wlug.org.nz/rtfm(1)
ok, if after you read that, and you're still not sure, it means Read The Fine Manual, Read the Fun Manual, or another version not suitable for polite conversation.
working for a large service center, i see a lot of equipment that comes in for repair which, frankly, wouldn't have to if people pulled out that mysterious book that comes with your shiny new home theater system, sat down and read it cover to cover just once. and those who should read the manual are not only the consumer, but the sales staffers who guide the consumer in their purchasing decisions. two examples of this are from actual pieces of equipment that came in for repair recently one of them is from a consumer, one is from a home theater sales "tech". the first one (from a consumer adding an additional feature to their home theater setup, i.e. a second TV monitor) is the complaint on a Blu-Ray player. the customer, already having an HDMI TV monitor connected, was adding a secondary monitor to the setup, by attaching the second monitor to the component jacks (red, green and blue plugs). his complaint? no audio through the second TV monitor...... no it doesn't work like HDMI, it also needs a pair of audio cables, which is shown on page 6 of the owner's manual.
the second came from a sales floor "tech". complaint? multichannel surround receiver only has 2 channels of audio out to the speakers. the "fix" for this one was a single push of the Surround Mode button on the front panel, which switched from 2CH Stereo to 5CH Surround...... BTW, that one was on pg 12.
the sales "techs" and consumers aren't completely at fault here. engineers and marketing execs have their place in this mess too... a recent editorial in an engineering magazine was talking about the consumer electronic industry's fixation on "Feature-itis". Feature-itis has always been part of the consumer electronics industry, but for a long time, there was a very real, physical limitation on how many features could be implemented in a piece of equipment, it's called FRONT PANEL SPACE. mechanical switches and controls were limited on how close together you could put them in a piece of sheet metal, and you could see where every single one was set. there were also circuit board real estate and power dissipation issues. the more features, the more PC board real estate required, and the more packed the PC board, the more heat had to be vented somehow (and packing PC boards closer together made this difficult).with modern technology, however, there is literally no limit to the amount of features that can be installed (actually programmed is a more accurate term) into a piece of equipment. all that's needed on the front panel is a very few small buttons, and a few square inches for a fluorescent or LCD display and a window for a remote sensor. inside the unit you have a power supply, an amplifier section (i'm using a receiver as an example), and input-output boards for the signals and speaker outputs. these all take up a generally standard amount of real eatate inside the chassis.
what is new is the electronic "magic" to a) control all of the systems, interpret user input, perform signal and power switching, b)take all of the input signals and manipulate the signals, even adding effects and filtering, and c) monitoring the system for fault conditions such as shorted speaker wires, all of this continuously.
and all of this "magic" resides in an epoxy square, about 1" (2.54cm) on a side and 0.1" (2.5mm) thick. it all resides in DSP code, there can be thousands of features and settings coded into this small device, menu upon submenu upon feature settings. so many submenus and choices it's easy to get lost and forget what you just changed. you can no longer see the whole "front panel" at a glance and say "oh, i forgot to switch this back to 'tape 2'". all of your settings are hidden behind the front panel, where you can't see or remember them, and any one of them can dig you in deeper when you try to correct a mistake that suddenly cuts the sound out or makes it sound terrible. don't get me wrong, modern technology is very useful, and DSP solves a lot of difficulties that audio designers have been wrestling with for years (yes, now there IS such thing as a "brick wall" filter, and it works!!!!), but having too many features, many of them hidden in layers of submenus, is a perfect breeding ground for Murphy's Law, "If there is an option that causes a malfunction, the option will be set." Fortunately there is (and this is usually in the owner's manual near the back) always the Master Reset, which is great for getting a piece of equipment working again, but then the consumer has to start all over (but this time hopefully he Reads The Fine Manual.....).....
http://www.wlug.org.nz/rtfm(1)
ok, if after you read that, and you're still not sure, it means Read The Fine Manual, Read the Fun Manual, or another version not suitable for polite conversation.
working for a large service center, i see a lot of equipment that comes in for repair which, frankly, wouldn't have to if people pulled out that mysterious book that comes with your shiny new home theater system, sat down and read it cover to cover just once. and those who should read the manual are not only the consumer, but the sales staffers who guide the consumer in their purchasing decisions. two examples of this are from actual pieces of equipment that came in for repair recently one of them is from a consumer, one is from a home theater sales "tech". the first one (from a consumer adding an additional feature to their home theater setup, i.e. a second TV monitor) is the complaint on a Blu-Ray player. the customer, already having an HDMI TV monitor connected, was adding a secondary monitor to the setup, by attaching the second monitor to the component jacks (red, green and blue plugs). his complaint? no audio through the second TV monitor...... no it doesn't work like HDMI, it also needs a pair of audio cables, which is shown on page 6 of the owner's manual.
the second came from a sales floor "tech". complaint? multichannel surround receiver only has 2 channels of audio out to the speakers. the "fix" for this one was a single push of the Surround Mode button on the front panel, which switched from 2CH Stereo to 5CH Surround...... BTW, that one was on pg 12.
the sales "techs" and consumers aren't completely at fault here. engineers and marketing execs have their place in this mess too... a recent editorial in an engineering magazine was talking about the consumer electronic industry's fixation on "Feature-itis". Feature-itis has always been part of the consumer electronics industry, but for a long time, there was a very real, physical limitation on how many features could be implemented in a piece of equipment, it's called FRONT PANEL SPACE. mechanical switches and controls were limited on how close together you could put them in a piece of sheet metal, and you could see where every single one was set. there were also circuit board real estate and power dissipation issues. the more features, the more PC board real estate required, and the more packed the PC board, the more heat had to be vented somehow (and packing PC boards closer together made this difficult).with modern technology, however, there is literally no limit to the amount of features that can be installed (actually programmed is a more accurate term) into a piece of equipment. all that's needed on the front panel is a very few small buttons, and a few square inches for a fluorescent or LCD display and a window for a remote sensor. inside the unit you have a power supply, an amplifier section (i'm using a receiver as an example), and input-output boards for the signals and speaker outputs. these all take up a generally standard amount of real eatate inside the chassis.
what is new is the electronic "magic" to a) control all of the systems, interpret user input, perform signal and power switching, b)take all of the input signals and manipulate the signals, even adding effects and filtering, and c) monitoring the system for fault conditions such as shorted speaker wires, all of this continuously.
and all of this "magic" resides in an epoxy square, about 1" (2.54cm) on a side and 0.1" (2.5mm) thick. it all resides in DSP code, there can be thousands of features and settings coded into this small device, menu upon submenu upon feature settings. so many submenus and choices it's easy to get lost and forget what you just changed. you can no longer see the whole "front panel" at a glance and say "oh, i forgot to switch this back to 'tape 2'". all of your settings are hidden behind the front panel, where you can't see or remember them, and any one of them can dig you in deeper when you try to correct a mistake that suddenly cuts the sound out or makes it sound terrible. don't get me wrong, modern technology is very useful, and DSP solves a lot of difficulties that audio designers have been wrestling with for years (yes, now there IS such thing as a "brick wall" filter, and it works!!!!), but having too many features, many of them hidden in layers of submenus, is a perfect breeding ground for Murphy's Law, "If there is an option that causes a malfunction, the option will be set." Fortunately there is (and this is usually in the owner's manual near the back) always the Master Reset, which is great for getting a piece of equipment working again, but then the consumer has to start all over (but this time hopefully he Reads The Fine Manual.....).....
Total Comments 2
Comments
-
afterthought........
when i was a Calibration Tech in the Army, every calibration manual began with this instruction step:
STEP 1: Read the entire contents of this manual before continuing.
when it came time for our yearly inspection, everyone had to perform a calibration on a piece of equipment for the inspector. if the tech did not read the entire manual before even plugging in the equipment or gathering the required test equipment, they were FAILED on the spot.Posted 22nd July 2009 at 03:21 AM by unclejed613
-
follow up.... this one is priceless
ok, so a store sends a Samsung home theater receiver in to the shop. the model is one of a series of similar models, some models in the series have more features than others. there are 6 speaker jacks and a wireless card slot on the back of the unit. the 6 speaker jacks are marked "L-front, R-front, Center, Subwoofer, L-rear, R-rear", and they are color coded with various colors to match the colors of the speaker plugs. unit comes in with the complaint " rear channels not functioning properly". so the technician orders an amp board after verifying that the left rear channel is dead. the tech gets the new board, and installs it and tests the unit. same problem. so the tech calls me over to look at the unit, thinking they may have missed something. we do a reset, thinking some option may be set wrong. same problem. so i tell the tech to go into the setup menu and go to the speaker test page. so we start the speaker test, which steps through all of the speakers one at a time outputting white noise to each one. not only does the left rear channel not work at all, the right rear works only when the test signal is sent to the left front channel, as if the right rear and left front channels are wired together. so i take the original board since it was handy, and begin following the traces on the board back from the speaker jacks. the left rear channel traces go to what should be a pair of inductors (the amp outputs are bridged class D), but instead is unpopulated. same thing with the right trear except that there are two 0 ohm resistors (surface mount jumpers) tying the right rear channel connection to the left front. this obviously is some kind of mistake, unless Samsung was attempting "kluge surround" where the rear speakers are cross connected to the opposite front channel (L-F to R-R and R-F to L-R), but Samsung isn't THAT cheap, and even if that were so, forgot the jumpers for the left rear. so we looked at the schematic, and sure enough, the schematic was wired exactly the same way as what we traced out on the board. this is getting weirder by the minute. the tech calls Samsung tech support who tells the tech to return the amp board as DOB (defective out of box). i had a sudden thought, look in the owner's manual. so we look up in the owner's manual (which is written for not just the one model, but the whole series) and look up the speaker connections for this particular model. no speaker connections for the rear channels are plugged in to the amp, but the rear channels use a wireless card and wireless receiver. the setup for another model was on the previous page, and the rear speakers get plugged in to the amp on that model, and the schematic (which is also for the whole model series) shows that on that particular model, yes the inductors are there. so here we have a manufacturer cutting corners by not covering up the unused connectors, and not leaving them unmarked in the silkscreen for that model, and further confusing things by connecting one of the unused outputs to the output of a working channel, but it took looking at the user manual to find something that wan't mentioned in the service manual. seems that the store personnel should have RTFM as well.Posted 8th August 2009 at 04:47 AM by unclejed613
