Hi I am stripping and refitting my QED P300 as my first big project, just a quick question.. I relaise that the codes on the boards are the same as resistor parts names would this be true for the other parts ?
Example of my board / is there a universal code for the components? Does anyone have a website with them all on ? i.e R39 is a ...?
Example of my board / is there a universal code for the components? Does anyone have a website with them all on ? i.e R39 is a ...?
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The resistors them selves use a color band code , those stripes indicate the Resistance value and tolerance , going through all of the codes can be time consuming and tedius , use a digital multimeter to measure the resistors resistance but you usually have to lift one of the resistors legs from the curcuit board and measure it to get a accurate reading ....
You wouldn"t generally replace resistors unless they are of inferrior quality or visably burned out or broken , they look like fair quality metal film resistors ......
On circuit boards they use letters and numbesr to show what type of component it is and its number in relation to the schematic .....
R -Resistor
C-Capacitor
Q-Transistor (sometimes T)
D-Diode
L-Inductor/Choke
T-Transformer (sometimes Transistor)
Then there are Varuous codes used for parts that don"t conform to the above codes and these codes don"t allways follow any particular convention .....
Cheers
You wouldn"t generally replace resistors unless they are of inferrior quality or visably burned out or broken , they look like fair quality metal film resistors ......
On circuit boards they use letters and numbesr to show what type of component it is and its number in relation to the schematic .....
R -Resistor
C-Capacitor
Q-Transistor (sometimes T)
D-Diode
L-Inductor/Choke
T-Transformer (sometimes Transistor)
Then there are Varuous codes used for parts that don"t conform to the above codes and these codes don"t allways follow any particular convention .....
Cheers
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I agree with Minion - virtually all resistors and a lot of silicon can be kept as is. I recommend archiving as much component ID info as one finds for future reference. Unless memorizing things like the E48 resistor series is appealing to you. I also agree with DF96 - you'd do well to get a schematic. It's safe to assume "A" is test point A, but the more unconventional markings of Ta and Tb. for the middle TO92s are a mystery to me.
http://itunes.apple.com/us/app/ohm-sense/id453570510?ls=1&mt=8
Ohm Sense - The only app that lets you take a picture of a four band, beige resistor and have it tell you its resistance value with accuracy!
Ohm Sense - The only app that lets you take a picture of a four band, beige resistor and have it tell you its resistance value with accuracy!
I think I will use one of the free schematic programs to document the parts and create the layout, if what you say is correct, then one “R38” for example should be the same as all the others on the board. After reading several post it may be pointless replacing all the components in one go , but better to start by swapping a few and then test them for improvements in quality. I’m quite lucky as the QED has an inspection plate on the bottom of the case, so I don’t have to strip it to the board every time I want to replace a part.
My first part of the project will be to find out why it makes my TDL RTL2’s buzz continuously , once I have sorted that out I can then get recommendations for replacing components.
My first part of the project will be to find out why it makes my TDL RTL2’s buzz continuously , once I have sorted that out I can then get recommendations for replacing components.
Not sure what this refers to, but there should be only one "R38" on the board. It may have a twin in the circuitry for the other channel, but that's about it.
If the buzz is in both channels, it may be a power supply issue. If it is in one channel only, you can use measurements from the good channel to compare with the bad.
Sofasud is correct, if you had more than one R38 (or any other designator) you wouldn't be able to populate the board. The reference designators (R38, C28, D1 etc) all relate to the BOM (bill of materials) for the PCB, and each will have a component value and type specific to that designator. When you have SMD components the reference designator will also be used for the pick and place data, so they must always be unique.
Second the buzzing, look at the big picture first before going down to board and component level.
Second the buzzing, look at the big picture first before going down to board and component level.
Hi, I think I confused myself, what I meant was, that if the codes on board next to the components don’t have a real world value .. i.e a R38 = a specific component that you can look up “Resistor 38”, on the internet and it is always the same part. But instead, the codes are specific to the manufacturer or even that particular board, then that’s ok I can understand that. And I was using R38 as an example sorry, but then on the board anywhere where the code R38 is should be the same component (whatever the real world component may be).
And so as not to get cross threads, I have already opened another about my amp buzzing
No, because the reference designator also relates to the components position in the schematic. The rule is one unique reference designator per component. Plus in a pick and place file (used mainly for SMD, but also for through hole) you have as well as the reference designator, you have the X,Y and rotation data for the part, so each component has a specific location.
All schematic/PCB software I have used either will report duplicate designators as an error, or prevent duplicate component names.
All schematic/PCB software I have used either will report duplicate designators as an error, or prevent duplicate component names.
The numbers aren't really specific. By themselves they're mostly meaningless. They just tie together the schematic, PCB, BOM, etc. as marce stated. It's standard practice to start numbering circuit components beginning with those on the right hand side of the schematic and continuing across/down.
I think that basically answers my question.. thanks.
Marce , thanks I will just create a schematic from the board using software, it’s probably the safest option.
Here is the detail on parts designation for schematics
Electronic symbol - Wikipedia, the free encyclopedia
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Electronic symbol - Wikipedia, the free encyclopedia
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1. Virtually every electronics company that bothers to label their boards use a progressive based numbering system for component identification. It is relative ONLY to a specific board in a specific piece of equipment and has no correlation whatsoever to real world part numbering. R105 on an amp board will not be the same as R105 on a phase lock board in a signal analyzer or R105 on a horizontal drive board in an oscilloscope! It is only relative to the specific board, schematic, parts list and component map for the exact piece of equipment you are looking at. 2. Troubleshooting a hum problem by replacing every component in site is just plain silly. First start by listening to it. Is it 60 or 120 cycle (50/100 in europe)? If so look first for a bad ground or earth. Does it exist when all inputs are muted and the volume control is down? If so first stop is the power supply. Don't need a scope, just a DVM. Read the DC voltage of your supplies then switch to AC and look for a a high percentage AC reading. Look for swollen or leaky capacitors. But shotgun troubleshooting is generally not the best way to find a problem. Start with logic. Doc
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I built a test rig for theverin terminated backplanes, and as the backplane had to have power present, the lead to suppliy the power was made so that it could easily be replaced (screw down connectors). One of the connectors came loose on this lead! The test deparment stripped the unit down to it component atoms, before someone picked up the lead with its connector dropping off and realised, two days of two test engineers to find that fault. I think it is human nature to look for a complex solution to a problem, when most solutions are simple.
On Idents, since 2003 most boards I've done dont have idents, density and 0402 components means you just cant read them, still use them with viewers though as we still repair even these dense boards.
I built a test rig for theverin terminated backplanes, and as the backplane had to have power present, the lead to suppliy the power was made so that it could easily be replaced (screw down connectors). One of the connectors came loose on this lead! The test deparment stripped the unit down to it component atoms, before someone picked up the lead with its connector dropping off and realised, two days of two test engineers to find that fault
. I think it is human nature to look for a complex solution to a problem, when most solutions are simple.On Idents, since 2003 most boards I've done dont have idents, density and 0402 components means you just cant read them, still use them with viewers though as we still repair even these dense boards.
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