Re: gEDA-user: Couple pics from my new PCB
Kits of components are also worth considering. I think we have every 0805 resister know to man in quantities of 25. Same for capacitors 080 capacitors (high frequency filters) another bunch 3216 tantilum caps for power supply filtering. Anything we aren't quite sure of the final value we make sure we have a range of. We have also stock pilled a large variety of inductors some for power supply filtering others for building high frequency analog filters. Steve M. DJ Delorie wrote: >> BTW, I've decided that 0.1u caps are the hardware equivalent of >> semicolons... >> > > I like the analogy :-) > > I even bought a 50-pack of 0.1u leaded caps with 0.1" spacing for my > solderless breadboard. The leads were just the right length, too - I > pop them in all over the breadboard. > > Whenever I place orders for parts, I always buy bigger quantities of > things I think I'll use often, like 1u 0.1u 1k etc. I've taken to > buying minimum lots of 50 or 100 for discretes and extras of anything > else I think I might use later. > > > ___ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user > > ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
On Dec 22, 2007, at 8:50 PM, DJ Delorie wrote: > >> http://ad7gd.net/geda/panelusb-sm.jpg > > Am I the only one who tries to make the absolutely smallest board I > can still fit my parts on? My latest board would fit in the blank > spots between your chips. That's funny ... my current design is squeezing ten pounds o' crap into 2.125" by 5.125". 16 channels of ADC, plus ADC drivers, and a Spartan XC3S200AN FPGA in 256-ball BGA. Now that the 3ANs are available from Digikey, we're going to use them instead of the 3E. No external config EPROM, which saves space, and I saved some more by putting two Camera Link interfaces in the FPGA. Compared with the MSOP opamps and ADCs, the FPGA's oscillator is huge. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
> BTW, I've decided that 0.1u caps are the hardware equivalent of > semicolons... I like the analogy :-) I even bought a 50-pack of 0.1u leaded caps with 0.1" spacing for my solderless breadboard. The leads were just the right length, too - I pop them in all over the breadboard. Whenever I place orders for parts, I always buy bigger quantities of things I think I'll use often, like 1u 0.1u 1k etc. I've taken to buying minimum lots of 50 or 100 for discretes and extras of anything else I think I might use later. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
On Sun, Dec 23, 2007 at 05:08:55AM +0100, Igor2 wrote: > On Sat, 22 Dec 2007, DJ Delorie wrote: > > > > >>http://ad7gd.net/geda/panelusb-sm.jpg > > > >Am I the only one who tries to make the absolutely smallest board I > >can still fit my parts on? My latest board would fit in the blank > >spots between your chips. Most of the size of the board is due to the width. Those edge connectors (in the photo it's the near side) will actually be exposed from the device when it's done. The connectors on the far side and the left are internal. It could have been narrower, but not enough to significantly change the price. Not to mention the layout started with a fixed price for 60 square inches. Big area made it easy to keep the analog section away from the digital noise, too. > Btw, how do you guys solder those big SM chips with so many pins? That's the funny thing. The soldering on the QFPs is so much nicer than most of the 0603s because I do it bathed in flux. You just line up the chip, tack two corners, and then use the tip of your iron to drag a tiny ball of solder slowly along the pins. For the 0.5mm stuff I take no chances and I bathe it in liquid flux (and add more if I get any solder bridges). For fatter stuff (0.65mm or 0.8mm ) I'll just slather on flux with the pen. The downside is that I have to wash the board after using the liquid flux, but it's worth it. John Griessen wrote: > Hey, that's a lot of function you got going! Well heck, I'm a software guy. Now that I have the board, it's all downhill! BTW, I've decided that 0.1u caps are the hardware equivalent of semicolons... There are 128 caps on that board and 79 are .1u. And I'm totally relieved to see decent picture quality out of the ADV7183B, since I followed their zillion-cap recommendations to the letter. -- Ben Jackson AD7GD <[EMAIL PROTECTED]> http://www.ben.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
> Btw, how do you guys solder those big SM chips with so many pins? Hotplate and solder paste. If you don't have a hotplate setup, the trick is to put down extra solder the first time - use a big tip and swipe it over the pins to get them all soldered. Then go back with solder wick and remove enough so that there are no bridges. Either way, you want a flux pen too. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
On Sat, 22 Dec 2007, DJ Delorie wrote: > >> http://ad7gd.net/geda/panelusb-sm.jpg > >Am I the only one who tries to make the absolutely smallest board I >can still fit my parts on? My latest board would fit in the blank >spots between your chips. I do that too - saves cost but it's bad when I have to debug or replace or add parts. Btw, how do you guys solder those big SM chips with so many pins? I've just bought a chip with TQFP64_10, managed to iron and etch a board for it but I am still not sure how I would solder the chip. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
Ben Jackson wrote: > This is the 4-layer board I got into gschem/PCB to make. Looks good. The ADV7183B > is digitizing frames from a DVD player and the FPGA is streaming them out > via a very convoluted process (notice no SRAM installed yet for grabbing > whole frames). Hey, that's a lot of function you got going! John G -- Ecosensory Austin TX ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: silkscreen styles
Tomaz Solc wrote: > Hi > >> Could you point out a specific example? I can't guess what you're >> talking about. > > I think he's talking about this: > > http://www.tablix.org/~avian/blog/images/blog/20070716t131612-pict0002-m.jpg Yes, the white rectangle with text cut out of it in the lower center of that photo. The Sony TV diagram .pdf is huge -- I already deleted the copy of it I looked at. I'd like to be able to do reverse text that way on silk or copper layers. John Griessen -- Ecosensory Austin TX ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Couple pics from my new PCB
> http://ad7gd.net/geda/panelusb-sm.jpg Am I the only one who tries to make the absolutely smallest board I can still fit my parts on? My latest board would fit in the blank spots between your chips. > It's hooked up to USB with an FT232R (very nice chip and very nice > API, Yup. I waffled between that and the FT245R - same chip, parallel interface. Unfortunately, I needed two GPIO as well to do remote programming, which the FT245R was lacking. > slightly lacking in docs for the hardware interface side). At least they offer a Linux library, though. I'm using it with my usb-gpio board. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: Couple pics from my new PCB
This is the 4-layer board I got into gschem/PCB to make. The PCBs arrived last Wednesday and I have been incrementally assembling the first one. Here's a pic of the board on my desk: http://ad7gd.net/geda/panelusb-sm.jpg It's hooked up to USB with an FT232R (very nice chip and very nice API, slightly lacking in docs for the hardware interface side). The ADV7183B is digitizing frames from a DVD player and the FPGA is streaming them out via a very convoluted process (notice no SRAM installed yet for grabbing whole frames). Here's one frame I pulled off and converted on my PC: http://ad7gd.net/geda/first-tv.png -- Ben Jackson AD7GD <[EMAIL PROTECTED]> http://www.ben.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: silkscreen styles
Hi > Could you point out a specific example? I can't guess what you're > talking about. I think he's talking about this: http://www.tablix.org/~avian/blog/images/blog/20070716t131612-pict0002-m.jpg Silkscreen at the bottom center of the photo is in reverse. This style is often used by Sony to mark important components like big chips, not little SMD resistors like in this unusual example. This is a feature of PCB I also missed a couple of times. Best regards Tomaz ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: silkscreen styles (was: TV gurus lurking?)
> I looked at that Sony diagram and liked the reverse text blocks in > some places. It involved defining a rectangle, then text that > removes the layer superimposed on the rectangle. Could you point out a specific example? I can't guess what you're talking about. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: silkscreen styles (was: TV gurus lurking?)
Peter Clifton wrote: > On Fri, 2007-12-21 at 16:06 -0500, DJ Delorie wrote: >> The PCB overlays could be the "assembly" prints that PCB already does. > > I didn't say it was better, but I expect there are certain styles of > labels, annotations, silk screen text etc.. which we'd struggle to > achieve. I looked at that Sony diagram and liked the reverse text blocks in some places. It involved defining a rectangle, then text that removes the layer superimposed on the rectangle. That sounds like a function we don't have yet, but easy to output in PS or RS274X. John Griessen -- Ecosensory Austin TX ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Any TV repair gurus lurking?
Op vrijdag 21-12-2007 om 20:52 uur [tijdzone +], schreef Peter Clifton: > On Fri, 2007-12-21 at 15:17 -0500, Darryl Gibson wrote: > > > This is a very weird set of problems. > > > > RGB lines indicate a failure of the vertical amp, which the shrinking > > picture also indicates. > > > > Check the coupling capacitor between the vertical amp, and the yoke? > > Thanks, will do when I've got the set open again. It doesn't seem to be > AC coupled. Do you mean the supply cap to the vert. amplifier? Hello Peter, I'm an experienced TV repair technician, and I've encountered similar problems with this chassis. Apparently, there's something wrong with the vertical drive pulldown or its negative supply. Especially when the picture gets compressed and shifted to exactly the upper half of the screen, a supply problem seems the most likely candidate. A very common cause is a bad solder joint on the V-drive IC(*). These are the parts: V-drive IC: IC500 (STV9379) Positive 15V supply: flyback pin 6 - R509 (0.47 ohm) - L503 - D503 - C520, C515 (470uF/25V) - IC500 pin 2 Negative 15V supply: flyback pin 8 - R510 (0.47 ohm) - L502 - D502 - C517, C506 (470uF/25V) - IC500 pin 4 Also check C510 (220uF/50V flyback pulse cap) I'd start by checking the PCB for bad solder joints -- use a small flashlight and if necessary a good quality magnifying glass, as not all fractured joints are as obvious as the ones below. If nothing is found, switch on the TV and see if it's sensitive to vibrations -- lightly tap the board and the components between the flyback transformer and IC500 with a bit of PVC tube. If this doesn't provoke the fault, there's probably a non-mechanical failure. Most likely candidates are IC500 itself, R510, and D502; after this, the actual V sync signal (TP19) is suspect. You can measure the DC voltages behind D502, or (with an oscilloscope) the flyback AC voltages before D502. Also, you can swap D502 and D503 if you want to see whether D502 saometimes fails. *: This happens a lot with components which are mounted on a vertical heat sink. As the component heats up and cools down, its pins expand and contract, causing the solder joint to fail. I routinely check all such components on all boards. You'll find a clear example here: http://www.linetec.nl/electronics/badsolder2.jpg Other candidates for bad solder joints are larger pins in general, because these conduct the heat away from the solder joint in the manufacturer's wave soldering process, causing 'cold', brittle joints from the onset. And don't forget to check the SCART connector too. Hope this helps, Best regards, Richard Rasker ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: could not connect nets gschem/gsch2pcb/pcb
My proposal to solve the problem (and also the problem of hidden power connections): 1) rename all net=xxx attributes in all symbols with power=xxx, 2) have a little tool in gschem that can do a) add an external net=yyy attribute that connects (for example) pin 14 of U1 (which is 7400) to a net +5Vd, or b) hint what power symbol to use (74power-1.sym in this case), or c) create a custom power symbol (embedded?) if there is no suitable one available. Wojciech Kazubski > On Dec 20, 2007, at 5:47 AM, Klaus Rudolph wrote: > > > Having multiple netnames should not be a problem and work "sometimes". > > Methinks that having multiple netnames for the same net should ALWAYS > trigger a DRC error. > > -a > > > > ___ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Any TV repair gurus lurking?
On Saturday 22 December 2007, Darryl Gibson wrote: >Dan McMahill wrote: >> By far the worst shock I've ever received was 23 years ago working on a >> Fender Bassman that was unplugged. I will *never* forget to discharge >> caps again. Especially ones charged up to 500 volts. Thats one of >> those mistakes you won't make twice. > >Yep, that's a bad day, but you lived to talk about it, and pass on the >warning. > >My worst shock came when I was working on a plasma etching machine. Had >to stick my head inside to take some voltage readings, found the >voltage, with my pinky finger, rather than the meter probe. That was >bad, but,,, trying to get away from that, I hit my head on the 440vac >contactor which was over my head. That HURT, and I was wearing a hat! > >Told my boss he had choice, I was going outside and having a smoke, and >he could have the design engineer work on the problem, or, I was going >to find the blankety blank engineer, and pound him into the floor. > >The engineer showed up, and after we got things working, he decided it >wasn't a good idea to put the 440 contactor on the roof of the cabinet, >and he moved it to one of the side walls. > >I'm partly at fault here, I was taught in tech. school that usually the >shock won't hurt you, but getting away from it will. To prove the point, > the teacher made the lecture while holding a live suicide cord. Suicide cord? Not fam with that item. However, do not ignore the trauma of the shock, it can come to haunt you very very painfully in the ensuing time frame of 6 months or more. If you've ever had the chicken pox, aka herpes zoroaster, and is there one here who didn't have it as a child?, that virus lives dormant in your major nerve sheathing the rest of your life. The trauma of the shock can awaken it for another round, only this time its called 'shingles'. It will redefine your personal pain tolerance level, upwards. I managed to get across the tickler transformers in the HV cubicle of a GE TF-3a amplifier (part of a tv transmitter, that's my game) and got 2nd degree burns on both arms and my chest area before I got kicked loose. I was looking for a cotter key & washer for one of the HV shorting assemblies that I had dropped as I was getting tired after about 16 hours non-stop of fixing up a snake explosion & fire. I was instantly so tired I had to go take a nap for several hours, and eventually had my heart checked out but it was fine and still is. But 3 days later I had shingles breaking out all along the major path that about 260 volt 3 phase ac took through me. The pain was disabling and I missed about 3 weeks worth of work. Twas not fun by any sane definition, and to this day, 15 years later, my lower chest and diaphram area have never been completely pain free. >I still find it amazing how old timers can predict the future. That is often because we've been there, done that, even "bought the T-shirt" describing our carelessness. :) -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) A small town that cannot support one lawyer can always support two. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
