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Fried Demo Board! — Parallax Forums

Fried Demo Board!

RS_JimRS_Jim Posts: 1,766
edited 2013-07-24 15:43 in Propeller 1
After connecting +9 V to pin 7 of the prop chip on my demo board, I get that infamous "no propellers found" message from the spin tool. I really like the board for quick testing of projects. Is there anyone around that could jack up the old chip and drive an new one on the board? I unfortunaely have developed an age related tremor that makes smd work impossible.
Thanks,
Jim

Comments

  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-07-11 09:46
    Hi,
    I have had tremors for quite a few years. If you can remove the chip cleanly, try tacking down diagonally opposite corners first to get the position exactly right. Then the tremors won't matter all it. The rest is just a quick bit of soldering.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-07-11 11:25
    Jim,

    Send the board to me. I'll try to fix it.

    I'll PM you my address.
  • PublisonPublison Posts: 12,366
    edited 2013-07-11 11:52
    Duane Degn wrote: »
    Jim,

    Send the board to me. I'll try to fix it.

    I'll PM you my address.

    I PM'd him and hour ago. We will see what he gets first. :)
  • Cluso99Cluso99 Posts: 18,069
    edited 2013-07-11 17:22
    WTG guys. What a forum hey!
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-07-11 23:39
    With surface mount devices that have a lot of pins... soldering down a pin in one corner and they going to the diagonally opposite corner and tacking down another pin really does get alignment fixed so that one does not have to have nerves of steel to get all the pins right.

    Being in Taiwan and not having any surface mount Propellers on hand ... seemed wisest to let someone else offer.

    But you really can solder well with tremors if you take this approach. I did a Schmartt board with a GA144 that is much harder than a Propeller.. finer pitch and more pins. And I have done other stuff as well.
  • RS_JimRS_Jim Posts: 1,766
    edited 2013-07-12 06:06
    thanks guys, I just sent an email to Parallax to see if they would help. Will mark this as solved as I now have a couple of offers on the table.
    Jim
  • HumanoidoHumanoido Posts: 5,770
    edited 2013-07-13 11:01
    That's what robots and solder wash equipment are for. SMD was originally never intended for humans. Parallax should have some equipment and robots on hand. Guys, very nice of you to offer. You need the gold helper awards and recognition.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2013-07-14 02:24
    The PCB is the valuable thing here, and so the state of the Prop doesn't matter. Commercial PCBs are so much tougher than my homemade ones seem to be, a bit of ali foil shielding and a paint stripper (air!) gets most of the chips I want off, and only rarely hurts the chips.

    A bench lens, with light, is the thing that I find most useful on sticking the new one back down. Clean off the old solde wit some wick and then apply a layer of flux to all of the pads (I use a felt tip pen sort) and then with a merest hint of fresh solder do the diagonals. then put some more flux on top of the chip pins and get bold with a larger tip that has nicely rounded edges and just wipe the solder (0.5mm) along the rows. Any excess or bridges can be cleaned up with more flux and gravity or wick.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2013-07-14 02:28
    Forgot the pic! This one is 0.65mm pitch
    S7303144.jpg
    1024 x 768 - 122K
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-07-14 05:56
    I have a hot air station but I don't have enough experience with it to feel confident I could safely remove the Prop without damaging the PCB. Chipquik is my failsafe chip remover.

    To remove a bad chip, I've been told to cut the leads with a sharp knife and then remove the leads with a soldering iron. I think this method could work well with a bit more practice on my part but I've still managed to damage a PCB with this technique.

    I'm pretty sure all the chips I've removed with Chipquik have caused any damage to the PCB. I'm not really worried about soldering on a new chip. I've done that many many times. The first lead is alway the trickiest though.

    Cluso99 gave some smt soldering advice in Jazzed Tetra Prop thread (ignore my babblings). Once I followed his advice rather than trying to do it my way, I've been much more successful with soldering surface mount parts.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2013-07-14 14:55
    I have used Chipquick but I have never seen much more than a few inches of it at once, do they do reels of it? I assume that it works by being a very low melting point and so allows for all of the sides to stay liquid long enough so that you can get all aound the chip

    Cutting the individual leads is a way, by you have to be so careful that as soon as the lead is diconnected from the IC that it doesn't become an instant lever to stress the PCB.

    Blessed were the days when there were sockets, and the pins were a visible distance from each other.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-07-14 15:06
    Toby Seckshund wrote: »
    I have used Chipquick but I have never seen much more than a few inches of it at once, do they do reels of it?

    SparkFun sells 2.5 ft of it in their kit.
  • Cluso99Cluso99 Posts: 18,069
    edited 2013-07-14 17:28
    Glad it was useful for you Duane. I have now progressed much further. I use a pair of magnifying lenses on a headstrap (the ones used by jewellers). I purchased a smaller 1mm & 0.8mm soldering iron tips for my temp regulated iron. They work much better for the finer ICs and I am now quite comfortable soldering 0.65mm pitch and have progressed to 0603 R's and C's. For the R & Cs a pair of good nonmagnetised fine tip tweezers are essential. I never thought I would be comfortable soldering those 1206(4x0603) quad resistor networks, but they are easy as.
    For pcb layouts, just ensure you extend the pcb pads out at least 0.5mm more than recommended and you will be fine.
  • Ken GraceyKen Gracey Posts: 7,392
    edited 2013-07-14 17:33
    RS_Jim: if you don't get a successful repair from Duane I'd be happy to send you a new one.

    And Duane, if you are missing SMT parts to repair this board please contact me and I'll send whatever you need.
  • pedwardpedward Posts: 1,642
    edited 2013-07-14 18:08
    And (hint hint) if you buy the PropBOE, magic smoke will always be warrantied!
    image.php?u=40442&type=sigpic&dateline=1350446342
    http://forums.parallax.com/showthread.php/143015-Improvement-to-the-Propeller-BOE-Lifetime-Warranty
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-07-14 20:05
    Ken Gracey wrote: »
    And Duane, if you are missing SMT parts to repair this board please contact me and I'll send whatever you need.

    If it's the Prop that's bad, I should be all set. I have lots of QFP Props.

    Thanks for the offer. Hopefully Jim won't need to take you up on a replacement board.
  • RS_JimRS_Jim Posts: 1,766
    edited 2013-07-15 07:11
    Thanks Ken. The board goes off to Duane today.
    Jim
  • PublisonPublison Posts: 12,366
    edited 2013-07-15 09:59
    RS_Jim wrote: »
    Thanks Ken. The board goes off to Duane today.
    Jim

    Good on you Duane!

    Hey, I offered too. :)

    Duane, just watch that resistor by the microphone. :)
  • RS_JimRS_Jim Posts: 1,766
    edited 2013-07-24 06:52
    The patient has successfully survived the surgery and returned home. I can't imagine getting this kind of support from the "A" camp, up to and including an offer from the president of the company to replace it if it couldn't be repaired. No wonder I talk Parallax so pasionately when people come into my Radio Shack store.
    Jim
  • PublisonPublison Posts: 12,366
    edited 2013-07-24 13:21
    RS_Jim wrote: »
    The patient has successfully survived the surgery and returned home. I can't imagine getting this kind of support from the "A" camp, up to and including an offer from the president of the company to replace it if it couldn't be repaired. No wonder I talk Parallax so pasionately when people come into my Radio Shack store.
    Jim

    Good deal Jim!

    Duane, you rule!
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-07-24 14:20
    The scariest part of repairing a board to me is removing the old chip.

    With the help of ChipQuik I was able to get the old Prop off without damaging any traces.

    attachment.php?attachmentid=102997&d=1374699871

    The Demo Board is a little harder to work on than some of the other other Propeller boards because of the mic and other components in the area of the Propeller chip. I ended up resorting to my earlier smt soldering technique of using too much solder and the clean it up with solder wick. As you can see below, you don't have to be very precise when applying the solder.

    attachment.php?attachmentid=102998&d=1374699874

    I would have sworn the chip was straight when I soldered the first two leads but as you can see below it's a little crooked.

    attachment.php?attachmentid=102999&d=1374699891

    I didn't want to risk damaging the traces by attempting another chip removal so I left it a bit less than ideal. I'm pretty sure the only down side to the crooked chip is cosmetic. No one tell Jim; maybe he won't notice?

    I found demos to test each of the Propeller's I/O pins. I used LEDs to check P0-P7. It all seemed to work okay so hopefully Jim will be good to go.
    DemoBoardNoProp130724a.jpg
    746 x 590 - 278K
    DemoBoardNewPropDirty130724a.jpg
    721 x 628 - 289K
    DemoBoardNewPropClean130724a.jpg
    750 x 681 - 301K
  • PublisonPublison Posts: 12,366
    edited 2013-07-24 15:43
    Duane Degn wrote: »
    The scariest part of repairing a board to me is removing the old chip.

    With the help of ChipQuik I was able to get the old Prop off without damaging any traces.

    attachment.php?attachmentid=102997&d=1374699871

    The Demo Board is a little harder to work on than some of the other other Propeller boards because of the mic and other components in the area of the Propeller chip. I ended up resorting to my earlier smt soldering technique of using too much solder and the clean it up with solder wick. As you can see below, you don't have to be very precise when applying the solder.

    attachment.php?attachmentid=102998&d=1374699874

    I would have sworn the chip was straight when I soldered the first two leads but as you can see below it's a little crooked.

    attachment.php?attachmentid=102999&d=1374699891

    I didn't want to risk damaging the traces by attempting another chip removal so I left it a bit less than ideal. I'm pretty sure the only down side to the crooked chip is cosmetic. No one tell Jim; maybe he won't notice?

    I found demos to test each of the Propeller's I/O pins. I used LEDs to check P0-P7. It all seemed to work okay so hopefully Jim will be good to go.

    Duane,

    I have also had the same scenario repairing Proto Boards and Propeller Project boards. They look perfect when you solder the corners, but they look skewed afterwards.

    But they work!. That's all that matters.

    Good job Duane!
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