When you are having a bad day - Page 1
Forum section: electronics / general

author: TerraHertz
author_rank: Super Contributor
timestamp: December 02, 2016, 03:42:48 am
content: Like my bad day yesterday.This could have been in 'Repair', except it wasn't.An old friend has been doing some work with a Xilinx development board.This:http://zedboard.org/sites/default/files/documentations/PicoZed_FMC_CC_GettingStarted_v1_0.pdfmounted on this:http://zedboard.org/product/picozed-carrier-cardEven that carrier board is quite expensive - about $700. He's been using it for a while. There is *one* USB port for PC interface and loading, and the plug is a USB micro-B format. Talk about critical single point of guaranteed failure...Yep, the connector broke off the PCB. No he isn't ham-fisted. So he brought it round to my place yesterday to see if I/we could solder it back on. Neither of us have great eyesight anymore, and those things are tiny. At least I have inspection microscopes, and he doesn't.Well, the day didn't go well.The intitial idea was to secure the broken-off micro-B socket more solidly nearby on the board, and jumper it to the original pads.First check I wanted to do mainly from curiosity was with a couple of scrap USB cables, to try the data pair reversed. No, it doesn't work if reversed, while the splice did work fine with the data pair connected right way round.I thought I'd better check if short lengths of kynar wirewrap wire are incompatible with USB signals, or not, before hacking his $700 carrier PCB. While also verifying that I could actually solder fine wirewrap to the TINY leads of the micro-B socket.So made a short test setup: original USB-A to micro-B cable --> the broken off socket --> soldered kynar wire --> very short USB lead to Type-A female socket --> any random USB device.Aim: Plug it into my PC's USB hub, see if the device responds.Didn't take pics yesterday, unfortunately. Here's the "very short USB lead to Type-A female socket" part. The kynar wires started out about twice that long, bare ends were soldered on the micro-B pins. Yes, it was possible to hand solder to the tiny things.In setting that up, it turns out the micro-B connector has 5 pins not 4. And anyway, which way do the pins number? Also is the USB data pair polarity important? Apart from a few times I've had to extend/rewire USB cables, I've never looked at the specs in detail, after the first time I opened them years ago and decided I hated USB enough to never want anything to do with the details. (Master-slave, enumerated device classes only, polling only, half duplex, multiple connector types... f*ck.)So, pinouts from Wiki:https://en.wikipedia.org/wiki/USBNote the ambiguous word 'receptacles'. Which is the recetacle, the cable plug or the mounted socket?You know that thing where you are talking with someone, and so don't pay enough attention to what you are doing?That. Sucks.I took 'receptacle' to mean the board mounted socket. Result: I wired the connector back to front. And for 'random USB device' I'd grabbed my universal flash card reader box. Which being cheap Chinese has no protection against reversed polarity USB power. It took a little while to work out what was wrong, and in the process my card reader died. Death #1 of the day.Spotted that error, fixed it, determined the card reader was really dead, checked all the signal lines through that chain were right with no shorts and opens, still no USB device plugged in would work. They'd start to respond, the active light would light on the hub, then would go out again.OK, so about two inches of kynar wire is too long, impedance wrong, too much reflection etc. Not soooo surprising.I cut the lengths in half, to about an inch. Still doesn't work. Still the brief activity LED, then failure. Interestingly, if I also connected the shield braid through, it wouldn't even start trying to activate.This had taken a while. Now we decided, OK, just solder the micro-B connector back on the board where it was originally. Can do, with solder paste and a hot air pencil, though it has that horrible problem where the pins are underneath the end of the socket body, the spacing is very fine, and there's nothing to align the socket position, so it has to be placed very accurately by eye, then clamped there during hot-air soldering. Also there is no way in hell I could dispense solder paste in patterns just on the tiny, tiny PCB pad areas, or get the socket pressed down without smearing the paste. So it was awkward.That took me three tries before getting it right, with the pins aligned and no shorts or opens. As tested with a multimeter via a plugged-in USB cable and probing pins on the surface mount parts near the connector. (with needle point probes.)It had also turned out that the online schematic for the carrier board has some differences to the actual PCB, which didn't help at all.But sadly, it seems the USB to serial chip on the board is dead too. Why, don't know. Maybe it was overheated during the three plug solderings, since it's very close.Next best idea is to piggyback one of these modules, wired directly to the logic level serial lines:https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20161201155611&SearchText=usb+to+serial+adapterWhich is how the board should have been designed originally, to allow quick replacement when (not if) the stupid micro-B breaks.However getting one, even locally, won't happen that day.So an all round fail. But that wasn't the worst yesterday.There's a few things lying around on my desk. Including parts of a module from a military GRC-106 radio, that is in the hard basket. One of the components is a lovely, rare 5.0000MHz crystal with a glass case. At one point while talking to my friend I picked up the module to show him, forgetting that the crystal was just sitting loose in it.The crystal fell out on the concrete floor, and of course broke. Arrgh! When I ever get this thing fixed I can sell the radio for nearly two thousand dollars due to its antique collector value. Now it's minus the crystal, which I expect will be unobtainium.My clumsy fault, talking, not paying attention. But it really screwed my day.I don't suppose anyone has a dead 1A3 frequency reference module from a GRC-106 lying around, with an unbroken crystal?To round things off, in the evening a bit before 8pm I drove to the local Jaycar store to buy a replacement flash card reader. Thursday night, I didn't check their closing time. It's 7:30pm.Anyone else had a fail train day lately?

author: edpalmer42
author_rank: Super Contributor
timestamp: December 02, 2016, 04:41:14 am
content: Good news:http://www.ebay.com/itm/252645291829Bad news: $79That guy's prices are always too high IMHO.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 02, 2016, 06:51:22 am
content: Quote from: edpalmer42 on December 02, 2016, 04:41:14 amYeah. _That's_ not happening.I should also mention I have a bunch of these radios, so one busted crystal is not a disaster. It's just annoying. More hurt pride - clumsily dropping and breaking such a nice thing.

author: @rt
author_rank: Super Contributor
timestamp: December 02, 2016, 07:16:12 am
content: The crystal is beautiful! Such a shame

author: calexanian
author_rank: Super Contributor
timestamp: December 02, 2016, 06:43:34 pm
content: The actual crystal inside looks fine. It may very well still work. The cover is only to keep dust from changing the mass and frequency. I do not believe they are under vacuum. I believe its dry nitrogen inside.

author: Ampera
author_rank: Super Contributor
timestamp: December 02, 2016, 07:12:30 pm
content: You want one bad day?How about 2-3?I built a 486 gaming machine, beautiful thing, it has an AM486-DX4-100, EXP4045 motherboard, etc.etc.So I originally wanted to test the board outside of the case, but to my annoyance, I couldn't place the graphics card in because the bracket reached below the board (Get to the obvious solution to this later)so I'm like "Screw testing it outside, let's just throw it in the case." So I prepare the case, remove all the original components (Was an ATX case I stole from another machine) and throw the board in. Well this board is BabyAT, and has a screw layout slightly different to ATX. You can still place the board and screw it in just fine, and it will work perfectly fine, if you remove all the unneeded standoffs first.So after 3 days of bending the board and moving cards around (They were VL cards, so I was wondering if it was just a bad connection causing the cards to hang the system) in a game of musical chairs, I finally was given the bright idea to take the board out of the case, and test it (To test it I place it on the table with the card brackets hanging over the edge). Yes, it worked. and I found out my double jeopardy.There was a standoff I didn't remove, and there was a standoff I COULDN'T remove, to rub it in. It was a built in standoff that was in a place the board didn't have a hole, so it and the standoff I forgot to removewere touching some traces on the board. Thankfully, so bloody thankfully, I didn't bust the board, but I wasted 3 days and pissed myself off to no end trying to get the stupid thing working.Electric gaffing tape later, the standoff was covered, and the other one removed, board is working fine to this day.Except for the memory, which was different from what I orderedOh, and except for the sound card which was advertised and labled as a tested AWE64, except it was an OEM version for system builders that wasn't actually an AWE64, because it was missing the OPL3 chips and the MIDI synth, so it was just a crippled SB16 (Which is already weaksauce enough)

author: bktemp
author_rank: Super Contributor
timestamp: December 02, 2016, 08:54:00 pm
content: Quote from: TwoOfFive on December 02, 2016, 07:12:30 pmIf it works at the end, then it wasn't a bad day but a successful day.You have been very lucky. A couple of years ago I helped a friend finding the fault in his new gaming PC.Short version: While he had assembled the PC, a screw found its way into the narrow gap between motherboard and case and got stuck near the CPU.Even after removing the screw, the PC did not work: CPU fried, motherboard dead. That's what I would call a bad day.

author: imidis
author_rank: Frequent Contributor
timestamp: December 02, 2016, 09:01:09 pm
content: Definitely have those. When I break enough things, I decide okay, that's enough and take a break from things so I don't do more damage.

author: Ampera
author_rank: Super Contributor
timestamp: December 02, 2016, 09:21:16 pm
content: Quote from: bktemp on December 02, 2016, 08:54:00 pmThe bad day would have been the motherboard was from Russia, and I was in the US.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 03, 2016, 12:57:30 am
content: Quote from: TwoOfFive on December 02, 2016, 07:12:30 pmI'm sorry, can you explain this concept like I'm 5 please? A piece of metal you absolutely can't remove? What, is it made of Adamantium or something?The words 'angle grinder', 'vice grips', 'hammer and chisel or pin punch', 'tin-snips' and 'drilling' are opposing concepts to 'can't' anything with PC cases.In my experience building improvised PCs from old cases and partsusuallyinvolves cutting, hammering, folding and drilling. Just be careful to clean out all the iron filings.Quote from: calexanian on December 02, 2016, 06:43:34 pmYeah, probably right. However it's no longer fit for purpose, which is being part of a restored antique radio that works well. For one thing, being exposed to varying barometric pressure and humidity would probably make it drift badly. Plus, the fault with that module is flakey intermittent operation, so using a now-flakey crystal isn't helpful. Oh, and that crystal wasn't the problem.It's still pissing me off.Now for today's extra annoyance, one of the utilities supplied with my 3D printer, RepetierHost_155, during setup wants to download and install MS .NETBummer. That's one of the Microsoft products I refuse to have on my primary machine. I'll have to install it only on my laptop.Why: I trust Microsoft less than I trust virus writers. Scammers only *might* find a way to harm my system's integrity, but I consider it a known certainty that MS is doing their damndest to cripple personal computing capabilities, independence and privacy, by every means they can dream up. Hacker-scammers are just doing it for money, while MS's motivations are evil-ideological masquerading as profit motive, and they feel entitled to do anything they want. Which makes MS a far greater threat. So I consider everything from MS to be severely untrusted. .NET framework being about the same threat level as Win10.

author: Ampera
author_rank: Super Contributor
timestamp: December 03, 2016, 02:24:57 am
content: I mean couldn't in the sense of you can't shoot somebody in the head, you can't crash your car into a tree. You CAN, but I wouldn't have a case I could use properly AT ALL. Even though the screw doesn't match up, I still supports the board, so if I removed it the board wouldn't mount properly, and I could forget about mounting an ATX board properly.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 03, 2016, 11:56:53 pm
content: What's wrong with putting correct threaded metal spacers in the positions required for the motherboard holes? The grounding of those pads around mounting holes is probably part of the EMI suppression design.Or, it that's not possible, remove the wrongly positioned fixed post, and put a nylon spacer there.If you are just using tape as a separator, there's a risk of any high points on the motherboard just there, eventually pressing through the tape and shorting. Or at least use some of that tough plastic insulating sheet found inside PC power supplies and such.

author: Ampera
author_rank: Super Contributor
timestamp: December 04, 2016, 12:37:57 am
content: Quote from: TerraHertz on December 03, 2016, 11:56:53 pmI put a fairly thick layer, and the motherboard isn't under that great of a pressure. And it's a bump that is part of the case, it can't be easily removed and I do not feel like taking a Dremel to it. Not to mention, but those boards are normally design to have mostly nylon retainers for older cases. ALSO the PSU is directly grounding the motherboard with multiple connections, even when the PSU is off (No standby power) there still should be a ground connection.And the issue is that this bump isn't wrongly positioned, it's correctly positioned, for an ATX board, which I am not using. If I remove the post, not only do I no longer have the majority of the board being held up by the other end of the board (Standoff is in the middle) I can forget about mounting an ATX board correctly. Electric gaff tape is the working solution. It's cheap, it allows me to take it off for use with an ATX board, and I don't permanently mutilate the case, getting metal filings everywhere from removing it making an even BIGGER and potentially irreversible problem.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 04, 2016, 01:05:01 am
content: Oh, by 'standoff' I assumed you meant a post. Yeah, those pressed bumps are slightly more of a problem to fix neatly. And if you want to preserve the compatibility for other boards...So, please accept my apology for the criticism.

author: Ampera
author_rank: Super Contributor
timestamp: December 04, 2016, 02:37:37 am
content: Quote from: TerraHertz on December 04, 2016, 01:05:01 amIt wouldn't matter if it was a post welded in either.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 04, 2016, 04:32:46 pm
content: An embossed mounting point could be pounded flat with a hammer and anvil (or suitably massive working surface). Tends to warp the surrounding material though. Hard to keep flat. (Tape is much easier!)FYI: that there is a grounding point anywhere, isn't the problem. That there's a grounding pointnear where all the RF signals are being generatedis the problem.Speaking of vintage computing, I've finally got a Compact Flash card and interface in my XT clone.That took some fiddling around.Or speaking of modern computing, I've finally got HTTPS on my website! That took some fiddling around, too...Tim

author: helius
author_rank: Super Contributor
timestamp: December 04, 2016, 05:11:55 pm
content: Bumps in sheet metal can be reduced using the appropriate methods (shrinking hammer and dolly).Or the overkill approach with a 100,000 A pulse through a coil...

author: SeanB
author_rank: Super Contributor
timestamp: December 04, 2016, 07:35:58 pm
content: That was Thursday. 10AM I get a call the gate is not working. Go down, and there is nothing showing on the controller. Think either PSU or controller, and as PSU is cheaper, plus I have a "test" one in the other gate I swap PSU. Not the PSU, so the Vector control board it is.Choices are to get a new one from Centurion, 25km away, or pay the extra and get it retail from the security store 10km away. Phoned security store, they have one, and I have some other urgent things to do as well, along with fix the gate. Get the approval and the money, and grab my assistant Ste, and off we fly to get one, plus do a collection that was urgent. Collect the board, grab the other stuff and drive back, then get my trolley of tools, a chair and down to the gate we go, with the nice warm (28C) overcast day as company. Remove gate box ( damaged from UV) and put in a new one, then start putting the old knitting in there. Power for the gate is down 30m of cable, so I am glad I have my not so cordless cordless drill to do the drilling, and that there is nobody wanting to use the gate.Box in, and assemble the kit of parts till I have the controller and power supply, along with the 2 auxiliary relays needed for the maglocks, and the existing conduits are in there. No room for the battery though, but I had that before, they live in another box next to this one already so the gate will run for 12 hours in a power failure. New wiring in places, put the lot back together and apply power.New version of the controller, new firmware and new board revision, and they include a 150R resistor " for certain compatibility reasons on certain older actuators", and guess what, the new actuator I have ( replaced 2 months ago with the spare service exchange unit) is one of them. Add to that a display that requires me to kneel down to read it, and which is tiny as well, so I need to get up close to see what is there in the dark shade.At least I only had 1 person who wanted to go through the gate, 5 minutes to move tools and chair out the way, and then unlock the actuator and open the gate, then 10 minutes to get back to where I was.Run through setup, and get it to the point where it will run, then close up and go download and print the manual for this version. Then set up close times, delays and such, but this version at least is an improvement over the older ones. It has a display with graphics and text, plus it shows position and motor currents, and has more built in test functions. A whole lot better than the older ones, which have a UI comprising 2 buttons and a single LED that flashes to let you know the mode, and then you have a very short interval to program the data in before it leaved the programming routine.As I finished the rain started, so I was not doing a Fred Astaire. Even with the overcast I got a sunburn.

author: Ampera
author_rank: Super Contributor
timestamp: December 05, 2016, 07:16:56 am
content: Quote from: T3sl4co1l on December 04, 2016, 04:32:46 pmInteresting. I was thinking about using CF, but I honestly want to go fairly original. The newest part (Not counting brand new ones, the AT PSU (Not ATX) and the 486 cooler) is probably the case, hard drives, and CD drive in the order.