Just started assembling my Klein Bottle! I have some SMD questions though..
I'm totally inexperienced when it comes to SMD but regardless I decided to challenge myself! Anyway, I soldered all the chips in and I thought I would use the continuity tester on each pin to make sure there were no bridges. I found that on a few of the chips the continuity tester was beeping on the first couple of pins. I tried using a wick to attempt to remedy this but had no luck.
So I decided to get a hot air rework station to remove the chips and clean up the surface in order to try again. My question is will I damage the IC's removing them this way? I'm hoping I can reuse the same chips and just be a bit more careful 2nd time around. Any advice appreciated!
Some of the adjacent pins are actually supposed to be connected. I wouldn't recommend trying to fix every one of those "bridges" without checking the schematic first.
My board with the SMD chips presoldered has multiple big solder blobs bridging some pins in a very obvious way. I was horrified until I discovered that this was completely intentional.
Thanks for your reply! Do you remember where the blobs were by any chance? I've included a picture.. they all seem to have a 'bridge' in exactly the same place: the first 2 pins from the left, bottom row. So pins 1 & 2 of the OPA1604's and pins 5 & 6 of the OPA1602 @ IC9.
I tried looking at the schematic but I really don't know what I'm looking at :( Was looking for PIN numbers of the ICs on there like in other schematics I've seen. I really need to put some time into learning to read a schematic properly! :/
The lower left pins on the larger chips should definitely be bridged, so you are good there. I can't tell from my pics of the other. I'll pull up the schematic in a bit....
Edit:
Ok, I can confirm, pins 1 and 2 of each of your circled chips, i.e., pins at lower left, should be bridged.
Make sure your IC9 is oriented correctly. I can't see which way you have it in your pic, but lower left should be pin 1.
Oh jeez I was worried about putting them in the wrong way :/ I figured the line on the chip would line up with the writing on the board. Is this correct? Looks like I might need the rework station after all!! :/
By the way, thank you so much for taking the time to investigate this for me! Can you tell me where on the schematic tells you pins 1 and 2 are connected so maybe I can learn where to look in the future?
Annoyingly, the schematic didn't give me that information because the pins weren't numbered. The PCB trace diagram shows the connections though and has the outlines of the ICs. I assumed that it matched the finished board. I can open mine up to double check if you'd like.
If you don't mind that'd be really helpful! Hopefully they are the same ICs that I have.. but if you could confirm the orientation in regards to the line printed on the IC's that would be really helpful! Thanks again for your help mate :)
Line on the left for IC9.
Thanks man I'll have to correct that with the rework station. Hopefully I don't destroy the chip in the process. What about IC13 and the other 3 OPA1604's?
The orientation of the chips in this image is correct:
(http://i.imgur.com/zeQ8K9b.jpg)
For chips that just have a line, that corresponds to the pin 1 end (replaces the half-moon indicator).
So this is where I am confused.. I figured the line ie. marker for pin 1 would be aligned against the text for ICx. Like for IC9 I put the line closest to the text 'IC9'. So I guess the opposite is true? I'm really confused haha :/
Yes, don't go by the text. Use the half-moon indicators. Is IC9 the only one you have flipped around?
Fuck! I see them now! I feel really stupid :/ no it looks like I fucked up IC13 aswell. Damn, thanks so much for your help, I really am a moron! Wish me luck not cooking the chips with the hot air! Any tips there?
I've never had to remove a SMD chip before. I do know (I use that word very loosely) that some of these kinds of devices are moisture sensitive and absorbed moisture can cause failure during rework heating (by turning into steam and cracking the carrier, I believe). You would know if you have such sensitive chips by how they were packaged when you received them (sealed package with a moisture indicator card or a bizarre instruction to install the chip within a certain timeframe).
Good luck!
Yes they did come in packaging like that. I think I'll play it safe and just get replacement chips and take the loss as a learning experience. Thanks again man.
By the way, as a heads up (even though you won't get there for a while), Peter never reveals in his build instructions how he manages to solder the two potentiometer pads located between C5 and C21. This was the hardest part for me. The right-hand pad in that spot can be left unsoldered (it doesn't electrically connect to anything). The left-hand pad there is a tight reach. If I had to build this again, I'd leave C5 off until after the pots are soldered and then solder C5 in topside by keeping the leads long. But, you can come up with your own strategy when you get there. ;)
Thanks for the heads up, I'll definitely take that into consideration when I get there. Have had some challenging builds where it gets pretty tight when it comes time to solder the potentiometers.. I've definitely scorched a few caps! Would love to avoid this sort of thing though :)
Quick update: I used my new rework station to desolder those 2 chips and soldered a couple of new ones in the correct way this time :)
Man you weren't joking about the lack of space between the caps and pots!! Doesn't help I got the 4x .47uF WIMA caps from Tayda because Mouser didn't have them in stock.. they are a little thicker than the outline on the board so there's a bit of overhang on each side.
Anyway, I was thinking maybe I should solder in everything apart from the electrolytic caps that are obstructing my access to the pots, then just like in the video I'll put the pots and switches in loose then insert the lot into the enclosure and solder those in place so I know it's all going to line up perfectly with the drilled holes. Then I can take it all back out, solder the caps and wires in and continue on from there?
Will watch the video again and see if that is going to cause issues. Can't see that it will but better safe than sorry.
My .47uF caps were a bit wider as well, and I think I used the ones from Peter's shopping list (I did have to substitute a few components to avoid backorder, but I'm pretty sure I didn't change those).
For the trickiest solder joints, I ended up soldering all of the components but taking the board out of the enclosure to solder the pot pins from the back. I had to bend the pot out of the way a bit, but it still lined up fine afterward (not ideal, but should hopefully hold up well).
One more heads up while I am thinking about it: the powder coat on my enclosure was coating quite a bit of the inside of the box. If I were to simply assemble it as instructed, the enclosure would have been ungrounded due to this insulation around every jack (yours may be different). I chiseled off some of the finish inside the enclosure so that the output jack sleeve could make electrical contact.