swt61 Posted March 6, 2009 Report Posted March 6, 2009 There are a few of us building this amp, and at least two of us that have taken this on as a first project, so I'm thinking a thread is in order, since I'm sure that there will be some discussion and questions.
swt61 Posted March 6, 2009 Author Report Posted March 6, 2009 So I've ordered most of the parts for my build, and they're trickling in. I orderd two of the F5 Fairchild version parts kits. Two of these mammoth heatsinks... All the connectors, switches, IEC, fuseholder and an Alps pot (going to try adding the attenuator, as my build will be mainly a headphone amp for my K1000). Antech toroid, 4 huge frickin' caps, and a chunk of copper for a cool point to point power supply luvdunhill is working up... A sheet of 3/16" aluminum for the bottom and back plates (the front will be wood), and some perforated aluminum for the top plate. Plus most of the other incidentals. Looking forward to getting started.
deepak Posted March 6, 2009 Report Posted March 6, 2009 Nice! I was eager to try my hand at it, but lack access to specialized tools. I saw Marc posted this in another thread which sufficiently scared me off Another thing about buying on the "DIY-market" is that you really need a distortion analyzer to tune this amplifer, according to Nelson... that's the only way you'll get the specs posted, as he's been quite candid about that.
luvdunhill Posted March 6, 2009 Report Posted March 6, 2009 I love those heat sinks. I am using four double height versions of those.
Smeggy Posted March 7, 2009 Report Posted March 7, 2009 That's going to be a friggin monster! Can't wait to see it's progress.
swt61 Posted March 19, 2009 Author Report Posted March 19, 2009 So my soldering station arrived and I'm ready to get to it. I spread everything out on my work surface, checked that the soldring iron works, which it does, and start looking over the schematic developing a game plan. That's about when I realize that I'm missing several resistors from the kits I ordered. Well that sucks, but maybe I can get something done anyway. Following Marc's advice of generally working from the middle of the PCB out I realize that most of the mising resistors are the ones that belong in the middle of the board. I'm guessing that this is par for the coarse, and that my frustration is not singular, but still it's damned annoying. Unfortunately I don't have a Frys near by, or the equivalent. I'd really rather not have to wait on the kit seller to re-ship the parts to me. Does RadioShack carry a decent volume of common resistors?
pabbi1 Posted March 19, 2009 Report Posted March 19, 2009 They have Xicon, which is what my local surplus guy mostly has, and on par with what Fry's has (you'd be surprised how poor the choices are there). Mouser is also a 2 day exercise anywhere in Texas, though usually next day for me (60 miles away). Oh, add this into the '%#@! I forgot' thread - and let me know when you top my '3 in one day / 5 in one week' order records for Mouser. Ain't just you...
nikongod Posted March 19, 2009 Report Posted March 19, 2009 What values do you need? Rat-Shack has an OK selection in higher power ratings. Looking at the schematic, you should be able to get most of the resistors listed from them. The only issue is that the "part to part" matching may not be so good.
swt61 Posted March 19, 2009 Author Report Posted March 19, 2009 OK, I think I'll follow Al's lead and put together a Mouser order.
luvdunhill Posted March 19, 2009 Report Posted March 19, 2009 OK, I think I'll follow Al's lead and put together a Mouser order. Steve: They were all there when I repacked the little kits. I double checked. Most troubling. I can order the parts for you if you'd like, just PM me. Might as well pick up the missing Zetex transistors as well, they're dirt cheap.
swt61 Posted March 19, 2009 Author Report Posted March 19, 2009 Well maybe I'm misreading the values, but I don't think so. Maybe I can call you later and go over it?
swt61 Posted March 23, 2009 Author Report Posted March 23, 2009 OK, so now that most of my resistor issues are sorted out, I'm finally populating my boards. However I got one of the semi-round Black things (I don't know WTF it is) backwards. Obviously it's not going to be possible to heat all three legs and pull it off, and I don't own a solder sucker. I did remove as much solder as possible with copper braid. Any suggestions gentlemen?
spritzer Posted March 23, 2009 Report Posted March 23, 2009 That would be a transistor then... Buy a solder sucker is all the advise I can give you. In a pinch you could take a small piece of wire and place it next to all 3 legs and heat the wire with the soldering iron.
swt61 Posted March 23, 2009 Author Report Posted March 23, 2009 Well after checking I found a new solder sucker for $4.36 on ebay, and that was with free shipping, so I guess I can afford that.
spritzer Posted March 23, 2009 Report Posted March 23, 2009 I would get an anti-static one if you have the chance.
cetoole Posted March 23, 2009 Report Posted March 23, 2009 OK, so now that most of my resistor issues are sorted out, I'm finally populating my boards. However I got one of the semi-round Black things (I don't know WTF it is) backwards. Obviously it's not going to be possible to heat all three legs and pull it off, and I don't own a solder sucker. I did remove as much solder as possible with copper braid. Any suggestions gentlemen? Heat all three legs together by flooding them with solder.
luvdunhill Posted March 23, 2009 Report Posted March 23, 2009 Sorry Steve... I forgot to talk about mounting those. In general, I'd recommend leaving some leg on top of the board, meaning not to squash them down close to the board. The reason being that you want to keep these things cool. Most people press them down thinking that they are keeping the signal path short or something. If I would have remembered to mention this to you, you could just have clipped them off of the top of the board and easily removed the legs and then remounted them. I usually leave ~0.25"-0.5" or so on top of the board, and when I'm feeling fancy put a bit of small teflon tube around the legs to protect them from accidental bendage. I'd try what Colin recommended, as that's what I do. It seems counter intuitive, but adding solder usually makes board rework easier. So, add a lot of solder, then work the tip (actually, more like the side of the tip, as you have more contact area this way) of the iron so it comes in contact with all three leads (if possible), or at minimum the solder pools. Play with aligning the iron this way before you turn it on, so you get an idea of the angle needed. Then once you've heated things up, reach around and pull the device out from the other side of the board with your fingers. Then clean up the holes with the solder-wick. The trick with the solder sucker is that once you heat the solder up, you have to quickly put it down on top of the solder pool and pull the trigger. It takes a bit of coordination to do. What I do is put one edge on the board and then use this contact point like a pivot and then once the solder is heated up, pivot down so as much of the nozzle is on the joint, hit the button and then remove it from the board... heh, pretty hard to describe. In short, it's harder than it seems
Mister X Posted March 23, 2009 Report Posted March 23, 2009 Heat all three legs together by flooding them with Chip Quik. FIFY Although it's a little expensive that stuff kicks ass. Chip Quik SMD1 Product Sheet
cetoole Posted March 23, 2009 Report Posted March 23, 2009 Yeah, I have heard that stuff is very nice, but never tried it for myself. Honestly, I just usually massively overbuy on parts like transistors, so just cut the old ones out and replace them.
Mister X Posted March 23, 2009 Report Posted March 23, 2009 Ha, buying extra stuffs is a lesson many of us learned the hard way. In fact that should be the first line in the DIY audio hand book. Buy a lot more parts then you think you need because you will need them!!!!
swt61 Posted March 23, 2009 Author Report Posted March 23, 2009 Marc I did leave the transistors up off the board about 3/16' - 1/4". It just seemed natural to do so, as it would have required some pressure to get them closer. I think I'll wait for the solder sucker to arrive and try that first. Worst case is I'll by another transistor as you guys have described. Good news is that the boards are just about finished. Marc, where did you say the 100 Ohm resistors went again? I have three.
Smeggy Posted March 23, 2009 Report Posted March 23, 2009 Yeah, that quick chip is awesome shit. I dobbed it on and the chip just fell off! However, before I started, I didn't realize how easily it melts and it dripped on everything
luvdunhill Posted March 23, 2009 Report Posted March 23, 2009 Marc, where did you say the 100 Ohm resistors went again? I have three. er, 100 ohms? I don't think there are any in the circuit. Ya mean the 10 ohm striped resistors?
swt61 Posted March 23, 2009 Author Report Posted March 23, 2009 Hmmm, I have three resistors that are marked 100IF. They all were in one of the kits, and none in the other. I see no place for them to go, so maybe they were'nt supposed to be there. I've located the striped 10 Ohm as you've said.
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