DIY PASS F5 BUILD THREAD

[luvdunhill]

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.

heh... I'll be a bit of a tease.. try measuring them with your meter and tell me what you get

[swt61]

Yes you're absolutely right, they do measure 1K. Odd, why would they be different than the ones labeled 1K?

[Beefy]

Are you sure it is 100IF? Might actually be 1001F?

It probably follows the convention that the first three numbers are the start of the value, and the next number is how many zeros to follow it with. So a label of 1001 is 1000 ohms. 1002 is 10000 ohms.

At least that is how it is for Vishay Dale resistors......

[luvdunhill]

Yes you're absolutely right, they do measure 1K. Odd, why would they be different than the ones labeled 1K?

well, 1001 is another way to say 1K. 1002 would be 10K 1003 would be 100K and 1004 is 1M and 2201 would be 2.2K (see the pattern?)

I think you might have both CMF55 and RN55 resistors perhaps ("commercial" and "mil-spec" resistors, respectively)? I'm not really sure myself ... they could be older resistors that use this different naming convention. Anyways, sorry I should have caught this based on your previous PM.

[swt61]

well, 1001 is another way to say 1K. 1002 would be 10K 1003 would be 100K and 1004 is 1M and 2201 would be 2.2K (see the pattern?)

I think you might have both CMF55 and RN55 resistors perhaps ("commercial" and "mil-spec" resistors, respectively)? I'm not really sure myself ... they could be older resistors that use this different naming convention. Anyways, sorry I should have caught this based on your previous PM.

That's quite OK, because I think I'd feel better using the same resistors as used on the first board.

[swt61]

I undoubtedly will not be embarassing any DIYers anytime soon, but I'm pretty happy with my first PCBs.

[Beefy]

Its not too bad for a first effort. I've seen worse!

I would have put some heatshrink over one of the legs of the tiny black capacitors. And you'll need to clean off the flux with some isopropanol and a toothbrush.

[cetoole]

What capacitors? R6 and R7?

[swt61]

Its not too bad for a first effort. I've seen worse!

I would have put some heatshrink over one of the legs of the tiny black capacitors. And you'll need to clean off the flux with some isopropanol and a toothbrush.

Oh cool, I was wondering if there was a way to clean the flux off, thanks.

The heatshrink is a good idea too, I may redo them.

What capacitors? R6 and R7?

Colin I'm not really sure, and they confused me for a bit until Marc showed me that they were replacements. They're labled as 50 Ohm 5% 6.5W. Marc can chime in with more info.

Edited March 28, 2009 by swt61

[cetoole]

Yeah, normally it is two resistors paralleled for greater power handling, but it looks like you just got single larger resistors. I tend to use 91% or 99% isopropyl alcohol on cotton balls for cleaning off flux, but I also tend to bubble the ends, so the cotton doesnt catch. A toothbrush may work better for you. Acetone works great too, but you have to be a bit careful.

[Beefy]

What capacitors? R6 and R7?

Just below the white box caps, on the inside of the big transistors.

Perhaps they aren't caps? I can't read the silkscreen, but it may read TH1/2.... so thermistors perhaps

[cetoole]

Oh yeah, those are thermistors for temp compensation. Didnt even see them. Definitely would benefit from some heatshrink. I think the white boxes are actually resistors, but cant tell for sure.

[luvdunhill]

looks great Steve! The thermistors should be placed as close to the devices as you can. I wouldn't worry about the heat shrink myself, except on perhaps the thermistors.

Here's how NP did it:

yup, no stinking capacitors in the F5

Does this mean my package arrived?

Edited March 28, 2009 by luvdunhill

[swt61]

Does this mean my package arrived?

Yep, showed up today.

[luvdunhill]

Yep, showed up today.

yay! my jig shipped from front panel express, so I may send that down your way soon as well, if you don't mind. Do you happen to have 3.5mm and 4.5mm drill bits?

oh, when placing the devices on the heat sink, you'll want to place them so the long side of the board is oriented along the long side of the heat sink. You can center them, or actually mount the devices an inch or two down from center. This seems to work better in my experience and thermal simulations. I cannot wait to see them mounted with stand offs and what not. Also, those orangish Bergquist pads I sent are decently hearty, but try not to torque down and untorque the devices too many times. If a tear or some other sort of rip occurs in the pads, it will be bad news ... things will burn and you'll be unhappy. So, just treat them as fragile and try not to modify things too much once they get situated. Once the devices heat up, then they will sorta melt and form to the heat sinks. You can lightly sand the semiconductors (!) and the heat sinks as well before mounting the devices. I use 600 grit sandpaper. After your done sanding, clean the area to make sure no aluminum shards are hanging around.

Edited March 28, 2009 by luvdunhill

[swt61]

Here's a quick pic of the begginings of the F5 power supply.

The 1/4" copper plate was Marc's idea from another amp he'd seen. I think it really adds something.

[Dusty Chalk]

It really brings it together!

[luvdunhill]

swt61: you get an "E" for effort, but you might not want to turn things on quite yet. I'll take your pic and mark up the changes

edit: can you remind me where the "notches"/"cut off corner" are on those bridges, so I can orient the connections correctly?

Edited March 29, 2009 by luvdunhill

[spritzer]

Very Dartzeel of you...

[luvdunhill]

meh, nevermind. I'll call the top left cap terminal "A", top right "B", bottom left "C" and bottom right "D" and all the terminals touching the copper are GND... so you need:

terminal with the cutoff on the right bridge goes to "B" the terminal caddy-corner from that one goes to GND

terminal with the cutoff on the left bridge goes to GND and the terminal caddy-corner from that goes to "C"

next step is the following:

(1) 2.2K 3W resistor from "B" to GND (it's blue colored)

(1) 2.2K 3W resistor from "C" to GND

(4) 0.47 ohm resistors (also blue colored) from "A" to "B"

(4) 0.47 ohm resistors from "C" to "D"

Let's see what ideas you have to mount the above The 0.47 ohm resistors will get warm, so whatever you do you need to make sure the bodies aren't touching each other, so they can easily dissipate heat.

[luvdunhill]

terminal with the cutoff on the right bridge goes to "C" the terminal caddy-corner from that one goes to GND

terminal with the cutoff on the left bridge goes to GND and the terminal caddy-corner from that goes to "B"

sorry, got things swapped, the above is correct.

[swt61]

swt61: you get an "E" for effort, but you might not want to turn things on quite yet. I'll take your pic and mark up the changes

edit: can you remind me where the "notches"/"cut off corner" are on those bridges, so I can orient the connections correctly?

The notches are forward, toward the Blue caps, and inward toward the toroid.

Very Dartzeel of you...

Ooh, very snazzy indeed!

[swt61]

sorry, got things swapped, the above is correct.

OK, So this is correct so far?

[swt61]

(1) 2.2K 3W resistor from "B" to GND (it's blue colored)

(1) 2.2K 3W resistor from "C" to GND

(4) 0.47 ohm resistors (also blue colored) from "A" to "B"

(4) 0.47 ohm resistors from "C" to "D"

I have the 2.2K 3W resistors (I have 3), but I do not have the 0.47 Ohm resistors you speak of.

[swt61]

With 2.2K 3W resistors...