PL 700 Pro Build

[laatsch55]

Amen Joe!!

 

[George S.]

I saw a post where Lee told Darcy to use a "acid brush" to clean the flux off the board. Oh yeah! Much better than a tooth brush.

 

[laatsch55]

Plus they are cheap and disposable...And if you cut the first 1-4 to 3/8" off they can be rather stiff...

 

[MarkWComer]

Now it's time to adjust the output transistor emitter and base leads to fit the solder cups. Later, the output transistors will be attached to a magnet on a stick and dropped down between the heatsink fins. Those leads need to have the correct spacing to enter those tiny solder cups.
Once all 24 outputs are checked for lead alignment they'll be put away until the "bring up" procedure. Output lead alignment can also be checked at anytime using one of the old sockets.

I just made sure the legs were straight and unbent.
Every one dropped in easily.

 

[George S.]

I just made sure the legs were straight and unbent.
Every one dropped in easily.

Some of those outputs were off enough that it would be a struggle. None were bent, just off enough to be a issue. These seem to all have rather blunt tips, seems like the earlier ones were more pointed.
I also hate to force anything. Without pointy tips it will be more difficult to determine whether it just needs a little pressure.

 

[George S.]

For those of you who haven't built these before, all the component leads need to be flush cut below the PEM nut height. This insures no contact with the chassis which would be a short.
Clearance is not as tight as it looks as the nuts sit on the stepped washers.
Wiring will be installed in the backplane boards after the control board is built

 

[laatsch55]

A straight edge across the PEM nuts will tell ya all ya need to know...

 

[George S.]

Now I see why Joe's 700 replacement chassis are popular. I have a potential issue with two of the chassis screws. One will for sure make contact with the Phoenix connecter, and the other directly above it will be close to a output transistor bolt.
Think I'm going to cross thread a fine thread machine screw into those holes, cut the ends off with a Dremel cutting disk, stake the "filler" with a center punch so they can never be used again.
Two new holes will be drilled directly in between the backplane boards.
While I'm at it, I'm going to look at moving the main fuse holder to the hole for the original cord, and see if there's enough room to mount the accessory fan power plug in that bottom corner.

 

[George S.]

Thinking the chassis is ready for deburring, cleaning and a little paint touch up. I'm pretty happy with the power socket and fuse layout.
Got those problem screw holes filled and staked. Only way those fillers are coming out is by drilling. If I was painting the chassis I'd have brazed them closed. Don't want to take a chance of someone threading a screw into those way in the future. Got the new holes drilled and threaded.

 

[George S.]

Broke out the desoldering station to clean the terminals on the accessory power plug, thermo breakers, and bus bar.
While it was out, went ahead and removed the Zobel Network from Don's DCP board. Each channel gets a resistor and capacitor removed as these components are built into the backplane boards.

 

[George S.]

So last evening I cleaned the original busbar. On examination it's not as flimsy as I thought. Been thinking about it this morning. I'm going to reuse it. Will have to drill extra holes for additional ground wires because I'm wiring the backplanes in the dual mono configuration rather than daisy chaining them. Going to solder those connections to the busbar using added flux (Radio Shack rosin paste flux) and use the old Weller pistol grip gun. This is the one place on the build that added soldering wattage and paste flux is really advantageous.

 

[Wheel-right]

I use my Weller pistol grip way more often than not, acquired habit from auto stereo installations where a hot iron is not a good thing to have laying around.

 

[George S.]

When I was a kid the only soldering equipment I had ever seen were those old Weller guns. I can remember seeing guys fixing cars and old radios with point to point wiring with them. Every hardware store had them along with those funky tips that need to be bent just right.

 

[J!m]

I think I have one, in the original box. It’s used, and I’m not sure where it is right now, but I’m pretty sure it’s around.

I also have a butane one that I brought to Africa with me. Never used it there however.

 

[Wheel-right]

When I was a kid the only soldering equipment I had ever seen were those old Weller guns. I can remember seeing guys fixing cars and old radios with point to point wiring with them. Every hardware store had them along with those funky tips that need to be bent just right.

They still have them in most of the stores I frequent, tips are pre-bent now too. I still have two of them and use them too much probably...

 

[George S.]

For those who haven't built these before, Joe emails a extensive amount of documentation for the kits. That's 41 different WOAD files on the desktop. Each file is comprehensive and professional and covers a different aspect of using his kits.
I'm now starting assembly of the control board. I'll be building it fully complementary because I'm using the backplane kit and complementary outputs.
I now need to review the build documentation and set aside the parts that are for the quasi-complementary version.
Everything is labeled and prebent. A good thing as there are a HUGE number of components.
Finally, of photo of the bare board beside the original for those who are wondering about this. Real dramatic difference wouldn't you say!
Once I start soldering, I'll use a small chisel tip on the boards bottom side and a a very long pointy tip on the topside for touchup. Plenty of heat sensitive components on this board so use common sense and good soldering practices. This board has a much finer pitch than the backplane boards.

 

[George S.]

A precision 0 ohm resistor. LOL. Joe takes his designs to the extreme limits.

 

[laatsch55]

By god...0 ohms SHALL BE 0 ohms!!

 

[Gepetto]

By god...0 ohms SHALL BE 0 ohms!!

But they never really are...

 

[George S.]

But they never really are...

Your right(of course!), 0.2 ohms on the Fluke. Guess you needed a small amount of resistance there as they replace a trace. Looking at how you use them on the double sided board confuses me. I'll look at the schematic this evening.