Fairchild 670 DIY In Progress

[fazeka]

CJ! You're out of control, dig? I love it!  ;D

 

[dmp]

Where do you get the nice spools of wire?

 

[buildafriend]

This thread seems to be more fun than my electronics HW. Problematic for me, but so inspirational!! this is super cool looking thus far! Thanks for posting about it and adding pictures!

 

[CJ]

hey no problem,
you can get that cloth wire at antique electric supply in arizona,

single strand so no stripping,

 

[CJ]

had a slow day but made some progress, had to grind it out, rework, looking up new pinouts, checking out pics of a real unit, looking for missing tube socket pins, all the fun stuff,

did some work on the pwr supply section while waiting for more 9 pin sockets, installed the first turret, also mounted the first component, a metal can cap, soldered the lugs to the chassis so i could go cheap on the clamp and also get a kick ass ground down near 0.00001 ohms, 

should be able to skip the 47k-100 pf parts on the bh7a plates as this was probably an add on the make the control amp stable, with the newer output transformers, these parts will hopefully not be needed anymore,

 

[rob_gould]

This is completely bonkers. I love it!

 

[dagoose]

damn CJ..

 

[CJ]

mostly fab work today, figured i had enuff wires soldered so that flipping the chassis with all the iron on top would not have to be done that many more times,

sprayed the Sowter iron black to match the Chicago pwr trans and choke,

decided to use hardware to mount the pwr tube sockets as the heat from those guys could melt the panties off a  nun,s granny, this means the sockets lead a tough life and might need replacing,

that can is a 80/60/40/20 at 450.

the two 350 volt at 140uf will be changed from can type to axial sprague atoms under a can possibly, thinking of getting a Fender cap can to cover the caps and also look like a Sola constant voltage piece of you know what, no need for regulated heaters with today;s power, i hope,

no need for the 4 uf at 600 ac, that was a PCB cap back then, so we choose the chi town choke input combo, so no input chemical death cap from 1942 needed to be retro, 

we are running choke input here instead of cap input like the original,

the choke is matched to the pwr trans for choke input,  and if you run cap input, you use two different model numbers for that circuit also, they have the pwr supply tuned up for ripple rejection and and regulation and also to give you the same voltage, choke input needs a higher voltage transfomer i believe, and the henries are different, 8 vs 12, 8 for cap input, 12 for choke input if i remember right,  you can read about it in the chi town xfmr catalog from 1940 or whatever,

 

[zayance]

I guess flat head rivet would work also instead of soldering as you did for the Tube sockets.
Would still save space, and won't have sharp edges.
Wouldn't move anymore also.....
Just thinking.

 

[bockaudio]

You found a Chicago power xfmr?!

 

[CJ]

Andy's Garage

he has everything in there,

pop rivets would be cool, on my way to home repot,

 

[CJ]

bought some sheet metal for the sides, wired up the GZ34 socket, choke, mounted 5 turrrets, slow day but the sphagjetti factory should start to clean up, switched the wood sides to protect the turrets and added some blocks on the other side to make everything even with the pwr trans, notice the terminals are different than the original, the orig had flying leads, but the wires would be pretty toasty by now on an original, so good thing we have the solder lugs instead,

 

[mac]

Can't wait for the next chapter CJ.....raisin the bar brother!!!!


8)

Mac

 

[CJ]

picked out the resistors and caps, bought a heavy duty power cord and found some tubes in the tube caddy, gonna need more tubes and more iron, and a boat so i can use this for an anchor if it blows up, 

 

[mich]

wow,last pic starts to make sound.....
what tubes are you gonna use for the 6386's?6386?

 

[bockaudio]

Andy's Garage

he has everything in there,

pop rivets would be cool, on my way to home repot,

So I should stop by on my drive up to AES next month.......

 

[CJ]

you can stop by Andy's but we cleaned out all the good stuff, packrat and a few others, there are still some Lambda tube power supplies, if you never seen one of those, holy salmon, i bet they weigh more than the 670,

JJ tubes, these freaks on evilbay want $399 a pair, but it now, for tubes that might be third hand rejects, what a crap shoot, 120 a piece ain't bad considering the stress reduction, gold pins mean you can solder right to the tube, 

 

[Ethan]

CJ's back in the saddle! 8)
Go CJ go!

 

[buildafriend]

18 tubes and how many transformers? DUDE! I really can't wait to see more.

 

[DaveP]

CJ,

I remember seeing a really old pic of the schematic up on your wall, so this has been a long time coming.
Then there was the interview with  Narma which cleared up some important details.
You have really put in the hours on this project and its great to see it coming to fruition.
If anyone can recreate this beauty you can
great start Mate.

best
DaveP