Majestic12 builds Drip Fairchild 670

[Majestic12]

A few parts are backordered, so I still have to wait to finish the main pcb. In the meantime, I'm working on a stand for the whole unit since it's way to big to be fitted inside any usual studio rack.

 

[radiance]

Here a nice & cheap rotary for the lat/vert mode

http://www.ebay.com/itm/Grayhill-16-pole-3-position-rotary-switch-w-adj-stop-1-4th-Shaft-/350546551730?pt=LH_DefaultDomain_0&hash=item519e33e3b2

 

[groovypower]

@Majestic12, I am very impressed with your skills, very inspiring

I will be following closely, even though I just had to put up my PCB + full set of Sowter and Hammond iron up for sale on the black market forum. Someday, I will build this, but at the moment life is a little too crazy for me to go for it. I'll be drooling over your future posts...

 

[steve honest]

WOW
that look s amazing , and you have done a really nice job of the build ,
im drooling.

steve

 

[Majestic12]

Well, it's not finished yet and far from the first "power up"... but thanks for the kind words

I just got a bunch of tubes for it. Next month I will probably order the 8636 from JJ. Anybody else need some? I can get a good price when ordering a whole bunch of them.

 

[johnny dance]

hey yes! I need to order them too! (also building a 670 atm... just waiting on the transformers...)

btw, do you have any idea how you are going to wire up the time constant (what switch, what wire (ribon)?) That is one of the things I am not 100% on...

 

[Majestic12]

I simply put the time constant pcbs on the side of the case since they won't fit directly on the frontpanel. I already have some grayhill rotary switches that I will hook up with some ribbon cable (a heavier gauge one...not the cheap stuff...)

 

[johnny dance]

Would love to see some photos of this part.... if you have them....

 

[johnny dance]

My problem is that I am using Mundorf caps and they are on the side as well.. so the sides of my case are getting pretty crowded!

 

[Majestic12]

A just stack both time constant pcbs and put them on the side. They don't take up much space.
The ribbon cable is 20 AWG and rated for 4A / 300V. Just don't use the small diameter stuff that is (was) used for HDDs and so on...

Yesterday I checked some caps and burned on if the 8uF caps by applying 90V AC.... although it was rated 250V. Better check every part before soldering it in...

BTW, the 6,3V heater rail is working perfectly, I just put in some tubes to check it.

 

[johnny dance]

Looking good!

FYI what I am doing is putting the lower time constant switch in the Lat/vert slot... I am soldering the switch onto the pcb's


what are you using for the balance pots? I got the triple stacks drip mentioned, but they aren't fitting in the space...

 

[johnny dance]

I would also love to know what you are using for the Meter switches, as the ones I have (From the bom) don't have a long enough shaft given the metal 'holder' for them and the bias trims... have you come u with a solution there?

 

[Majestic12]

I would also love to know what you are using for the Meter switches, as the ones I have (From the bom) don't have a long enough shaft given the metal 'holder' for them and the bias trims... have you come u with a solution there?

Good point....I haven't ordered the meter switches yet (I just put in some alpha pots on the back on the frontplanel to have something to attach the knobs to and see what it looks like when its finished ).
There are some small sleves with two screws to extend short pot shafts. Maybe something like this will fit

http://www.conrad.de/ce/de/product/183731/KUPPLUNGSMUFFEN-66;jsessionid=8198B6A1F9E7508ED5861277CDD0A961.ASTPCCP9?ref=oz

Otherwise I would simply extend it by using some spare 6,3mm shaft and 2-component glue.

 

[johnny dance]

oh yeah forgot about them! thanks!

 

[gandhalf3]

Somebody tried something good for the stereo link ?

 

[Majestic12]

Stereo Link is realized by simply connecting both "+" pins from the time constant pcbs, just like in the schematic.

 

[gandhalf3]

So, I did it.
For doing a stereo link you have to :

- disconnect the + of each channel on the main PCB of the Timeconstant
- and connect together the + pins on the Time constant PCB with a piece of wire.

 

[rob_gould]

Any update on this project Majestic?  I'm sure I'm not the only one desperate to see how it is coming along!

Cheers

Rob

 

[Majestic12]

Unfortunately not. The PCBs are both ready, I'm still saving money for the tubes and transformers. In the meanwhile I tried to build a wood case for the whole thing but some of the wood panels got warped and right now I try to make them even again....

 

[radiance]

In the meanwhile I tried to build a wood case for the whole thing but some of the wood panels got warped and right now I try to make them even again....

Why the wooden case? Did the case in the photo above did not work out well?