[Nathan Slingerland]

Today I restuffed all of the bakelite blocks.

Bakelite Blocks

I took some pictures of what I do - which is to desolder the block entirely. Other people work on the blocks in place. Everybody does things differently and that's OK.
I guess I prefer to remove the block in order to make it easier to install the new components and clean it up a bit. When everything is unsoldered it's also a good opportunity to check the values of any connected resistors.

Also - for working with these block I highly recommend Steve Davis's tools.

[Image: https://farm5.staticflickr.com/4827/4663...9288_z.jpg]

Step 1 - Desolder and Mark Connections

Desolder the connections to the block. I use desoldering braid to soak up the solder and wire markers to keep track of how things are connected.

[Image: https://farm8.staticflickr.com/7847/4572...7e97_z.jpg]

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Step 2 - Disconnect Caps

Each terminal of the bakelite block is attached with a brass rivet. Wires connecting to the capacitors in the block pass through the rivets.
The blocks on this set are the variety where the rivet holes have been filled in with solder. Maybe Philco did this in an attempt to slow down the eventual degradation of the caps? Who knows.

I use a 1/16" drill bit to drill them out. If these were the blocks that have rivets that aren't filled with solder I would instead just use the screwdriver handle with a drill tool to cut the wires.

[Image: https://farm5.staticflickr.com/4908/4658...e9e3_z.jpg]

Step 3 - Heat and Remove Tar and Old Caps

Heat with heat gun (low setting) and push contents out with tool:

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Step 4 - Clean Up

As you can see this block is pretty dirty.

I use desoldering wick to remove any remaining solder from the terminals and also the connection points for the contents of the block (middle of each terminal).
Next I use a brass bristle brush to clean any dirt and flux off of the terminals.

[Image: https://farm5.staticflickr.com/4840/3276...4360_z.jpg]

Finally I put a small amount of Goo Gone on a paper towel to wipe off the sides. The block is almost like new at this point.  

Step 5 - Restuff With New Caps

I rely heavily on Ray Bintliff's Philco Condensers And More book (4th edition). More info can be found in the Philco Bakelite Block Condenser Data post in the Tech Section.

Just look up the part number in the index - that tells you which page the block's diagram can be found on.

[Image: https://farm8.staticflickr.com/7823/4658...81c3_z.jpg]

[Image: https://farm5.staticflickr.com/4882/4572...37d0_z.jpg]

Great! It's a dual 0.09uF block with connections as shown. I'll use 0.1uF 630V radial caps to restuff in this case.

[Image: https://farm5.staticflickr.com/4860/4572...95a9_z.jpg]

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Step 6 - Reinstall

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The other blocks were pretty much just rinse and repeat.

[Image: https://farm8.staticflickr.com/7906/4572...ae07_z.jpg]

The only special case are the 0.015uF capacitors across the AC line to chassis where you need to use Y2 rated capacitors. They're designed to 'fail open' rather than possibly shorting out when they eventually fail. There's some good info on justradios.com.