White Oak Audio Capacitor Upgrade for the PL 400 Amp

[mlucitt]

Here is the White Oak Audio Capacitor Upgrade for the PL 400 amplifier instruction sheet.

 

[Gepetto]

Remember to use 1 or 2 thicknesses of a manila folder (approx. 0.006†per thickness or 0.012†maximum) to space off the boards from the top rim of your caps when soldering the boards to the snap in tabs. It does 2 things:

Allows for thermal expansion of the cap and the board without putting stress on the snap in leads, the board or abrading the solder mask and can insulator.
Prevent the heat of soldering the snap in tabs and downstream expansion wires from melting the can insulator and having a short develop over time.

[attachment=1:2zp9h7hs]New_Cap_1.JPG[/attachment:2zp9h7hs]

When using a piggyback cap, I put a 0.020†thick plastic spacer shim between the top of the piggybacked cap board and the bottom of the primary cap can during the soldering operation for the 16AWG expansion wires from the primary to piggybacked cap. This allows for thermal expansion and avoidance of any contact of the piggybacked board solder connections with the plastic insulator on the bottom of the primary cap. I always prefer air as an insulator over relying on other insulating material. You can see this shim (black) in the photo below.

[attachment=0:2zp9h7hs]New_Cap_5.JPG[/attachment:2zp9h7hs]

Contrary to the picture above, I always put the shorter of the 2 caps on the front board with the terminals as this keeps the interconnect wires shorter.

 

[ksrigg]

I notice the snap-in caps you are useing have four terminals. Positive, Common and two BLANK. What do you do with the two "BLANK" leads from the Capacitors which are not used? Do you bend them down, or do you cut them off? Just wondered what the best way to deal with the "BLANK" tabs might be...

Oh, I think I see a place in the board for them...I'm sorry if this is already covered elsewhere...So they are soldered onto the board?

 

[Gepetto]

Cut them off flush with the top of the board. DO NOT attach these leads to anything. They are required to be NO Connect. These terminals are provided for assembly keying only. Ditto for the cap can, the can is supposed to be insulated from any connection (the shrink wrap performs this function).

 

[Gepetto]

Cut them off flush with the top of the board. DO NOT attach these leads to anything. They are required to be NO Connect. These terminals are provided for assembly keying only. Ditto for the cap can, the can is supposed to be insulated from any connection (the shrink wrap performs this function).

Those locating terminals are really not neutral, some of the manufacturing literature warns about that (you have to wade through a lot of fine print to find it though). They specifically say that these terminals are NO CONNECT, not to that they are not connected to anything. The can on the cap is also live in the same manner, while not tied to either one of the main terminals directly it is also NOT neutral. The can and locating terminals are loosely connected to the internals by the electrolyte connection that exists. You can notice this if the cap has any residual charge on it and you touch one of the locating terminals to either main terminal you will get a small discharge. This is why they advise you to ensure that the can insulation is not punctured or compromised as well.

When I build the cap assemblies with 4 terminal caps, I clip the locating terminals off flush with the top of the board.

 

[laatsch55]

Nice adaptation of the pana-vise.

 

[Gepetto]

Yes, it makes it easy to assemble the pair quickly with near perfect mechanical alignment.

 

[laatsch55]

Yep, love it Joe. When one has only 2 hands and 5 things to hold you figure out how to hold em or design it different.

 

[ksrigg]

Thank you. I did not know that. The two unused tabs are labeled as "BLANK" on those SAMWHA caps I got from Steve....which I really didn't understand. Now I do.