Crawls Backward (When Alarmed)

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Polishing the PAS Chassis

There are a couple of things I need to do next.  The first is some more snip, snip, snip on the old filter cap can.

This is the bottom of the cap can - I'm going to just cut off the resistors and wiring.  Saving the resistors for future projects.  At least putting them in the appropriate bin.

The new power supply board I build up has all this incorporated.  The board only came with a diagram of where the components should be installed.  There are some notations on it, but I want to double check it all just to make sure I'm running the right leads to the right place.  As an aside, the board also had one of the diagrams backward, as if one were looking *through* the board...yikes.

I took a look at the Dynaco schematic for the PAS and now know where everything should be connected...but I need to check the connections to the 12X4 rectifier tube.

So...I consult an RCA tube manual.  I have 2 of them on the bench, one is earlier - it's an RC-15 from 1940 (which doesn't have the 12X4 since it was developed later...) and this 'modern' one - it's RC-23 from 1963.

I find out that pins 1 and 6 are the plates, 2 & 3 are the heaters, and 7 is the cathode.

What this means is that the HT (unrectified AC) voltage from the power transformer goes to pins 1 and 6, the 12V filament line goes to 2 & 3, and the rectified DC voltage comes off pin 7.

Here's the aforementioned bin with parts I'm removing from the PAS.  Some of these I'll reuse possibly - some of the wire for example.

The old selenium rectifier should just get thrown away.  The two electrolytic caps for the filament supply should still be good - I put them in about 10 years ago and they should have some life left.




After sitting at the workbench pondering my next move, I started looking at the chassis and I got a crazy idea.

Before I knew it, I had some aluminum polish in hand and was starting to polish the chassis.  You may have noticed there were some marks on it that were probably put on by the original builder.  For example, "PC-5", "Right," "Left," and a couple others.  I figure the polish will take them off, and also clean the chassis up.

Here it is after about 20 minutes of work.  Looks pretty good.  I also polished the can just for the heck of it.

I thought about polishing the inside of the front and back panels, but decided to pass.   They're pretty clean, and I'd have to either work around or take a bunch of stuff off.  I'm a bit too lazy for that right now.   The original builder did label the pots...eh...I'm not gonna bother.  Nobody's gonna see this anyway in the long run.  I just polished it cause I felt like it.

This is a good picture of the semi-nekkid chassis.  No PC boards, no power supply board, all the topside wiring gone.   Soon all that will change.

 
 
 
 

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