[Heathkit] [Boatanchors] Heathkit SB-200 Question - Seekingadvice

[Joe Stefanelli]

Has anyone tried "PB Blaster."  Buy it at your local car parts supplier.  It 
is the most amazing rust-dissolver/penetrant.  I was skeptical, but after 
breaking two wrenches and failing with a torch and penetrating oil, I 
sprayed PB Blaster on four rusty bolts on my wife's car and waited 10 
minutes.  All four then screwed right out with minimal effort.  Nothing's 
like it.

I would only caution you to keep the unit positioned so that the liquid 
won't drip into the electronics.  Let capillary action draw it up and around 
the shaft.  Just keep the outside edge of the hole wet and give it time to 
work, or let gravity help, but apply sparingly.  Also, wipe off of paint or 
finish quickly to prevent damage to that.

-Joe

-----Original Message----- 
From: WQ9E at btsnetworks.net
Sent: Saturday, April 09, 2011 12:20 PM
To: whitebear1122 at comcast.net ; boatanchors at mailman.qth.net
Cc: heathkit at mailman.qth.net
Subject: Re: [Heathkit] [Boatanchors] Heathkit SB-200 Question - 
Seekingadvice

Scott,

What has worked best for me in freeing stuck shafts is to heat the shaft 
with a fairly large soldering iron and then add light (5W-20) full synthetic 
oil which will get pulled in between the shaft and bushing as it cools.  It 
usually takes half a dozen heat/cool cycles but only once has it failed to 
work and that was in a radio that came from long term storage on the floor 
of a damp basement.  Use full synthetic and don't use anything larger than a 
soldering iron or you will cook the oil and make it worse.

Rodger WQ9E

----------------------------------------
From: whitebear1122 at comcast.net
Sent: Friday, April 08, 2011 8:50 PM
To: boatanchors at mailman.qth.net
Subject: [Boatanchors] Heathkit SB-200 Question - Seeking advice

I just acquired a nice SB-200, looks nearly new. The frequency knob doesn't 
turn. It doesn't budge. When I couldn't get the knob off I figured I was at 
the verge of a new adventure in restoration.. I eventually got the knob off 
but I had to wale on it. Oddly the knob insert stayed on the shaft.. 
Geez.... I got the insert off with the pliers. Don't know what the deal is 
with that.

The detent mechanism grease looked minimal and old I though perhaps it was 
stuck on old grease so I sprayed it with WD-40 and let it set for a while. 
Still wouldn't move so I removed the whole rotary switch assembly. It was 
easy enough to remove. I did have to unsolder some of the wires on the 
outside wafer so it would move out of the way and allow the shaft to back up 
enough to lift the whole assy out.

I then disassembled the rotary switch assembly and removed the detent and 
shaft from the wafers. The shaft still doesn't turn. I put the edge of the 
detent mechanism into the vice and used some pliers to work the shaft back 
and forth. Nothing. It doesn't turn like it should, but the bushing moved 
along with the shaft. Geez.... I'm guessing the shaft is corroded into the 
bushing.

About all I can think of is to saturate it with WD-40 with the bushing 
facing down, hopefully getting the WD-40 inbetween the bushing and shaft, 
then put it a baggie to minimize evaporation, and let it sit overnight.

As I think about it, I suppose I could try to heat up the bushing assembly 
and see if there can be some expansion to pull away from the shaft.

I have never encountered this difficulty before. What a pain. Well, I am 
able to get further into the amp and clean out the dust.. hi hi

Since I've got you on the line, one of the 572's has a loose cap. What is 
the glue of choice to secure the cap to the glass envelope?

Any suggestions are appreciated. Thanks. 73, Scott WA9WFA
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