[GreenKeys] Minor problem with my Model 20

[Don Robert House]

Hi Bill,

First off 30 weight oil is only recommended in the Teletype practices  
for tropical climates when the machine is in 24/7 service.
The KS oil we used in the Bell System was canned under contract with  
the American Oil Co. of New Jersey.  It was SAE 20.
In cold climates Teletype recommended SAE 10 with a small about of  
Kerosine added to lower the viscosity even further.

Your symptom of intermittent garble after oiling the machine is a  
classic.  Normally this is caused by the oil migrating into the  
selector mechanism.
The selector is not supposed to get oil into the armature.  The only  
lubrication in that area is to put a small amount of grease on the  
springs.

Our method for caring for this problem is to use strips of 20-25 pound  
bond paper about 1/2 inch wide and 3 inches long to clean the armature  
and the top of the selector magnet surfaces. You keep putting clean  
strips of bond paper between the magnets and the armature and hold the  
armature and pull out the strips of paper until the paper comes out as  
clean as it went in.

You could have other problems but this is my best advice for now.

Good luck,

Don



On 20 Jan 2009, at 12:17 PM, Bill Buzbee wrote:

The recent flurry of email regarding the Model 20 that was recently on  
eBay made me want to get my Model 20 up and running again.  A year or  
two ago, I moved it out to the garage to make space for guests, but it  
never made it back in.  Anyway, it was a warm and sunny weekend, so I  
took the opportunity to give it a good oiling (mostly 30-weight non- 
detergent motor oil), and then tested it while still in the driveway.   
It worked perfectly, and I moved it back into the house.

The next morning, however, I fired it up and was greeted with  
extremely garbled text.  I assumed I must have knocked something out  
of adjustment moving it into the house, and so spent a half-hour or so  
fiddling with the baud rate and range finder.  After a while, it was  
printing perfectly again.  However, later in the day I tried again and  
got garble.  Only then did I realize that it wasn't out of adjustment  
- but the bad copy was a function of whether the machine was warmed up.

I did one more experiment this morning.  I turned in on, but printed  
nothing for a half-hour (not running open, just running).  Same garble  
when I started printing, and it cleared up after about 20 minutes of  
copying text.  Following is a link to a photo of the same paragraph  
(from the AP "News on the Hour") with a cold machine, and again after  
20 minutes of printing:

http://www.homebrewcpu.com/garble.jpg

So, what would folks recommend I do?  Am I likely correct in assuming  
that I've just got some old gummy oil somewhere - or did I perhaps  
miss something that needed oiling.  Any advice would be appreciated.

Thanks,
...Bill Buzbee

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