[GreenKeys] ASR-33 going crazy in local mode

[Seth Morabito]

Hello Wayne and the Group,

Well, you were absolutely right -- the answer-back drum was now too far back, and the suppression contact was touching.

I aligned it according to the manual, but then I got the "constant 0's" problem again! I almost gave up for the night, but then I figured out the real problem:


PEBCAK. "Problem Exists Between Chair And Keyboard" :^)


I had very stupidly not aligned the brush holder when I put it back on, so it was completely out of alignment. It wasn't in the correct stop position, so ALL of the timing was completely off. Of course it wouldn't work. This is a reminder to myself to read the darn manual!

So, first, the GOOD NEWS: I aligned the brush holder, and it behaves almost perfectly in local mode now!

Now, the BAD NEWS: Some characters are not printing correctly. Here is my observation of what happens:

When I press any of 0 1 2 3 4 5 6 7 8 9 0, the correct character is printed.
When I press any of Q R S T U V W X Y Z, the correct character is printed.

BUT!

When I press any of A B C D E F G H I J, the characters Q R S T U V W X Y Z (respectively) are printed in their place.

When I press any of L M N O, the characters \ ] ^ <- (respectively) are printed in their place.

If you're familiar with ASCII coding and the ASR-33 typewheel, you've probably already noticed the same pattern that I did.

At first, I was sure that things were not being coded correctly. I thought that ASCII bit 5 (corresponding to the No. 5 codebar) was stuck "on" somehow. But on closer examination, this is not the case.

When I type A B C D (etc...), those characters are being coded correctly. I even punched some tape to make sure I wasn't imagining it -- the correct bit pattern shows up on the tape. A and Q punch different, B and R punch different, and so on.

So, the problem must be in the carriage assembly. It is raising the typewheel to the 4th row when it should only be raising it to the 2nd row.

Visual inspection doesn't show anything out of whack. I guess I'll have to remove the carriage assembly and see if I can figure out what the problem is without actually taking it apart.

-Seth

On Oct 6, 2013, at 11:30 AM, Teletypeparts <teletypeparts at aol.com> wrote:

> Seth,
>  
> Oh boy, the answer is almost surely in the AB positioning.  I never remove the AB contact block because it is difficult to replace it perfectly.  There is a contact wire in the AB in the middle that is called the suppression contact.  If its touching the contact bar you will get nothing from the kybd.  Its the one with the little rectangle brown phenolic insulator on it. 
>  
> With the AB in home position adjust the AB block forward and backward till the suppression contact matches the other 8 contacts and has the same distance from the contact bar.  Sometimes the suppression contact is a little more away from the contact bar than the other 8.  Not touching the bar is important.  Make sure the contact block is squarely positioned in the base of the 33, not twisted in either direction.  Unfortunatley, the position of the Here Is white tab also affects the suppression contact, so maybe you should adjust the contact block slightly until it seems to rotate and fall into the home position correctly and then the Here Is white tab adjustment to get the proper positioning of the suppression contact.  I am changing my suggestion midstream here as I think about it.  The two adjustments affect each other so it will be a trial and error effort.
>  
> Wayne