[GreenKeys] KSR-33 chattering issue - both local and line - shouldn't be keyboard

Sat Aug 22 17:18:20 EDT 2015

Thanks Wayne for the response.  Just to be clear, the video is not my unit, but someone else’s I found on the internet (unfortunately they didn’t update the forum with their final fix if they ended up finding one) with a similar problem.  My problem unit is a KSR-33 (no tape reader, the power supply was most likely for loop power).

Thanks for the info on bypassing the keyboard loop.  I will try this out.  I did check all the fuses with a meter and they are all good.  I’ve already removed, checked and re-soldered the leads on the UCC circuit board (also cleaned up the edge connector pins).  

I did get a response from Dave who asked me to check the magnet power (pressing break key while in “off” mode).  I did and had no clicking sound, so looks like at least one problem is no magnet power.  I ran the same test on my working ASR-33 (well, mostly working) and did hear the clicking noise so it does seem like this is the issue.  Not sure what the typical cause is for no magnet power, but I’ll start tracing out the wiring.  If you have any thoughts on what typically causes no magnet power I’d be grateful to hear them.

And, yes, per your suggestion, I am focused only on local mode right now. 

Thanks,

PJ

_____________________________________

PJ Bennett, BSEE

918.704.7055 |  <mailto:pj at pjbennett.com> pj at pjbennett.com | pjbennett.com

From: teletypeparts at comcast.net [mailto:teletypeparts at comcast.net] 
Sent: Saturday, August 22, 2015 3:19 PM
To: PJ Bennett <pj at pjbennett.com>
Cc: GREENKEYS BULLETIN BOARD <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] KSR-33 chattering issue - both local and line - shouldn't be keyboard

PJ,

The 33 in your video is an ASR. 

Swapping out the kybd is probably not the first step you should have taken but oh well....

The extra power supply in the UCC-6 is the PS for the tape reader. 

Check the fuses in the UCC-6, one controls the local loop current. 

Try to make the 33 type in Local first.  Let Line mode wait till later. 

If you jumper Molex # 7, (kybd Molex) pins 10 and 11, this will eliminate the kybd loop.  

You can remove the Molex and use a paper clip opened up instead of the special plug in the pic.

Check the SMD card in the UCC-6 for a loose top resistor.  The big one on the only circuit card that slides out vertically. 

Lots of visual checks on a 33 can usually find the trouble.

Best regards,

Wayne

KB1FDW

  _____  

From: "PJ Bennett" <pj at pjbennett.com <mailto:pj at pjbennett.com> >
To: greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net> 
Sent: Saturday, August 22, 2015 11:55:41 AM
Subject: [GreenKeys] KSR-33 chattering issue - both local and line -        shouldn't be keyboard

I have two teletypes, an ASR-33 which is working fine and a KSR-33 which is chattering in both local and line mode.  I have switched out the keyboard with the other unit and no change.  I tried adjusting the H bar, no luck.  The KSR-33 had an extra, homemade power supply included in the UCC, but I think this was only to provide loop power.  I took it out and I think the UCC is back to normal.

I’ve read as much as I could find on the various websites and forums, and several point towards the keyboard, but I’m pretty sure this isn’t the problem since I tried a working (from ASR, which I think is compatible) keyboard.  The problem is just like the one in this video:  https://www.youtube.com/watch?v=ODdcUSgReYM  The KSR chatters and the distributor advances one rotation with every key press.  Exactly the same in both line and local mode.

Just looking for suggestions on other things to check.  My next step is to trace out the wiring for the UCC and make sure the previous owner who added the power supply didn’t make any other changes (doesn’t look like it though).

Thanks for any suggestions you may have.

PJ

_____________________________________

PJ Bennett, BSEE

918.704.7055 |  <mailto:pj at pjbennett.com> pj at pjbennett.com | pjbennett.com

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