LGP-30 Video Update

COURYHOUSE at aol.com COURYHOUSE at aol.com
Sat Feb 25 20:59:11 CST 2017

Keep up the  good  work Cory!
yes, heads have to be  close  to  work..
at least that is  the  way it was  with the VRC drums   for storage on the 
GEPAC process control systyems
Ed# _www.smecc.org_ (http://www.smecc.org)  
In a message dated 2/25/2017 7:24:30 P.M. US Mountain Standard Time,  
coryheisterkamp at gmail.com writes:

Some  promising news on getting the LGP-30 up and running. With all systems 
stable,  I tightened the head spacing on the three timing track heads 
(using brass  0.001" feeler gauges though I may have to go closer). This has 
resolved  'hanging' when hitting Start; it actually appears to execute for a 
cycle  before toggling back to Stop for each press of the Start key. Of course  
without being able to see what's happening, it's likely just 'executing'  
garbage, but it's a solid first step.

In Manual mode, keystrokes from  the Flexowriter now trigger a Stop/Compute 
toggle for each key entered and  status neons on the flip-flop cards are 
registering unique bit patterns as  each comes in. 

I put the scope on the (rebuilt) clock generator card  and we have good 'T' 
and 'T-bar' signals propagating, but still haven't licked  the 'digital 
display' issue. After further probing, the display began to  stabilize and the 
single line expanded into the proper 3 for Counter,  Instruction and 
Accumulator, and eventually a bit pattern emerged for the  Instruction. No signs of 
data yet for Counter nor Accumulator, and there is an  extremely pronounced 
'throbbing' and visible refreshing. Here's a video:  

System timing looks spot on (top trace),  but I also see some 'throbbing' 
when putting my scope on any of the three  timing heads which seems a little 
strange to me (example on lower trace).  Here's a quick vid: 

One thought is that  the timing and short register heads are still too far 
off the drum surface for  a solid signal, purely conjecture at this stage.  

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