Sweet! Marc
> On Mar 19, 2017, at 2:39 PM, Cory Heisterkamp via cctalk > <[email protected]> wrote: > > Hey guys, figured it was time for an update on the LGP-30 resuscitation. > > Some further detective work found a leaky 1500uF cap in one of the B+ > supplies which was causing the 'surging' issue on the scope. For good measure > I replaced all six 1500 and 3000uF caps even though ripple was low. Better > safe than sorry and if it means pulling that chassis and its covers again, > all the better. I attempted to weigh it on my shipping scale, but it only > registers to 100 lbs and the indicator flew right past that. > > There had been a small thermal event in the AC junction box that the twist > lock connector mounts to, and I suspect it occurred pre-60's refurb. It's not > too surprising as the wiring on the computer side is aluminum and the feed is > copper. The box needed replacing but was a unique Hubbell variation of a std > 4" box with special ears. I couldn't find anything even close to that at any > of the supply houses online, probably because it violates today's conductor > fill rules (it's only 1" deep but the socket consumes most of that depth and > 75% of the area). I eventually settled on drilling/tapping a standard box and > cleaned up the wiring. > > The sequencer unit is now working correctly after I found an NOS relay to R&R > contacts with. The blower is still steady and quiet with its new bearings, > and no issues (knock on wood) with the drum after greasing the end bearing, > belt and 'tightening' up the tolerances on the timing and short register > heads. > > Some good news- I now have three horizontal lines on the scope, rock solid > and where they should be. I can get the occasional pattern for Instruction > contents, but Order and Accumulator still aren't reading/writing/displaying. > All in good time. > > http://radar58.com/LGP30/wp-content/uploads/2017/03/lgp.jpg > > Even better news is that the three timing tracks appear to be intact on the > drum and the supporting hardware is working. > > http://radar58.com/LGP30/wp-content/uploads/2017/03/scope-e1489957963176.jpg > (1, 2 and 3 correspond to S1, S2 and S3) > > Now to investigate those short registers... -Cory
