Apr 1: With spring arriving and the project list growing ever longer, this seems like a good stopping point until I can once again devote the time with the machine these resto-sessions require (likely when Fall turns to Winter). The work has been documented, scope oscillograms saved to disk, all parts reassembled and it’ll get wrapped in plastic. In the last 3 months, this LGP-30 has gone from a neglected warehouse curiosity to a turn-key machine. While we’re not yet computing, the foundation is now set. The last thing to do for now is put together a video from the clips I shot recently and get that posted to Youtube. Below are a couple pics with the side panels back on and adjusted.
Mar 24: After a full rebuild of the power supply last weekend, we now have a rock-solid CRT display. The supply chassis tipped the scales at over 100 lbs, which accounts for 1/7th the machine’s weight! From there, work was able to progress on diagnostics. The three system timing tracks are in tact (!) and we have a functioning Instruction register. However, without a working accumulator, you can’t get contents into the machine to transfer to the Inst. Reg. The Program Counter is also MIA. I took a second shot at adjusting those heads but came up empty. Click pic for a short vid of the three timing tracks and clock signal while running.
Mar 11: Time for an update- Video Here Troubleshooting has proven difficult given the instability in the o-scope display (but data on the scope looks promising!). It occurred to me that perhaps one of the B+ supplies was noisy, and an o-scope on the 150V supply proved this out. Details in the Power Supply section.
Feb 23: Links to a couple of Stan Frankel’s articles have been added to the What’s an LGP-30 Section. Diagnostic work has started now that the Sequencer has been repaired. More in the General Section.
Feb 18: Locating a correct 4″ square j-box for the AC connector continues to be a mystery. The box that arrived Feb 10th had similar mounting ears but was 4-11/16″ square which isn’t going to work.
The Clock, Vert and Hor modules have now had their mica caps replaced and the Digital Display chassis has been rebuilt. Functional troubleshooting has now started on the system. See General Section for details.
Feb 13: An NOS 3-pole open frame relay was found and ordered that closely resembles the 4PDT ‘Run’ relay that has obvious contact degradation. Having individual parts, it’s hoped I can swap over the new contacts. (Update: Success!) See the Sequencer Section for details.
Feb 11/12: Diagnostic work continues now that the machine is back together. Mica caps were ordered for the Clock Generator, Vertical and Horizontal modules along with fresh resistors for the Digital Display chassis. The ‘Run’ relay in the Sequencer Unit is not as reliable as I would like and a replacement may need to be found. More work was done on the drum, this time relating to a squeaky bearing. See Mag Drum, Modules and General Sections for updates.
Feb 10: The mystery of the j-box has been solved and a correct part located and ordered. See Power Supply Section for details. The afternoon was also spent working on the drum getting all the heads adjusted correctly (see Drum Section for more) and installed on the machine for the first time since its arrival. A full power-up commenced…checkout the General Section for more.
Feb 4: The new bearings for the blower motor arrived and were installed using a couple thermal contraction/expansion tricks. By the afternoon, the blower unit was reassembled and installed in the LGP-30 and the blower operated smooth as silk with isolated power. The logic cards were gradually reinstalled and the machine was put through its power-up and standby sequences. Details in the General Section.
It’s also worth dropping by the Power Supply section to see the condition of the machine’s twist-lock j-box.
Feb 1: ¼” white translucent acrylic stock arrived which will be used to replace the missing ‘wings’ that mount on the machine’s top cover adjacent to the control panel. Based on internet photos, most of these are missing and it’s easy to see why. Details in the Control Panel Section.
Jan 28/29: In the General Section you’ll find details on this weekend’s work related to panel installation and alignment, serial number spotting and work on the Flexowriter’s support table. Additionally, the blower motor assembly had to be pulled due to bad bearings after fireup with the new motor start cap. The motor was disassembled and the old bearings pressed out. More in the Blower Section. The 12/3 cord stock also arrived and was matched to the new heavy-duty plug and receptacle.
Jan 26: The bakelite twist-lock connector arrived, an order was placed for 12/3 cord after a local search failed to turn up what was needed, and plastic clamps were purchased to replace the brittle originals used to secure wiring to the frame.
Jan 21/22: After chasing a few niggling issues, the Flexowriter is complete and functional both hot and cold. Work also began this weekend on the massive power supply chassis and additional units were pulled from the frame for inspection and scrub-down. Details in the Power Supply and General Section.
Jan 19: The original air filters were toast; measurements were taken to custom make some from off the shelf filters. A vintage bakelite Hubbell #7313 twist lock connector was obtained for the primary power cord build. See Blower and Power Sections for Details.
Jan 18: More Flexowriter work after confirmation was received from Christian Corti regarding some of the keybar codes.
Jan 17: The big news, the machine arrives! See the General Section for the details on the unloading (with a tractor of all things) and inspection.
In other news, the correct 7/8” paper tape arrived and work could proceed on the Flexowriter, including rebuilding the ‘remote’ power cord. See the Flexo Section for details.
Jan 15/16: With fresh capacitors on hand, recapping of the 34 modules could begin. This included card cleaning and diode checking/replacement. New snubber caps were also installed on the Flexowriter. More in the Modules Section.
Jan 14: Recoding of the Flexowriter keyboard begins…and occupies several days. More in the Flexowriter Section.
Jan 12: More work on the Flexowriter, with an interesting discovery. Why was the machine loaded with 5-level tape? And why did ‘playback’ produce gibberish from the machine’s own punch? See the Flexowriter Section for the whole saga….
Jan 9: More investigation into the history of this particular machine. While the serial plate reads #393 which would put it in the 1960 time-frame, it contains a number of parts that date back to 1956, and a number of places within the unit, other serial numbers have been found. See the General Section for details….
Jan 7/8: Work begins on the control panel: disassembly, cleaning and testing of switches and lamps. See the Control Panel Section for details….
Jan 6: I put in the order for the replacement capacitors (total of 112 wax and sml electrolytic on the way). Any of the pF value will be left alone for now and replaced on a fix-as-fail basis. An ESR meter was also ordered to deal with the huge electrolytics in the power supply. A plea was put out for an English version of the Maintenance Manual; to date, only a German version exists.
Jan 5: Modules were inventoried, compared against schematics, and parts lists made for all needed capacitors and tubes. See the Modules Section for more….
Jan 3: The “resuscitation list” was put together for materials and supplies including 0.001” brass feeler gauges. Some work on the drum progressed by taking all the mounting bars up with 0.004” paper spacers. With heads off the drum surface, it spun freely. I gapped the recirc register heads and put the unit aside.
Jan 2, 2017: With machine yet to arrive, an initial inspection was performed on the drum. The good news: it appears clean and serviceable. The bad news: It was jammed. See Drum Section for more….