Wednesday, November 1, 2017

CHM work day but did clean the faceplate to of HP 1000 to remove magic marker defacement


George Ahearn is finishing up the SMS card tester, designed by Grant Saviers back in 2009 but not built until George started on it in late 2016. It is producing all the signals correctly, but one of the voltages (-12) is not working correctly yet due to a problem in the voltage regulator circuit.

We used a bench supply to deliver -12V and tried to test out a card, a quad inverter board, but the first three of the gates we checked didn't work. Since it was near the end of the workday, this will be continued next Wednesday. 


Console faceplate cleanup

The console faceplate has been defaced by black magic marker by a prior owner who documented the disk bootup procedure. It consists of marks for which S register bits are set to ask the boot ROM in slot 11b to try to boot the device in slot 13o (the 13037 disk controller card). It also has small numbers indicating the sequence of buttons to push, such as Halt, Preset, S reg, the register bits, IBL, Run, etc.

I have to find a solvent to remove those marks without damaging any labeling or coloring on the plate. My first test was with isopropyl alcohol carefully applied in an area with minimum impact if it effects the factory colors/labels.

Marker defacement of my control panel

Another example of marker scribbled on panel
The results were quite satisfactory. There are only tiny remnants, visible only when you look closely. I expect that I can go back over these to completely remove any hint of the markings.

Marker almost completely removed

Just a small amount remaining on the side just to left of the switch
The panel already looks much better, having invested just 20 minutes cleaning time. The magic marker residue dissolved quickly, probably because it had an alcohol solvent originally. I have some tiny dots of color and some residue from the tissue when I wiped, which I will remove when I have better lighting.

Panel after its first cleaning to remove magic marker defacement

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