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After having brought in a different storage scope to my temporary shop, not having the Tektronix 7633 Variable Persistence Storage Scope here (it's at my other shop, building leased out to CenterStaging client, so no access to it), I recently used this early 1970's vintage Dual Beam Storage Scope, which has Bi-Stable Storage (all phospher storage modes) on trying to figure out the weak Tremolo Modulation vs stronger Vibrato Modulation on a newer-vintage Vox AC30-6TB amp. I had just replaced the power cord on this R5031 scope, it being a short coil-cord molded AC Mains cord that Tek had for some reason decided to use on some of their instruments. After I got that power cord replaced, I brought up the instrument quite slowly on the Variac/Power Analyzer, hoping I didn't have issues with aged electrolytic caps in the power supplies. I hadn't had this instrument powered up since maybe 1998. It was used as an XY display to mate with a HP 3570A Network Analyzer, HP 3571A Spectrum Analyzer, both slaved to a HP 3330B Frequency Synthesizer.
Anyway, I noticed once I got the scope up and running, there were some segments out on the optical deflection factor readout display adjacent to the CRT. Tek only created this 'novel' approach to briefly in their scopes, prior to changing to readouts in the CRT system, rather than having silk screen legends around their vertical and horizontal controls. It had been decades since I had to pull their optical readout system out from the instrument, accessed by removing the Front Panel CRT frame, plastic cover, black mask to finally expose the front of the CRT and the slide-in Optical Readout assembly. They did beautiful harness work back in those days, and with six tightly-packed multipin connectors that mated with gold header pins off of the interface PCB, each row was tethered in the harness, so you didn't have to mark the wiring for correct reassembly. I unplugged the assembly, and carefully slid the display assembly out from the chassis.
I had opened up my service manual to the Vertical Channel's schematic, which showed the front and rear lamp assemblies, each light segment switched by gold-plated leaf springs soldered onto the PCB and operated by Tek's rotary cam switch assembly, hidden under a cover on the PCB assembly. This instrument is a real marvel of engineering. Tektronix created their own rotary switches, relays, interlocking illuminated pushbutton switches and numerous other assemblies in their 7000 series scopes. This R5031 was one of four scopes (5030, R5030, 5031, R5031) that were essentially non-plug-in 7000 series scopes. Only 1MHz BW, but equipped with two differential amplifiers covering the range of 10uV-10V/Div, as well as having a current probe amp, range from 200mA to 1mA/Div.
So, I had to relearn this optical readout system, which used tiny T3/4 size 5V/60mA long life incandescent bulbs, soldered into tiny PCB's, with fiber optic light pipes coupling the output from the light assemblies to feed the special front readout block. The last time I had to service one of these instruments (my original R5031 bought in 1976), I had to also disassemble the Horizontal Rotary Switch assembly to address a specific leaf spring that wasn't switching...activated by their elaborate cam switch drum. A real service PITA. I didn't yet know if this adventure would take me there, or just find out it was burned-out incandescent lamp. Following the schematic, and using a 5VDC supply to power the lamp segments, connecting to the harness header pins on the interface PCB, I could see the individual lamps light up. I had to remove the cover over the front and rear optical assemblies, which was made up of machined aluminum blocks, tiny shaped PCB containing the tiny lamps, and fiber optic light pipes that coupled to the individual lamps in the aluminum blocks, which ran up to the front character readout assembly. A real maze of crazy engineering!
After finding just two lamps that were out on all of the segments of the three optical readout assemblies, I put the cover back on the Horizontal Readout assembly, and slid the assembly back into the scope to see if all was now working properly.
That took care of the all the burnt-out lamp segments. I did find on Ch 2, part of the 'V' in the readout would sometimes not have the bottom portion of the 'V' present. That seems to be controlled by the Volts/Current switch. Thankfully it's not one of the leaf springs under the rotary cam assemblies.
This instrument is nearly 50 years old. Back in those days, you found all the PCB's with Gold plating over the copper, and all sockets, leaf springs, headers, connectors, etc were gold plated. A real marvel of elaborate engineering. Maybe one of these days, if I live long enough and find the funds, I'll pick up a Tek 576 Curve Tracer. Those convert nicely to serve for measuring vacuum tubes. The CRT system in that instrument is part of this instrument family.
Anyway, I noticed once I got the scope up and running, there were some segments out on the optical deflection factor readout display adjacent to the CRT. Tek only created this 'novel' approach to briefly in their scopes, prior to changing to readouts in the CRT system, rather than having silk screen legends around their vertical and horizontal controls. It had been decades since I had to pull their optical readout system out from the instrument, accessed by removing the Front Panel CRT frame, plastic cover, black mask to finally expose the front of the CRT and the slide-in Optical Readout assembly. They did beautiful harness work back in those days, and with six tightly-packed multipin connectors that mated with gold header pins off of the interface PCB, each row was tethered in the harness, so you didn't have to mark the wiring for correct reassembly. I unplugged the assembly, and carefully slid the display assembly out from the chassis.
I had opened up my service manual to the Vertical Channel's schematic, which showed the front and rear lamp assemblies, each light segment switched by gold-plated leaf springs soldered onto the PCB and operated by Tek's rotary cam switch assembly, hidden under a cover on the PCB assembly. This instrument is a real marvel of engineering. Tektronix created their own rotary switches, relays, interlocking illuminated pushbutton switches and numerous other assemblies in their 7000 series scopes. This R5031 was one of four scopes (5030, R5030, 5031, R5031) that were essentially non-plug-in 7000 series scopes. Only 1MHz BW, but equipped with two differential amplifiers covering the range of 10uV-10V/Div, as well as having a current probe amp, range from 200mA to 1mA/Div.
So, I had to relearn this optical readout system, which used tiny T3/4 size 5V/60mA long life incandescent bulbs, soldered into tiny PCB's, with fiber optic light pipes coupling the output from the light assemblies to feed the special front readout block. The last time I had to service one of these instruments (my original R5031 bought in 1976), I had to also disassemble the Horizontal Rotary Switch assembly to address a specific leaf spring that wasn't switching...activated by their elaborate cam switch drum. A real service PITA. I didn't yet know if this adventure would take me there, or just find out it was burned-out incandescent lamp. Following the schematic, and using a 5VDC supply to power the lamp segments, connecting to the harness header pins on the interface PCB, I could see the individual lamps light up. I had to remove the cover over the front and rear optical assemblies, which was made up of machined aluminum blocks, tiny shaped PCB containing the tiny lamps, and fiber optic light pipes that coupled to the individual lamps in the aluminum blocks, which ran up to the front character readout assembly. A real maze of crazy engineering!
After finding just two lamps that were out on all of the segments of the three optical readout assemblies, I put the cover back on the Horizontal Readout assembly, and slid the assembly back into the scope to see if all was now working properly.
That took care of the all the burnt-out lamp segments. I did find on Ch 2, part of the 'V' in the readout would sometimes not have the bottom portion of the 'V' present. That seems to be controlled by the Volts/Current switch. Thankfully it's not one of the leaf springs under the rotary cam assemblies.
This instrument is nearly 50 years old. Back in those days, you found all the PCB's with Gold plating over the copper, and all sockets, leaf springs, headers, connectors, etc were gold plated. A real marvel of elaborate engineering. Maybe one of these days, if I live long enough and find the funds, I'll pick up a Tek 576 Curve Tracer. Those convert nicely to serve for measuring vacuum tubes. The CRT system in that instrument is part of this instrument family.
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