That was not enough to compete against the "big" competitors like Dumont, RCA, Varian, General Electric(?). The early 501 contained advanced circuitry but it was too big and heavy on the bench. The first number "5" stood for the screen's diameter, "01" indicated the first model. These scopes come in many different models and the differences between them are not obvious.ĥ00 series 501 oscilloscope Weight went from a light 3.5 lbs for the diminutive 212 all the way to 24 lbs for the 2467. In 1988, prices started at about $2000, and went to $12,000+ for the 2467 with MCP CRT, all with 2 to 4 channels. From 500 kHz bandwidth all the way to 400 MHz. Notable with these portable models is the abundance of offerings and option choices. These were still heavy little scopes, and the chassis was complicated and expensive to build. These were quickly followed by the 460 series, the 470 series, and the 480 series.Įach upgrade resulted in wider bandwidth and better triggering. There was also a 422 15MHz AC/DC portable made. In the 1960s Tektronix introduced the relatively compact 450 series, starting with the 50 MHz 453. Might just go ahead and replace all of them.A Tektronix 465 portable analog oscilloscope is a typical instrument of the late 1970s. They are 400V 1A silicon rectifiers - pretty sure a 1N4004 is a good replacement. All 4 blown? Then how is it possible to have any voltage on the test points? Thoughts? I'm thinking to desolder one end of one and see how my DMM likes it as a diode.
The bridge rectifier diodes on the "Mains Input Board" have weird resistance measurements - all 4 measure 48K ohms in both directions. I shut the scope down and started tracing from the mains input. So, yeah, still sounds like the power supply. They all read low - 40-60% of what they should be. I took a number of voltage readings at various test points labeled on the bottom of the main board. No obvious signs of burnt components, bulging electrolytics and such. First order of business was a visual inspection. Pretty sure it is a power supply problem. This is an amazingly well constructed and documented piece of equipment. Dave's 2225 teardown video was a nice find.
So I got the service manual and took the case off. At least there's one cap somewhere that works. Probably will keep it, Any way, the only additional symptom is that, after switching it off, the Power and Sweep LEDs light up for several hundred mS. But it's been a good friend to me and it's so well designed and constructed, I want to repair it. I'm taking this as a sign that I need to replace it with a DSO. My Tektronix 2225 (50 mhz analog, 1980s) scope died on me. I'm no repair-Pro so hoping some smarter folks than I can help me.
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