Might just go ahead and replace all of them. 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. Tektronix hereby grants permission and license for others to reproduce and distribute copies of any Tektronix measurement product manual, including user manuals, operators manuals, service manuals, and the like, that (a) have a Tektronix Part Number and (b) are for a measurement product that is no longer supported by Tektronix.
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