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Bob Albert
Once you have replaced the electrolytic capacitors, you need to evaluate the diode choice.? For most of the rectifiers, a 1N4007 will suffice.? For the higher voltages, you can put two or three of them in series.? They are very cheap so you might as well buy 100 or so just to have around.? The 1N4007 rating is 1000 Volts so any power supply section up to perhaps 300 Volts can use them.? Anything higher and you need more.? When in doubt, use more.? But the 1.0 Ampere current rating is adequate for nearly anything in that unit.? The forward drop and/or dynamic resistance might be too low for some applications, so a series resistor of perhaps 47 Ohms might be advised, about a 1 Watt rating should do.
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A good idea would be to use a Variac to bring up the power slowly.? Make sure you are using the correct fuses. With the manual, you can see that the power supply voltages are correct. At this point, you should have a working unit.? Any other problems should be simply corrected, such as calibration issues, trace quality, drift, dirty switches, burned out lamps, etc.? Now it's ready for alignment and calibration. Bob On Monday, November 5, 2018, 10:34:00 AM PST, Jack <goldmort@...> wrote:
Welcome...I in a sense have a similar issue....whether to resurrect my 564.It must be 30 years since I fired it up and found no screen change (apparent 'on'). Presumably I discovered it had no filament voltage as I had two filament transformers wound to high voltage insulation, which cost a motza, Today my approach would be considerably more exacting and circumspect, Then the complexity of Tektronix CRO's and the unwilingness of Tektronix at Nth Ryde? to assist 'on that old model' other than at rates I could not afford saw me in mortal fear of the word Tektronix....Exorcism of my CRO? was considered . After spending many hundreds on the transformers and finding that installing one made no difference, I resisted melancholia by putting it all away (chuckles)? but the Tektronix CRO's of that type and era have a sort of character that seems to mysteriously bring out a maternal instinct. That's why I kept it!...One of the brighter and more experienced? people will help you with your specific restoration as they are way ahead of me...however as a general rule ordinary diodes are much of a muchness in simple rectification or doubling. Replacing them with others should see them chosen well into and exceeding the current and piv limits of the originals, if for no more reason than personal satisfaction.. When changing capacitors... as well as that also test resistors and the actual voltage delivery of your transformer where possible and safe, In my view visual inspection, photos and notes are a wise preliminary before reaching for the soldering iron. Give close visual inspection of soldering, pcb tracks, firmness of mounting screws and connector cleanliness. A final thought...some Tektronix CRO's did not use ordinary solder? but a silver-content solder. I don't know if that was the case with your models however I mention it because the heat required to melt it can damage components...so I have read. Make sure caps are discharged through using a resistor to ground rather than a screwdriver. If one thing in my comment helps, that's good. If not, others will oblige also that's a certainty. Alliteratively, 'Best of British' to you Brenda. My regards. Jack |
