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Re: Up to date capacitor list for Tek 2465A and 2465B scopes (2018)
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Menahem,
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Any slight offense is in the past, lets go forward. ? My goal here is to "first do no harm" then to payback for the help I have received from others.? I don't usually speak up right away, instead giving time for more experienced scope technicians to lead the way.? But I am very experienced with a wide technical base.? Like you I repaired radios and TVs (in the 1960's for me) and was appalled at the corners some manufacturers took to save a few cents.? After graduation from college (1963), I worked for the old Bell Telephone Laboratory, then Collins Radio (both quality minded, high technology organizations).? During my career I worked on the Nike anti-missile system, the first GPS receivers, auto-pilots, cockpit flight instruments, and many other avionics products.? I sometimes consulted for Rockwell International on computer matters.? If you ever ride in a Boeing airplane your pilot uses instrument displays done by the organization I lead.? The Tektronix 24xx series of oscilloscope was everywhere during those working years.? Often even in the conference rooms.? At one time, as Director of Engineering for Air Transport, I authorized purchase of 75 of them in one year.? I tell this story to better introduce myself and to validate my statement that I, too, seek quality in our work. I think your goals for a perfect (or near perfect) BOM are admirable and I encourage you to lead that effort.? I will contribute when able and when my contributions are helpful.? But perhaps we should consider that some users are unable to source all parts or from all vendors.? At one time, the list I posted included part numbers from Mouser as well as Digikey so they could be ordered form either.? But it was tedious to keep up, especially when some parts are not available from both vendors.? And my goals do not prevent part substitutions when the perfect part is difficult to source. Finally, what capacitors do you advise to use on the 24x5B A5 board?? I am now repairing my second one and need to make choices for at least the electrolytics.? Both boards I have are missing pads from missing electrolyte leakage.? I clean the boards and replace the pads.? But if I replace the capacitors with electrolytic caps it is certain they will fail one day and it is certain they will further damage the board and my replacement pads are not as robust as the originals.? I see one seller of rebuilt A5 boards uses tantalum electrolytics.? But tantalums are notorious for failure unless significantly de-rated for voltage.? For now I have used electrolytics but have started a plan to change them out for tantalums, derated 2:1 or more. On ?Monday?, ?June? ?18?, ?2018? ?01?:?54?:?55? ?AM? ?CDT, M Yachad <yachadm@...> wrote:
Hey Ron Nice to get to know you! Thanks for telling us your story. I understand your dilemma with your wife - we all empathize, even if we won't admit it as candidly as you did ;-) I had no intention to deprecate, even if if it came across that way, and if I offended you, please accept my apology. My purpose here is to build an iron-clad 2465 BoM, which will offer ALL users (experienced or not) an optimal long-lasting solution which will not require subsequent intervention under the cover again in our lifetimes. In short, bringing together ALL our combined knowledge to provide an expert community solution. I would not be writing all this, if it was not for all your help, because 9 years ago, when I started out on this journey and overhauled my own 2465B, I had no idea where to start, or which parts to select. All I knew was audio and linear PSU's. Only by asking these questions on this forum, was I able to get the info I needed, to do this once-only-required overhaul. Today, SMPS overhaul (especially in TV's) is a substantial part of my workload, and I have built up my knowledge base substantially, regarding which component types are suited best in which areas of the circuit. I normally go through a few hundred capacitors every month, in these repairs. So, I bring that acquired knowledge back to the forum, as a form of gratitude. 9 years later, the 2465B is still operating flawlessly, except for 2 problems (unrelated to the overhaul) - U700 failure, and a diode failure. Solved quickly and painlessly, with the help of the generous people here. I expect to pass all my lab equipment onto my middle son, aged 17, who is the only one of my 4 children who shows any serious interest in my work. With the maintenance I do on my equipment, I expect it to last 30 years for him as well. Regarding suppliers, when approaching a project like this, I have learnt to not skimp, and if I have to source the optimal BoM from more than one supplier, then the small additional shipping cost (from the 2nd supplier) is peanuts, when figuring in the 20-30-year lifetime of a job done perfectly, not requiring any redo's in the future. I use both Mouser and Digikey, but for the 2465 kits, Mouser offers me the parts I want, and also cheaper than Digikey by a few $ for this particular selection. So that extra $1 which you may pay Mouser for shipping, you'll probably save on individual parts costs. Ancel, I have used Nichicon PJ in the past as well - I have no aversion to them at all - and I normally use Nichicon PW (a tighter-tolerance brother of PJ) as my #1 choice. That preference was based entirely on the datasheet specs, I did no comparison testing at all. Menahem |
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