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Re: letter series plugins
I am quite late to the party when it comes to old scopes. Have a couple of old Heathkit Tube scopes, but no TEKTRONIX tube scopes. I do have several slightly later transistorized scopes, and though probably almost as antique, they still meet my needs. I have a 465B, 475A, T922, T935, 5113 (2), 7623A and 7633. My prized obsolete piece is a Type 576 Curve Tracer, this is one piece of equipment that has no equal in modern electronics. I have also managed to collect a few pieces of digital Tektronix equipment, and find these equally useful in some situations. However, I find the older equipment to be superior in construction and craftsmanship, as well as infinitely more repairable. I am learning electronics as hobby, mostly by self taught observation and study, so these wonderful old Tektronix scopes fit my needs to a tee.
-- Michael Lynch Dardanelle, AR |
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Re: letter series plugins
It is good to hear from a younger person collecting and enjoying older equipment. The 500 series is still viable for occasional use in a sound system shop, space is more of a concern in most cases than anything else. One great advantage of the older scopes is they are far quieter electrically than newer ones with switching power supplies and sometimes digital signal processing. That is a big help when restoring a communications receiver or AM radio tuner. Another benefit is that an "OOPS!" probe encounter with higher voltages in vacuum tube sound gear is less likely to result in damage to the scope. They also are far more resistant to interference in a ham shack or other high RF level environment. Old boat anchors are still viable in a surprising number of places today. I agree fully as well regarding the care and quality of construction- and they have style too. Enjoy!
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Bruce Gentry, KA2IVY On 8/4/19 10:32 PM, Jamie Ostrowski wrote:
I'm 44 years old. I've never worked with one of the 500 series |
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Re: 2445 LVPS Issues
I did not remove mine, when fixing mine. It was little dusty so I used a
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brush. It works, so I don't fix what isn't broken.... ha ha ha BUT my memory isn't that good to remember if it is glued or some set-screw - sorry. Is your fan working? On Sun, Aug 4, 2019 at 9:32 PM n4buq <n4buq@...> wrote:
I've already pulled on it harder than I was really comfortable doing; |
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SC501 questions
I have an SC501 I looked into awhile back but life got busy and I didn't get to resolve its issues. I've got some free time so I'm back at it.
The CRT shows no trace whatsoever. The unit burned out the 10 ohm resistors in its HV OSC section. A lot of this seems similar to what jerry massengale posted about on 11/22/15. I found C378, C380, C382 and C420 were all out of tolerance so I replaced them as well as the burned 10 ohm resistors. I turned it back on and in under 30 seconds one of the resistors was starting to smoke so I turned the unit back off. While these resistors are still within spec they will get replaced just to play it safe as one of them has a chunk burned clean through to the conductor inside. I did a thorough visual inspection and saw an odd residue on the rows of ceramic disc caps near T380 as well as an odd coating on CR389. I figured I could pull the caps, test them out of circuit with the LCR and get in closer to look at CR389. A shorted cap while unusual for a ceramic cap could explain the excessive draw. I did so and found that most of the caps in that area have an off-white waxy\greasy coating on them. I can't determine a source of the residue. CR389 turns out to be black on its lower half and orange\clear on its top half. All the caps and the CR check out with the LCR with a few exceptions. C394, C395 and C397 all have a similar part description in the manual. not exactly the same part but I'm hung up on one point with all three when determining their status. One thing I have noticed about working on equipment older than I am is the subtle differences in documentation over time. As such I wasn't 100% sure how to process this and thought I'd ask for a more experienced interpretation. C397 283-0013-00 CAP.,FXD,CER DI:0.01UF,+100-0%,1000V Now most of it reads just fine what is odd for me is the "+100-0% portion". Does it mean that the tolerance is anywhere from 0% below spec to +100% or an I totally wrong here (ie never lower than 0.01UF but can be up to 0.02UF)? I believe the base of my problem is Q360 and Q365. Time ran short yesterday so I was not able to pull them out of circuit for proper testing though I did test them in circuit as if they were diodes with a multimeter. There may be an in circuit test situation muddying my results but neither acts as they should. The testing was done without power applied to the unit and Q360 conducts in both directions which is very unlike an unpowered SCR. Q365 had similarly odd behavior under the same situation conducting form any pin to any other pin in either direction except for base to emitter. I noticed the previously mentioned post where they discussed similar concerns. My plan is to pull both and test them out of circuit before I call them bad though. I checked the windings on T380 and they seemed fine. I am also not the first person to do rework in this unit which is always a box of surprises. The last person was rougher with the AUX board wires than I would have preferred and I was looking to replace them with fresh wire. Any recommendations for appropriate gauge\insulation wire? So the long and short of this is; 1. Any ideas on what the off-white waxy\greasy coating on my ceramic caps is? 2. Any ideas as to what the half and half coloration on CR389 is? My guess is that waxy stuff got on it's lower half and then it got hot? 3. Am I understanding the nomenclature on the part listing correctly? 4. Is there anything else I should check out to cover my bases? 5. Anybody know a good replacement wire type for the AUX wires? |
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Re: letter series plugins
I'm 44 years old. I've never worked with one of the 500 series
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professionally, so using these scopes doesn't really "bring me back" to days of working in a TV repair shop, so for me it isn't about nostalgia, per se. I just really appreciate the quality and the craftsmanship that went into their design and construction, which is why I enjoy collecting them and why I'm interested in learning more about them. On Sun, Aug 4, 2019 at 9:12 PM Abc Xyz <yawrdanza@...> wrote:
This Jim Williams sounds like quite a guy! |
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Re: 2445 LVPS Issues
I've already pulled on it harder than I was really comfortable doing; however, the instructions state to use "firm pressure" to pull the fan blade off.
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I'm wondering if the slotted screw is intended to be used to push against the motor shaft and push the fan blade off. If that were the case, though, I'd think that would be in the instructions so I'm thinking that's not a proper approach. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Tony Fleming" <czecht@...> |
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Re: letter series plugins
This Jim Williams sounds like quite a guy!
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On Sun, Aug 4, 2019, 7:10 PM Morris Odell <vilgotch1@...> wrote:
Greg wrote: "a stable and reliable product that may have grown gray hair" |
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Re: letter series plugins
Greg wrote: "a stable and reliable product that may have grown gray hair" - that sounds like me!
Greg and Chuck both make good points. Nobody today would use the old instruments for professional work but they are treasures for knowledgeable hobbyists like me who grew up with them, spent most of my working life in another field altogether but retained an interest in electronics as a hobby and can't justify spending a lot of money on up to date gear. I use my 547/1A4 all the time but have a limited range of more modern instruments for when I need them. The important thing is knowing the limitations of what you're using and interpreting the results accordingly. Another example - despite knowing it's obsolete and there are more advanced ways of doing things these days I really enjoyed repairing a faulty HP (can I mention that here?) 32S RPN calculator recently which I will get a lot of pleasure using. If I was still working as an engineer I would no doubt be using other techniques for calculating things but that old HP is a wonderful example of the sort of inspired engineering Jim Williams admired so much and which we are lucky to have been able to experience in our lifetimes. Morris |
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Re: letter series plugins
fiftythreebuick
Hi Kurt-
I think the Type N is probably the rarest of the letter series. I have the only one I've ever seen for sale and I found it back in the early/mid 80s. Have not seen one on the market since. The Type P is not very common either. Probably not many complete sets out there.... Tom |
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Re: letter series plugins
fiftythreebuick
Hi Chuck-
Actually, if working with RF anywhere in the lower HF range or MF (such as AM bcst) or any number of analog circuits, the old 500 series mainframes provide plenty of bandwidth. And the controls are laid out in a very logical manner, the controls are big enough to grasp without having to be careful not to hit something you don't mean to touch. The display is razor sharp. And maybe it's just that Greg and I are old, but I'm right with him on hearing the fan spin up, the time delay relay pull in and that delightful smell of vacuum tube electronics. When the old scope has enough capability for the job at hand, there is such an extreme "pleasure of operation" factor involved for some of us. I solved the heat issue in my old shop decades ago by adding a small window unit air conditioner to run when I was using either my 555 (particularly if I needed two of them at once!) or my Collins 30L-1. The extra cooling from the window unit did the trick and was a very equitable trade for the opportunity to use those instruments in comfort. My new shop has plenty of capacity in its own dedicated central air conditioner so there's no problem there. I think it's just a matter of what you like. I have a 7104 and a 7934 sitting within arm's reach and they get used regularly, but when it's up to the job, the 555 is my first choice! :-) Hope you have a good night! Tom Chuck Harris wrote: Au Contraire? Mais non, certainement pas! Even Jim Williams was vexed by the 50MHz limit imposed by his favorites, the 547, and 556....but for opamp, and low performance switching supply work, they were adequate, as long as you didn't consider the environmental aspects of using such a scope (by environmental, I use the traditional usage, as in: the environment in the lab...). I grew up as an engineer in the waning days of the 545B, 547 and 585A. I have used all of them for serious electronics work, as they were what we could get, and I was damn glad to have them at the time. Still, I simply don't know of anyone that does serious work with 500 series scopes anymore. The limitations are too severe. They can't even keep up with a modern USB port. 1MHz switching supplies have spikes that they cannot even come close to seeing. Just because your scope can't see them, doesn't mean they won't burn out your transistors and diodes. Disregarding the low bandwidth, the heat they produce is enough to eliminate them from serious consideration. I not so fondly remember my lab in graduate school over taxing the building's air conditioner with all of the HP and Tektronix gear we needed for our research. It was intolerable to have the lab get over 110F in the summer; doors open, huge floor standing fans blowing papers everywhere. It was so hot that the thermal overload switches in the scopes were tripped. Nostalgia is great, especially if you remember only the good stuff. Thinking fondly of using a scope in the '70s, and using it for serious electronics work today are not the same thing. I pull out my 547, 545B, and 585A from time to time to play with, but when work needs to be done, they are parked in their corral. My 7854 does most of my heavy lifting, scope wise. -Chuck Harris |
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Re: letter series plugins
I can't help but chime in as well. My love of the vintage scopes started with a chance opportunity to acquire a very nice condition Tektronix 503 about a year ago thinking the differential inputs and better than average X-Y mode could be useful in vacuum tube audio equipment power supplies and to build a simple octopus curve tracer. In this application, the low bandwidth was not a concern and I figured it would be a nice restoration project. Being able to use the differential input to check ripple B+ vs Cathode or B- without 2-channel math is a fantastic convenience. One of the first things I did with it was replace all the capacitors with high quality modern ones and just did an overall good cleaning.
Then to my surprise, when I pressed it into service, I found it would trigger on events nearly immediately that I would have perhaps assumed to be digital artifacts. It has become a very valued and trusted member of my lab. In many cases, I will dig into a project with it first just to see what it reveals before worrying about trigger hold-offs, sample lengths, averaging and what all else. In a lot of cases, the old tube and tunnel diode triggers can make modern digital scopes feel like you have to have to work a lot harder to see things as clearly so quickly. Don't get me wrong, I love all the advanced automated measurements, higher bandwidths, lower power consumption and, let's be honest, less mass of the newer equipment.. but for the sheer "let's have a quick peek to see if anything pokes out at us" quality, the old 503 is truly a gem. |
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Re: letter series plugins
Certainly nothing wrong with enjoying the aesthetics of the old 500 series
scopes. By all measures, the modern sportbike motorcycles outperform the cruiser Harley Davidsons in acceleration and handling, yet the Harleys still remain incredibly popular. On Sat, Aug 3, 2019 at 9:44 AM David Holland <david.w.holland@...> wrote: On Sat, Aug 3, 2019 at 9:42 AM snapdiode via Groups.Io |
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Re: 2445 LVPS Issues
They are VERY FRAGILE! Do not apply much pressure or it just brakes.
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I don't know how to remove it without braking it, sorry! On Sun, Aug 4, 2019 at 7:13 PM n4buq <n4buq@...> wrote:
Got everything removed except the fan. Any hints/tricks to getting that |
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Re: 2445 LVPS Issues
Got everything removed except the fan. Any hints/tricks to getting that off? Loosened the nut but the fan blade won't budge and I don't want to pull any harder unless it is recommended. I have a feeling that's some kind of collet and perhaps pressure on the slotted screw would release it but just don't know.
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Thanks, Barry - N4BUQ ----- Original Message -----
From: "Barry" <n4buq@...> |
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Re: 2445 LVPS Issues
Thank you very much! Tony
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On Sun, Aug 4, 2019 at 5:47 PM Ancel <protofabtt@...> wrote:
This project of mine might provide some useful info. |
Mlynch001
Jason A.
Ancel
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