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Electromyograph EDX-1 - Based on Tektronix 5000 Series Mainframe
Hello,
Acquired an interesting device at a recent swap meet - an Electromyograph ("EDX-1") based on what appears to be a 5000 series mainframe. I posted a few pictures in the photos section under "Electromyograph EDX-1". I did some googling but couldn't find a whole lot (other than another one of these that sold on eBay Canada not too long ago). Haven't done any detailed assessment yet. Just wondering if anyone has any information about this. Trying to decide whether it is worthwhile restoring. Thank you, wschraml, KI7PFX |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
I still have a 556 which I built my own cart for. I have it next to my test bench and use it often. I bought it with the manual for $25 at a HAM fest about 15 years ago. Other than needing a vertical driver tube (which cost me 30 bucks at the time) it has worked great. I have a bunch of plugins for it including a 1L5 Spectrum analyzer (a subject for another day that I'll have to pick the brains of the people here!) and a 1A4 4 channel plug in. Friends are impressed when I use a 2 channel in the other bay and can put 6 different traces up on the screen! Though it's only rated 50MHz I've displayed a stable 100MHz on it.
Amazing scope for its time and still quite a performer today. Plus it keeps me warm in my office on cold winter nights!!! I also have a single bay scope that I acquired with some other equipment. I believe it's a 545B? I've not even attempted to plug it in yet. It's sitting in the wings waiting for some much needed TLC. While we're on the subject does anyone have an extension cable for the plugins that they would like to sell so I can work on a couple sick ones? |
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Re: TEK 475 voltage issues.
OK, I understand the +105/+160V measurement problem! There is some screen printing on the 475 PCB near Q1490 that says '+105/160V' and it is printed on one of the PCB traces but that trace does NOT connect to the +105/160V line (and it measures about 10V!). The schematic shows a +105/160V test point but I can't find it. You can measure the real +105/160V on R1423, mine measures around 125V.
Roger |
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Re: TEK 475 voltage issues.
I'm trying to measure the +105/160 from the labeled trace. This trace with +105/160 printed on it ends on the + of C1452. So, basically, I was trying to find +105/160 on C1452. Maybe I'm trying measuring in an incorrect spot. There is an unlabeled measurement pin near Q1496 that has +142 v. The metal top of Q1497 (2n2907a) has +142v. The metal top of Q1496 is where I think I should find +110 but right not I just got 87.4 and the same at the +110 pin.
Q1497 from the parts list. My serial number is > 275000 tek part no Serial/Model 151-0301-00 XB080000 |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
On 28 Mar 2019, at 01:07, John Williams <books4you@...> wrote:
Hi folks. I have been observing the topics of interest here for a few weeks, and I am not seeing much on older scopes ie before the 7000 series.I have a 549 with Type Z, 1A2 and 1A4 plugins. I love it and it just works, though I need to do some mechanical restoration work on one of the 1A4 channels. I also have a 564 which produces a trace and the storage works, but I need to fix the plugins. I haven’t posted about them much because so far I haven’t encountered anything on them I felt the need to ask questions about. I’d like to get my hands on a 575, but here in the UK they’re relatively rare. |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
There's still an interest!? ? I have a 575 (used irregularly) and a 545 (used OFTEN).? ?but it just works every time I turn it on.? ?I haven't needed to fix it in a few years.? ? I completely disagree that the 500 series are useless "boat anchors" or "room heaters" .? ?Yes, they are bigger than a modern scope, but if you have the bench space, they are every bit as useful.? ?Mine are on carts.? More so, for general experimenting, there are a lot input and out put connections on the 545 made by banana jacks (on my older version).? ?that makes it very easy to set up an experimental setup, rather than to just monitor a signal.? ?It's a great scope to *use*!
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? Dan On Thursday, March 28, 2019, 7:07:02 AM EDT, Brian via Groups.Io <brianas1948@...> wrote:
Hi everyone , I also have 500 series scopes , 547 , 2 x 549 and a 564 . I even have a 661 that still works . I like all these scopes and will hang on to them as long as I have the space as they are all reminders of my early working life as they (547,549 and 564) were all new and state of the art when I started work Despite my liking of these I also have a number of 7000 series scopes and even a couple of TDS scopes , one of which I am attempting to repair as for me buying broken ones and fixing them is the only way I can afford any of them having retired now . Brian |
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Re: Advice sought on 7934 vs 7904A mainframe
Chuck Harris
David DiGiacomo wrote:
.... Both the 7934 and 7904A have fans that are loud enough to be annoyingOk, when I read the above line, I immediately snorted! Then I realized he was talking about the cooling fan, and not scope aficionados. -Chuck Harris |
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Re: Tek 2465B Calibrator issues
Chuck Harris
That is not what the OP is talking about!
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The 2465 family has a variable frequency calibrator, which always shows a couple cycles of the calibrator signal, regardless of the sweep speed. The purpose of this fancy calibrator is threefold: 1) scope probe calibration 2) sweep speed and cursor/graticule verification 3) it was nifty, and made the scope look special compared to all scopes that came before. [The calibrator's frequency is derived from the crystal oscillator that is the microprocessor's reference on the A5 controller card. The calibrator's amplitude is derived by the DAC, and its reference, and a digital constant that is determined and stored during scope calibration. The sweep's frequency (rate) is derived by the Miller integrator's precision capacitors, and some digital calibration constants stored during scope calibration. The cursor's relationship to the graticule is determined by the DAC and the trimmer pots that adjust horizontal and vertical size and centering... all adjusted during calibration. It is good to be able to relate all three to each other, and gives a nice indication of the calibration state of the scope.] When you make a calibrator whose frequency rises in lock step with the sweep speed, you will eventually reach a point where the scope's bandwidth is too low to show the calibrator's wave form as a square wave. Remember, Fourier Transforms: a square wave is a sum of an infinite series of sine waves all harmonically related, something like: f + 1/3 f3 + 1/5 f5 + 1/7 f7 + ... + 1/inf finf Where f is the frequency, f3 is the third harmonic, f5 is the fifth harmonic... Well, to see something that resembles a square waveform, the vertical amplifier has to be able to pass up to about the 7th harmonic without distorting its amplitude. Even then the wave you see will have ripple on its top and bottom. The operator's guide doesn't adequately inform the user about this fact, so many a new 2465 user eventually runs into this on his own, and thinks his scope is broken. For me, that happened in 1985 after I brought my brand new 2565 home and ran it through its paces. I'm not sure which is the worst marketing: showing your flagship scope does something ugly, or letting your user think his new scope's broken because it is doing something ugly. It's all water over the bridge at this point. -Chuck Harris Brian Cockburn wrote: Hi Marcial, |
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Re: TEK 475 voltage issues.
Hi,
I am struggling to understand your measurements. The +105/160 is the unregulated supply to Q1496 which regulates the +110V line, so it is hard to understand why the output voltage from the series regulator (86.1V) is higher than the input voltage (10.7V). Q1456 is the series regulator for the +5V line, and yes it does run quite hot. I can't find Q1497 in the parts list. Are we talking about the 1970 ish 200MHz analogue scope? There is also a 475A model. Roger |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
Hi everyone , I also have 500 series scopes , 547 , 2 x 549 and a 564 . I even have a 661 that still works . I like all these scopes and will hang on to them as long as I have the space as they are all reminders of my early working life as they (547,549 and 564) were all new and state of the art when I started work
Despite my liking of these I also have a number of 7000 series scopes and even a couple of TDS scopes , one of which I am attempting to repair as for me buying broken ones and fixing them is the only way I can afford any of them having retired now . Brian |
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Re: Need Help repairing a 7104 oscilloscope
Hi,
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7104 is a very special instrument with a MCP CRT, which is very susceptible to damage from excessive brightness and static images. You can easily destroy it if careless, or if the instrument is faulty and generates static images (like your in case). Given the state of your instrument, I'd turn the brightness down so that the image is barely visible. Readout on 7104 should be off unless you need it, to avoid MCP burn in. Before attempting any repair, thoroughly read the documentation on tekWiki, and search for posts on this group discussing MCP CRT and 7104 in general. Based on your video, I'd say that something may be wrong with the high voltage circuit driving the CRT, therefore the focus issue. This CRT contains a complex internal electrostatic lens that expands the image after deflection, and is fed by numerous voltages (those black potentiometers under the clear protective shield on the right side of the instrument). But I would not touch any of these before I did the following: - get thorough familiarity with this special instrument from documentation and group posts - check each plugin in a known to work mainframe - check the PSU voltages for ripple and value - check internal connectors for bad contacts, including plugin slot connectors - give knobs and buttons some exercise, patina and corrosion from old age are a major nuisance for instruments which haven't been used for a while 7104 is worthy of care and attention, don't rush things (touch adjustments) if unsure, equip and prepare properly before going in. Best Regards, Nenad On Thu, Mar 28, 2019 at 1:01 AM Fast Hardware <Mandosd49@...> wrote:
Hello all |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
I still use a 547 as my main bench scope and a 575 to test semiconductors.
Fortunately I have the skills to maintain them. I have several 7000 series and a DSO but don't need their facilities very often. Later model Tek curve tracers are very rare and expensive down here in Australia. The 547 is a wonderful scope, and works perfectly even though it's over 45 years old. Morris |
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Re: Tek 2465B Calibrator issues
I'm unconvinced it could check the measurement accuracy in one sense, since I assume the cursors and calibration signal are derived from the same source.
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It could be used to check the X linearity and the X magnification, but personally I'd just use other independent equipment for that. On 28/03/19 01:18, Siggi wrote:
The point of this on the 2465s is that it allows the user to validate the |
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Re: TEK 475 voltage issues.
Tony G4NGV
Sorry, there was a resistor with 104V on it and this resistor was touching
the groundplane of the PCB. On Thu, Mar 28, 2019 at 6:46 AM Tony G4NGV via Groups.Io <tonyvirago2= [email protected]> wrote: On mine, I had a fault where the 104 was dragging down the 110v-- *From November 2013 I am using tonyvirago2@... <tonyvirago2@...> as my email address.* *My o2 email is going soon.* |
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Re: TEK 475 voltage issues.
Tony G4NGV
On mine, I had a fault where the 104 was dragging down the 110v
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The 104v was shorting/arcing to the ground plane of the pcb as it was touching and over the years the paint on the R wore off?. I monitored the 104V while lifting parts of the cct to eliminate them. Hope this helps. Tony UK <> Virus-free. www.avast.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Wed, Mar 27, 2019 at 11:01 PM Glen Layne <gelayne@...> wrote:
Hey all. I'm new to the group and trying to restore 475 scope. when I --
*From November 2013 I am using tonyvirago2@... <tonyvirago2@...> as my email address.* *My o2 email is going soon.* |
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Re: I wonder if there is much interest in vacuum tube oscilloscopes such as the 500 series
Leanna L Erickson
I have a bunch of 500 series working scopes.
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Real room heaters. Keith Wayzata, mn. On Mar 27, 2019, at 9:52 PM, John Williams <books4you@...> wrote: |
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Re: Advice sought on 7934 vs 7904A mainframe
Craig Sawyers
I have an opportunity to buy a 7934 mainframe. I would have preferred a 7904A but the 7934 has comeThe 7934 is somewhat rare (much rarer than the 7834), and is a fine storage scope. Like all Tek's "multimode" storage scopes, bistable is useless (ridiculously low contrast), but in variable persistence and fast variable persistence it has astonishing performance. The other main difference is that driving a storage scope is an acquired art; it is quite easy to damage the storage meshes, particularly where the readout is. If you get the chance to try before you buy, check that out. Also the 7934, and the 7834 before it, has a relatively low acceleration voltage (8kV) as compared with 21kV on the 7904A. That makes the 7934 trace appear somewhat dim as compared with any non-storage scope, like the 7904A. The 7934 uses a much lower acceleration voltage because it is optimised for storage. But if you want to store a single shot (or even repetitive waveform) for photography or visual inspection, that is the way to go. And it is very impressive to see a single shot with a sub-nanosecond rise stored. If it was available to buy, I'd buy it in a heartbeat. And then look for a 7904A. I suppose it goes without saying that I have a 7834 and 7934, and 7904 and 7904A. But then again I'm almost certifiable. Craig |
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Re: 577 Curve tracer ringing CRT and noisy step generator
I have found that moving the horizontal volts division selector around significantly affects the trace artifact with the step generator on. Some horizontal volts / division causes a aggravated trace artifact while other selections completely eliminate it. When selecting the lowest horizontal / division the trace artifact is almost eliminated.
When I have the horizontal / volts selection at the selection that causes the worst aggravated artifacts 0.5V / div, moving the step amplitude to a higher value causes the artifact to get worse while lower values incrementally decrease the artifact until it is not noticeable at or near the lowest step amplitude setting. |
Brian
Brian Cockburn
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