Re: [dead tek 485] Can i fix it ? (newbie here)
Jose,
I am just going to give a quick reply to the first issue.
It looks to me like there is a problem with the calibrator output. I think you have another scope so can you feed the calibrator output into the second scope. I looks like there is some noise on the calibrator output just before it switches - both from high to low and from low to high. I would try pressing the 1kHz / 1MHz switch many times while displaying the signal on the second scope. While at 0.2msec/div see if you can make the trace move sideways by adjusting the trigger level control, it may be that the scope is triggering from the first 'noise' pulse rather than the main low-high transition.
Looking at your pictures and even allowing for some over-exposure effects you seem you seem to have the single trace both high and low at the same time which is a physical impossibility, hence my suggestion of noise. This could also explain why the scope seems to be triggering around the half-way point at 0.2msec/div.
More later!
Regards,
Roger
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Re: 7B53A not working as delayed tb
Thanks Fabio, I just wanted to work through the circuitry to see why the delayed time/div did not appear on the readout.
Roger
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Re: [dead tek 485] Can i fix it ? (newbie here)
Jose,
That is one pretty scope. Consider me appropriately jealous.
I have seen similar supposed horizontal inaccuracy on my scopes, but it's hard to know if that is a problem with the scope's time base, or with the input signal, unless you have a calibrated instrument to compare against. I have tried to verify/triangulate my scopes against several uncalibrated, but believed to be accurate sources (e.g. outputs from several different crystal oscillators, comparison to multimeters with Hz modes, other scopes, and the Leo Bodnar fast pulser), but it's an open question whether I was successful.
I have also noticed that the calibration signals on different scopes have different frequencies: they are only accurate to about 5% (on a 50 year old scope). The 475 and 475A have no means (other than replacement of components) to adjust the frequency of the cal signal. Lacking proper equipment, I have not attempted to calibrate the horizontal time base on any of my scopes.
The NORM trigger operation looks consistent with what I see on my 475 and 475A, except that the dots should be at the left hand side of the display. In NORM mode the trigger mode, according to the 475 operators manual, "Sweep is initiated by the applied trigger signal. In the absence of an adequate trigger signal, there is no trace. When the trigger rate is too low for AUTO use NORM."
When the manual says that there is no trace, what they mean is that there is no sweep. The "trace" is still there, but it's not being drawn across the screen, it's waiting at the left edge for a sweep to occur. Ideally it is also "blanked" by the Z-axis circuitry, but this is not always perfect, or it may actually be malfunctioning, which is why you see a line (if there were no vertical signal you would just see a dot).
The deformation of the signal when using AC coupling could point to a problem in channel 1: maybe the AC coupling switch contacts are dirty, or maybe the coupling capacitor is bad? Both should be fairly easy to fix. If the contacts on the 485 are anything like those on the 475 you clean them using a strip of high quality bond paper soaked in isopropyl alcohol: you open the switch contact, slip the paper between the contacts, close the contact, trapping the paper, and pull the paper out. Repeat several times for each contact.
These seem like minor issues which you should be able to fix fairly easily. Congratulations on scoring such a beautiful scope.
-- Jeff Dutky
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Re: [dead tek 485] Can i fix it ? (newbie here)
Make sure to use a good contact cleaner / lube and clean ALL of the controls! Dirty switches can make for very interesting symptoms. I once acquired a 475 that almost did nothing - cleaning the controls brought it back to 90% working.
The 50 ohm switch issues could be a dirty switch for example. But other controls like intensity and offset controls can result in no display if they are dirty. I love Deoxit D5 for this.
Good luck! the 485 is a beautiful little scope but man is it hard to work on. I believe it was originally developed to provide field service engineers a 1nsec scope that would fit under the seat on an airplane. And I think it may have been the first 1nsec scope Tek made?
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Re: 7904 Power Supply Capacitors
On Thu, Nov 24, 2016 at 02:21 PM, David Hess wrote:
I need to start thinking about rebuilding my 7000 power supplies. I
think I will start on a spreadsheet showing the parts used in each
model.
I just fixed a 7904 where 3 of these capacitors had failed (2 in the suppy, one on the main board), I was wondering if you ended up doing the capacitor replacement spreadsheet you mentionned. Regards Jose
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Re: Tek 576 step generator problem
Hello,
thanks for your answers!
I checked already the caps and also the supply voltages (5V, 75V and 100V)... unfortunately they are all fine...
Could someone help me out and compare my waveforms with a working 576?
I wonder about 50uA and 1mA... is it normal that the steps are not even?
Following settings were made:
- Polarity: NPN
- Mode: NORM
- Steps: 5
- Offset: Zero
- Steps: PUSHED
- Step Family: REP
- Rate: 2x
Measurements were done between Emitter (ground of scope) and Base on the base fixture with a 100k resistor paralell
Step-Amplitude: .5uA with 100k resistor paralell
Step-Amplitude: 5uA with 100k resistor paralell
Step-Amplitude: 50uA with 100k resistor paralell (looks strange?)
Step-Amplitude: .1mA with 100k resistor paralell (looks strange?)
Step-Amplitude: 1mA with 100k resistor paralell
Step-Amplitude: 10mA with 100k resistor paralell
Step-Amplitude: 50mA with 100k resistor paralell
Step-Amplitude: .05V (no resistor)
Step-Amplitude: .5V (no resistor)
Thank you very much!
BR,
Dave
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Alternative for Snap-On knobs on 22XX and 24XX scopes??
Hello all, I have the Tek-virus, that means: I buy a broken scope for parts to repair one of my projects, but in the end I just cannot take it apart, so I will fix that one too.... ;-) Since I love the 24XX series and the 22XX series too, the reality of life is, these little Snap-On knobs are always missing. And because I am Dutch (they call us cheap :-) ), I just refuse to pay $6 or €5 per knob to replace them! (Except for my 2467B, that one is special!) That is why I started looking for a reasonable alternative, and I might have found something. On AliExpress I found these cheap knobs of which I thought, these might fit. I immediately admit, they are NOT original, they have the wrong color, but still, look for yourself here: /g/TekScopes/album?id=259257How I did it: First I ordered these knobs: in grey, not black. (No affiliation with the seller!) Second, by hand, I removed most of the inside of the knob, that even left a little slot at the end, almost like in the original knobs. You can see this in the pictures I uploaded. Mind you, it seems that the dark gray Tek parts (on my 2235) where the knobs snap on are slightly shorter than the white ones (at least on my 2465B), so for the dark grey ones, use a 6.5mm drill. For the white ones, use a 7mm drill. (I have no idea what that would be in Imperial???) I just put the drill in a vice, and by forcing the knob by hand on the drill, I removed the little plastic parts, used for a D-shaped shaft, from the inside of the knob. As someone else (Chuck or Dennis ?) suggested before, just use a little bit of silicone to "glue" them on, so that they can be removed again if necessary. For the pictures, they were put on just fit using a tight fit, and I think they were already more solid that the worn out original ones by Tek. What do you think of the result? Stay safe, Leo
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FS: TM500 stuff for parts/repair
Hello All,
I have for sale some TM500 equipment for parts/repair for sale as a lot.? It is dirty and banged up a little from sitting around for many years.?? The lot includes 1 TM501 frame (working), 2 TM503 frames (working), 1 SC 502 scope (not working, blows the 0.3A fuse), 1 DC502 counter (working), and 2 DC503A power supplies (working).? I only tested these briefly.? They have not been powered on in a long time so they will probably need some recapping or other things to work reliably.? The front panels all have some issues (i.e., broken plastic around the edges and knobs).? The price is $165.00 for the lot plus shipping.? Items are located in Maryland USA.
Tom Bryan
N3AJA
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5440 scope vertical creep/jitter (intermittent)
Hey all,
Right in the middle of working on reviving a 5S14N and PG506, my 5440 scope started losing control of the vertical position setting. It creeps up and and then down and it¡¯s occurring on all plugins. I remember several years ago reading somebody¡¯s tip about what causes this on the scopes vertical board. But I can¡¯t find the thread.
Has anyone ever dealt with this and fixed it?
Thanks, Rick
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Re: [dead tek 485] Can i fix it ? (newbie here)
Hi Jeff, hi gang, On Sun, Jan 10, 2021 at 10:37 AM, Jeff Dutky wrote: You should post some pictures of the scope, so the rest of us can fell
appropriately jealous.
-- Jeff Dutky Here is a link to a google drive directory containing some pictures : You'll find some pictures of the 485 scope (front and board views). I also uploaded some pictures of the 5V 1kHZ calibration signal for ch1 and ch2. Some things puzzle me : => CH1__Cal-5V-1kHZ-NormTrig-1.jpg and CH1__Cal-5V-1kHZ-NormTrig-1.jpg show the signal with two different Time/div value (.5 and .2 ms per div). The signal is almost at 5div vertically, but lacks of accuracy on horiz display : the half square wave is not properly aligned to reticule marks (as I understand it should be). When in .2ms/div, the trace is not wery neat as you will see on the pictures. => CH1__*NotTrigered*.jpg (2 files) This is to show the behaviour of the scope when using "Norm Trig" and "Auto trig" sweep modes when signal is not triggered. I'm surprised that when the sweep mode selector is on "Norm Trig", I only get 2 dots on the right side of CRT screen instead of proper sweep trace (2 parallel lines) like on CH1__Cal-5V-1kHz-Not_triggered-AutoTrig.jpg image ? => CH1*ACCoupling.jpg Ok! This was to show you that when i'm selecting AC Coupling (A Trigering) and putting CH1 in AC mode, the square wave is not that squarred anymore. => CH2 fimages Basically, if I got the 1Mohm/50ohm pushbutton in (as it is when using Channel 1) : I do not get a square wave trace. If I release this 1Mohm/50ohm button, then I get the 2 images of the calibration signal (.5 and .2ms / div). Quite sure those pictures will raise some more comments/advices ! I'm just prepare for receiving them ! ;o) Jose
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FS: Tektronix TDS2014 Oscilloscope
Hello All,
I have for sale a Tektronix TDS2014 100 MHz, 4 channel, oscilloscope.? It passes all self tests and self calibration and has a good display.? There are some cracks around the edges of the case and on a corner of the front panel. The power button has been replaced with a 3D printed button.? It does not include an option module or probes.?? I cannot guarantee the calibration on this so I am selling it AS-IS.? The price is $275 plus shipping. Located in Maryland USA.
Tom Bryan
N3AJA
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FS: Tektronix TDS2024 Oscilloscope
Hello All,
I have for sale a Tektronix TDS2024 200 MHz, 4 channel, oscilloscope.? It passes all self tests and self calibration and has a good display.? There some staining on the top of the case where it looks like someone used a solvent to remove a sticker.?? It does include a TDS2CMax communication module.? It does not include probes or other accessories.?? I cannot guarantee the calibration on this so I am selling it AS-IS.? The price is $375 plus shipping.? Located in Maryland USA.
Tom Bryan
N3AJA
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Re: 2465B all OPT, power supply reassembly: Cables?
Egge, many thanks I have just found that manual.
Will search deeper.
Still any photos of the arrangement of PSU, HPIB, option board ion a fully optioned unit will be helpful,
Kind Regards,
Jon
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Instead of a latch, I used a small cabinet pull for the module extender I built. I don't see a need for latches for anything short of California's "big one".
John
toggle quoted message
Show quoted text
On 1/10/2021 9:06 AM, Harvey White wrote: I agree, latches are different.? What I was thinking of is that the extrusions for the 7000 series, if worked upon, could be used.? I'm assuming that the extrusions are the difficult part, and if the latch is not important, it may be left out.
Harvey
On 1/10/2021 10:58 AM, magnustoelle via groups.io wrote:
Good day,
may I correct you here, Harvey; the TM500/5000 use?the same mech design as used in the?Tektronix 5000 Series of oscilloscopes, not the 7000 series. ?We have had?a few related discussions earlier.
Jared, I wanted to congratulate you on your design and the time and effort that went into this! ????Particularly impressed by?the mechanical design, i.e.?how nicely the front panel mounted components fit etc.?I have searched for the 3D CAD software you used and it?seems you are using Rhinoceros, which aims the?professional designer community... That would explain a lot...
Cheers,
Magnus
Am Sonntag, Januar 10, 2021, 16:47 schrieb Harvey White <madyn@...>:
If you have some machining capability, or leave out the latch, you might
be able to use the rails from a dead 7000 series scope plugin.? The
extrusions seem to be the same size, width wise. They are, of course,
longer and have a different latch mechanism.
Might be useful to check.
Harvey
On 1/10/2021 3:41 AM, momemeca wrote:
Hello Larry,
Thank you for confirming and offering to add me to the list ?
Estimated costs are ok ?
My details as follows:
Rick LE GUEN
12 Bayvista Rise
Somerville
Victoria 3912
Australia (not Austria ?)C
Since I did not read the very original message of this post, can you please
clarify/confirm that the scope of supply is for PCBs only or other?
BOM included?
I am currently looking for an empty or U/S TM-500 module or a series 5000
module.? Please let me know if you have or know where I could get one (I do
know that they¡¯re like chicken teeth ATM) ?
Cheers,
Rick.
On Sun, 10 Jan 2021 at 09:51, Larry McDavid <lmcdavid@...> wrote:
Rick, I need your full name to proceed. I can still add you to the list
of purchasers but you need to be aware postage by First Class Package to
Australia will be? US$27.75 plus US$5 for packaging. I'm reasonably
confident the board set will be priced at US$38.
This will be a flat package, not a box (which costs lots more), and
there will be a stiffener to prevent bending.
Larry
On 1/9/2021 5:30 AM, momemeca wrote:
Hello Larry,
I hope that I am not too late in requesting a complete board set for the TM500 Mainframe Tester.
If at all possible, please include me to the list and advise of the total cost including shipping to Somerville Post Code 3912, Victoria,
Australia.
Cheers,
Rick.
On 4 Jan 2021, at 17:39, Larry McDavid <lmcdavid@...> wrote:
Here is another update list of those wanting the TM500 tester board set, with additions and minor changes. Please check this list carefully for
inclusion of your name in the two groups.
ML
PA
SM
DC
HB
GL
MH
JR
WR
JT
EW
RD
AW
SG
DS
JF
MU
PE
SN
SC
AA
BH
EPa
WS
KT
RDD
PM
GM
CC
BH
BK
LR
MP
MP
SA
BG
JK
LM
In addition to those above, the following have indicated an interest
but there is some issue that must be resolved before you can be included in
the order:
AA
PD
BO
CH
EP
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California? (SE of Los Angeles, near Disneyland)
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California? (SE of Los Angeles, near Disneyland)
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Check HV windings and HV cap.
Both subject to failures, so shorting inverter load
See service manual for the operation and frequency of HV section.
Jon
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I had a similar thing with a 2235 once.
I did a ringing test that showed me the transformer was bad.
Google "ringing test transformer" and you will find info.
Basically it's very simple to do:
Use a low repeat rate fast rise square wave generator and apply this pulse to the primary winding, this can be done in circuit.
Use a scope to look at one of the secondary windings, you should see the ringing being damped out slowly and nicely.
If it damps out in only 2-3 cycles, the transformer has a short.
Good luck,
Leo
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If you do a little search, I repaired a SC-502 a few months back. I¡¯ll have to go through my notes, but I do remember something about Q555. Don¡¯t give up, they are very nice and handy little scopes.
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The final outcome is negative. Fried Q855 twice, The HV supply won't oscillate and draws a lot of current that
quickly destroys Q855. I give up.
RIP SC502
Giovanni IZ5PQT
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Re: 2465B all OPT, power supply reassembly: Cables?
Hi Jean-Paul,
See 24X5B/2467B Options Service Manual (070-6864-02 for SN B050000 and Above). Pdf pages 369,370 and 371. Notch (1) is where a Triangle/Arrow is marked on the Board.
Succes,
Egge Siert
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Re: Tek 576 step generator problem
It looks like a "broken trace " issue to me. Please ref to my 577 repair log: < /g/TekScopes/topic/tek_577_d1_repair_b07xxxx/77914568?p=,,,100,0,0,0::recentpostdate%2Fsticky,,,100,2,0,77914568> Please check the waveform of the staircase if you have a scope. Jack
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Jose Luu
satbeginner
Jean-Paul
Giovanni IZ5PQT