Re: Tek 576 step generator problem
Hi,
thanks for ur help!
What about the 50uA and 100uA (.1mA) waveform with the 100k paralell? Maybe you can check it on your 577 or someone else could check it on a 576 if it looks strange aswell.
Thank you!
David
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Re: Alternative for Snap-On knobs on 22XX and 24XX scopes??
Hi Jeff, Tam,
These knob don't break beyond use, sometimes the little latch inside comes loose.
But this is an easy fix using silicone kit.
As it turns out, these knobs are made already using a 3D printer, I think.
I found this:
I don't have a 3D printer, so that's no option for me.
Saludos,
Leo
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Re: [dead tek 485] Can i fix it ? (newbie here)
Jeff, the Tek probe cross reference from TekWiki says P6101A for passive 1X, P6106A for passive 10X, P6063B for passive 1X/10X, P6009 for high voltage 100X, P6015 for high voltage 1000X, and P6201 for active.? None indicated as being originally shipped with the 485 scope.? TekWiki is your (and my) best friend.? ? Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Jeff Dutky <jeff.dutky@...> Date: 1/10/21 8:39 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] [dead tek 485] Can i fix it ? (newbie here) Tom,I've been reading everything that I could find about the 485 since this discussion started, and the one thing that I can't find is any mention of what probe would have been standard with the scope. The 485 was released the same year as the 475 (with which I am quite familiar). The 475 would have shipped with P6075 probes (or maybe P6063 probes? My father's scope, which he started using in 1975, was shipped with P6075A probes).The manuals for the 475 clearly list what kind of probe would have been standard equipment with (and, apparently, were specifically designed for) the scope. Depending on which manual you look at the 475 manuals list either the P6075 or the P6106, but I haven't found any such listing in the 485's manual.I've been using cheap Chinese 200 MHz probes to test my new (to me) 2465, and the effects of the probes' bandwidth are evident. What probes would have been used on a new 485 in the early to mid seventies?-- Jeff Dutky
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Re: 7904 Power Supply Capacitors
Hi, Jose'.? I haven't seen Dave Hess post on TekScopes for a long time.? Try eevblog; he seems to be more active there lately.? ? ?GL.? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Jose Luu <jose.luu@...> Date: 1/11/21 6:14 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 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.RegardsJose
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Re: Alternative for Snap-On knobs on 22XX and 24XX scopes??
Leo,
These pre-made knobs are very nice. I have ordered a few score, of different types, to see how they will work.
I have also (because I am an American who does not understand thrift) ordered several of the $5 original manufacture press-on knobs. I have not installed them yet because I would like to try making replacement resin knobs from a silicone cast of the originals.
I will report back on both experiments.
-- Jeff Dutky
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
It occurred to me that if one were to successfully use a 7000 series plugin frame, the frame would stick out significantly, and allow you to have extra (and ventilated) room.? It wouldn't be workable with the current board set, but might be useful for a "checkout" style project.
Harvey
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On 1/11/2021 5:37 AM, John Kolb wrote:
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
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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Re: Tek 576 step generator problem
Step-Amplitude: .5V (no resistor)
The staircase looks ok! it's not broken trace issue. The design of step generator circuit is different between 576 and 577. In case of 577 the traces synchronize with the collector supply 4 traces per period(one trace per 90 degree). This could be seen by the timing between collector supply and staircase. < /g/TekScopes/photo/255563/29?p=Created,,,100,1,0,0> < /g/TekScopes/photo/255563/30?p=Created,,,100,1,0,0> Hope it helps. Jack
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Re: [dead tek 485] Can i fix it ? (newbie here)
Jose,
Nice scope! All of these 4xx series scopes are favorites of mine. I have not read back through the entire thread of posts. One minor issue that I see in the pictures, besides those already mentioned is the lack of illumination of the 1X or 10X indicators on the Ch1 Or Ch2 input. In addition, the 1M or 50Ohm indicator illuminators do not appear to be working. Not at all being picky, just mentioning them so you can add them to the list of things to fix. I bought a very similarly ¡°nice¡± 485 in Dallas, TX. As many have suggested, a thorough cleaning of every switch is one of the very first items on your list. Mine had similar issues and almost all went away after a careful switch cleaning. Mine had a very dirty beam finder switch that was causing the trace to wander off the screen from time to time (among other things). Looking forward to hearing more of your adventure with this fine scope.
--
Michael Lynch
Dardanelle, AR
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Re: Type 503 ¡ª power supply question
Dan,
Thanks for these links and recommendations. Fantastic stuff!
I love all the old audio equipment! Those machines are great for teaching the history of sound recording, radio, etc. with it. I've worked on both wire recorders and on a few old record cutters. I did a course on sound art where we restored a bunch of old Meissner record cutters and had the students cut their own discs. The challenge with those units is that the crystal cutting heads are all dead and have to be rebuilt. Anyway, I'm happy to talk about any of those projects if you (or anyone else) is interested. (Or just email me off list.) And I did use a Tek scope on them--my normal bench oscilloscope--but I wish I had the 503 back then!
All best,
Brian
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Re: [dead tek 485] Can i fix it ? (newbie here)
On Mon, Jan 11, 2021 at 07:15 AM, dnmeeks wrote:
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?
I guess to clean all contacts, some disassembling is required to access certain contacts (acces to intensity potentiometer is quite easy)
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Re: Alternative for Snap-On knobs on 22XX and 24XX scopes??
Dutchperson: if you send me a picture or a broken knob, I will try to 3D print a few for you.
--
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
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Re: [dead tek 485] Can i fix it ? (newbie here)
Jose,
Jeff is correct, the non-flatness of the Ch1 signal in AC coupling should be correctable as part of the Ch1 calibration procedure.
Your first picture of the Ch2 signal has the vertical sensitivity set to 0.1V/div instead of 1.0V/div! The trace shows something that looks a lot like the noise I mentioned in the previous post. The next picture, which I believe has the input set to 50 ohms shows the correct display since the calibrator output drops to 0.5V when terminated by 50 ohms.
With no trigger signal and 'normal' mode selected the beam spots should be on the left hand side and not visible until you turn the intensity up beyond its normal level. The electron beam should be blanked off by the Z axis circuitry, waiting to be unblanked when the time base is triggered. There is a 'holdoff' circuit which makes the timebase wait a set amount of time before retrace and the next trigger - maybe this is not working properly. Try rotating the 'A trigger holdoff' knob back and for several times in case it has developed bad contacts.
Regards,
Roger
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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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satbeginner
Mlynch001
Jose Luu