Re: Advice on fixing 2465B slow horiz sweep
On Thu, Jul 22, 2021 at 03:02 PM, Grayson Evans wrote:
My 2465B has been sitting on the shelf for a few months. I notice when I
fired it up today that the horizontal sweep is slow, by that I mean that the
calibrator square wave does not line up with the screen scale lines. It sweep
starts out on the left correct but by the time it reaches the right side, it
is off about 1/2 cm.
I checked the calibrator output on another scope and it is correct. The Delta
T measurement shows that the calibrator timing is correct, but it just doesn't
line up with the screen scale. Same for B sweep.
Could this be a screwdriver/pot adjustment (too good to be true Im sure), or
some software calibration? I have maint manual which seems to reference R860
for horizontal gain, but discusses a CAL 01 procedure in detail, more detail
than I can follow.
Any one else have this problem?
------- There are good suggestions in the other posts too. Given that delta-T measurement has the same wrong horizontal scale factor, horizontal gain could be an issue as you suspected, although it is strange that the gain is off by ~ 5% (0.5cm error in ~ 10cm). One more test to check horizontal gain is to apply a signal, e.g. 1kHz sine wave, with 8 division amplitude to channel 1. Then switch to X-Y mode with nothing connected to Ch2, and with only Ch2 selected in the mode switches. Do you see a 8 division horizontal line, or is it compressed too? If you now turn on Ch1, do you see a 45 degree diagonal line? I did this experiment on my 2467B (almost same as 2465B). You can also use the calibrator output as signal generator, then you will see two dots in X-Y mode. You will need to adjust Ch1 volts/div for 8 divisions amplitude or best measurement accuracy. Looking at the schematic there is some interaction between x10 gain and x1 gain pots, if you see the gain off in x10 mode it could still be R860. If you touch R860 you may want to mark the original position in case it is something else. Again 5% error all of a sudden is strange. Ozan
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Re: Advice on fixing 2465B slow horiz sweep
Hey Grayson, It'd be helpful if you could describe what you've done and seen in some detail. Detailed observations are vastly more likely to produce useful advice than writing up your conclusions. Inline... Siggi On Sat, Jul 24, 2021 at 12:57 PM Grayson Evans <wa4gvm@...> wrote: I suspect horizontal gain drift since that fits the symptoms and I don't
know of any other problem.
Like I said, if you have the *same exact* offset at *all* sweep speeds, and on the cursors, then this could plausibly be horizontal gain. From what I can see, the 1X and 10X CRT gain are adjusted separately, so you can further verify that it's the 1X gain that's out if the sweep is OK at 10X. This is a case where you can describe what you've done and what you've observed in order to get better advice. The horizontal gain is adjusted first in the CAL01 procedure with R860 (1X) and R850(10X). Note that the sweep speeds are under software control through control voltages from the DAC on the A5 board. These are adjusted throughout the rest of the CAL01 procedure. I replace all the electrolytics in the power supply and everywhere else I
could find one. Do you have surface mount electrolytic caps on your A5 board? Had they leaked?
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Re: Advice on fixing 2465B slow horiz sweep
I suspect horizontal gain drift since that fits the symptoms and I don't know of any other problem.
I replace all the electrolytics in the power supply and everywhere else I could find one.
Just not sure if the horiz. gain is adjusted using a pot, (R860) or in the confusing CAL 01 procedure.
Anyone done that procedure?
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Re: DM 501A Mode Select Switches Issue
Jared,
Thanks, very helpful.
--
Michael Lynch
Dardanelle, AR
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Re: New (old) 2247a enquiry
If nothing else, sounds like you need to perform the trace rotation which is a screw trim adjustment which can be accessed from the front panel between the Focus and Readout control knobs just under the CRT face. That adjustment should allow you to get the trace even with the "horizon". If there is also any "bowing" on the trace you might need to perform the Geometry adjustment first, which as far as I remember is inside the scope. I don't have the SM manual handy so best you take a look into it. Manual is available here:
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Re: AA 501A Parts, DM 501A Probes
Amphenol If they have the cable you need. Tend to be a little on the pricy side. $20 for a longish BNC but one of the top shelf brands before you get in to the exotic high frequency cables and interconnects. Mouser and Digikey should stock them. For banana do you need shielding?. I make my own with meter lead so they are SUPER flexible. Unless I need shielding then I need to look at other wire.
Zen
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of sweetbeats Sent: Friday, July 23, 2021 3:21 PM To: [email protected]Subject: Re: [TekScopes] AA 501A Parts, DM 501A Probes So, a *sort* of related question, can anybody recommend a ¡°can¡¯t go wrong¡± set of female BNC to female BBC patch cables as well as banana to banana patch cables? Cory Oace
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When the output falls is the frequency outside the selected range? I have one that will let me set the frequency quite a bit low and high on the selected range but the leveling is not specified outside the selected range frequency range So this might be "normal" behavior. I just did a full calibration on one of the units I have. The manual calls out NOT to adjust the coils or trimmers unless necessary. And if those need adjustment you will need a spectrum analyzer to get the adjustment correct as these have a great deal of effect on the harmonic content of the waveform.
Zen
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of romeo987 Sent: Saturday, July 24, 2021 4:59 AM To: [email protected]Subject: [TekScopes] SG503 question Guys, Apologies in advance if I am doing the wrong thing; I posted this question on the TM500 group a while back, but there seems to be little activity over there, while there is a lot of action here ( I have been following for quite a while), and a lot of it to do with the TM500 world. The question is as follows: I have a couple of SG503s that I decided recently to ¡°get working¡±. Largely successful to the extent that I can monitor the output level to the required accuracy without the special Knick knacks called out in the manual. But one interesting effect I notice on both units (to a greater extent on one than the other) is, that on the 5-10 and 10-20 MHz ranges, at the extreme low limit of the dial (below 5 and 10MHz respectively) the output falls away to zero. Only on these two ranges. I have spent a bit of time rummaging around in the circuit, and at the moment it looks as if Q300 (the current source for the oscillator, driven by the leveling amp) can¡¯t quite push enough current to keep the oscillator Q130 going. But before I spend a lot more time, I would like to hear whether this is a common effect, and whether there is a known solution. Any advice gratefully received .
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Guys,
Apologies in advance if I am doing the wrong thing; I posted this question on the TM500 group a while back, but there seems to be little activity over there, while there is a lot of action here ( I have been following for quite a while), and a lot of it to do with the TM500 world. The question is as follows:
I have a couple of SG503s that I decided recently to ¡°get working¡±. Largely successful to the extent that I can monitor the output level to the required accuracy without the special Knick knacks called out in the manual. But one interesting effect I notice on both units (to a greater extent on one than the other) is, that on the 5-10 and 10-20 MHz ranges, at the extreme low limit of the dial (below 5 and 10MHz respectively) the output falls away to zero. Only on these two ranges.
I have spent a bit of time rummaging around in the circuit, and at the moment it looks as if Q300 (the current source for the oscillator, driven by the leveling amp) can¡¯t quite push enough current to keep the oscillator Q130 going. But before I spend a lot more time, I would like to hear whether this is a common effect, and whether there is a known solution.
Any advice gratefully received .
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Re: New (old) 2247a enquiry
I have noticed the traceand cursor lines dip down slightly from left to right. They have a slight curve to them. Is there an adjustment that can be made to fix this easily ? The service manual is a little overwhelming.
Regards
Richard
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Re: File /Tekscope 1975 V7 N4 Repairing Push Switches.pdf uploaded
#file-notice
Thanx for that, very helpfull !
¸é±ð²Ô¨¦
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Re: in-circuit capacitor testing (ESR tester) -- ideas appreciated.
Hey Bob, chill it with the negativity. Let people use the tools they want to. No one here is worse than the rest. On Sat, Jul 24, 2021 at 2:00 AM Bob Albert via groups.io <bob91343@...> wrote:
Roy, ESR is a sort of object for those trying to flount something special. Measuring it is usually a waste of time. If a capacitor's ESR has a high value, that is generally made obvious by a high D when measured properly on a bridge. If you need capacitance, you probably don't want a high D, whether that is from ESR or leakage.
For several years a popular DIY project was to build an ESR tester. I don't think they are worth much. For some reason, most people prefer the short cut of measuring a capacitor with a DMM that has a capacitance function, and those that use them generally have no idea how that device performs the measurement. A proper bridge is the way to test capacitors.
Bob
On Friday, July 23, 2021, 12:59:54 PM PDT, Roy Thistle <roy.thistle@...> wrote:
On Thu, Jul 22, 2021 at 05:00 PM, Ronan wrote:
my topic is not spam
Hi Ronan:
No worries:
Anything, and everything, I post (unless it's in quotes) is all and only just my opinion. (The moderators are the arbiters, not me.)
Thus, it's just and only my opinion that the posts about ESR Meters, on TekScopes, are spam.
To explain... ESR is a parasitic parameter that appears in the component model(s) for a particular realisation of capacitor(s).
ESR has its own parameter(s)... like frequency.
As such, I think the way ESR is popularly interpreted is baloney.
--
Roy Thistle
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Re: DM 501A Mode Select Switches Issue
Here's an article on repairing and servicing these push button switches I just uploaded. I have serviced a tone of these in my TM500 modules and with a little care, it's relatively easy to do, most often you don't even need to remove them from the PCB. /g/TekScopes/files/Tekscope%201975%20V7%20N4%20Repairing%20Push%20Switches.pdfTo clean them, I disassemble the switch, clean all the parts with isopropyl alcohol and a small paint brush/Kimwipes (Using a q-tip to scrub inside the switch body), then I use a new q-tip to apply Deoxit red inside the switch body along with some Deoxit on the spring contacts that sit in the central plunger, then finally a reaallllyyy thin smear of plastic safe lithium grease on the plunger and reassemble. I find holding the spring contacts in place in their recesses on the plunger and inserting the whole assembly into the switch body from the rear is the easiest way. With a little practice, you'll get the feel for it. Jared.
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File /Tekscope 1975 V7 N4 Repairing Push Switches.pdf uploaded
#file-notice
The following files have been uploaded to
the Files area of the [email protected] group.
By: Jared Cabot <jaredcabot@...>
Description:
How to repair and service push button switches
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Re: Replace/Repair TM 500 Module Side Panel Latch
The thing everybody forgets about 3D printing is that there is no economy of scale once you've amortized the costs of building the model. However I sell things through Shapeways and I consider their pricing much too high. I can only slap a 20% margin on my things at best and remain within the bounds of sanity. OfficeWorks in Australia charges $15 for 15 minutes, again too high. But it's mostly human intervention of course.
However you don't need Shapeways or Tek production quality on these. They only have to hold the side on for opening once a year, and they only need to be considerably better than the sticky tape we've all been using, which isn't hard.
I can print 10 on my $200 home 3D printer in under an hour. As a service to Tek group members I'm prepared to do so for $15 per set of 10, as long as people don't mind removing a bit of stringing and trimming and tolerating a maybe 10% failure rate. Heat gun or hair dryer requried for assembly. Postage from Australia 3182. Don't all shout at once please ;-)
EJP
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Re: Paper Used in Older Tek Manuals
Greetings,
I used a Dial Thickness gauge AKA snap gauge on the pages of my 1960 Tektronix 517A manual. It indicated the page thickness at 0.0054 inch.
Examining several paper weight to thickness charts I found the following:
24 pound bond = 0.0050 inch
28 pound bond = 0.0060 inch
I did find a reference to 100 pound Coated Text Dull paper stock = 0.0054 inch
I did not find a reference for 26 pound bond.
I hope this helps.
If you have an original Tektronix manual and access to a local print shop, not an office supply store or copy shop, but a place with real offset printing presses, they may be very willing to help determine exactly what paper you seek.
Regards,
Ken
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On 23Jul, 2021, at 7:26 PM, Jeff Dutky <jeff.dutky@...> wrote:
I'm resorting to printing one of my own manuals (which doesn't appear to be available in hard copy from the usual suspects, and is thankfully relatively short). I've got it printed now on normal 20 lb paper, but it's much flimsier than the original manuals I have. I'm looking into making a much nicer copy with blue covers and comb binding, and would like to get closer to the quality of the original article.
Does anybody know what weight of paper was used to print the old manuals? If not, I guess I just buy some reams of heavier weight papers and see what feels right.
-- Jeff Dutky
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Re: Paper Used in Older Tek Manuals
Jeff,
I contacted and worked with Lacy Communications on eBay: to see about getting a 2236 manual. He went to the trouble of finding and correcting a pdf to print up a manual. I think he is very helpful and eager to create a useful facsimile of needed manuals.
Perhaps reach out to him to see if he can build the manual you need. If he doesn't already have it on hand.
Dave
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On Friday, July 23, 2021, 6:27:01 PM PDT, Jeff Dutky <jeff.dutky@...> wrote:
I'm resorting to printing one of my own manuals (which doesn't appear to be available in hard copy from the usual suspects, and is thankfully relatively short). I've got it printed now on normal 20 lb paper, but it's much flimsier than the original manuals I have. I'm looking into making a much nicer copy with blue covers and comb binding, and would like to get closer to the quality of the original article.
Does anybody know what weight of paper was used to print the old manuals? If not, I guess I just buy some reams of heavier weight papers and see what feels right.
-- Jeff Dutky
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Gary Robert Bosworth <grbosworth@...> updated the album TDS2014B screen bottom malfunction: The bottom 1/2 inch of my screen is smeared. I tried to send a photo of my screen, but it did not seem to go through correctly.
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TDS2014B bottom 1/2 inch of screen is smeared
Can anyone point me in the direction of what is wrong with my TDS2014B when the bottom 1/2 inch of the display screen is smeared? I will try to send a photo, but at this point I cannot attach the photo to this post.
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Re: DM 501A Mode Select Switches Issue
Thanks, Jeff.
Actually I don¡¯t think this is that issue. The buttons are not ¡°sticky¡±. This is a different mechanical issue. The resistance mode button, if not held when pressing other buttons, can hyper extend past its normal stop a little bit. That¡¯s not normal. And like I said if it is held in a little the other buttons will latch, and their action is crisp when released. It¡¯s not that feeling like they got costed in honey I¡¯m dealing with on some of my other modules.
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Re: Paper Used in Older Tek Manuals
Just by memory of the feel, I'd say 24# or 26#
Harvey
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On 7/23/2021 9:26 PM, Jeff Dutky wrote: I'm resorting to printing one of my own manuals (which doesn't appear to be available in hard copy from the usual suspects, and is thankfully relatively short). I've got it printed now on normal 20 lb paper, but it's much flimsier than the original manuals I have. I'm looking into making a much nicer copy with blue covers and comb binding, and would like to get closer to the quality of the original article.
Does anybody know what weight of paper was used to print the old manuals? If not, I guess I just buy some reams of heavier weight papers and see what feels right.
-- Jeff Dutky
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Mlynch001
Jared Cabot
Dave Peterson
Gary Robert Bosworth