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Re: FG 504 function generator odd behaviour
Colin Herbert
Oops! I have checked the voltages and while the +25V (+24.99), +15V (+14.98)
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and -15V (-14.98) are just about bang on, the -25V is sitting at -3.58V. I really can't remember if this was the case when I checked previously, but it is now. I did manage to short something out with the DMM probes, so that may have given this problem, but sure as sure it needs to be fixed, but how? Colin.
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Dave Daniel Sent: 10 July 2020 18:13 To: TekScopes@groups.io Subject: Re: [TekScopes] FG 504 function generator odd behaviour The first thing to do is measure the power rails to make sure that the voltages are in spec and clean. DaveD On Jul 10, 2020, at 13:04, Colin Herbert via groups.io<colingherbert=blueyonder.co.uk@groups.io> wrote: shows asymmetry in that the negative peaks of the wave are rounded-off at any frequency and the positive ones have a similar but lesser problem at higher frequencies. This also seems to manifest itself as what looks like cut-off on the negative peaks of the sine-wave and lesser cut-off on positive peaks. While the triangle-waves are more-or-less symmetrical, the sine-waves are definitely not so, showing a nearly three-to-one voltage ratio in favour of positive peaks. There is also noticeably overshoot on the square-waves at anything above 1kHz and only a DC offset at frequencies below 80Hz. I am totally ignorant of how this function generator producestriangle-waves, but I do understand that the square-waves and sine-waves are derived from the triangle-wave. Does anyone have any help that they can offer? I would be grateful to get this useful function-generator working properly. Colin.
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Re: Tektronix 2230
Saroj Pradhan
Hi Raymond
Thank you for the information. Saroj
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Re: Tek 465 Turns on, No Dot, No Trace
There is a wire jumper at board location A-5 that provides the ground to the HV multiplier. (note that I am going from old memory so take with a grain of salt). Measure to ground to see if it is grounded. It is next to a mounting screw for the multi module. Just lift one end and see if the HV osc comes up.
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If the HV osc is not running, all the CRT vltage readings will be off. Regards
On 7/11/2020 6:31 AM, Stephen wrote:
I notice something I didn’t pay attention to before. That is TP1486 should go from 15V to 75V depending on the position of the Intensity control knob. However, mine goes from 15V to only 31V with the intensity maxed out... --
This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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Re: Looking for
stevenhorii
For those seeking a 7J20/J20 or parts, after the other posts on this, I’ve
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decided I won’t continue searching for one other than out of interest of what the price might be. It would be a novelty for me as I have equipment I need to do the testing I do. By the way, there’s an interesting module on eBay: https://www.ebay.com/itm/1pp-1-qty-tektronix-dp-100-digital-video-probe/264388939882 Apparently a TM500 plug-in (TekWiki) and a pod is shown with it on the TekWiki page but not by the seller on eBay. I have several older Tek NTSC video test items. I had a 1910 digital generator that was useful in the days of SDTV. If I am not mistaken, Tek acquired Grass Valley. Group. They made (make, I think) broadcast video equipment. The Tek test signal generators, waveform monitors, vector scopes, sync generators, etc. were made by Tek. Steve H.
On Sat, Jul 11, 2020 at 11:27 Kurt Swanson <kurt2135@frontiernet.net> wrote:
I have a 7J20. Unfortunately, I don't have the sampling head. I've had
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Re: Tektronix 2230
Saroj Pradhan
Hi Satbeginner
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Understood Thanks
On Sat, Jul 11, 2020, 10:12 PM satbeginner <castellcorunas@gmail.com> wrote:
Hi Saroj,
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Re: Tektronix 2230
Hi Saroj,
Connect one winding to oscillator, also Ch1 of the scope to the same winding. Now use Ch2 of the scope to check the other windings. I would connect the dot-side of the first winding to the signal generator, the other side of the winding to ground. That way on the other windings the dot-side should be in fase with the winding connected to the oscillator. Keep going, success, Leo
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Re: Tektronix 2230
Saroj Pradhan
Hi Satbeginner
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Right now I am looking for kapton tape in the market. Yes, I have another scope and signal generator.If I am not wrong, probing at dotted points scope should show voltages at same phase. Thanks Saroj
On Sat, Jul 11, 2020, 3:04 PM satbeginner <castellcorunas@gmail.com> wrote:
Hello Saroj,
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Re: Tektronix Blue paint - source in the UK ??
Dave Daniel
The other problem is that once mixed, it is difficult (but not impossible) to spray it on the parts to be painted. If one has a paint sprayer, it’s not too big a deal, except for having to clean the sprayer afterwards.
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I heard a while back that one or more paint vendors would mix it and package it in spray-paint cans. I don’t know that was or still is the case. DaveD
On Jul 11, 2020, at 11:57, Robin_Birch <robinb@ruffnready.co.uk> wrote:
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Re: Looking for
Dave Daniel
The J20/7J20 spectrometer had two (optional) fiber optic probes available. As nearly as I can tell, the base instrument did not come with a probe. One of the optional probes was described in the (1975) catalog as transferring light to the entrance slit. The second was described as a UV quartz fiber optic probe for transferring UV light. Both came with mounting rings (there are photos of the UV probe on the TekWiki site).
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There were also an external normalizer and a filter holder available as accessories. In some 20-odd years of looking for this instrument I have only ever seen one J20/7J20 come up for sale. I’ve never seen a standalone probe come up for sale. DaveD
On Jul 11, 2020, at 11:26, Kurt Swanson <kurt2135@frontiernet.net> wrote:
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Re: Tektronix Blue paint - source in the UK ??
Yes,
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All automotive paint suppliers will colour match and create a good match for you. The problem with quoting a specific paint supplier’s base or mix colours is that only works where that manufacturer’s colours are available. Cheers Robin
On 11 Jul 2020, at 15:31, Stephen Hanselman <kc4sw.io@kc4sw.com> wrote:
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Re: tektronix 2465b rom.
James Theonas
Thank you my friend!
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On Saturday, July 11, 2020, 5:12:06 PM GMT+3, Chuck Harris <cfharris@erols.com> wrote:
Yes, and no... You know what the values should be, and you know relatively where they exist in the calibration file, but you have no idea how, or where, they exist in the 2K RAM. Tektronix went out if its way to avoid telling you that little tidbit of information. Looking at your screen pictures, and looking at the data in a hex editor, you can probably figure out where in the 2K byte RAM the constants are, but you also have to figure out where the checksums for the whole file exist. I know there is a routine in the EPROM that lets you write back the calibration data, but it is not available to the unwashed masses. Someone told me about it once many, many, years ago, but I remember nothing about it, only that it exists. Well, that's not quite true, I recall it is a simple button press from within the EXER02 routine. Tektronix would never use such a routine, outside of development, as they would simply recalibrate the scope to restore any errant calibration data. -Chuck Harris James Theonas via groups.io wrote: Hi guys! I opened exerciser 2 on my scope and copied all the data from 00 to ff by looping through all of them as I was recording a video. If I input the said data in my programmer and flash a new chip will it work? Is that all that is needed?
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Re: Looking for
Kurt Swanson
I have a 7J20. Unfortunately, I don't have the sampling head. I've had it for a long time, and when I got it, I knew it was uncommon, but I figured a sampling head would eventually turn up. No such luck - at least so far.
I got it wanting to do some optical spectroscopy work, and still would like to get it working for that purpose. If anyone has a sampling head, let me know, otherwise I might reluctantly let this one go for sale or trade (and I do mean reluctantly). Regards - Kurt
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Re: New member with a currently-dead 2465
Siggi
On Fri, Jul 10, 2020 at 8:02 PM Tom Miller <tmiller11147@comcast.net> wrote:
Just replace U2556. It is a cheap part. Cut the leads close to the chipIn an over-the-counter repair shop, this would be sage advice, and I'm not sure I'd take you up on that bet. I believe Vincent is, however, more interested in the journey than the destination, and by measuring and thinking through all the things, you learn more :).
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Re: Cleaning TM500 module pushbutton switches
J Mcvein
Early on e.g. 1960's, WD-40 used fish oil. It changed to petroleum
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around the 1970s when fish oil became more valuable as a food supplement. That has not stopped the salmon fishermen out here from spraying their herring baits with it. Old practices die hard. JimMc
-----Original Message-----
From: "Greg Muir via groups.io" <big_sky_explorer=yahoo.com@groups.io> Sent: Friday, July 10, 2020 9:18pm To: TekScopes@groups.io Subject: Re: [TekScopes] Cleaning TM500 module pushbutton switches Roy, My experience with WD40 came when working on a project in Hawaii under high humidity conditions. The stores sold WD40 in gallon cans because everyone was using it to prevent their tools from rusting. I followed the crowd and applied heavy coatings to anything ferrous with the stuff. Some of the tools went for several months before they were brought into use. But when they came out it was found that the WD40 coating on them had turned into something similar to Cosmoline and required washing it off with solvents to clean them before they could be used. Obviously the tools did not rust. But there was something at play here that made the WD40 very messy. May have been the humidity. And from that I decided that WD40 was not very useful other than for storing things and loosening frozen items. I’m wondering if WD40 Company has changed the formulation since then. Greg
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Re: New member with a currently-dead 2465
Siggi
On Fri, Jul 10, 2020 at 7:33 PM Vincent Mallet <vmallet@gmail.com> wrote:
Tested +5V and GND pins of U2556 and they are as expected.That's not too surprising. The only inverter input where it is reasonable to do is the 1-2 inverter. The input there is weakly biased, rather than being positively driven from another logic output. Surprising things happened next when I tested the 1-2 inverter. I started I redid the experiment after putting another probe on TP505 U2092-37 and ISounds like there's something just marginal in the oscillator. If you catch the oscillator napping, you can infer the values of the biasing resistors (R2571/R2573/R2553) by the voltage drop across them. You also want to validate that the output of the 1-2 inverter is making the right output voltages. Low is below 0.8V and high is above 2.0V, if the output is in between there, you're nowhere. Same for the inputs. You measured 1.05V, which is in no-man's land, so now you need to figure out why. Either the biasing resistors have drifted (this happens with carbon comp resistors in particular) or your 1-2 inverter is marginal or bad, or there's leakage somewhere. I pulled the legs of C2565, C2566, C2572 to measure them with an LCRIf you catch the circuit in a non-oscillating state, you can measure the voltage drops across the respective resistors. From Ohm's law and the resistor nominal values, you should then be able to guestimate the current going through them. If things don't add up, you either have resistors that are out of spec, or you have leakage through the capacitors - measuring the resistors will tell you which. You can probably get quite near the truth by measuring the resistors in-circuit. I should have access to a better desoldering tool soon and I'll pull theGood luck! Siggi
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Re: Tek 465 Turns on, No Dot, No Trace
Stephen
On Fri, Jul 10, 2020 at 12:10 PM, Tom Miller wrote:
I think now I understand what you asked me to do. If you were referring to these wave forms shown before the CRT section I should be expecting at different points, I don’t. Point 87 (J6-10) and 88 are just fat and blurry traces. Nothing like the square waves shown in the service manual. Of course I used the same settings (5ms/50mV)
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Re: FG-504 not-so odd behavior
John Ferguson
with the FG 504 set at start freq 10, stop freq 40, multiplier at 10^2, sweep off,
measured on my 2445b, Sine freq 982.3 Hz, Sawtooth 975.9 Hz and Square wave 24.5 mHz. The square wave is an asymmetrical sine wave, not the Sawtooth I was expecting. Since I have two of these things and this one at least does this, and also the sweeps and other functions, all except a square wave, and the other one does nothing, this might be the one to fix. What do you think? john
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Re: DP512 12 GHz Digital Prescaler
Holger Lübben
HI!
A german Tektronix fan constructed three plugins: 1) RO510 10MHz Rubidium Oszillator. Two protoypes were built. http://w140.com/tekwiki/wiki/RO510 2) DP512: A 12GHz 1:1000 prescaler. One prototype was built. It worked up to 14GHz. 3) GS510: A 10MHz Oszillator based on a trimble GPS module. One prototype was built http://w140.com/tekwiki/wiki/GS510 All prototypes were constructed around this card: http://w140.com/tekwiki/wiki/SD_TEK_500_Prototype_Card There was a plan to finish the construction and to sell these plugins. But unfortunately the constructor died. None of the involved people had any relationship to Tektronix. Holger
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Re: Tektronix Blue paint - source in the UK ??
Stephen Hanselman
I’m not sure about folks outside of the US but if it were me I’d take a side panel down to the paint store and have them color match it. I’ve used this method on my house where it works well, no reason it shouldn’t work on test equipment
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Regards, Stephen Hanselman Datagate Systems, LLC
On Jul 11, 2020, at 04:26, Colin Herbert via groups.io <colingherbert=blueyonder.co.uk@groups.io> wrote:
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Re: DP512 12 GHz Digital Prescaler
stevenhorii
I believe at one time a company called Spectracom built a TM500 rubidium
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frequency standard plug-in.
On Sat, Jul 11, 2020 at 04:36 Egge Siert <eggeja2@hotmail.nl> wrote:
Hi Joe,
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