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Tek 576 step generator problem

Dave S. All Messages By This Member #176307 Hello Guys, i need help with my Tek 576. Theres something pretty strange with the step generator... On some settings of the number of steps the lines start to flicker/jump around like something is not synced right. I uploaded a little video where you can observe the video (first its set to 5 Steps, then i change the knob to 6 steps and the lines go crazy) Even when its set to 5 every 2nd line of the measurement seems faulty aswell. Did everyone of you ever experience this problem? Could it be a problem of the output stage of the step gen? Hope someone can help me BR, David
- All Messages By This Member #176312 Did you try cleaning the step selector switch? Does it do that in every position? toggle quoted message Show quoted text On Sun, Jan 10, 2021 at 2:37 PM <hifi-workshop@...> wrote: Hello Guys, i need help with my Tek 576. Theres something pretty strange with the step generator... On some settings of the number of steps the lines start to flicker/jump around like something is not synced right. I uploaded a little video where you can observe the video (first its set to 5 Steps, then i change the knob to 6 steps and the lines go crazy) Even when its set to 5 every 2nd line of the measurement seems faulty aswell. Did everyone of you ever experience this problem? Could it be a problem of the output stage of the step gen? Hope someone can help me BR, David
Mlynch001 All Messages By This Member #176314 Does the unit flicker on the odd numbered settings? These things typically flicker visibly on the even numbered settings. This flicker is almost nonexistent on the odd numbered settings. -- Michael Lynch Dardanelle, AR
Dave S. All Messages By This Member #176315 Yes i tried to clean it already.. nothing changed at all. I just checked it again... the problem of the "jumping/unsynced" lines occurs on step-setting 2, 4, 6, 8 and 10
zenith5106 Member Profile All Messages By This Member #176320 On Sun, Jan 10, 2021 at 08:36 PM, Dave S. wrote: Theres something pretty strange with the step generator... On some settings of the number of steps the lines start to flicker/jump around like something is not synced right You could try this: /H?kan
Chuck Harris #176325 The filter capacitor for the 5V logic section is known to be bad, almost always, with these curve tracers. It is about 10K uf, and fairly low voltage, and it becomes open circuit. When the 5V supply capacitor is bad, it causes very erratic operation. -Chuck Harris hifi-workshop@... wrote: toggle quoted message Show quoted text Hello Guys, i need help with my Tek 576. Theres something pretty strange with the step generator... On some settings of the number of steps the lines start to flicker/jump around like something is not synced right. I uploaded a little video where you can observe the video (first its set to 5 Steps, then i change the knob to 6 steps and the lines go crazy) Even when its set to 5 every 2nd line of the measurement seems faulty aswell. Did everyone of you ever experience this problem? Could it be a problem of the output stage of the step gen? Hope someone can help me BR, David
Jack2015 All Messages By This Member #176343 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
Dave S. All Messages By This Member #176360 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
Jack2015 All Messages By This Member #176371 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
Dave S. All Messages By This Member #176378 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
Miguel Work All Messages By This Member #176383 I will check it later with mine -----Mensaje original----- De: [email protected] [mailto:[email protected]] En nombre de Dave S. Enviado el: lunes, 11 de enero de 2021 19:23 Para: [email protected] Asunto: Re: [TekScopes] 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 Scanned by McAfee and confirmed virus-free. Find out more here:
Miguel Work All Messages By This Member #176391 Hi Jack, my measurements. Is normal, try to put a 10 k resistor /g/TekScopes/photo/94656/0?p=Name,,,20,1,0,0 Max voltage in current mode seems 13V aprox., above this voltage constant current mode is not working. Regards! -----Mensaje original----- De: [email protected] [mailto:[email protected]] En nombre de Jack2015 Enviado el: lunes, 11 de enero de 2021 17:44 Para: [email protected] Asunto: Re: [TekScopes] 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 Scanned by McAfee and confirmed virus-free. Find out more here:
Jack2015 All Messages By This Member #176410 Hi David, Miguel did the tests for you,I believe this is what he wants to show us: </g/TekScopes/photo/94656/6?p=Created,,,100,1,0,0> Jack
Dave S. All Messages By This Member #176462 Hello, thank you very much guys for your help! So it looks like my step-gen performs ok and like Michael Lynch said it seems to be normal that the waveform flickers a bit more @ 2, 4, 6, 8 and 10 steps. Anyway i ran into another problem (or is it a problem?!) ... Maybe someone can do another (pretty easy) check/comparison I shorted the C and E terminal, set the vertical range to 5uA and turned up the collector supply to have 2 divisions (10uA). When i change the vertical range now from 5uA to 10uA the reading is not 10uA but suddenly almost 75uA. Is that normal due to internal change of measurement resistor? 5uA-Range: 10uA-Range without changing collector supply: BR, David
Mlynch001 All Messages By This Member #176486 On Wed, Jan 13, 2021 at 07:10 AM, Dave S. wrote: Anyway i ran into another problem (or is it a problem?!) ... Maybe someone can do another (pretty easy) check/comparison Did you get an answer to your question? I was going to check and the power went off at the house. -- Michael Lynch Dardanelle, AR
Dave S. All Messages By This Member #176489 Hi, unfortunately not. Maybe you could help me and make a quick check for that issue :) Thank you! Dave
Miguel Work All Messages By This Member #176491 Hi David, It seems normal, mine jumps from 10 to 65uA Regards Miguel -----Mensaje original----- De: [email protected] [mailto:[email protected]] En nombre de Dave S. Enviado el: miércoles, 13 de enero de 2021 14:11 Para: [email protected] Asunto: Re: [TekScopes] Tek 576 step generator problem Hello, thank you very much guys for your help! So it looks like my step-gen performs ok and like Michael Lynch said it seems to be normal that the waveform flickers a bit more @ 2, 4, 6, 8 and 10 steps. Anyway i ran into another problem (or is it a problem?!) ... Maybe someone can do another (pretty easy) check/comparison I shorted the C and E terminal, set the vertical range to 5uA and turned up the collector supply to have 2 divisions (10uA). When i change the vertical range now from 5uA to 10uA the reading is not 10uA but suddenly almost 75uA. Is that normal due to internal change of measurement resistor? 5uA-Range: 10uA-Range without changing collector supply: BR, David Scanned by McAfee and confirmed virus-free. Find out more here:

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