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Old 18th Feb 2018, 4:15 pm   #1
ramifer
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Default Oscilloscope Telequipment D1011. missing traza CH1

I have a Telequipment D1011 oscilloscope that lacks the trace corresponding to channel 1 (CH1) and I would like to repair it. I have little knowledge of the oscilloscopes, and I wanted to know if there is a (flow diagram), for example as in the (Tektronix oscilloscopes), for the repair of this Telequipment D1011 oscilloscope, since I do not know where to start checking.
I also need help to try to repair it.
Greetings.
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Old 18th Feb 2018, 11:59 pm   #2
Argus25
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

Quote:
Originally Posted by ramifer View Post
I have a Telequipment D1011 oscilloscope that lacks the trace corresponding to channel 1 (CH1) and I would like to repair it. I have little knowledge of the oscilloscopes...
Hi,

The oscilloscope is a system of attenuators and wide band amplifiers for the vertical deflection and a synchronizable or triggered time-base for the horizontal deflection.

To be able to see the results of the activity of these sub-circuits the CRT itself has to be set up and working properly and all of the electrical potentials around the CRT's gun and deflection plates and final anode correct.

However, there are very high voltages and high resistance circuits around the CRT and these exceed the capability of many common multi-meters to test them.

With a two channel scope, if one channel is working, you can sometimes use it as a tool to fault find the other channel fault, if you don't have another scope for diagnostic purposes. A 100:1 and other high voltage probes can be helpful.

Also, in twin trace oscilloscopes there are channel switching circuits that are moderately involved to chop or alternate the beam to each trace, although some early types had twin beam CRT's.

You may not need to delve into the high voltage circuits, but at this point that is not definitely known.

If you have little knowledge of oscilloscopes, this is the risky area, for you safety wise, due to the high voltages, if you plan to attempt to work on it yourself.

So given what you have said, it could be safer to have it looked at by an experienced engineer instead.

If you want to go down the fix it yourself road, the best advice I could give is read up on oscilloscope circuitry and systems and CRT support circuitry and high voltage power supply measurements etc, then study the design of your particular scope for a while first (you will need the service manual and schematics), before diving into it unprepared, which will likely bring you trouble.

When it comes to flow diagrams for fault finding, most experienced engineers know they are usually not worth the paper they are written on and often do not help to resolve the problem, unless say it was a very simple issue to begin with.

Last edited by Argus25; 19th Feb 2018 at 12:18 am.
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Old 19th Feb 2018, 6:24 am   #3
Boater Sam
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

Have a look at this site for some info.

http://bee.mif.pg.gda.pl/ciasteczkow...ment/D1010.pdf

http://bee.mif.pg.gda.pl/ciasteczkow...ment/D1010.pdf

If that has not come across well, PM me please.
Sam.
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Old 19th Feb 2018, 10:25 am   #4
MrBungle
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

Not sure what your electronics expertise is, but if you don't have at least some experience, fixing scopes can be a big hill to climb over.

Firstly, get yourself a copy of the service manual from above and have a read through: http://www.sphere.bc.ca/test/tek-par...ing-scopes.pdf

If you have one channel working and not the other, it's not likely to be anything high voltage or particularly hazardous. However you still need to be careful around those bits of the scope as it's possible to come into contact with them.

Now here comes the big problem. If you have a broken oscilloscope you need to have another oscilloscope to fix it really.

When I get a scope with a dead channel it's usually one of four things:

1. Dirty switches (alt, chop)
2. Dead chop/alt oscillator.
3. Blown up attenuator or follower.
4. Dying channel switch.

Each of those is easy enough to debug if you follow the schematics and Tek info above.
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Old 19th Feb 2018, 10:37 am   #5
robinshack
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

I do not know if it is like your problem, but sometimes the lever switches can be faulty or intermittent. I had one scope years ago that I soldered a link across the open circuit contacts to get it working on one channel. They are a difficult part to obtain.
They can be checked safely, without power, using an ohmeter and referring to the circuit diagram.
Rob
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Old 19th Feb 2018, 10:37 am   #6
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

To those I would add the obvious, trace driven off the screen by miss set shift control.
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Old 19th Feb 2018, 10:42 pm   #7
MotorBikeLes
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Default Re: Oscilloscope Telequipment D1011. missing traza CH1

Rob is right about all four of those selector switches. They have thin, printed gold as I recall, and were very unreliable. When Tek stopped support for all TQ stuff, I ordered a dozen of them, don't recall fitting them, so must have sold them, and I have a 1010 myself to sort if I get time.
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