EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: jjaeger on November 30, 2019, 07:44:26 pm

Title: DS1054Z - broken channel
Post by: jjaeger on November 30, 2019, 07:44:26 pm
Hi everyone,

I have a question about my DS1054Z which I used bought a few days ago on eBay. The first channel seems to be broken. With this channel, no matter what Setting, no signals can be measured. All other inputs are working properly. I have tested almost everything, but unfortunately I can not find a solution. When the device is switched off, I do not measure a passage in the BNC Connector of the first channel. The other three channels are around 1MOHM. I think that the previous owner has broken the chanel with wrong measuring. Which components in the oscilloscope are the first to break? Which one could I exchange?

Many thanks and best regards from Germany
Julian  :-+
Title: Re: DS1054Z - broken channel
Post by: james_s on November 30, 2019, 07:49:33 pm
Was it sold as broken? If it was supposed to be working then you should send it back for a refund, or ask for a partial refund and keep it.

If you bought it as-is then the easiest thing to do is get in there and start measuring, find out where a signal applied to the input stops.
Title: Re: DS1054Z - broken channel
Post by: xrunner on November 30, 2019, 08:07:15 pm (
Title: Re: DS1054Z - broken channel
Post by: ted572 on December 14, 2019, 03:09:03 pm
Hello Julian:

This should be easy to troubleshoot.  Feed a signal into two Channels of your O'Scope (a working channel, and the non-working channel).
Configure the working channel for a proper display of the signal.  Then configure the non-working channel settings the same as the working channel. If you don't have a convenient signal source to use, them simply connect both channels via their probes (using their clip-on tips) to the Calibration signal Test Point on the front of the Scope (provided for 'probe compensation adjustments'). Now using a third working channel trace the signals through the two channels (the working, and the non-working). Trace through both to see where you loose the signal in the non-working channel.

The video that xrunner generously provided should  help you understand the oscilloscope's Front-End circuitry, so that you know where you are, and what is that you are probing, etc.

Hopefully you should be able to determine the problem and apply appropriate corrective action to get it working.   If you have any questions I will try to assist you.

   Good luck, Ted
Title: Re: DS1054Z - broken channel
Post by: Kleinstein on December 14, 2019, 04:39:30 pm
Not seeing the 1 M input resistance when turned off suggests an error right at the input. This could be as simple as a cold / broken solder joint, bad BNC connector or a bad relay contact.

For one more test, one could repeat the measurement with the scope turned on and switching to different vertical scales (e.g. 10 mV/div and 5 mV/div) and DC coupled mode. This should use both possible configurations of the input divider.
For testing the circuit one may not even need a scope running. Just resistance test with a DMM should be sufficient to find a broken joint of open relay.
Title: Re: DS1054Z - broken channel
Post by: TurboTom on December 14, 2019, 09:43:44 pm
Since your scope has our channels, you can even use ch3 or ch4 to diagnose (by comparison with ch2) the defective ch1, so you can use the scope to diagnose itself  :). Btw a good argument for a four channel scope!  ;)