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Products => Test Equipment => Topic started by: tchiwam on September 15, 2020, 02:57:43 pm

Title: TDS694C
Post by: tchiwam on September 15, 2020, 02:57:43 pm

I have this unit with a SPC fail, I got the channels 3 and 4 behaving well and the channel 1 and 2 are showing something reasonable at 200mV and up ( upper side of the relays)

Few questions:
Is the ADC the same for both range 10mV to100mV and 200mV to 1V or is it on different pins ?

Anyone having a drawing / diagram for that unit ?

I suspect the ref signals for the SPC or relays to be bad, if I tweak cal, I can see reasonable traces...

Title: Re: TDS694C
Post by: tchiwam on September 15, 2020, 03:12:31 pm

Don't you love it when they say As Is because we can't test it ...

Then you open it and someone really tried to frill it...

Title: Re: TDS694C
Post by: tchiwam on September 17, 2020, 01:08:16 pm

Well, I have at least 2 good trigger chips and maybe a 3rd one. Can't test the channel 1 yet...

Title: Re: TDS694C
Post by: rvalente on September 17, 2020, 01:21:33 pm

Did you try to check the service manual?

https://www.tek.com/oscilloscope/tds794d-manual/tds500d-tds600c-tds700d-tds714l-service-manual (https://www.tek.com/oscilloscope/tds794d-manual/tds500d-tds600c-tds700d-tds714l-service-manual)

Title: Re: TDS694C
Post by: tchiwam on September 17, 2020, 02:38:53 pm

Yes, I need something closer to a schematic of the A10 board.

I am suspecting that one of the relay is dead, channel 1, then I think the reference for calibration is out of specs, it is warming up the internal termination.