Author Topic: TDS3014 no trace no reponse of frontplate.  (Read 223 times)

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Offline madao

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TDS3014 no trace no reponse of frontplate.
« on: April 26, 2020, 10:24:49 am »
Hello people.

 I got  a  TDS3014.

Fault:  Startup  complete.  Message "Selftest passed"  :palm:    No  trace (despite  Auto-Trigger) and no reponse of frontplate.
Not one  LED is flashing while bootup.

Check of oscillator (48Mhz and 75,757 MHz) : OK
Check of oscillator from MCU on frontplate: dead.
Check with  new  4Mhz xtal: no oscillation.

I think: MCU of frontplate is dead.  Only reset line is asserted (from  low to high, while bootup.)
MCU is  NEC 78011
https://www.datasheetarchive.com/pdf/download.php?id=a9ce913475b09e2128212699d1690d1fab71bf&type=O&term=78011%2520NEC



Have you experience with this fault on TDS3000 Series ?
Has someone   frontplate for me ?  (bad encoder is not a problem for me :-) )

Greetings
matt
« Last Edit: April 26, 2020, 11:15:56 am by madao »
 

Offline daveyk

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #1 on: April 26, 2020, 07:11:39 pm »
Try holding in the B-TRIG button while it boots-up.  That forces a system RESET.  Fixed a few problems in the past.  Other than that, there is not repairable on those scopes. 
 

Offline madao

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #2 on: April 26, 2020, 07:16:13 pm »
This way doesn't work, because  MCU of frontplate is dead. No reactions and no oscillation on xtal.

 

Offline daveyk

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #3 on: April 26, 2020, 08:01:08 pm »
Sorry, I jumped the gun there.  I am very interested in these scope of own three of the (two TDS3052's and one TDS3054.  The TDS3052 were TDS3032s and my TDS3054 was a TDS3014).

I want to follow your repair in case I run in to it in the future.  The RESET line is NOT being held low on the processor correct?  I'm not sure how you could check the crystal other than replacing it.  Was it this way when you got it?  Perhaps it was dropped and the crystal broke?  I would think it's rare for a processor just to fail, especially hidden behind on a front panel board.  Its life is probably not stressed.  If you change the XTAL, and it is still bad, it's not an easy fix.  Is it the processor, external memory chip or some peripheral chip?

Let me know if you made any progress.

Dave
 

Offline madao

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #4 on: April 27, 2020, 05:07:56 am »
Reset is  only line, which it is asserted. While bootup change reset line from low to high. It is correct.   No oscillation,  it is same after change of XTAL (orginal is 10 MHz type)

NEC 78011 is single chip MCU (all in one, same as Atmega).. this is why i need  other frontplate (bad encoder is not a problem)

Failure-cause: probably ESD-discharge/overvoltage on Tekprobe-Interface. Not one  voltage clamp on   TekProbe-Interface ( old TDS500/700 has Diode  as voltage clamp on I²C line)

Today, i 'll borrow TDS3012B and  check with their frontplate.
 

Offline madao

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #5 on: April 27, 2020, 01:09:27 pm »
It live,  old frontplate is  cause for this failure.
Frontplate is borrowed from TDS3012B .
Reason for no trace:  it was added with offset.. :-DD this is why: no trace.


Now  i am looking after frontplate with good nec 78011 MCU.

Greetings
Matt
« Last Edit: April 28, 2020, 06:52:08 am by madao »
 

Offline madao

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Re: TDS3014 no trace no reponse of frontplate.
« Reply #6 on: April 28, 2020, 06:57:30 am »
Next  failure:   Channel 1  100-200-500mV/DIV amplifier is dead.  It is found by intensive  check.
 I have thinked at this point: it was added mit offset.

Now , i know, why is  channel 1 and  frontplate broken:  overvoltage ! :-BROKE   This explain, why "no trace" and "no reponse of frontplate"

It is funny , where got i   hybride and  desoldering of hybride is  painful job.

A useful scrap. (3 channel works )

Greetings
matt

 


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