Author Topic: Tektronix TDS754D diagnostic test failure, dsp68kInMemTest  (Read 675 times)

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Offline wukiduki

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Tektronix TDS754D diagnostic test failure, dsp68kInMemTest
« on: June 10, 2018, 03:35:31 pm »
hello!
Recently got a tds754d oscilloscope, the function looks normal, but the processor self-test cannot pass.
 I have cleaned the PCB, the problem still exists.
 Does anyone know which chip is related to this error?
 Need some help. :-BROKE

ERROR Log read via gpib:
Code: [Select]
THU JUN 07 13:06:34 2018  ERROR: diagnostic test failure, dsp68kInMemTest,
** addr = 0x7028200  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x7028204  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x7028208  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x702820c  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x7028210  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x7028214  exp data = 0x55555500  actual = 0xff555500,
** addr = 0x7028218  exp data = 0x55555500  actual = 0xff555500
 

Offline Haatveit

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Re: Tektronix TDS754D diagnostic test failure, dsp68kInMemTest
« Reply #1 on: June 10, 2018, 07:51:56 pm »
It could be a bad assumption, but since all the addresses tested get the same bit pattern wrong, I might suspect some memory address PCB traces could be corroded? I know that was a problem of many of these scopes. Electrolytic capacitors leaking and the following corrosion on the board itself.
 

Offline madao

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Re: Tektronix TDS754D diagnostic test failure, dsp68kInMemTest
« Reply #2 on: June 03, 2020, 07:51:35 pm »
Old questition, i know, but  it may be helpful for other people with search word "dsp68kInMemTest"

But, i want tell about this ERROR.

I got a TDS754C from israelite surplus shop.
This unit has same fail.

Quote
cpuDiagDsyAccess ............... pass
dsp68kMemTest .................. ***FAIL***
..error details:
ERRORID: 162 diagnostic test failure dsp68kInMemTest
** addr = 0x7000000  exp data = 0x7fffff00  actual = 0x7f5fff00
[attach=1]

Reason:  one of three bad  SRAM for   Tristar DSP
U870(middle below ), U871(middle upper, this is bad), U872 (upper). 

Greetings
Matt

BTW: dsp68kD1MemTest  = bad U1008 or U1009.
« Last Edit: June 03, 2020, 08:28:30 pm by madao »
 

Offline snoopy

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Re: Tektronix TDS754D diagnostic test failure, dsp68kInMemTest
« Reply #3 on: June 04, 2020, 03:38:39 am »
I got a 784A that did a similar thing and everyone was saying that it was one of the memory chips but I located it to some dry solder joints on one of the big arse QFP chips on the main acquisition board. Use a fine dentist tool and carefully pull on each leg of the QFP and see if it is firmly soldered to its pad.
 


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