Electronics > Repair

Tektronix DPO4104 self test errors. Repair attempt diary

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cgz2001:
I have a DPO4034.  I want to try and help but I’m real busy in the near term and very unfamiliar with telnet.  I am following your posts so you aren’t talking to yourself :).  I’ll try and take a further look at this soon, possibly this weekend if not tomorrow.

analogRF:
Here is a picture of the Acq part of the main board in DPO4104.

I think ADC1 (U271) takes care of Ch3&4 and ADC0 (U251) is for Ch1&2
and then there are 4 demux for 4 channels.

I dont know what U370-B (in my error log) means. any suggestion?

The memory chips are Micron MT47H32M16CC-3 revB. I cannot figure out why/how they used these chips and so many of them here?
Each channel has maximum 10MS record length, with 8 bit ADC it is 10MB, right?
But each of these chips is 32M x 16bit and there are 4 of them for each channel, why so much?
besides they could have used the 64Mx8bit configuration but they didn't. Any explanation of this confg is welcome


analogRF:
now, back to my problem, in manufacturing mode and Engineering mode, I ran the self tests and also checked the temperatures

I get those errors that I mentioned before and they refer to U271 (ADC1), U370-B (demux 3)

however, in temp monitor, I noticed that demux0,demux1,demux2  always show 0 but demux3 is hovering around 59C
maybe demux temp only shows a number if it is above a certain value to indicate a problem?


all preamps always show 0 even though they are the hottest chips on the board  ??? :o

ADC0 always shows around 65-67c while ADC1 always shows around 82-83C  ??? :o

I dont think these numbers are that accurate but the relative values must be telling something... maybe the heatsink is not sitting tight on ADC1?  I had that issues once in an Agilent 6014. Taking off those glued heatsinks is a huge pain in the a**



analogRF:
can somebody please check the temp monitor in their DPO4000 and share the results?
also the result of GND state measurements in post #8?

temp monitor appears under self test> warmup timer when you enter the manufacturing mode (can do it easily from the scope built in web page)

analogRF:
For those who might be interested, here is the uart console boot log and also the list of debug console commands when you telnet to the scope
as per instruction by andytuk in other old threads. notice that the commands are a bit different than MDO4000 that he was playing with.
still I have not found the RX pin of UART and need more testing but the boot log has some good information for those who are interested
also the self test errors that I am getting are visible near the end of that log.

none of these are of any interest to me at the moment though...I just need to figure out how/if the scope can be repaired to get rid of those errors
although it seems to be working...I love its interface, the DPO7254 is THE worst interface ever made by any vendor although the scope itself rocks

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