Attempting repair of TDS540C - Option 1G - Fail Processor

[Tantratron]

Hello, I'm on my learning curve on repairing and/or upgrading TDS500-700 C and D series.

As of today, I do have two of these, one TDS540C 500MHz - 2GS/s which works pretty good and another one with option 1G.
Not sure if the 1G or standard 2G is important here, the 1G has failed messages at start, please see 3 pictures attached in this thread.

Any idea, suggestion on how to solve at low cost the main issue (Failed Processor) then SPC issue ?

Thank you, Albert

[shakalnokturn]

The first thing to check for is signs of corrosion on the PCB.
If such is the case it is usually a low-cost fix, you could spend countless hours though.
Search online there are many discussions on that problem.

[madao]

This is a result of dead battery in NVSRAM. It is harmless failure.

Replace DS1486 and calibrate him. (Or, you can use dump of other good running TDS540C for him)

1G Option, it is better remove this option. but it is already away by dead batterie. Not every option is good. 1G is downgrade.

Regards
Matt

[Tantratron]

Hello Matt,

Do you happen to sell DS1486 or any alternative to find these new ?

What does it mean " you can use dump of other running TDS540C "... sorry I'm french so not english native speaking ?

Would you know the GPIB sequence of commands to remove 1G option so it will become 2GS/s as the other TDS540C which I've purchased lately on eBay ?

Thank you, Albert

[Tantratron]

Hello Shakalnokturn,

Just removed the cabinet and took 4 pictures attached here. For the moment I left the accumulated dust in many places but I do not see any rust or issues on the PCB traces.

By the way, what is bets method to remove or vent the dust without creating any ESD due to triboelectric effect ?

Thanks, Albert

[radioguy123]

You can buy ESD free brushes on ebay.
The dallas nvrams aren't being made anymore.
Don't be fooled by the fake Chinese junk on ebay.

This guy sells replacements for the two nvrams.

https://www.ebay.com/itm/Tektronix-TDS784D-700x-600x-exact-functional-replacement-for-DS1486-and-DS1250Y/302913384290?hash=item46870b6f62:g:uuwAAOSw9V5bFXZt

[madao]

Yes,  DS1486 is actually big problem.
Other solution:  Use  DS1245,  but Clock & Date would not running.  (DS1486 has RTC) This is a good alternative, if you can forego clock.
DS1245 is yet in production.

Or, you can cracking  NVSRAM and solder battery.




1G Option,  normally is  option saving into  NVSRAM, which you can removing with  gpib- commando.
This was my thinking about it.
But  one has trying hacking their  TDS540C to TDS580C (1GHz) and found one  interessing notice.

1G is  hardcoded.  You must  soldering correct resistor-ID on your acquisition board for removing of  1G option.
You found ID-resistor on botton side of Board. Interessing, i didn't know about it.

https://www.eevblog.com/forum/testgear/conversion-of-500mhz-tds744a-to-1ghz-tds784a/msg2834010/#msg2834010

I have tried to convert my TDS540C to TDS580C, by take out the 4 capacitors and only short the R1064, it shows 4Gs/s, but the banner shows TDS xxx. my firmware is FV:v5.0e. 
Passed SPC.
Maybe it is the firmware version problem?

Did you try 1061 instead of 1064?
What was the original resistor configuration?

Thanks thm_w. The original ID resister is R1061,1062,1063 shorted.
I will try R1061 today, to see If it works.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Report the progress. short R1061 only, it shows TDS540C, the sample rate max 1G for 1 or 2 channel on.
So, I changed back to shorting R1064 only. Very possible the FW version too low.
Have to bear the 'TDS xxx' now, until upgrade the FW.

[radioguy123]

Hi madao
Is that an xray of an actual DS1486 ?
Why is the picture title DS1486counterfeit ?

[Tantratron]

Both NVSRAM on the A11 board are DS1486-120 and DS1650Y-100

Do each NVSRAM contain batteries or only DS1486 ?

What is the role or function of each NVSRAM and do you confirm this explains the FAIL: processor as reported in the attached picture ?

If it can help, I do have a perfectly running TDS540C - 2GS/s so would it be worth compare visually side by side the A10 acquisition board to spot the resistor-capacitor in charge to hardwire 1GS/s

[madao]

Hi madao
Is that an xray of an actual DS1486 ?
Why is the picture title DS1486counterfeit ?

This was a china fake  DS1486 and runs not stable.

[madao]

Both NVSRAM on the A11 board are DS1486-120 and DS1650Y-100

Do each NVSRAM contain batteries or only DS1486 ?

No, DS1650  contains also batteries, but save only waveform (i am not sure), it is not fatal, if batteries empty.
DS1486 save setting  , calibration, Option.

What is the role or function of each NVSRAM and do you confirm this explains the FAIL: processor as reported in the attached picture ?

If it can help, I do have a perfectly running TDS540C - 2GS/s so would it be worth compare visually side by side the A10 acquisition board to spot the resistor-capacitor in charge to hardwire 1GS/s

1G Option is BAD, normally TDS540C (also TDS754C) runs up to 2Gs/s.  (export restriction?)

Error message, Diagnostic test failure nvLibrariansDiag, Libs with crcc failures:, ExtConst" and  "diagnostic  test failure extebded cal librarian reset"  It means,  calibration constant in NVSRAM is corrupt (CRC fail) and it is resetting to default.
I seen,  Clock runs fine.  Correct ?

[Tantratron]

Error message, Diagnostic test failure nvLibrariansDiag, Libs with crcc failures:, ExtConst" and  "diagnostic  test failure extebded cal librarian reset"  It means,  calibration constant in NVSRAM is corrupt (CRC fail) and it is resetting to default.
I seen,  Clock runs fine.  Correct ?

Yes I've just turn-ON again the scope and the date/time is correct after many days.

[radioguy123]

Try and keep running SPC and see if it clears out the errors. I had a TDS540C that had errors until ran the SPC multiple times.

[james_s]

It's not hard to cut the old battery out and install a new one.

On the TDS700 series the calibration is not stored in NVRAM, I don't know for sure about the TDS500 series but I think they are largely the same except monochrome.

[Alfons]

It's not hard to cut the old battery out and install a new one.

On the TDS700 series the calibration is not stored in NVRAM, I don't know for sure about the TDS500 series but I think they are largely the same except monochrome.

Yes, it creates confusion. One says calibration data is stored in NVRAM, the other says in SRAM. After what I've read, the Cal data in the TDS 500/600/700 series is stored in SRAM and not in NVRAM. Would be nice if we could agree on that.

[madao]

Calbration constant is saved in  NVSRAM (DS1486) and  a bit  cal constant (Bandwitdh & Voltage-reference, only guesting) in  I²C EPROM on acquisition board.

500 and 700 is same , except of  color-display

clock runs fine, it tells you: Batterie is not really empty.  You can writing him with good dump of other TDS540C.

Try and keep running SPC and see if it clears out the errors. I had a TDS540C that had errors until ran the SPC multiple times.

No, it would not helping, because  all  calibration except SPC is initialized  (= default-value, not good for using)


regards
matt

[Tantratron]

The fundamental question with this scope, the logfile says specific sentence " FATAL: 250 NV storage too small - more bytes requested than available "... see again attached picture

Not sure if both NVRAM have their batteries dead by the one in charge of keeping time-date works fine since the Oscope always provide correct time-date. Maybe it is the 2nd NVRAM who has depleted battery... unless we need to troubleshoot what chip is FATAL failing to logfile " FATAL: 250 NV storage too small - more bytes requested than available "

As for the SPC, it states PASS but the other parameters are only INITIALIZED so NOT PASSED, please see again other picture

[Alfons]

" FATAL: 250 NV storage too small - more bytes requested than available "

This means: Error log is full, there is no more space for new logs. The memory can be deleted via GPIB. What you can still do: Set OK in the utility menu "Tek Secure Erase Memory". Maybe it helps. This removes all the garbage that has accumulated.

[madao]

" FATAL: 250 NV storage too small - more bytes requested than available "
This error is not fatal.  Ingored him for at first.

Yes,  you say, clock run fine -> batteries is not empty. But fact exists: few bit had tilted. Result:  CRC failed,  ->  calibration constant in NVSRAM is gone.


Recalibration of him. You got Software for him  -> http://www.ko4bb.com/getsimple/index.php?id=download&file=Tektronix/Tektronix_-_TDS5xx_TDS6xx_TDS7xx_Digital_Phosphore_Oscilloscopes/Tektronix_TDS700C_Field_Adjustment_Software_PN_063277401.zip

This software needed old PC with ISA-bus and NI GPIB-PCII or PCIIA.
And  DCV/I Kalibrator, good DMM.
Signalgenerator (Tektronix  SG504 and SG503 recommend, i use  Rohde Schwarz SMY02)
few high quality BNC cable and T- adapter
and many time and patient. (5-10 hours)
(more info is in  Service Manual for  500C/700C)

I recommed you,  saving dump of NVSRAM from good TDS540C and put it in other  TDS540C. Then, you can seeing, "processor fail" disappear.
  Have you  EPROM-Programmer, which can write/read  DS1245 (just a DS1486 without clock)   or running tekfwtool ? (I know, you use MAC, i have not knowing about it)

[Tantratron]

" FATAL: 250 NV storage too small - more bytes requested than available "

This means: Error log is full, there is no more space for new logs. The memory can be deleted via GPIB. What you can still do: Set OK in the utility menu "Tek Secure Erase Memory". Maybe it helps. This removes all the garbage that has accumulated.

I do not think the issue is about lack of memory to store more info in the log file. Each time I run power, the log file will add with new stamp time/date the error in the log file.

Few days ago, I did "tek secure erase memory" which did clear some stuff and the oscilloscope was again able to display signals on all Channels. However this erase did not at all clear the log file content.

What is the GPIB command to erase the log file since I've been able 2 days ago to interface my MacBook Air with GPIB-USB device from National Instruments and its Mac OS suite ?

[Tantratron]

"I recommed you,  saving dump of NVSRAM from good TDS540C and put it in other  TDS540C. Then, you can seeing, "processor fail" disappear.
  Have you  EPROM-Programmer, which can write/read  DS1245 (just a DS1486 without clock)   or running tekfwtool ? (I know, you use MAC, i have not knowing about it)

Hello Matt,

Please find my first success to GPIB interface my second TDS540C working with my MacBook Air
https://www.eevblog.com/forum/repair/gpib-usb-control-between-macbook-air-(macintosh)-and-tds540c/

Could you teach me what are the exact chain of GIPB commands for 2 operations.

1. Dump NVSRAM from my good TDS540C then upload to the bad TDS540C

2. Read the Flags of different options (1M 2M 2F...) then upload the new flags to enable options like 2M or 2F from VISA Interactive Control software

Thank you, Albert

[shakalnokturn]

Hello Shakalnokturn,

Just removed the cabinet and took 4 pictures attached here. For the moment I left the accumulated dust in many places but I do not see any rust or issues on the PCB traces.

By the way, what is bets method to remove or vent the dust without creating any ESD due to triboelectric effect ?

Thanks, Albert

Your photos show mainly tantalum capacitors so that's one problem less to consider.
You do have SMD electrolytics on the console serial PCB so take a closer look at those, I don't know if failure to communicate with the UART on this board would cause a "FAIL: Processor", you could always disconnect it to be sure, it is an optional PCB.

I'd agree to say that the error log memory is full, each new entry would be pushing the oldest one into oblivion.

[Tantratron]

Bonjour Shakalnokturn,

Please note for the clarity that I've two TDS540C in my lab, one which I've purchased on eBay working fine and another one which is partially failed.

This morning I've removed as you suggest the RS-232 and Centronics optional board from the main A11 board. When starting the scope, now it will not display the Option 13 on the banner so it seems the TDS540C self-detect by hardware the presence of Option 13. Unfortunately I still have FAIL - Processor so there must really something on the A11 processor/display board.

By the way, I notice a strange thing when running side by side the healthy TDS540C (2GS/s) versus the failed TDS540C (1GS/s option 1G). When I push to the limits the horizontal scales up to 50ns, the left-top screen will correctly display " tek Run 1GS/s " but if increasing the horizontal speed, the healthy TDS540C will always keep tek run 1GS/s so this strange because normally it should offer 2GS/s standard. However on the partial fail TDS540C Option 1G, I can push to faster horizontal speed up to 100 GS/s at 50 ps except it displays additional ET SAMPLE

So one TDS540C has printed 500MHz - 2GS/s whereas the other 500 MHz - 1GS/s Option 1G.... which one is fastest after all ?

Anyway sorry for the rambling where the topic is understand how to eventually repair the A11 process or fail which by the ways freezes the SPC initialized.

Lastly I really confirm the size of the log file is not the problem, each time I re-run the scope it will add same error estimates with new date and time but keep the oldest log file data from 2003. I'm attaching the historical logfile from 2003 where it seems this Oscope had many problems in the past then kept sitting alone with the last problem, namely Processor failed.

[shakalnokturn]

Not certain as I no longer have a TDS 54x at hand, IIRC the maximum real-time sample rate depends on number of active channels. (2GS/s single, 1GS/s dual, 500MS/s triple or quad?)

[Tantratron]

Bingo my mistake... indeed when I tested the healthy TDS540C there was both Ch1 and Ch2 with Math doing Ch 1 x Ch 2

Removing all traces and only keeping one channel active provides Tek Run 2 GS/s

Merci