TDS3034B date & time not working :|

[f14]

Hi Guys,
I have issue with my tds3034b I use this some years and  date and time was stopped in july/2019 . after check I found date and time only work when turn on the scope and didn't work when I turn off and remove the power cord . seem like  ran out the batteries ( like the PC mainboard) but I didn't see any batteries in tds3034b mainboard
So How to fix this issue ?
Thank you!

[Jwalling]

The Dallas chip is almost dead. DS1742W-120 it's in a PDIP
Likely that if it just stopped recently, SPC constants are still OK. But not for much longer...
Part is EOL. Don't buy any fakes from China!

[MarkL]

You can also search this forum for "DS1742W".  There's a bunch of posts about this timekeeper/SRAM chip and most of them related to the TDS3000 series.

[f14]

So now i need  find and buy this chip then replace the old one in my tds3034b.  No more step?
Btw if i keep use the old ds1742w and dont care about time not working. My scope still woking fine ? Becuase find this chip is so hard. China sell a lot of with cheapest price ~5 to 10$ but im not sure it original :|
Thank you!

[Jwalling]

So now i need  find and buy this chip then replace the old one in my tds3034b.  No more step?
Btw if i keep use the old ds1742w and dont care about time not working. My scope still woking fine ? Becuase find this chip is so hard. China sell a lot of with cheapest price ~5 to 10$ but im not sure it original :|
Thank you!

When the battery dies completely, you will lose your SPC constants. If that happens, you will need to run it again on every power up.
I'm not sure whether the chip gets power when the scope is powered off, but still plugged in. I don't think it does, but not sure.

[f14]

Thank you for your reply.
If I change the new one without reprogaming . just blank chip
 The spc constants will work ?. Or need do SPC everytime i power up

[Jwalling]

Thank you for your reply.
If I change the new one without reprogaming . just blank chip
 The spc constants will work ?. Or need do SPC everytime i power up

Ideally, you would read the data from the old one and program into the new one. But if you don't have a programmer, it should still work OK. Use a socket in case anything goes wrong. You'll just need to run SPC once and you're done.

Question: If the scope is plugged in and the power switch is off, Does the clock keep running and keep good time?

[f14]

Question: If the scope is plugged in and the power switch is off, Does the clock keep running and keep good time?

I just test this in the morning and date & time only working when turn  on the scope .not working when the scope is plugged in and the power switch is off 
I ordered some new part DS1742w-120+ and 150+ from some shops (china) . and I will open up some with dremel to check it fake or not( but i dont know the orginal look like.) . the last option I will mod the old one in my scope with external cr2023 battery 
Thank you very much.

[Jwalling]

Question: If the scope is plugged in and the power switch is off, Does the clock keep running and keep good time?

I just test this in the morning and date & time only working when turn  on the scope .not working when the scope is plugged in and the power switch is off 
I ordered some new part DS1742w-120+ and 150+ from some shops (china) . and I will open up some with dremel to check it fake or not( but i dont know the orginal look like.) . the last option I will mod the old one in my scope with external cr2023 battery 
Thank you very much.

You'll be able to compare the "new" ones with the one in the scope. They're probably fakes, but you never know...  Let us know how you make out!

EDIT: Just thinking... I wonder if you isolated pin 24 from the socket (if you put a socket in) and make a small 3.3V voltage regulator that is powered from the power supplies +15V output, if that would work? When the scope is plugged in, +15V is always present.
A bit of a kluge, but it would probably work until a power outage.

Thinking about that, and it's a dumb idea. It would probably get corrupted easily on a power cycle since it wouldn't know the power is lost.

[MarkL]

I just got done doing the "cut open the old one" technique because I ended up getting a non-working fake from China.

Updated post in another thread here:

  https://www.eevblog.com/forum/repair/repair-of-tek-tds3014b-need-a-source-for-a-ds1742w-nvram/msg2644260/#msg2644260

Good luck!

[f14]

I will received the Ds1742w-120+/150+ in around next week. because I dont know how different inside  between orginal or fake,  so I  remove the old one . put the 24pin socket then insert the new one. if the scope boot up ok ,I will do SPC cal . change correct date time. then power off & leave it some minutes then power on and check the new chip is working or not . I order 8pcs in 4 different shops .I hope I have one is alive
I will update when the chip arrived. 
thank you !

[james_s]

I've bought 4 or 5 different Dallas RAMs from China that were all non-working fakes. Most of them mostly worked but had various problems. I'm not really sure why because the basic design is not complex. One simply acted like the write enable pin was not connected. On the bright side, you can usually get them for free by requesting a refund for the counterfeit part.

[f14]

update some mod with old chip.
everything look fine . now I waiting for battery and battery holder . because I use 24p socket so this make the chip higher some mm. and I think if I put battery holder sit on top the chip is not fit then I wiring battery in another place (thanks MarkL about this Idea)
I turn on this scope without chip battery external. it working fine except time and date return to year 2000
before desoldering  I erase this by tek secure erase  to clear all data store in this chip
thank you!

[f14]

new(fake) chip had come some days ago . and badly all didnt working ( scope not responding in boot screen. although I hard reset with press B trig button)
I opened and found the battery not sit on top like orginal and all trace line go to one die chip in the center

[james_s]

The thing I can't figure out about these fake Dallas chips is why they don't put in just a little more effort to make something that works. I mean if it doesn't work it may as well just be an empty package.

I don't know if it offers anything anyone hasn't seen already but I did recently overhaul one of these DS1742 chips with an external CR2032 holder glued to it. If you try this approach, do check first to make sure there is sufficient space to reassemble the instrument.

https://www.eevblog.com/forum/repair/tds3014-adventures-(seeking-75-75mhz-oscillator)/