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Dallas DS1742W-150 Timekeeping RAM

BigBoss

BigBoss

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I need to replace Dallas DS1742W-150 Timekeeping RAM for my Oscilloscope because it's almost dead.
Who's gonna help me ? Is there any chance to replace an equivalent with ?
 
I don't know of any alternative but somewhere in my memory I remember a modification that allowed an external battery to be connected when the internal one has died. It was something like adding a diode in the supply line to isolate the DS1742 then feeding the alternative supply from a battery. Try a search for your oscilloscope number and see if it turns anything up.

Brian.
 
betwixt said:
I don't know of any alternative but somewhere in my memory I remember a modification that allowed an external battery to be connected when the internal one has died. It was something like adding a diode in the supply line to isolate the DS1742 then feeding the alternative supply from a battery. Try a search for your oscilloscope number and see if it turns anything up.

Brian.
Click to expand...
I know there are some temporary solutions but I desire a pin-to-pin compatible solution. I'm not a computer man and someone may create an equivalent using with modern components. There will also be many clients who actually use this model and I couldn't see any "consistant" solution for that.
Eiter they open the cap of the module and replace the battery or fake/crap IC's are used etc.
 
Hello!

I need to replace Dallas DS1742W-150 Timekeeping RAM for my Oscilloscope because it's almost dead.
Who's gonna help me ? Is there any chance to replace an equivalent with ?
Click to expand...

What do you mean by "almost"? Is it dead or not?

I know there are some temporary solutions but I desire a pin-to-pin compatible solution.
Click to expand...

There is some missing information. If you want a pin to pin solution, why not buying a DS1742W-150 and replace it?
Is it an obsolete component? DS1642 seems to have the same pinout and possibly others. Are you sure you cannot find
any replacement?

Some more info would be helpful.

Dora.
 
Hi,

Did you check on Asian online marketplaces to buy one?

You should be able to find out whether the case is glued or completely molded.
Glued should be easier to open ... or cut off the cap.

If molded:
If you want it to open then I'd first got to my dentist to ask him for an XRAY of the device to locate the battery.
Then gently use a DREMEL or similar tool to remove the plastics.
Needs some skills and patience.

Klaus
 
The problem with these devices is the internal battery eventually expires. It is an obsolete device since 2016 so since the last production run they have all slowly been decaying. Even if one is available from other sources, the chances are it is already on the way to the graveyard.

It may be possible to replace the battery as Klaus suggests, otherwise I think I would consider designing a small PCB with alternative parts and a standard lithium cell that could be a drop in replacement.

Brian.
 
doraemon said:
Hello!



What do you mean by "almost"? Is it dead or not?



There is some missing information. If you want a pin to pin solution, why not buying a DS1742W-150 and replace it?
Is it an obsolete component? DS1642 seems to have the same pinout and possibly others. Are you sure you cannot find
any replacement?

Some more info would be helpful.

Dora.
Click to expand...
RTC Can not register the date and time anymore. It has also calibration saving data feature. It seems work but the date and time are always wrong. This is well known problem for TDS3000 series oscilloscope owners. DS1742W is obsolete and not manufactured anymore by Dallas/Maxim/AD.
DS1642 has also been obsoleted many years ago. Therefore there are some inconsistent solutions in ebay or other second hand sellers, I do not trust frankly those sellers.
--- Updated ---

KlausST said:
Hi,

Did you check on Asian online marketplaces to buy one?

You should be able to find out whether the case is glued or completely molded.
Glued should be easier to open ... or cut off the cap.

If molded:
If you want it to open then I'd first got to my dentist to ask him for an XRAY of the device to locate the battery.
Then gently use a DREMEL or similar tool to remove the plastics.
Needs some skills and patience.

Klaus
Click to expand...
It's molded and de-capping is dangerous. If you crack the IC, the oscilloscope cannot start anymore. Because there is a firmware in it to my knowledge and this small software is used by main program. There are many Asian marketplace sellers in AliExpress or in others but they are reported as fake by many victims.
 
I suggest your first step is to see if there is a way to read the existing SRAM contents and save them for later. Usually in Tek scopes there is some hidden menu that dumps the memory to screen, either as a hex table or a readback of the calibration settings. Get it while you can, the SRAM will be lost completely when the battery dies.

Somewhere there is a design for a 6116 SRAM with a piggy back RTC as a replacement for the DS1742.

Brian.
 
BigBoss said:
If you crack the IC, the oscilloscope cannot start anymore. Because there is a firmware in it to my knowledge and this small software is used by main program.
Click to expand...
What?
then buying a new one wouldn´t be a solution at all. You won´t be able to buy one with the installed firmware.
If the battery is down, then all memory will be lost.

RTC Can not register the date and time anymore. It has also calibration saving data feature. It seems work but the date and time are always wrong.
Click to expand...
Can not register the date and time .. or
it can not count the date / time?

Klaus
 
Take a look. You haven't told us what model the 'scope is but if it isn't one of these it might be worthwhile contacting the author of the video to check compatibility.

Brian.
 
KlausST said:
What?
then buying a new one wouldn´t be a solution at all. You won´t be able to buy one with the installed firmware.
If the battery is down, then all memory will be lost.


Can not register the date and time .. or
it can not count the date / time?

Klaus
Click to expand...
You adjust the date and time but it stays stuck at that day and time. I doesn't count when the oscilloscope is powered off.
If you power on the scope, it counts again but of course with days/weeks/years of delay.

You're right, the firmware should be transferred first but I don't know how to do it. Is there any easy way to clone a RTC ??
 
Cloning is easy if you have an EPROM programmer.
If you look at the pin outs they are identical to 2K x 8 EPROMs (2716 for example). You should be able to read it as such. The RTC part is just the top 8 bytes of the memory space so if you copy them it doesn't matter because you will set the time and date again when the replacement is fitted anyway.

The 6116 SRAM is also pin compatible and very cheap. If you can wire a coin cell to its VCC pin, maybe by bending it back so it doesn't fit back in the socket and wire a pull up resistor between its enable pin and battery supply you can make a DS1742 replacement that doesn't have an RTC but should work otherwise. I'm not sure if the scope keeps time in software and just updates from the DS172 when switched on or whether it constantly reads from it.

Brian.
 

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