Electronics > Repair
Reverse engineer Dallas DS1742W?
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zebity:
Hi James_s,

I found this Maxim Real-Time Clocks Selector Guide from June 2009 which still has the DS1742 as one of the "bytewide" available options (though is does indicate that PowerCap variation was made), but has no bare IC equivalent.

So as you say the IC was likely never sold seperately.

This leave option of:

1. Refurbish existing chip
2. Take out IC from existing chip and put on new board
3. Backward compatible replacement design / build
4. Build backward compatible replacement with larger NVRAM variation like DS1747 (as per your adaptor)

Option (3) It would be interesting project to do as learning exercise in Digital electronics, but (1) is the low hanging fruit for most people who can now see both the physical and x-ray view of chip and should be able to drill their existing chips to keep host machines running.

Cheers from Oz,

zebity/jwhat/John
darkstar49:

Can only confirm that the 'james_s' solution works like a charm... indeed maybe not the cheapest option, but given the number of problems a failing RTC can give with the TDS3000(B), I don't really understand the fuss... 70-80$ shouldn't be the point !

https://www.eevblog.com/forum/repair/tds3014-adventures-(seeking-75-75mhz-oscillator)/msg2733286/#msg2733286
Rasz:

--- Quote from: darkstar49 on November 12, 2020, 10:48:11 am ---RTC can give with the TDS3000(B), I don't really understand the fuss... 70-80$ shouldn't be the point !

--- End quote ---

Lets say you have a ~1970 car that sat in a barn for 30 years and carb is clogged. Do you buy a $80 rebuild carburetor, $15 carb kit or $10 gasket kit and just clean jets/float?
The way I see it you are throwing away perfectly good part because battery ran out.
james_s:

--- Quote from: Rasz on November 12, 2020, 04:48:34 pm ---
Lets say you have a ~1970 car that sat in a barn for 30 years and carb is clogged. Do you buy a $80 rebuild carburetor, $15 carb kit or $10 gasket kit and just clean jets/float?
The way I see it you are throwing away perfectly good part because battery ran out.

--- End quote ---

If the carb is welded shut and I have to grind off the welds and mangle it to get it open and then goop it back together with JB Weld when I'm finished then I'd buy a new carb, one that is held together with screws that I can easily remove to service it the next time.

I only made the adapter after I had a part fail such that replacing the battery did not fix it. I've hacked new batteries into Dallas chips many times, but it's always a hack, and the PowerCap package is easily serviced later, a significant improvement in my mind for what I see as a trivial amount of money.
Tantratron:

--- Quote from: james_s on November 12, 2020, 05:05:23 pm ---
--- Quote from: Rasz on November 12, 2020, 04:48:34 pm ---
Lets say you have a ~1970 car that sat in a barn for 30 years and carb is clogged. Do you buy a $80 rebuild carburetor, $15 carb kit or $10 gasket kit and just clean jets/float?
The way I see it you are throwing away perfectly good part because battery ran out.

--- End quote ---

If the carb is welded shut and I have to grind off the welds and mangle it to get it open and then goop it back together with JB Weld when I'm finished then I'd buy a new carb, one that is held together with screws that I can easily remove to service it the next time.

I only made the adapter after I had a part fail such that replacing the battery did not fix it. I've hacked new batteries into Dallas chips many times, but it's always a hack, and the PowerCap package is easily serviced later, a significant improvement in my mind for what I see as a trivial amount of money.

--- End quote ---
I'm bit lost here due to my non-native english speaking or not grasping 2nd message.

What exactly do you recommend as a method solve the issue ?

By the way, the same issue occurs in older tektronix, see this synthesis https://www.eevblog.com/forum/repair/nvram-of-oscilloscope-tdsxxx-serie-c-and-d/ so could it a universal new design chip with firmware able to accommodate different brands of DS or Maxim ?

If we want to keep these legacy oscilloscope, the problem number one is these DALLAS nvrams potted battery so it would nice to have a plug&play board with ease to change battery and emulating the same RTC and memory function
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