TDS 684C NVRam Backup

[james_s]

Ok here are the images. My scanner is terrible at scanning film but I was able to achieve reasonable results. This is a DS1250 and also a DS1386 I had on hand, I suspect the internal layout is very similar if not identical to the DS1486. The top down shots are taken at two different kVp settings, the higher the kVp, the more penetrating but the less contrast you get with lower density materials. You can clearly see the pads marked + and - where the battery attaches near the middle of the PCB.

[Armadillo]

Are we looking at these 2 pins? Is that 2 batteries, one piggyback onto each other.? Is this a fake or a genuine? thanks.

[james_s]

I think the - pin is the one below the + pin, the one in the upper-left I'm not certain, it may be for mechanical support. I plan to do some careful milling to remove the battery at which point I'll know exactly where the wires are. I think these pictures provide enough to do some reasonably educated surgery.

The DS1386 I know is genuine, the DS1250 has had the top sanded and re-marked but I believe it too is a genuine part based on the image. I think it's just an old pull that they re-marked and sold as a new one.

I just realized one top-down shot of each IC is flipped vertically, that happened when I scanned it. I believe the high-kvp shot is correct, looking down from the top with the battery under the Dallas logo based on the ground pin being in the lower-right but now I don't remember for sure. I really need to remember to keep track of this.

[Jwalling]

This is a DS1250 and also a DS1386 I had on hand, I suspect the internal layout is very similar if not identical to the DS1486.

A while back, I posted a picture of a DS1486 that I cut open. I can't seem to find it for some reason, so here's another picture.
This chip has TWO batteries, so it can't be like the chips you x-rayed.

[Armadillo]

Looks like a very hard material. The second battery is buried deep, will be hard to reach. 

[james_s]

Many epoxies will soften if heat is applied, so it may not be all that difficult. I have repaired quite a few potted HeNe laser power supplies, and even completely de-potted a couple of them. Just hit it with a heat gun and then dig the epoxy out before it softens. These Dallas chips are in a plastic housing that will stink so probaly best to cut the top off that first.

[Jwalling]

Looks like a very hard material. The second battery is buried deep, will be hard to reach. 

It is quite hard, as it's epoxy. Since I did that surgery with an X-acto knife, I've invested in a Dremel. 

[Mosaic]

Hi,
Would a TDS694C have the same NVRAM to replace?

[Jwalling]

Hi,
Would a TDS694C have the same NVRAM to replace?

Yes, it has the DS1486 as well.

[Mosaic]

Ok, My 694C was calibrated and is still in cal so I'd like to preserve the NVRAM.

I have a Willem PCB50 parallel port programmer, runs on XP, can anyone advise which settings to use for the DS1486 and DS1250Y?

http://www.mcumall.com/support/DualPoweredWillemUserGuide.htm#Supported%20Device%20List

[Armadillo]

So the chips DS1486 and DS1250Y finally came. It looks black like charcoal, every bits of it looks fake.

Anyway, I read the DS1486 using my TL866 set to DS1245Y but all read back as "FF". The time clock 14 bytes never change upon reread. Can anyone advise if this is normal or the fake needs to be rejected.

The DS1250Y all read as "00".

Thanks.

[james_s]

The DS1644 I read has the time bytes change every second so they're different with each read, I would expect the DS1486 to be the same. The DS1250 should all read FF IIRC, the one I bought came with data on it. Yours are probably re-marked pulls, if they were sold as new you should ask for a refund, you'll probably get it and be able to keep the chips. They may well be genuine internally but they're not new.

[Mosaic]

I ordered a pair from here:
http://www.ebay.com/usr/hkutsource?_trksid=p2057872.m2749.l2754

We'll see what they are when they arrive.
I hope the Willem PCB50 parallel port programmer can do them. I did a DS1225Y for a TEK2465B scope with it before.

EDIT: BTW since this exercise requires going inside the scope....have a look at this (my project) concerning the acq. chips cooling.
https://hackaday.io/project/12087-tektronix-tds-694c-trigger-cooling-workaround

[Armadillo]

I ordered a pair from here:
http://www.ebay.com/usr/hkutsource?_trksid=p2057872.m2749.l2754

We'll see what they are when they arrive.
I hope the Willem PCB50 parallel port programmer can do them. I did a DS1225Y for a TEK2465B scope with it before.

EDIT: BTW since this exercise requires going inside the scope....have a look at this (my project) concerning the acq. chips cooling.
https://hackaday.io/project/12087-tektronix-tds-694c-trigger-cooling-workaround

Same from UTsource.... :-(
Fake and defective.... what a nonsense.

[Armadillo]

The DS1644 I read has the time bytes change every second so they're different with each read, I would expect the DS1486 to be the same. The DS1250 should all read FF IIRC, the one I bought came with data on it. Yours are probably re-marked pulls, if they were sold as new you should ask for a refund, you'll probably get it and be able to keep the chips. They may well be genuine internally but they're not new.

ebay is directing me to paypal and paypal is directing me back to ebay.... both of them playing the Chinese taichi, pushing the problem around... 

[Mosaic]

What about  using an external Tadiran batt with a schottky diode to maintain the NVRAM Vcc at  3.6V so the 3.0V internal batt never comes into play?

[james_s]

That ought to work for the NVRAM-only variety, those with the RTC are not going to be as simple although it's certainly possible to construct something if you have the time and motivation.

I think the DS1644's I ordered are coming from utsource, I've gotten some good stuff from them before but I fully expect these to be re-marked pulls. Hopefully I can mill into them and replace the battery, I just want to have a good spare rather than risk damaging the original ones that are in the scopes. If they're not genuine I'll ask for a refund, and if they don't send me a refund I'll file a claim. Ebay's protection is heavily slanted in favor of the buyer, something I'm not real fond of but it's useful in cases like this.

If they just sold the things as used pulls for the same prices I'd still buy them, I don't know why they bother faking them. I'm also not sure why no Chinese company seems to have come up with a line of self-branded compatible devices, the technology within these Dallas chips is all commodity stuff, good quality replacements could be made for a small fraction the price of a new one. If I didn't have so many projects in my queue already I'd do it myself.

[Mosaic]

So the chips DS1486 and DS1250Y finally came. It looks black like charcoal, every bits of it looks fake.

Anyway, I read the DS1486 using my TL866 set to DS1245Y but all read back as "FF". The time clock 14 bytes never change upon reread. Can anyone advise if this is normal or the fake needs to be rejected.

The DS1250Y all read as "00".

Thanks.

It could be the DS1486 is genuine and has not been initialized to start the clock.
have a look at page 5 here:
http://www.dataman.com/media/datasheet/Dallas/DS1486_DS1486P.pdf

[james_s]

If you're lucky, it's a genuine part that has been re-marked with a current date code.

[Mosaic]

What is the date code on the parts?

EDIT:
I see the DS1250Y is still active, in production:
https://www.maximintegrated.com/en/products/digital/memory-products/DS1250Y.html

The suggested replacement for the DS1486 is the DS1556:
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1486.html

[Jwalling]

What is the date code on the parts?

EDIT:
I see the DS1250Y is still active, in production:
https://www.maximintegrated.com/en/products/digital/memory-products/DS1250Y.html

The suggested replacement for the DS1486 is the DS1556:
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1486.html

The DS1586 is not a drop-in replacement. The clock registers for the DS1586 are at the top of memory space while the DS1486 registers are at the bottom. I hate Maxim with a passion.

[Armadillo]

Question: What if instead of the DS1486, we plug in DS1245Y the memory non-volatile static ram instead without the clock, date, watchdog etc.... will the scope still stay to function. Anyone tried that?
Well it is definitely much cheaper than the DS1486 which is destined to be extinct.

[Armadillo]

Sorry Guys, I checked my DS1486 backup from the original scope IC and noticed that the first 50 bytes are actually "FF". The bytes that will varies automatically actually start at byte 51.
Now how do you tell TL866 to start programming from bytes 51 onwards?

Edit: So, that's the reason why TL866 does not have a device named DS1486.

[Mosaic]

What is the date code on the parts?

EDIT:
I see the DS1250Y is still active, in production:
https://www.maximintegrated.com/en/products/digital/memory-products/DS1250Y.html

The suggested replacement for the DS1486 is the DS1556:
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1486.html

The DS1586 is not a drop-in replacement. The clock registers for the DS1586 are at the top of memory space while the DS1486 registers are at the bottom. I hate Maxim with a passion.

No, that is not so clock data are at the top n both cases. The DS1556 has an extra 2 bytes of data used for the clock, for the full century, I think= Y2K ready.
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1486.html
https://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1556.html/tb_tab0

[Armadillo]

Jwalling is correct, not direct drop in replacement.