The RTClock disassembly with pictures

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AndyF
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The RTClock disassembly with pictures

Post by AndyF » Tue May 22, 2012 1:40 pm

Note: This unit was already very dead, even after having it plugged in and powered up for a day, an original (v106) L3 server disc still threw a "Clock Failure" message, shame really as I would of expected it to work even with a dead battery if it was powered up.

As no one that I am aware of has done this, well I've not seen any pictures...

There's very little inside these things:

Two Resistors (or 1 Resistor and a Diode)
One IC
One Crystal
One Battery
The cable connector

That's it.

Disassembly was not very easy as I did not want to hack it to bits too much, however as usual things did not go to plan.

Initially I use a junior hacksaw to cut about 3mm into each corner, then I carefully chiselled the outer plastics away. After that it was a case of drilling some 2mm holes in a line then attempting with a tiny sharp chisel to remove the coating without breaking the board.

See the following pictures. Please note I did my best with my crappy camera but despite playing with auto / iso settings / and everything else I could not get a really decent picture. I will have another go at that in a few days. I was hoping a step by step "as it comes apart" but things did not work out.

There was no visible number on the IC, I was reasonably careful to remove the resin as best as I could although it did shatter a bit. Unfortunately, it flew out of the garden shed and went into some bark chippings :( , despite my efforts I have been unable to find it or the crystal just yet.

On the solder side is written:

JK 0000 280
Side 1
Iss C

On the component side:

(something) 0000280 ISS C

Pics:

clock_8.jpg
clock_8.jpg (49.09 KiB) Viewed 720 times
clock_9.jpg
clock_9.jpg (243.38 KiB) Viewed 720 times
clock_10.jpg
clock_10.jpg (188.89 KiB) Viewed 720 times
clock_11.jpg
clock_11.jpg (165.85 KiB) Viewed 720 times
clock_12.jpg
clock_12.jpg (190.38 KiB) Viewed 720 times
clock_13.jpg
clock_13.jpg (161.06 KiB) Viewed 720 times
clock_14.jpg
clock_14.jpg (140.69 KiB) Viewed 720 times
clock_15.jpg
clock_15.jpg (152.17 KiB) Viewed 720 times
clock_16.jpg
clock_16.jpg (142.57 KiB) Viewed 720 times
clock_17.jpg
clock_17.jpg (58.23 KiB) Viewed 720 times

Kind regards, the butcher of startdot. :oops: :oops: :oops:
Last edited by AndyF on Wed May 23, 2012 9:28 am, edited 1 time in total.
Andy

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Re: The RTClock disassembly with pictures

Post by paulv » Tue May 22, 2012 2:31 pm

:shock: :-#

There are no words!

Paul

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Re: The RTClock disassembly with pictures

Post by AndyF » Tue May 22, 2012 2:38 pm

paulv wrote::shock: :-#

There are no words!

Paul
I don't know to read that as:

"Well Done :D About time someone took a look"
or
"Burn The Heretic [-X "

Hence my "Kind regards..." bit under the pics.


It did seem to me to be one of the remaining "secrets", for want of another expression...

I guess the IC is similar to the units fitted in the Arc's albeit an older design given the larger IC maybe.
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Re: The RTClock disassembly with pictures

Post by paulv » Tue May 22, 2012 2:48 pm

AndyF wrote:
paulv wrote::shock: :-#

There are no words!

Paul
I don't know to read that as:

"Well Done :D About time someone took a look"
or
"Burn The Heretic [-X "
It is what it is :lol: Just shock and silence ;)

Seriously though, it's likely that the crystal is a 32.768 kHz type as is common in most RTC designs and the IC could be one of these or similar if I'm counting the holes on the PCB correctly...

Paul

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Re: The RTClock disassembly with pictures

Post by 1024MAK » Tue May 22, 2012 2:52 pm

There are a number of RTC chips that come in 16 pin DIL packages...

Does your camera have a macro mode? The images you posted are suffering from a focus problem. To get better focus for close-up items switch to the macro mode.
If you do not have a macro mode, but have lots of mega-pixels, take the picture from at least 1 metre away, then once in the computer, crop the image.

Mark

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Re: The RTClock disassembly with pictures

Post by AndyF » Tue May 22, 2012 2:53 pm

:)

It just seemed like it needed doing, especially as no one had as far as I'm aware. There was a discussion on the mailing list about it ages ago but nothing came of it.

What made my mind up was the fact it was dead, due to the design (oversight perhaps?) the "charge" current is not enough to actually power it, unfortunately.

I know they are a bit thin on the ground and it seemed a shame but at least there's now some information around.

The pics I tried to tidy up a bit, although its not actually in as bad a condition as the pics make it appear given their blurr.
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Re: The RTClock disassembly with pictures

Post by AndyF » Tue May 22, 2012 2:54 pm

1024MAK wrote:There are a number of RTC chips that come in 16 pin DIL packages...

Does your camera have a macro mode? The images you posted are suffering from a focus problem. To get better focus for close-up items switch to the macro mode.
If you do not have a macro mode, but have lots of mega-pixels, take the picture from at least 1 metre away, then once in the computer, crop the image.

Mark
Will try that later, thanks. yes it does and I did try both with that and without. I'll do the "stand a distance away" thing as the pics are reasonably large straight off it.

I also need to look for the chip too, although it did not have any numbers that I could see, there was a 37 underneath it where it started to come off the PCB though but the top was clear as far as I could tell (purposely done before assembly?)

Job for this evening, camera batteries now flat.
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Re: The RTClock disassembly with pictures

Post by 1024MAK » Tue May 22, 2012 2:59 pm

AndyF wrote:Will try that later, thanks. yes it does and I did try both with that and without. I'll do the "stand a distance away" thing as the pics are reasonably large straight off it.
Also with my camera, at close range, the auto-focus gets confused by shiny bits on PCB's. So I aim for a non-shiny section, half-press the button and then move to get the picture that I want.
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Re: The RTClock disassembly with pictures

Post by 1024MAK » Tue May 22, 2012 3:04 pm

AndyF wrote:I also need to look for the chip too, although it did not have any numbers that I could see, there was a 37 underneath it where it started to come off the PCB though but the top was clear as far as I could tell (purposely done before assembly?)
More likely the print got stuck to the epoxy resin and so left the chip case blank...
I can't see them bothering to remove the marking, as it was going to be encapsulated.

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Re: The RTClock disassembly with pictures

Post by AndyF » Wed May 23, 2012 9:29 am

The original terrible quality pics have been replaced with some of a slightly better quality. At least you can see the tracks now properly on the (single sided) PCB.
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Re: The RTClock disassembly with pictures

Post by BeebMaster » Sun May 27, 2012 5:17 pm

Well, I think this is great work!

The more we can learn about how the Econet RTC works, the better!

Hopefully this will help us learn how to read and write the clock inside the module using the user port.

There are patched versions of the L3 server code which bypass the detection of the clock module anyhow, so taking one out of service isn't too much of a crime!
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Re: The RTClock disassembly with pictures

Post by AndyF » Sun May 27, 2012 5:26 pm

Thanks. :)

As above pics were replaced with slightly better ones (not sure if you saw the first ones, they really were terrible :oops: )

I would not of butchered a working one, but as it was completely dead I did not see the harm in doing it as they are not *that* rare and more interestingly no one else had tried it that I'm aware of.

Perhaps the IC / Crystal had died instead, I was expecting it to work if the battery was flat, ie: the "charge" current would be enough to allow it to work with a dead battery, but you never know I guess.
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Re: The RTClock disassembly with pictures

Post by poink » Mon May 28, 2012 2:45 pm

paulv wrote: Seriously though, it's likely that the crystal is a 32.768 kHz type as is common in most RTC designs and the IC could be one of these or similar if I'm counting the holes on the PCB correctly...
I count 16 holes as well.

We can probably discount a number of chips quite quickly though.

Any chip that fits needs to be compatible with either (depending on IC orientation):

GND at 4,9,10 and 16
Data 11,12,13,14,15
Battery 8 (+), 7 (-)
XTAL 5, 6
NC 1,2,3

or

GND at 1,2,8 and 12
Data 3,4,5,6,7
Battery 16 (+), 15 (-1)
XTAL 13, 14
NC 9,10,11

(I suspect that the former is more likely - pin 1 would be the same north as the Acorn logo.)

There's a hideous likelihood that I've flipped something wrong or missquinted at a track.

The above pinout requirements suggest to me that the RTC is not: DS1305, DS1306, CDP68HC68T1 (ie., none of the RS chips) nor does it seem to be an MSM58321 (but then the number of data lines suggest a serial protocol of some sort) or an M41T84 OR M43T94.

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Re: The RTClock disassembly with pictures

Post by IanB » Tue Aug 21, 2012 12:58 am

poink wrote:
Any chip that fits needs to be compatible with either (depending on IC orientation):

GND at 1,2,8 and 12
Data 3,4,5,6,7
Battery 16 (+), 15 (-1)
XTAL 13, 14
NC 9,10,11
I just came across a reference to an RTC chip and I thought I'd check the pinout against the above and it seems a pretty good match:

Philips PCF8573

This has the battery across 15 & 16, xtal across 13 & 14 and I2C data on 4 & 5
Also pin 8 is GND and the usage of the rest of the pins looks sensible.

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