Suitable 32.768KHz oscillator for Pulsar Modules...read on..

[azimuth_pl]

how do you find this helpful in this interesting hunt for Pulsar know-how? diagrams by the Pulsar "engineer" below.

[rewolf]

No Rx and Ry on the diagrams .
But I think the case is already solved: Rx and Ry connect GND resp. Ve+ to the oscillator supply input pins of the IC, as OldTom pointed out.
Only one question remains: the red line in my picture posted above must be connected to the positive battery terminal (Ve+) somewhere. I can't see this on the board, it must be by external wiring (including the reed switches whitch all seem to be conncted to Ve+ on one side). Any Pulsar owner should be able to verify this easily.
It would be really great to have a diagram of the chip INTERNALS in this area. I know that Phil Bowler (former member leddwatch) has these. I have some internal diagrams, but not of the oscillator part.

[azimuth_pl]

the red line is connected to positive with a wire going directly from the battery underneath the substrate. grab a dead Pulsar for analysis and it will be far easier.

[rewolf]

Ok, so this is solved. I updated the picture in my posting above accordingly.
If I had a dead Pulsar for analysis I wouldn't ask so many dumb questions

About Rx and Ry probably being meant as inductors: If the intention had been to create as much inductance as possible on the given board area, they would have used a spiral-shaped trace. In fact, the meandering type is the way to get as little parasitic inductance as possible (less than a straight line of same length).

Edit: "just for fun" I tried to estimate the trace length of Rx: counted 4432 pixels in my picture (I'd say +/- 5%), guess 31.2 pixels/mm from the pin spacing of the LED display (2.54mm) -> 135.4mm = 5.3". So specific resistance is 89kΩ/135.4mm = 657Ω/mm.
Did the same with Rb resistors (2.22kΩ) that appear to have identical trace width: 120 pixels = 3.85mm -> 2.22kΩ/3.85mm = 577Ω/mm - that's 12% less, but still a rather good match considering the quite inaccurate method of measurement.

[azimuth_pl]

how about this diagram.
Ry and Rx might be voltage dividers for reeds.

[rewolf]

A bit better, but still no Rx and Ry.

As for reeds - rather not, see http://dwf.nu/viewtopic.php?t=3918&postdays=0&postorder=asc&start=44#25414. There is no connection from either resistor to the reeds (other than that both Ry and the reeds are connected to V+ on one end).

I took the freedom and edited your schematic to show how I currently believe Rx and Rx are used:

[andrew-0001]

Ian
Can you please tell me which pin numbers you need to use as the positive and negative supplies. Also, I cannot see that pins 1 and 4 are connected together from the photo. Is there a wire over the top of the chip ? Thanks.

[Handy]

OK.
Pins 1 and 4 to +ve.
Pin 2 -ve
Pin 3 Output

[andrew-0001]

I have installed the chip exactly as shown in your photos and your last instruction and it seems completely dead now, not even a single digit. I have also noticed that the other contributor , Azimuth, has a chip that does not have pins 1 and 4 connected together. Is there any advice you could offer. Thanks

[rewolf]

... I have also noticed that the other contributor , Azimuth, has a chip that does not have pins 1 and 4 connected together. Is there any advice you could offer. Thanks

That depends of course on the oscillator chip used:
Handy's chip (EPSON SG3030JF) requires Pins 1 and 4 to be both connected to V+ because Pin 4 is the supply pin for the oscillator and Pin 1 the supply pin for the output driver.
I don't know which chip azimuth_pl uses, but presumably it does not have separate supply pins for oscillator and output, thus only one connection to V+ required.

[andrew-0001]

Thanks for your input. I have used the Epson chip exactly as advised, with pins 1 and 4 connected. I am now getting a single random digit (as before), but now it does not correct itself when heat is applied - the single digit remains lit. Any advice would be appreciated.

[azimuth_pl]

an oscillator chip does not repair all broken modules so it might be permanently dead.

[andrew-0001]

azimuth

With the symptoms as described - With quartz crystal -single digit giving way to normal operation when heated and With Oscillator - single digit not improved by heat - Do you think it is a module you could repair ?
If so, what is your address so that I may send it to you.

Regards, Andrew

[azimuth_pl]

such repairs are limited to a quartz swap or an oscillator chip and if that doesn't help then the module is more than likely 99% dead. there is hardly any cure left for this problem, unless some of the resistors and capacitors are busted but that is very uncommon.

however a magic solution might work... sometimes.
a single-digit-of -death also tends to appear due to the smallest amount of battery leakage which causes shorts in the circuits. the acid residue acts like a conductor leading to malfunction.

this trick should be applied as the first stage before any surgery in any kind of electronic module, no matter the issue:
dip the module in warm (not hot) clear vinegar for 10 minutes and rinse twice in demineralized/distilled water.
vinegar is a light acid which dissolves potassium and copper hydroxide residues (the green ugly stuff).

remove excess water and dry for an hour or so by placing the module on a TV set or similar warm environment.

check functions... and if that doesn't help you will be better off with a Strikes&Spares transplant.

[bucko170]

dip the module in warm (not hot) clear vinegar for 10 minutes and rinse twice in demineralized/distilled water.

Anything that easy has to be worth a try, when you say 'dip' do you mean immerse?

[azimuth_pl]

Dip, immerse, either way as long as the vinegar covers the circuitry. This is a great solution for all those exposed Hughes modules and alike.

[retroleds]

I love it - after all the discussion of the resistors traced onto the P2/P3 boards below the main IC, someone sends me alink to the forum at oldpulsars.com Mr. Klien claims he was told by a Pulsar engineer that those traces are there to extract heat produced by the IC. I'm thinking that is the most implausable explanation I have heard yet regarding their intended function. If someone who visits there can get an explanation of how and where those traces are carrying off heat, I'd sure like to be enlightened on that.

[rewolf]

... Mr. Klien claims he was told by a Pulsar engineer that those traces are there to extract heat produced by the IC. I'm thinking that is the most implausable explanation I have heard yet regarding their intended function. ...

That's rather easy: they are actually negistors, not resistors, i.e. they have negative resistance.
A resistors heats up when current is forced through it, but a negistor induces current when heated up, similar to an inductor in a variable magnetic field. It is a combination of the Seebeck effect and the Peltier effect.
In the Pulsar, this heat-induced current is used to drive the oscillator. A very clever way to retrieve some of the battery energy turned into heat by the rest of the circuitry - so the oscillator runs on "free" energy, prolonging battery life. And, 2nd effect, it helps cooling the chip - the Pulsar is nothing but a (time) computer, and as we all know from our personal computers, proper cooling is essential for the main chip.

I'm totally serious! Engineers never kid laymen - granted!

[clockace]

awesome! the knowledge here as well as with those who developed these circuits amazes me. one thing about repairing antique timepieces is that nothing has changed, negating the need to keep up with technology peter

[charger105]

It also shows in that thread (I recommend that all interested go to the Oldpulsars forum and have a look), several prototype boards where those resistors are actually surface mounted........possibly indicating they were there for their resistive properties.

On another prototype board the traces are away from the IC, and eventually made it under the IC since this was the only real estate left.... possibly indicating the original intent was not to absorb heat.

Rgds,
Andrew.

[retroleds]

In the Pulsar, this heat-induced current is used to drive the oscillator. A very clever way to retrieve some of the battery energy turned into heat by the rest of the circuitry - so the oscillator runs on "free" energy, prolonging battery life. And, 2nd effect, it helps cooling the chip - the Pulsar is nothing but a (time) computer, and as we all know from our personal computers, proper cooling is essential for the main chip.

I'm totally serious! Engineers never kid laymen - granted!

This might be theoretically possible, but the lack of ANY physical interface between the IC and the traces makes this highly unlikely due to the inefficiency. There is over .5mm air space between the IC and the resistors and the heat generated by the IC is so little, coupled with the abysmal efficiency of Peltier devices....really, a hole in the circuit board would have been more cooling. And the purpose of the traces OUTSIDE the IC chip zone would be ...what? Generating electricity from the wearer's body heat?

I think engineers often presume to baffle laymen with b.s. - granted!

Time for some zzzs

[clockace]

so i been snookered???? peter