P2/P3 "dot" displays less reliable?

[Erinn]

I read somewhere that the dot displays are less reliable than the P4 "segment" displays.
1. Is this true?
2. If true, is this simply because they are a few years older?
3. Or because, as 1st generation displays, they were still somewhat experimental?
Clearly, if true, this has implications for collectors who also wish to wear these old watches.

[bruce wegmann]

Nothing in my experience as a collector (16 years and counting) suggests this is true. On the contrary, I have lost a few "bar-segment" displays (on P4 and Ladies models), but only one "dot-segment" one (on a P3). Actually, the P4 and Calculator displays are still essentially dot-segment construction. The difference is, while the P2/3 displays had 5 dots in each segment, the P4s and Calculators had 12 or 13 dots per segment; they are then so close together, and so small, that the eye cannot resolve the individual dots, and they blend into a continuous line (a very rare version of the Calculator display has segments composed of just 6 dots each). I assume this change reflects the rapidly-escalating state-of-the-art in micro photolithography (as the Ladies models represented the next stage in miniaturization of the electronics). In almost any branch of electronics, or mechanics, increasing complexity carries the price of being more failure-prone.

[Erinn]

Thank you for that informative reply.

Sometimes when a technology is very new, in an established field (e.g.--watchmaking), the initial efforts at development are more impressive, because there is more pressure to succeed. I am thinking now of the admiration my old watchmaker expressed for the workmanship of the original Accutron, in another example.

I am reassured.

[SASM]

Well, there were at least two manufacturers for Dot Displays and two for P4 line Displays as well. Early dot Displays have contact legs instead of pads and they are much better than the dot Displays with Pads. The Digits also Look slightly different.

From my experience the very early dot Displays with legs and very late dot Displays which were epoxied on Frontier modules used in the Omega Digital I and some Hamiltons are the most reliable Displays. If you turn a P4 line Display on the back side there´s a Version without any visible trace and one with a trace running from the middle of the Display to the g-bar. The Display without the trace makes almost always no Problems. The one with the visible trace is the weakest of all Displays named here.

[gjlelec]

Perhaps we should have a "crappiest module competition " lol- "And the winner is - Uranus, followed closely by Heuer

[SASM]

@gjlelec: Well we should have four categories:

worst module holder construction: 1st place: Frontier. Close the case and with a bit of luck you´ll break the ceramic circuit board or one of the contact bars. The electronic part is shitty as well, there are so many modules looking good but are not repairable.
worst production quality: Definately Uranus, but Hughes Aircraft comes close. Late Sanyos come into my mind. Even Sinclair is 1000 times better than the crap of the top three.
worst overall engineering fault: Synchronar. Destroy the module housing to change the battery but don´t mind, they last forever.
worst battery drain: E/D module, followed by the SASM10. OK, it was not the best idea to run the module on 2MHz. At least the time conunting was very precise (...)

The most solid modules are placed in the the GP Casquette except for the 1st series. Early Pulsars (RCA), early Sanyos which were manufactured under RCA license and Chronex are solid as well. Also National Semiconductor modules aren´t bad at all, same for Fairchild and TI. It seems that the big US Semiconductor companies made a good job back in the day.

[bruce wegmann]

The type of encapsulation that has the short "legs" is called a "beam-lead" package, and while it is mechanically quite robust, the pinout is very different from the later surface-mount version, and so the two are not interchangeable. The beam-lead display is found only on the 2800 (P1) and early P2 modules (201-1, with the horizontal light sensor). Time Computer had two manufacturers producing LED displays...Monsanto, and Litronix; the Litronix displays are seen more often; my impression is that they are both quite reliable.