HP11c with a dead R2D2

[Marcovecchio]

I got a non-working 11c. Generally, Voyagers are not hard to repair: cleaning / repairing pcb traces, LCD replacement, etc. But I got one that refused to work after all PCB traces / passives were confirmed good.

The only life sign I got after cleaning was the full LCD blinking in an approx 1Hz frequency. I mean, all segments turning on and off continuously. No keyboard action could change it. Also, the LC tank oscillator got working continuosly, and not only during keypresses, which is not correct.

So I got a fully working, same era, 12c, and swapped the R2D2 (1LH1-0305 on the 11c, and 1LH1-0304 on the 12c). The 11c PCB, now with the R2D2 from the 12c, worked fine, so the bad 11c became a 12c. Conclusion: 11c PCB and nut processor were all right.

But the 11c R2D2, now soldered to the 12c pcb, showed the same blinking behaviour as before, to my frustration. I think the 11c R2D2 is bad, and I doubt I can do anything to fix that, other than finding a donor 11c to get a working R2D2.

But my question is: how often old Voyager ICs go bad? I fixed about 30 Voyagers so far, and never ever found any with a bad IC. Do you guys have any idea on what may have killed this one? The calculator has never been opened, rubber feet untouched and heat stakes were still there.

Any experiences you could share are welcome, thanks!

Eduardo