Pioneer organ transplant killed donor. Have I learned anything?

[butforwales]

I got a dead 32 sii that does not power on. After trying shorting the leads and pressing down below the bezel it is still dead as a brick. I opened it up and found everything in good mechanical conditions, contacts are clean, even the foamm is clean and firm.
I then opened up a known-good 10b and put the PCB from the 32 sii in there, it does not power on. Next I put the 10b PCB into the 32 sii housing, it does not power on either. Last, I put the 10b back together, now it is also dead.
Have I learned anything? Maybe something in the 32sii housing/keyboard/LCD first became defective that it killed the original PCB, then killed the PCB from the donor 10b?

[Thomas Klemm]

F‌‌ ‌‌ ‌‌ ‌‌ ‌‌ ‌‌

[Marcovecchio]

A few things to consider:
- 32s and 10b LCDs are different, did you keep them paired with their PCBs when transplanting? To do that, you need to unglue them from the metal housing, and on doing that, you loose the delicate alignment between LCD and PCB contacts. So, to make a conclusive test, you need to carefully align the contacts, and also make sure the rubber strips are very clean and correctly positioned.

- the metal twities play an important role on grounding the calculator. If they don't provide good ground contact to the minus side of the battery, pioneers will not work. I usually test them outside the housing, providing power directly to the PCB, not relying on the metal frame.

- I fixed about 30 pioneers, and so far, just one had a dead CPU. Chances are both calculators are fine, and your problem is fixable.

- the weirdest problem I had on a pioneer, was a stuck key, and that was caused by a carbon flake in the flex keyboard circuitry. It required me to break all those heat stakes from the keyboard, undo the flex sandwich, and clean the contacts.

Eduardo

[GreyUser]

The keyboards are (electrically) identical for all pioneers so you did no damage with the cpu swap but as already mentioned, the lcd’s are incompatible between those models.

Some possible things come to mind that would prevent a 32sii from powering up, in order from least likely to most likely:

1) open pc board traces, in the battery supply, open from corrosion.

2) broken processor pins at the solder interface. Caused by crushing the unit, placing force on the raised ic package protruding from the top of the circuit board.

3) open on/off traces in keyboard due to getting wet and leaving the batteries in place. Electrolysis will cause the carbon based traces to rise to 100k and up which prevents turn-on. Refer to the schematic and measure resistance with On key press per document below.

4) shorted key in the matrix due to failed hinge or end of life flex dome. Measure all columns to rows per schematic.

https://www.hpmuseum.org/cgi-sys/cgiwrap...i?read=451

PS: always discharge any residual charge on the tantalum capacitor before reinstalling batteries. A sure sign of a shorted key is easy to diagnose with the following:

With unit assembled, discharge cap and install fresh batteries. Turn unit on. Observe display. If a key is shorted, it will appear onscreen, i.e. ‘Enter’.

If you see a key name upon first turn on, it’s shorted. It will not accept any keystrokes and once it turns off, it will not turn back on until you remove batteries, short the capacitor and reinstall batteries. Repeat above behavior.