Just got a WP34S.....DOA ?

[ytterligare]

Hello, I got a WP34S on ebay from a seller which has impeccable feedbacks.

The calc arrived very carefully packaged with 2 sets of spare batteries.

Insert the first set of 2 batteries, and clicked on the "exit" button, which has also the "ON" written below : nothing happened, the screen is blank.

Is there a particular sequence of keys to press to turn the calc on, any initialization to perform to have it finally showing something on the screen, or is it DOA ?

Please advise.... :-(

Andrea

[Craig Bladow]

On one of my two WP34s calculators I need to be more deliberate with my key press, pressing more firmly and holding down a little longer. I just had this experience with the ON key, you are using the correct one. The other thing is to check the orientation of the batteries and the voltage if you have a meter.

[Leonid]

(11-30-2020 06:39 PM)ytterligare Wrote:  Insert the first set of 2 batteries, and clicked on the "exit" button, which has also the "ON" written below : nothing happened, the screen is blank.

Make sure batteries is relatively fresh or just try with new CR2032 batteries.

[ytterligare]

@Craig Bladow : tried to press firmly and letting the key pressed for more than a couple of seconds didn't work. Washed with isopropyl alcohol both sets of battery to remove possible dirt, and tried a fresh ( third ) set of batteries with no luck.
Orientation should be ok, with negative down and positive up...anyway there's no possibility of a polarity inversion as if you insert the battery the wrong way, the negative pole doesn't connect to anything..

@Leonid : as I said, I tried a fresh new ( third ) set, with no luck.

Are there any reset procedure which doesn't involve any weird shaped connector ?
Any key combination ? Had aproblem with an (apparently ) dead HP Prime and I was able to revive it with a paper clip and key combination pressed I read about somewhere....

I'm really disturbed by this event : I was so happy when the package arrived this afternoon..soon to be replaced by growing frustration...

A.

[Massimo Gnerucci]

Did you try the reset hole between the two batteries?

[ytterligare]

(11-30-2020 10:27 PM)Massimo Gnerucci Wrote:  Did you try the reset hole between the two batteries?

Yes I did...but no joy ! :-(

Andrea
P.S:
Massimo...se sei tu quello di Milano, abbiamo un amico in comune su FB...era per caso il Persivale ?

[ytterligare]

An update : I noticed that measuring the two poles of the calculator I can read 1.3 Volts, quickly decreasing...is this normal ( charged internal capacitor ) or what ?



Any thought...?

A.

[Dave Frederickson]

(11-30-2020 11:59 PM)ytterligare Wrote:  An update : I noticed that measuring the two poles of the calculator I can read 1.3 Volts, quickly decreasing...is this normal ( charged internal capacitor ) or what ?

Yes, a discharging cap.

Since the two batteries are in parallel, you can install one and measure the voltage under load at the terminals of the other battery socket.

Note: On some 30b's there is only one battery.

Dave

[ytterligare]

(12-01-2020 12:30 AM)Dave Frederickson Wrote:  Yes, a discharging cap.

Since the two batteries are in parallel, you can install one and measure the voltage under load at the terminals of the other battery socket.

Thank you dave, did that, but there's no really any load since the calc doesn't turn on.

So I installed one battery and read 3.24V at the other terminals, which is the battery actual charge...

Andrea

[Dave Frederickson]

It's a soft power switch so there's always a load. See the 20b schematic.
http://commerce.hpcalc.org/HP20b_Development_kit.zip

So it's not a battery issue. That means you need to try to reprogram it.

Dave

[Massimo Gnerucci]

(11-30-2020 10:38 PM)ytterligare Wrote:  

(11-30-2020 10:27 PM)Massimo Gnerucci Wrote:  Did you try the reset hole between the two batteries?

Yes I did...but no joy ! :-(

Andrea
P.S:
Massimo...se sei tu quello di Milano, abbiamo un amico in comune su FB...era per caso il Persivale ?

Yep! :'(

[ytterligare]

Final update ( I hope) :

The eBay seller contacted me kindly offering a replacement, and before accepting I performed the last test...
I left the calc without batteries overnight and this morning it worked !!

I have no idea why...all I can think is about some discrete component retaining a charge which was preventing the correct boot...but it's a speculation.

Any idea ?

[Albert Chan]

(12-01-2020 12:11 PM)ytterligare Wrote:  I left the calc without batteries overnight and this morning it worked !!

I have no idea why...

Many many years ago, I spilled water to Dell keyboard, and it had failed.
So, I get a replacement, and stuffed the bad keyboard to the drawer.

Few years later, the replacement keyboard also failed (also due to spillage )
Just for luck, I tried the bad one again ... and it work !
And, it keep on working for 20+ years (still going !)

My guess is the moisture trapped inside get evaporated ...

[David Hayden]

Maybe the contrast was too low? To adjust, hold down the ON key and press + or - to raise or lower the contrast.

[johnb]

Hey, @ytterligare:

On a different note, do you mind sharing how much it cost you, and whether this seller has any more?

I built a WP-34S and it works great, but I have v3 software with the v2 overlays, so sometimes I have to dig out the book to know which button to press! :-)

I'll eventually be able to get those v3 overlays, but if the finished calculator is not too expensive from this seller, I might just get myself a second one while I wait.

[teenix]

(12-01-2020 12:11 PM)ytterligare Wrote:  I left the calc without batteries overnight and this morning it worked !!

I have no idea why...all I can think is about some discrete component retaining a charge which was preventing the correct boot...but it's a speculation.

Any idea ?

Probably correct.

The calculator software might have failed and was running incorrectly, maybe due to an invalid memory location. When you removed the batteries for a while the calculator internals were probably able to reset properly, and all worked again.

I imagine removing the batteries and shorting the calculator battery terminals might achieve the same result.

cheers

Tony