HP-71B Chirp (solved)
09-17-2019, 10:25 AM (This post was last modified: 09-18-2019 03:06 AM by Sylvain Cote.)
Post: #1
 Sylvain Cote Senior Member Posts: 1,126 Joined: Dec 2013
HP-71B Chirp (solved)
I received a HP-71B today (s/n: 2401A00190) and it has the same behavior as Adam Jones’s unit in 2013.

The small computer emit a chirp (brief sound) each time the display is changed, a key is pressed on in some cases at each minute.

Test cases:
1. on blinking cursor : a chirp is emitted at each .5 seconds
Code:
cursor on, cursor off, cursor on, cursor off, ...
.
2. on key press .......: a chirp is emitted on each key press detected by the internal keyboard scanner
Code:
there is a lot of chirp going on if I press the left arrow and keep pressing the key
.
3. at each minute ....: a chirp is emitted at each minute when the display is frozen
Code:
DISP "TEST3" [ENDLINE] then wait for the chirp, no key pressed
.
4. on display update : a chirp is emitted at each 3 seconds until the for/next is completed, then at each minute if I do not press any key.
Code:
DELAY 3 [ENDLINE] FOR I=0 to 10 @ DISP "TEST4" @ NEXT I [ENDLINE]

Some clue as to what could be the cause of this ?

Thanks,

Sylvain
09-17-2019, 12:29 PM (This post was last modified: 09-17-2019 06:50 PM by rprosperi.)
Post: #2
 rprosperi Senior Member Posts: 3,572 Joined: Dec 2013
RE: HP-71B Chirp
I have a 71B that did the 'chirp on every key-press' but I do not recall it doing the other kinds of chirping you describe (though I did not try to write and run programs while in that state). I tried many things to identify the cause, but eventually gave up with no success. I put it aside for a couple weeks with no batteries installed and when I next tried it, it was fine, behaving normally with no chirping at all, and it has remained OK ever since.

So, in that case at least, it seemed to be some kind of very confused hardware state, only resolved by very deep power drain of electronics. It is indeed odd that it took so long as I had tried shorting the terminals, removing batteries overnight, etc. with no success, and we also know that unlike the 41C, the 71B is quite sensitive to battery removal, typically getting a ML after even extremely brief removal.

Can't hurt to give it try - let it sit while at HHC?

--Bob Prosperi
09-17-2019, 06:15 PM
Post: #3
 J-F Garnier Senior Member Posts: 319 Joined: Dec 2013
RE: HP-71B Chirp
According to your observations, the chirp happens each time the HP71 exits sleep state: key pressed, blinking cursor (software blinking), one-minute periodic battery-checking (when idle and no blinking cursor), end of DELAY.

It can be due to either software (bad configuration) or hardware (weak shortcut between a bus line and the speaker line, bad cpu i/o).

Can you check:
- check if any LEX file present, if yes remove them.
- remove any external modules (RAM, ROM, HPIL), does it change anything?
- check MEM and that the 4 internal 4k ports are not FREEd, if not CLAIM that ports. Any effect?
- Basic reset (INIT 1). Any effect?
- master software reset (INIT 3). Any effect?
- last resort, hardware reset: remove the batteries - at least one - and discharge the internal power supply. Remember to shortcut the supply lines not at the battery terminals but in the card reader slot, see here.

J-F
09-17-2019, 06:57 PM
Post: #4
 Sylvain Cote Senior Member Posts: 1,126 Joined: Dec 2013
RE: HP-71B Chirp
(09-17-2019 06:15 PM)J-F Garnier Wrote:  According to your observations, the chirp happens each time the HP71 exits sleep state: key pressed, blinking cursor (software blinking), one-minute periodic battery-checking (when idle and no blinking cursor), end of DELAY.
It can be due to either software (bad configuration) or hardware (weak shortcut between a bus line and the speaker line, bad cpu i/o).
I thought as much.

(09-17-2019 06:15 PM)J-F Garnier Wrote:  Can you check:
- check if any LEX file present, if yes remove them.
- remove any external modules (RAM, ROM, HPIL), does it change anything?
- check MEM and that the 4 internal 4k ports are not FREEd, if not CLAIM that ports. Any effect?
- Basic reset (INIT 1). Any effect?
- master software reset (INIT 3). Any effect?
I did several INIT 1 and INIT 3, I also did a INIT 2 to check ROMs just in case but to no avail.

(09-17-2019 06:15 PM)J-F Garnier Wrote:  - last resort, hardware reset: remove the batteries - at least one - and discharge the internal power supply. Remember to shortcut the supply lines not at the battery terminals but in the card reader slot, see here.
I also did several battery removal and shortcut supply lines ... at the battery terminal ... ... damn, I got burned again, completely forgot to do it at the card reader slot ... I will do it tonight.

Merci Jean-François. (and Robert)

Sylvain
09-18-2019, 03:05 AM (This post was last modified: 09-18-2019 03:06 AM by Sylvain Cote.)
Post: #5
 Sylvain Cote Senior Member Posts: 1,126 Joined: Dec 2013
RE: HP-71B Chirp
The chirp has stopped after short-circuiting the first and last card reader slot pins.
Jean-François you're the king of the HP-71B ... and of the HP-IL of course.
Thank you very much!
Sylvain
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