HP 41C DOES NOT BEEP

[aurelio]

I've checked if the BEEP could be enabled/disabled by a flag (actually I dont remember so) but it seems to be not.
This nice 41c I hold in my hands, does not beep and even "tone", just I see on the display "BEEP" when I execute the command

So strange is that this is a "serviced" calculator, I guess: the display is rounded like in the halfnut, but the calculator is a "C";by the way I've tested the calculator, writing a couple of programs and crunching a few numbers without to find (it seems up to now) any other "strange" behaviour

[Jim Horn]

Flag 26 is the audio enable / disable flag. Try SF 26.

[Les Bell]

(08-26-2014 02:55 PM)aurelio Wrote:  I've checked if the BEEP could be enabled/disabled by a flag (actually I dont remember so) but it seems to be not.
This nice 41c I hold in my hands, does not beep and even "tone", just I see on the display "BEEP" when I execute the command

So strange is that this is a "serviced" calculator, I guess: the display is rounded like in the halfnut, but the calculator is a "C";by the way I've tested the calculator, writing a couple of programs and crunching a few numbers without to find (it seems up to now) any other "strange" behaviour

The wires that connect the beeper to the PCB are quite fine and easily damaged while the calculator is in pieces. Is it possible that whoever "serviced" the calculator accidentally broke one of them, probably at the point where they're soldered to the beeper? If so, then two minutes work with a soldering iron will give you the fix.

[aurelio]

(08-26-2014 09:30 PM)Jim Horn Wrote:  Flag 26 is the audio enable / disable flag. Try SF 26.

unfortunately seems not to be a matter of flags: SF 26 does not "help"

[aurelio]

(08-27-2014 03:52 AM)Les Bell Wrote:  

(08-26-2014 02:55 PM)aurelio Wrote:  I've checked if the BEEP could be enabled/disabled by a flag (actually I dont remember so) but it seems to be not.
This nice 41c I hold in my hands, does not beep and even "tone", just I see on the display "BEEP" when I execute the command

So strange is that this is a "serviced" calculator, I guess: the display is rounded like in the halfnut, but the calculator is a "C";by the way I've tested the calculator, writing a couple of programs and crunching a few numbers without to find (it seems up to now) any other "strange" behaviour

The wires that connect the beeper to the PCB are quite fine and easily damaged while the calculator is in pieces. Is it possible that whoever "serviced" the calculator accidentally broke one of them, probably at the point where they're soldered to the beeper? If so, then two minutes work with a soldering iron will give you the fix.

It means that to solve the problem I must absolutely open the calculator.
let me say, Les, that I've not a good feeling with "posts"
Anyway that's a good chance to know a little more about servicing performed .
I thought that rounded displays need a different driver, so that maybe has been swapped the PCB as well

[aurelio]

I've so opened the calculator and believe me, the scenario is quite unusual (at least for me) .....no zebra connectors o PCB connected to the mainboard, not any of the things I met before and I know....now, may you help me to understand what is this "release"?

I share here the pictures I just took

       

[Geoff Quickfall]

Okay, according to a guru, there were no halfnut 41Cs. That is not to say that HP service didn't have fun with labels at the foot of the 41c or the project team didn't play.

Now, having said that, what you have I have never seen. I always thought the halfnut with the rounded display and the large removable PCB replaced by the soldered half board was the last 41C variant.

That board looks to be a variant of the halfnut with the soldered half board fully replaced by the IC. It was probably kluged to a spare 41c keyboard shell and may be a prototype with a new chip. The project may have been shut down by the 42s development and 48 series.

So my guess is, unless someone can correct me, this is a prototype designed with 41c specs to test the new IC. If successful the memory, xtended functions and quartz timer would be added later, but that did not happen.

As I type this, a discussion with Wlodek comes to mind from years ago so I will see if he knows more about it. Maybe Richard does?

The bender (piezo) wires at the solder point look blackened, bad solder fix or is it just coloured. That may be the problem.

Geoff

Pictures of the serial number and more pics of the board with the black cover removed would be interesting.

[Mark Hardman]

(08-30-2014 04:13 PM)Geoff Quickfall Wrote:  Pictures of the serial number and more pics of the board with the black cover removed would be interesting.

Could you also please verify that the halfnut is actually a 41C and only has 63 registers?

[aurelio]

(08-30-2014 04:46 PM)Mark Hardman Wrote:  

(08-30-2014 04:13 PM)Geoff Quickfall Wrote:  Pictures of the serial number and more pics of the board with the black cover removed would be interesting.

Could you also please verify that the halfnut is actually a 41C and only has 63 registers?

Hi Geoff, hi Mark, the halfnut is really a 41c (63 registers) and I've checked for the serial it was made in the 82 year , 35th week, in Singapore (2235S4XXXX).
Geoff, I could send you pics in the original size (not formatted for the forum) but I think you need to see the rear of the board and I'm a little scared in removing it
Somebody knows the IC in place of the half-board?
I think maybe the "beep" missing could be due to a cold soldering, I added a magnified pic of the board and it seems the upper point could be one of those.

Actually I'm half-happy of the "sickness" of this beauty, otherwise never I was going to open it and find what we see

[Mark Hardman]

(08-30-2014 04:13 PM)Geoff Quickfall Wrote:  Okay, according to a guru, there were no halfnut 41Cs.

The "soldered half board" you mentioned is the CX ROM/RAM of the HP-41CX Halfnut version. The HP-41CV Halfnut version has no daughter-board.

From "Halfnut - An Internally Improved HP-41C,CV,CX" by Richard Nelson and Jeremy Smith (CHHU V2N4):

"There Are Three Halfnuts: The Halfnut models that are being shipped to dealers - as of early September [1985] in the US - are HP-41CV's and HP-41CX's. There is an HP-41C Halfnut, but this model won't be used except for service of returned HP-41C's. HP-41C Halfnuts will be used only after existing supplies of repair parts are consumed."

For my part, I've been looking for a Halfnut HP-41C since 1985 and have never seen one. Aurelio, this is really a rare and valuable find. I could just about eat my face from jealousy.

[jebem]

(08-30-2014 05:31 PM)aurelio Wrote:  I think maybe the "beep" missing could be due to a cold soldering, I added a magnified pic of the board and it seems the upper point could be one of those.

Hi Aurelio, good work!
After getting this far, if I were you I would use a new 15 watt low power pen soldering iron to unplug the two wires.
Then remove that solder mess on the PCB. Clearly it was not correctly soldered.
Now you need a audio oscillator (I use my multimeter that has a built in 2Khz signal) to test the buzzer and make sure it works.
Then resolder the wires using a low melting point good quality solder, using adequate heating to make a good solder joint (if the soldering iron requires more than 2 seconds to make an good melting it means you are using a underpowered tool).
Good luck with it.

[aurelio]

(08-30-2014 06:44 PM)jebem Wrote:  

(08-30-2014 05:31 PM)aurelio Wrote:  I think maybe the "beep" missing could be due to a cold soldering, I added a magnified pic of the board and it seems the upper point could be one of those.

Hi Aurelio, good work!
After getting this far, if I were you I would use a new 15 watt low power pen soldering iron to unplug the two wires.
Then remove that solder mess on the PCB. Clearly it was not correctly soldered.
Now you need a audio oscillator (I use my multimeter that has a built in 2Khz signal) to test the buzzer and make sure it works.
Then resolder the wires using a low melting point good quality solder, using adequate heating to make a good solder joint (if the soldering iron requires more than 2 seconds to make an good melting it means you are using a underpowered tool).
Good luck with it.

Jose, I bought a couple of years ago the soldering iron you'll see just I'll find it out, and maybe it will be helpful that, but I'm sure that my brother, who has hand better than mine, 'll be helpful as well

[Geoff Quickfall]

thanks Mark,

actually, I am reminiscing from a conversation many years ago. The statement should have been, no half nut 41Cs for retail, only for repair and return and therefore very rare. At some point the returned Cs got a CV board as a replacement.

There were of course, halfnut CVs and CXs at the retail level.

[aurelio]

(08-30-2014 04:13 PM)Geoff Quickfall Wrote:  Pictures of the serial number and more pics of the board with the black cover removed would be interesting.

Hi Geoff re-reading your words I understand (and of course only this should have a sense) that you mean the paper black cover (the bottom of the battery compartment) should be removed and not the keyboard. I'll do it asap, while fixing the bender wires bad solder problem.

I would like to avoid to open and close too much the calculator: broken posts are waiting for me every time like a doom
The first thing I did today was therefore to reassemble it and assuring that there were not bad contacts, this time, of course not related to the half board but in the upper area.

[Mark Hardman]

(08-30-2014 07:33 PM)aurelio Wrote:  I'll do it asap, while fixing the bender wires bad solder problem.

The bender is also taped to the back cover upside-down so that the solder joints are not visible in your photos. It is entirely possible that the issue is on the much less delicate buzzer than on the motherboard.

[aurelio]

(08-30-2014 07:41 PM)Mark Hardman Wrote:  

(08-30-2014 07:33 PM)aurelio Wrote:  I'll do it asap, while fixing the bender wires bad solder problem.

The bender is also taped to the back cover upside-down so that the solder joints are not visible in your photos. It is entirely possible that the issue is on the much less delicate buzzer than on the motherboard.

Thank-you, Mark, I'll test first the buzzer as from Jose's advice, anyway I think to have, in case at least one spare buzzer, the one on the 41c halfboard swapped on my CL

[aurelio]

I have found here , on Diego's site this kind of board: it's the one on the left bottom corner!

[Geoff Quickfall]

AHHHHHH!

that explains a lot. see the PCB that has been removed from the board that looks like yours?

That is the CX version containing the extended functions, memory and timing chip. So your board is a standard halfnut with the CX portion removed.

Good research, should have checked with Diego first. You can see the attachment points for the board to convert it to a CX. They are the four contact solder points on either side of the keyboard PCA.

d8-)

so in a nutshell or halfshell you have a:

1. repaired 41C with the halfnut board as this was never a retail option.
2. the board is the same as the CX and CV board but minus the mini board containing the timing and extended memory functions.
3. to turn it into a CX you would require the mini board or an extended functions, extended memory, quad memory and timing modules. But why mess with that raritiy...
   

[aurelio]

(08-30-2014 08:25 PM)Geoff Quickfall Wrote:  AHHHHHH!

that explains a lot. see the PCB that has been removed from the board that looks like yours?

That is the CX version containing the extended functions, memory and timing chip. So your board is a standard halfnut with the CX portion removed.

Good research, should have checked with Diego first. You can see the attachment points for the board to convert it to a CX. They are the four contact solder points on either side of the keyboard PCA.

d8-)

so in a nutshell or halfshell you have a:

1. repaired 41C with the halfnut board as this was never a retail option.
2. the board is the same as the CX and CV board but minus the mini board containing the timing and extended memory functions.
3. to turn it into a CX you would require the mini board or an extended functions, extended memory, quad memory and timing modules. But why mess with that raritiy...
   

the circle is now closed but:

1) sure it's a repaired version and somebody could have easily attached a new 41c label at the foot of the calculator, maybe a CX or a CV after removed the miniboard, but.... IMHO, HP instead prepaired specially new complete boards with keyboards, I mean , with white frames (in place of the yellow ones) for this kind of "quick" replacement.
For this reason only it could be really a interesting rarity

2) of course far from me the idea to add any miniboard which I guess shold be attached in the upper area (back to the display), the calculator came already supplyed with additional memory and X-functions .....just let me plug a time module when needs

[Geoff Quickfall]

it is a rarity as was explained years ago as it is a repair of a fullnut with a halfnut that does not contain the 41CX mini board. I had my keyboard replaced twice on my 79 41C and all they did was give me a new 41C keyboard and reused my rear shell with the serial number. both repairs occurred before the halfnut was developed.

The halfnut you have is a fully dedicated 41C as indicated by the silver strips and with that in mind it is an original and rare 41C halfnut. The only difference being that it was a repair versus a retail version of which there were none documented.

therefore the only way to have a 41C halfnut is based on a repair in or out of warranty by HP. By 1983 most of the calcs were CVs and CXs so they did not prepare many of these boards.

I agree, don't touch it inside, if you need a CX then load up the modules!!..

Geoff