I need information about Voyagers IC's



#2

Hi;

I've been resurrecting one old Voyager and I intend making an internal trading.

The to-be-resurrected Voyager is an earlier HP15C, with the electronics built in a flex-PCB (I gave up trying to recover the flex-PCB; it has many broken trails, others are no longer bonded to the flex board and the LCD shield already has two broken claws) . I have an old HP11C that no longer works, and it is a newer model. After removing all bezels and both logos, I am ready to trade their guts. But I'm afraid the HP15C's keyboard scanner is not working, and I am almost sure the HP11C's equivalent IC is working. But both HP11C and HP15C's keyboard scanners have different codes!

The Voyagers (I do not know the HP10C internals, so I'll refer only to the HP11C, 12C, 15C and 16C) have two basic IC's: the R2D2 (RAM/ROM & Display Driver), that is a big one and is built in the opposite side of the LCD, and the keyboard scanner, that interfaces the keyboard and R2D2.

The fact is that I opened some newer voyagers (an HP12C and both HP15C and HP16C) and I became confused. In these machines, the keyboard scanner is the same as the one found in the HP11C (except for the Malaysian HP12C, which has only one VISIBLE all-in-one IC). All of these IC's in the newer calculators are built in one single PCB that accommodates all electronics: KBD contacts, IC's, LCD and the three external components. The table bellow summarizes all IC's codes for these Voyagers.

         KBD scanner    R2D2      ??? (third HP15C's IC)
earlier |
HP15C | 1LF5-0301 1LE2-0321 1LH1-0302
|
newer |
HP15C | 1LM2-0001 1LH1-0306 1LH1-0302
|
HP11C | 1LM2-0001 1LH1-0305
|
HP16C | 1LM2-0001 1LH1-03xx (I'm not sure; printing is too light)
|
newer |
HP12C | NONE(*) 1RR2-0001

(*)2001 model, made in Malaysia

I remember trading posts with Tony Duel about the third HP15C's IC. We may notice that only the HP15C has it, and those who deal with the HP15C know that it has a bigger memory capacity when compared to the others (67 registers, I included; about three times the memory available in the other voyagers). The organization of the HP15C's memory lead to some conclusions. In the HP15C, registers I, Ro and R1 are built in the R2D2 (RAM/ROM Display Driver, as Tony mentioned); all others have all memory in this same IC, as they share the same keyboard scanner and do not have the third IC. So, in both HP11C and HP16C all RAM is contained in the R2D2. I cannot see another possibility than the third HP15C's IC being the 64 registers block. As a coincidence, some operations available in the HP15C that deal with registers use only one byte of program memory when addressing registers I, R0 and R1, needing two bytes for the other registers (2 to .9). These functions are x<>, DSE and ISG. I know this is not a proof of this reasoning, I just call the attention for the coincidence. I also agree with Tony that part of the HP15C's ROM is built in this IC, too.

My major concern is the following. Both earlier and newer HP15C use the same third IC: 1LH1-0302. Signal levels and control lines must be the same from this IC to the others. I also checked the board, and all visible connections are the same. I'm gonna remove the 11C's IC's from its previous board and place the 15C's IC's there. All I want to know is if anybody have already mixed the earlier 15C's IC's (1LF5-0301 and 1LE2-0321) with the ones in the newer 15C (1LM2-0001 and 1LH1-0306), say, earlier KBD controller with newer R2D2 and vice-versa. If it works fine, I'll have to transfer only two IC's instead of three, and this procedure not only eases the job but also involves less risk to the components.

If anybody already had this experience, please, let me know. I'm delving into this "guts transplantation" next week, so I'll have time to think about it and read related posts. If there is any confusing explanation, please, let me know. I believe I wrote everything correctly, but... you know what I mean! I know Portuguese by heart...

Thank you a lot.

Best regards.


#3

Hi Luiz,

Sorry I don't have any experience with this, and i'm sure this is obvious to you, but it seems to me that the only logical step is to put the two 15C IC's (R2D2 and the third one) on the 11C board while keeping the 11C keyboard scanner in place, since you think the 15C keyboard scanner is bad. Maybe you can test it at that point (before assembly). BTW, why do you think the keyboard scanner is bad on the 15C; with so many broken traces couldn't that be the problem?


#4

Hi, Steve;

your questions are valid and they are some of the ones I also have.

I believe the first step is to be sure about the 15C's keyboard scanner. I still have an HP16C with an original 11C's keyboard scanner. This 16C lost two key columns, and I tested all cooper trails and their contacts. Every key working fine, every soldering fine... No response to those keys. I merely replaced the keyboard scanner (1989) and it's still working fine.

This 15C started with frozen keyboard, no ON/OFF action and sometimes Pr Error. I have seen many voyagers with unreadable display (random segments) and some sort of problems, including this one, and cleanning/resoldering IC's terminals used to be a good solution. I tried that and it kept freezing. After opening and closing it about once a month, it stopped completely. I try rebuilding as many trails as I could by using conductive ink, but after a while, the ink itself cracked. Dealing with flexible PCB demands special care...

Chances are that the 15C's scanner is still working, but I had to make many soldering "craft" closed to it. Static and heat are not the best friends a MOS PQPF can keep. I am between moving all three 15C's IC's at once, but if it did not work I'll i'll have to remove the 15C's scanner and place the 11C's back. So, why not just let it there?

That's why I want to know in any of the guys in here have already mixed the IC's. In the case the answer is Yes, I'll not remove the HP11C's keyboard scanner, avoiding its destruction (as probably I have done with the 15C's kbd scanner). I'd like to be sure that I'll cause no harm to each IC's by mixing them, that's why I am trying to firstly check.

Some connecting lines from the R2D2 and the keyboard scanner are exclusive o them both, not shared with the rest of the calcualtor, and this does not mean the signals in these lines are common for both pairs. Do you agree?

Any suggestions? I thought about insering s few resistors (1Kohm, 3K3, other) between each connecting terminal from the R2D2 and the keyboard scanner, but I am not sure this will help or disturb.

Thank you again. As soon as I have some news I'm posting them here


#5

Hi Luiz

<<That's why I want to know in any of the guys in here have already mixed the IC's. In the case the answer is Yes, I'll not remove the HP11C's keyboard scanner, avoiding its destruction (as probably I have done with the 15C's kbd scanner). I'd like to be sure that I'll cause no harm to each IC's by mixing them, that's why I am trying to firstly check.

I would be less concerned about incompatibility between
the chips than damage from soldering. I think most likely
you'll find logic incompatibility rather than electrical
incompatibility, if there's any at all. But if you
have a current-limiting power supply to test the new
configuration that might be the best compromise.

Some connecting lines from the R2D2 and the keyboard scanner are exclusive o them both, not shared with the rest of the calcualtor, and this does not mean the signals in these lines are common for both pairs. Do you agree?

If the lines are common on both types of keyboard
scanner I would find that encouraging.

Any suggestions? I thought about insering s few resistors (1Kohm, 3K3, other) between each connecting terminal from the R2D2 and the keyboard scanner, but I am not sure this will help or disturb.>>

I would go for the least amount of soldering as possible. Besides, you don't know if these resistors would be helping or hurting so why bother?

#6

My guess is that they are pin compatible chips. HP seems to place different part numbers on the same (or internally compaible) chips.

All the Woodstock machines have different part number ACT chips, but they interchange freely between all the machines. An HP21 ACT works fine in an HP97, etc. The same thing goes for the CPU chip in HP35/45/55/70 machines. I have seen three different part numbers, but they all seem to be interchangeable. Same for the display driver chips in the classic machines.


#7

HI;

I believe I can give these guys (the IC's) a try. On Monday I'm gonna take some hours and carefully make a "transplant surgery", placing the two 15C's IC's (R2D2 and 1LH1-0302, the third IC) with the 11C's keyboard scanner. As soon as I have the news, I'm posting them here.

If there is anything else you, guys, want to post, please, feel free; if you believe you should e-mail me directly, be my guest.

Thank you all for your support.

Best regards.


#8

<<I believe I can give these guys (the IC's) a try. On Monday I'm gonna take some hours and carefully make a "transplant surgery", placing the two 15C's IC's (R2D2 and 1LH1-0302, the third IC) with the 11C's keyboard scanner. As soon as I have the news, I'm posting them here.>>

Yes, please be careful; you are no longer doing it for just yourself, you know ;-)


#9

Hi;

I am going to add a series resistor to the batteries' contact so if there is more current then the expected (short circuit?) the voltage will drop across the resistance. Do any of you know what's the average (mAmps? uAmps?) current consumption when a voyager (preferably an HP15C) is OFF and ON? That would help computing the resistor value (I have no such precise multimeter for low current measurement; the one I use is a rebuilt unit that had its current input destroyed by previous owner that tried to measure AC outlet with mode switch in mA position...). If nobody knows about it, I'll try to find someone that can borrow me a precise ampmeter.

Thanks in advance.


#10

Luiz:
A guess, since I have no Voyager to measure. I would assume that a normal current should not exceed 20 mA. Assuming a voltage drop of 0.3 Vols in VBat, (not to make it drop too much in normal use), the answer would be 15 ohms. 1/8 Watt is enough rating for the resistor.

Please think in some manner in which you could shortcircuit the resistor later, once you feel safe, so not to lose that battery power just heating the universe...

As always, is nice hearing from you. Regards.

Andrés


#11

Hi, Andrés;

I'd say the same reading your post. Thank you.

Well, to the business: did you take in account normal operation of the three MOS IC's? In any way, you called my attention to one fact: I have a working HP15C and I can simply place the resistor in series with this 15C's batteries and measure the voltage drop (Duuh!). I'll place the same resistor in the 15'stein (please, don't blame me...) and measure with the same equipment. No need to be that precise; if voltage drop is a lot different, I'll plug it off and try the original keyboard scanner. Thank you for the suggestion.

Now, going to our countries: today we had the election for president and some political staff "actors" in Brazil (I don't know the terms for Deputado and Senador the way they use here and in Argentina). Well, let's hope something diferent happens here. What about Argentina?

My best regards and thank you for the kind words.

Cheers.


#12

One of my favorite jokes is: "We are doing well. We sink at the planned speed"

Not to be so pessimistic, things have been more or less stable for the last 3 or 4 months, but a zero derivative doesn't guarantee a nice steady state... We will have presidential elections in March and maybe some "Senadores" and "Diputados" renewal at the same time...

#13

Hi, folks;

forgive-me not posting anything so far; I did not find the (enough, specific, dedicated) time to do the trasplantation. As I get to it, I'm posting in a new thread.

Thank you for your support and patience.


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