HP Forums

Hi there

Not sure if you guys can help or not. Many years ago I opened up my HP-33E (solderless) because it was not reliable.
It has been open ever since and I have recently decided to re–assemble it. But the three 8 pin ICs have fallen out of their locations and I do not know which one goes where. Does anybody know which IC goes where?

The three ICs are:
00031-80008 Silver (from the web described as RAM)

IMAI 0004 SGP785024

IMAI 0378483 SGP3

Does anybody know where I can get a copy of the circuit diagram of a HP-33E?

And/or does anybody have a HP-33E for sale to replace this very sick one?

Thanks
Dirk
Canberra Australia

The position of the ICs is not critical. They are alle wired in parallel. But the orientation has to be correct. Pin 1 has to be in the correct position. I am sure you can find the orientation somewhere on the web.

(09-01-2016 11:52 AM)DJSCaver Wrote: [ -> ]Not sure if you guys can help or not. Many years ago I opened up my HP-33E (solderless) because it was not reliable.
It has been open ever since and I have recently decided to re–assemble it. But the three 8 pin ICs have fallen out of their locations and I do not know which one goes where. Does anybody know which IC goes where?

The three ICs are:
00031-80008 Silver (from the web described as RAM)

IMAI 0004 SGP785024

IMAI 0378483 SGP3

My HP-33C has only one 8-pin IC, ILB901-81251-SGP01. Here's the picture in case it can be of help:



It was unreliable also (two or three sets of like LED segments would turn off frequently). I've just disassembled, cleaned and reassembled it. Apparently this has been fixed.

Best regards,

Gerson.

P. S.: A better picture for your purpose, from this very museum:

(09-01-2016 11:55 AM)Harald Wrote: [ -> ]The position of the ICs is not critical. They are alle wired in parallel. But the orientation has to be correct. Pin 1 has to be in the correct position. I am sure you can find the orientation somewhere on the web.

If it is a E model like 33E you are right. If it is a C model like 33C, then the RAM chip must be placed in the first/upper position, because only this place gets battery power when swithed off to retain Continuous Memory data.

In Gersons case, there is used a single combined ROM/RAM chip.

Bernhard