HP48S, different hardware construction



#7

I recently disassembled two of my 48S, one was dead and I wanted to transplant its screen to another who had a bad display. The transplant worked, but I was surprised to see that the internal construction of the two calculators is WAY different. The motherboards just don't look like the same calculator at all. One is yellow/gold, the other is green (like the 48G); one - the green version - has a standard format processor, the other has the silicon of the processor in plain view, mounted on a sort of "holder" that is then soldered to the mainboard.
I couldn't find any information about this difference, does anybody know when/why they changed? It must have been a great effort to totally re-design the board and processor...

Cristian


#8

The "holder" assembly you describe is "TAB" (Tape Automated Bonding).

HP and other electronics companies redesign their products from time to time to deal with availability of components and for cost reduction.


#9

TAB packaging in S and SX was a carry over from the Pioneer design.

When the 48 was updated to the G series, the processor was repackaged in what was then a standard molded flat-pack. HP then updated the S and SX logic boards to use the later package design. The same processor repackaging occurred in the 17Bii. The 42S was not updated even though the 17Bii was basically the same hardware. HP must have had a big pile of 42S TAB processors on the shelf which says alot about how rapidly the calculator market declined in the mid-nineties.


#10

Thank you for your replies... I suspected something like that, I just thought it wouldn't be worth the effort and the expense to re-engineer the motherboard for a product "almost" about to be discontinued. And the "updated" S/SX boards must be much rarer than the original ones... I opened maybe 6-7 series S and I only saw one of the newer boards!

Cristian


#11

It would be interesting to know at what week (and serial number) this change in the S/SX hardware occured. This might be helpful to add to article 991 here.

TomC

#12

Quote:
The 42S was not updated even though the 17Bii was basically the same hardware. HP must have had a big pile of 42S TAB processors on the shelf which says alot about how rapidly the calculator market declined in the mid-nineties.

I think that the sales volume of the HP 42S was never great because HP went out of its way to hide it, or at least not advertise it, all through its short 1988 to 1995 life span. I remember a lot of HP advertising in IEEE Spectrum magazine and other publications for the HP 28S in 1988, and for the HP 48SX in 1990, but nothing ever for the poor unheralded HP 42S except what was in EduCalc catalogs. When I finally obtained an HP 42S to replace my old HP-15C, I was stunned by its capability. It made my trusty HP-15C look like a half-baked kludge. No doubt HP downplayed the 42S to direct buyer attention to the upper-end HP 48SX and follow-on models. It's little wonder that the HP 42S during its production life was never popular. I wonder why HP bothered to revise the firmware up to rev. C.

We didn't realize what we had until it was gone and only the mediocre HP 32Sii was available.


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