comparing early flex circuit vs late rigid circuit series30 calculators


Hello, I am new at this HP calculator world. Here is my first question: can anyone tell me how to tell which version of the HP-38C series I have without taking off the back cover and cking? i.e is it the early (flex circuit) or late (rigid circuit) series 30 calculator that I have?

Perhaps you can you tell by the serial number if it is an early version or not?

Thanks in advance for any info!



The earlier flex PCB 30 series machines had 2 distinct caracteristics:

1. They were rather heavy, as they had a steel plate inside to back up the flexible circuit boards.

2. The key detents were VERY firm with long travel (they used plastic snap domes).

One more thing

Because the flex circuit board machines were solderless, they were prone to having display segments blank out occasionally (a little twist on the housing usually brings them back).

Hope this helps.

Best regards, Hal



If weight=220 g or 7,76 oz => early version with pressed components.

If weight <= 220g => latest version with soldered components.

Best regards


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