I recently repaired an amp with a manufacturing date on the plate on the back of 2004. The 4558 op-amp ICs inside had apparent datecodes of 4038. Do some companies put 4038 instead of 0438 for 38th week of 2004 and same for 2001 to 2009 ? , what about year 2000?
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
NC-
I don't know the real answer, but they might be using a Julian date. Such a date might look like 4038, refering to the 38th day of 2004 (or any year ending in a 4).
I would expect a 38th week date format to be 0438 to distinguish it from
1994, et cetera. Similarly, the Julian version might be 04038. It would not be unheard of for recently manufactured equipment to use components made in 1994, especially if it is an older design.Fred
same
4558s have been around a long time but I imagine the Just In Time / accountancy wallahs would have something to say about componentry sitting on shelves for a decade-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
Can you tell us what brand the 4558s are? Often the manufacturers' datasheets tell how to interpret the date codes. I've recently bought SMD op-amps and DIP microcontroller chips with '96' date codes, so they can sit around in storage for long periods.
Bob
on
manufacturer JRC
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