Franc Zabkar wrote in message
...
I was recently looking through a datasheet for a Sharp IR3M02 PWM
regulator and found the following information on date codes.
date code example 226A = 1st week of June, 1982
2 2 6 A
| | | |--- production week A,B,C,D,E (1st week)
| | |----- production month (1,2,3 ... 9,X,Y,Z)
| |------- denotes last digit of year (1982)
|--------- denotes the I.D. No.
I don't know if other Japanese manufacturers of that time used the
same coding, but I thought the information may be useful in any case.
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
To get the decade you have to look at the quality/font/style of the
lettering
I will add yor info to my tips files
Some hints for determining the age of equipment not marked on serial
plate,dating old kit.
The best is date codes on ICs. These are usually 3 numbers say 712 distinct
from the IC type number which is usuallly letters then numbers. For 712 12
is
the number of weeks (ie march) into the year ending 7 . But is it 1977 or
1987 etc. The
70s printed numbers are usually more angular as though printed in the fonts
available to
an XY plotter. Also the IC series number is usually indicative of the era.
For Sanyo ICs a number like 4C1 probably means 1984 from the '4'.
Larger (power handling)
package/hybrid ICs of the 70s were a lot less standardised than later. Other
indicators dark brown paxolin board would suggest 60s rather than 70s as
would
carbon resistors rather than metal oxide (no bulges at the ends of the
barrel).
Also the sizes of 60s and 70s resistors tend to be larger than what is
actually
required for heat dissipating. E-line transistors come in the 80s .
Places to find dates are sometimes large
electrolytic capacitors, polycarbonate capacitors,large
transformers,loudspeakers ,relays,
microswitches,motors , some
small rectangular radial lead caps ,body of air vane tuning caps and some
small transistors
have a datecode. Clear wrapped ribbon cable tends to be 70s, grey covered
ribbon
cables tend to be 80s and thin tape type with foil conductors tends to be
90s.
PCB traces from 60s onwards tend to get less angular and more curved by the
90s ,double
sided traces on boards tends to be 80s onwards.
The year of introduction of certain types of connectors
gives a lower bound. eg Scart/Peritel would not be found
earlier than 1977 and those would be in French kit,
the earliest date for mini-din would seem to be 1985.
The pitch of IC pins of course gets less than .1 inch only 80s onwards and
surface
mount tends to be 90s onwards. LEDs started coming in early 70s.
For Technics / Panasonic ICs of the 1970a date codes probably take the
form a single number then in smaller script an underlined
HEX digit. ie 9 plus small underlined D would mean 1979 14/16 ths into the
year.
After year 2000, eg 5007 presumably week 07 of 52 in year 2005
JRC IC maker seems to use this convention of reversing post-millenium
dates - do
others ? Unless you find 2 or more IC date codes from
different manufactirers agreeing it is often more a feel
or balance of probabilities for a date.
After about 2000 pcb overlays often have the date as distinctive slanted
"7 segment display " font numerals of 2 number year then 2 number week
as a 4 digit code as on iCs.
Date marks on mouldings and PCBs
Moulding example
Plastic moulding with raised print 82 83 84 85 with a small moulded
pip over both 82 and 83.
Then a 1 to 12 'clock face' both with an arrow next the figure 8.
A centre pop dimple in the mould above
82 in 1982 and then another over 83 in 1983. Leading to
raised small conical pips on the plastic. Probably means
8/12 year or August 1983
PCB example
White silkscreen printed
panel on the overlay of a PCB, presumably with date coding.
A left panel and right panel consisting of
1 to 6 along top and 5 dots in each column so 6 x 5 dots
Right panel marked 7 to 12 and similar array of dots
but the third one down under the 7 was missing.
Probably third week of 5 weeks of July.
Central panel had marked like this
02
??
??
05
The queries were probably the remnant tops of numbers from scrubbed out
03 and 04 so probably like in the plastic case 03 is scrubbed
in 2003 and 04 scrubbed in 2004 but still leaving the 03 mark.
So probable screen printing date of mid July 2004
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/