6 Jul
2014
6 Jul
'14
3 p.m.
At 01:28 PM 7/6/2014, Mattis Lind wrote:
When repairing a TU60 drive that had faulty DEC8881 I
replaced them with
DM7439. They were $2.76 each when buying 25 pieces. The original faulty
chips were marked 7439 on the backside.
By way of confirmation, I have a bunch of (I think Signetics) 8881
chips marked 7439 on the bottom as well.
-Rick
6 Jul
6 Jul
6:02 p.m.
On Jul 6, 2014, at 6:00 PM, Rick Murphy <rick at rickmurphy.net> wrote:
At 01:28 PM 7/6/2014, Mattis Lind wrote:
Interesting. It could be a date code?
paul
When repairing a TU60 drive that had faulty
DEC8881 I replaced them with
DM7439. They were $2.76 each when buying 25 pieces. The original faulty
chips were marked 7439 on the backside.
By way of confirmation, I have a bunch of (I think Signetics) 8881 chips marked 7439 on
the bottom as well.
-Rick
6:36 p.m.
At 09:02 PM 7/6/2014, Paul Koning wrote:
On Jul 6, 2014, at 6:00 PM, Rick Murphy <rick at
rickmurphy.net> wrote:
think Signetics) 8881 chips marked
7439 on the bottom as well.
At 01:28 PM 7/6/2014, Mattis Lind wrote:
> When repairing a TU60 drive that had faulty
DEC8881 I replaced them with
> DM7439. They were $2.76 each when buying 25
pieces. The original faulty
chips
were marked 7439 on the backside.
By way of confirmation, I have a bunch of (I -Rick
Interesting. It could be a date code
paul
It's consistent over several samples (a couple of
dozen.) Yes, that may be a coincidence.
However, looking at those I see top markings of
7317/DEC 8881
S7531/DEC 8881
S7631/DEC 8881
S7720/DEC 8881
S7711/DEC 8881
S7712/DEC 8881
etc. Looks like date code/part number on the top;
all have 7439 markings on the bottom.
Not all of my 8881's have that 7439 marking.
Looking at the datasheet, the 7439 has the same
pinout and function as an 8881. I'm convinced
that this is at least as good a replacement as a 7401.
-Rick
6:43 p.m.
I believe Texas Instruments like to put the part number on the bottom of
7400-series ICs.
Kyle
6:46 p.m.
On Jul 6, 2014, at 21:36, Rick Murphy <rick at rickmurphy.net> wrote:
Looking at the datasheet, the 7439 has the same pinout and function as an 8881. I'm
convinced that this is at least as good a replacement as a 7401.
It's not at all unlikely that 8881s are just specially-binned
7439s in this case; that's consistent with what DEC did for
other transceiver chips sourced from major manufacturers.
- Dave
7:07 p.m.
On 07/06/2014 06:36 PM, Rick Murphy wrote:
Looking at the datasheet, the 7439 has the same pinout
and function as
an 8881. I'm convinced that this is at least as good a replacement as a
7401.
A quick search for DM7439 comes up with a datasheet for a 4x2-input OC
NAND with the same pinout as a 7401, but with 48 ma max output current.
There's an SN7439 as well.
Offhand, I'd say they were the same thing as the 8881.
--Chuck
7 Jul
7 Jul
12:50 p.m.
At 01:28 PM 7/6/2014, Mattis Lind wrote:
I could ask if that was the date code, but actually, the 7439 (TTL
number) is similar to the 8881, and I could easily beleive that DEC 8881s
were (sometimes?) selected 7439s
-tony
When repairing a TU60 drive that had faulty
DEC8881 I replaced them with
DM7439. They were $2.76 each when buying 25 pieces. The original faulty
chips were marked 7439 on the backside.
By way of confirmation, I have a bunch of (I think Signetics) 8881
chips marked 7439 on the bottom as well.
3594
days inactive
3595
days old
6 comments
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