10 Apr
2008
10 Apr
'08
1:51 p.m.
"Roy J. Tellason" wrote:
Have any of you guys ever heard of this chip? It's new to me...
---------- Forwarded Message ----------
Subject: [roys-tech-chat] Building replacement for TTL counter DM8552
(National Semiconductor)
Date: Thursday 10 April 2008 08:58
From: "Michel" <itloiiw at yahoo.com>
To: roys-tech-chat at yahoogroups.com
Hello all,
I am trying to repair a Systron Donner Frequency Counter model 6254
that does not count well. This counter is build with "simple" TTL
chips only. (I have no manual nor schematic).
The culprit (found by swapping chips) is a TTL chip from NS : DM8552
It is a decade counter with latches and tri-state outputs.
Since I did not find any source for replacement chip, I have thought
to build some equivalent circuit with maybe 74LS160 and 74LS393.
My problem is that I have no datasheet except pinout for DM8552
(found there http://www.datasheetarchive.com/pdf/1215336.pdf ).
Does anybody have more information about it ?
Many thanks in advance,
Michel
Grenoble - France.
Usually I'm asking about weird NatSemi chips, but this is one I can help with,
I have it documented in a 1976 NS TTL databook. I'll communicate with the OP to
try to get info to him. The 8552 has some other unusual features to support
zero-blanking.
(..always happy to talk about electronic counters, just yesterday I got an HP
524B from
1957 functioning, after two weeks of cleaning it up.
It's a boat anchor, but it's tube digital (84 tubes). (But it's probably OT
for
this list).