SN74141 - SN7441 info??
Fred
ic's..... that is if I did'nt want to troubleshoot it first! And hav'n
said that it's pretty hard to troubleshoot any old equipment without
first changing or re-caping first then find the problem. The Ic's are
just common TTL devices you can get them in ECG,NTE.
Most surplus operations just list by the suffix 7441 & 7414
http://www.mcmelectronics.com
http://www.mouser.com
http://www.jameco.com
http://www.mpja.com
http://www.alltronics.com
http://www.allcorp.com
Martin Ackroyd wrote:
> Could some kind soul point me where I can access information
> about obsolete SN74*** devices? [preferably via the WWW].
>
> Background
> ==========
>
> For use in aligning the rf circuitry of old radios, a friend
> gave me an old frequency meter that has a Nixie tube display.
> It has an attached label: "two tubes not working".
>
> I think, in fact, the tubes are OK. (They light up on all
> digits at once.) I suspect that, in fact, the driver IC's
> are knackered. One or two show evidence of having been
> replaced at some stage.
>
> Some of the driver IC's are SN7441. Others are SN74141.
> The counter is a Systron Donner model 114.
Bill Noble
4 input nand buffer, - I made a quick check in an old TI
pocket data book (1984) and it does not list a 7441 in the
ALS, AS or LS series. NTE shows a 74144 - it's a
counter/latch/decoder/driver with open collector output. it
also shows a 7441
74141 is a BCD to decimal decoder/driver for use with cold
cathode indicator tubes - pate 1-290 of my NTE book
I had one of those systron donner counters as part of a early
DVM - I got the schematics from systron donner - I donated it
to my high school a long time ago though and I don't have the
schematics any more.
just trace the circuit around the tubes -
to get you started, the 7441, A QUAD 2 input nand buffer with
open collector outputs, in NTE is:
pin function
1 1A
2 1 b
3 nc
4 2y
5 2a
6 2B
7 gnd
8 3A
9 3B
10 3y
11 4a
12 4b
13 4y
14 vcc
The 74141 is as follows
1 output 8
2 output 9
3 input A
4 input D
5 VCC
6 input B
7 input c
8 2 output
9 output 3
10 output 7
11 output 6
12 gnd
13 output 4
14 output 5
15 output 1
16 output 0
as you can see, this takes in BCD and outputs decimal, open
collector, to drive the nixie low side
hope this helps
"Martin Ackroyd" <martin....@virgin.net> wrote in message
news:397244CA...@virgin.net...
Martin Ackroyd
Martin Ackroyd
http://www.wps.com/archives/7441-BCD-decoder-Nixie-driver.JPG
Many thanks
Martin
Martin Ackroyd
Many thanks for the helpful info.
I feel pretty sure it's the driver ic's at fault. Most of the nixies
are working fine. Just two of them are lit up on all digits simultaneaoulsy,
as of the driver transistors are blown. So far as I can see from looking
at the physical unit, any capacitor faults would affect all of the nixies.
Thanks for the info sources. The info I have does not include them, presumably
due to their no longer being produced by any of the suppliers my retailers
deal with.
Many thanks again,
Martin
Fred wrote:
>
> Well i would suspect the caps in an older nixie tube unit before the
> ic's..... that is if I did'nt want to troubleshoot it first! And hav'n
> said that it's pretty hard to troubleshoot any old equipment without
> first changing or re-caping first then find the problem. The Ic's are
> just common TTL devices you can get them in ECG,NTE.
>
> Most surplus operations just list by the suffix 7441 & 7414
>
> http://www.mcmelectronics.com
> http://www.mouser.com
> http://www.jameco.com
> http://www.mpja.com
> http://www.alltronics.com
> http://www.allcorp.com
>
Geoff Blake
: Fred,
: Many thanks for the helpful info.
: I feel pretty sure it's the driver ic's at fault. Most of the nixies
: are working fine. Just two of them are lit up on all digits simultaneaoulsy,
: as of the driver transistors are blown. So far as I can see from looking
: at the physical unit, any capacitor faults would affect all of the nixies.
: Thanks for the info sources. The info I have does not include them, presumably
: due to their no longer being produced by any of the suppliers my retailers
: deal with.
It is almost certainly the driver chips that are at fault - this was quite a
common fault with these devices. The 7441 went through several generations
(7441 - 7441A - 74141 - 74141A) before technology (7 seg LEDS) replaced
them. The usual line up was 7490 decade counter - 7475 quad latch -
7441(etc) decoder display driver.
The 7441 decoder driver (4 to 10 line decoder) had 40V rated open collector
outputs, these would ground the individual cathodes of the nixie tubes and
(in theory) no current would flow into the open circuit collectors. Trouble
was, leakage did occur and thus the odd output would go s/c.
I don't think that there is any simple way of replacing them, maybe a
daughter board with a 4-10 decoder and external FET switches may work.
HTH
Geoff
--
Geoff Blake geoff (at) palaemon . co . uk linux 2.0.36
Chelmsford g8gnz @ g8gnz . ampr . org sparc - i586
Please, only use the .ampr.org address if you know what you are doing
Intel create faster processors - Microsoft create slower processes
Bill Noble
up a decoder and then drive some HV transistors (NPN) with
grounded emitters - but it's much easier to just replace the
one IC with another of the same type
"Geoff Blake" <ge...@nospam.demon.co.uk> wrote in message
news:Fy2Ix...@nospam.demon.co.uk...
Geoff Blake
: actually, if you want to replace them, it's not hard to wire
: up a decoder and then drive some HV transistors (NPN) with
: grounded emitters - but it's much easier to just replace the
: one IC with another of the same type
Erm, if you can get them. Haven't seen a 74*41 for an age!
If you can get a suitable 4 - 10 line decodes, preferably an open collector
output, drive the NPN transistors in common base mode via a suitable value
of resistor (about 4k7 ohms).
Bill Noble
which at least hints that there may be some available.news:Fy5B5...@nospam.demon.co.uk...
Andrew Cowley
http://www.donberg.ie/ has plenty of 74141's at 1.21 euro each.
in the U.S. I think Mouser has them in the catalogue.
the 141 is a good bit more robust than the 41 fwiw.
Andy Cowley