Tony,
Here's a guy not to far away from you that shows 98 in stock:
http://alle-ersatzteile.de/
prices seem reasonable for shipping inside Germany, and it says
'International Shipping on request'.
----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <cctalk_at_classiccmp.org>
Sent: Sunday, September 08, 2002 4:01 PM
Subject: 74H52 chip
> Last week I mentioned I was repairing an HP9810 programmable calculator.
> I've now traced the last fault to the 74H52 AND-OR gate chip on the
> memory timing PCB (09810-66522). Needless to say this chip is
> unobtainable as far as I can see.
>
> I've worked out a kuldge using a 74LS51 which works in this circuit (as
> only 2 sets of inputs on the 'H52 were used). I'll stick details of that
> at the end of this message in case anyone else ever has to do the same
> repair (unlikely...).
>
> But the repair is a kludge, with wires flying everywhere. So does anyone
> have/know where to get a 74H52 chip?
>
> -tony
>
> -------------------------------
> Replacing the 74H52 IC on the memory timing PCB (09810-66522)
> -------------------------------------------------------------
> Well, have you ever tried to get one :-) However, _on this PCB_ it can be
> replaced by a 74LS51, suitably wired.
>
> Remove old IC carefully, in case it's still good.
> Bend out all pins of a 74LS51 apart from 1, 7, 14. Put this chip in place
> of the old one. Solder 1, 7, 14 to the PCB. Solder wires (wire-wrap wire
> is ideal) as follows :
>
> PCB 2 -> IC 13, IC 12
> PCB 3 -> IC 11
> PCB 4 -> IC 10
> PCB 5 -> IC 9
> IC 8 -> IC 2, IC 3, IC 4, IC 5
> PCB 8 -> IC 6
>
>
> mu(26)/ -------|\
> | \ +---|\
> ALU(0) ----+---| >-----+ | | >----+
> | | / | +---|/ |
> +---|/ | | +---)\
> +---)\ | ) >o---- TRegSin
> ) >o---+---|\ +---)/
> mu(25+24/)/----|\ +---)/ | | >----+
> | \ | +---|/
> T(0)-----------| >------+
> | /
> mu(26)---------|/
>
>
>
>
Received on Sun Sep 08 2002 - 15:24:00 BST