Usually devices like this have the common data and address lines plus somthing like ?CS (chip select), RW (read write), PG (program) and supplies...
I dont know this specific device in this instrument but i suspect CS would be the one to hold the chip in a given state.
Hope it helps..
Sent from Samsung by banging a nail into a piece of wood.
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-------- Original message --------
From: "oliver johnson via Groups.Io"
Date:10/02/2019 05:29 (GMT+00:00)
Subject: Re: [HP-Agilent-Keysight-equipment] Hp 8903b display issue update
Thanks for the reply , was thinking of something? like you mentioned,? the only problem is i do not know what pin i have to remove.? I am also going to use the scope to probe around and see if i can make some? progress,? again all help would be great .
On Sat, Feb 9, 2019 at 4:41 PM, paul swedberg
<paulswedb@...> wrote:
Oliver we all like to blame the most difficult and unknown thing. In this case it may be the prom is suffering from memory rot. I have a partially bad one on a 8501 display normalizer.
(Just haven't gotten around to replacing it) Thank heavens the HP docs some what explain what the code is.
So I would take the following approach as a suggestion. The prom should have a pin to disable it. Disable it. Plug the board in if it still hangs the system then just maybe its not
the prom. Thois not to say that maybe an output or address line isn't stuck and hanging the system. Scope will give you that hint.
Good luck
Paul
WB8TSL
