[Techtoolslist] Designing a 9010 replacement LED display?

[Brad Gass]

There doesn't appear to be small-pitch alphanumeric LED displays available (at least that I could find) that would work here without being much too large for the space.  There are a couple Noritake Itron graphic VFD's that might work, but those are going to be expensive, and don't appear readily available either.

I think what might be a workable approach would be to use a 40x1 character LCD module with a reasonably bright backlight.  There seem to be a couple models pretty readily available on the surplus market that may work out.  It's not perfect, and the surplus displays may or may not support "inverted" displays (light text on black background), but anything is a lot better than nothing if you have a bum display!  But no matter what the approach, additional design effort would be needed to capture the segment drive data for each character, decode it into character data for the LCD, then output it to the LCD module.

In looking at pictures of the display PCB, this may be retrofit-able on the existing board with a bit of clever craftsmanship.  From the schematic, abandon U3 through U10 in place, pick off character clock (U6 pin 9) and data (U6 pin 7) from the head of the character drive shift register chain, and get segment clock (U13 pin or U14 pin 3) and data (U13 pin 2 *and* U14 pin 2) from the segment drive shift registers.  Decode the captured data into ASCII (or custom) characters, then send them out to the LCD, updating only the LCD character positions that change between VFD "refresh cycles" to keep the LCD character flicker to a minimum.
 
Does anyone know the full "character map" of the 9010?  As near as I can recall, it's all standard ASCII characters but I honestly don't remember if there was any oddball symbols that might need to be mapped to custom characters on the LCD.  I've been busy with other life issues and away from the bench for much too long now, but wouldn't mind working at this a bit if there were others interested in helping out.

--Brad

----- Original Message -----
From: "Technical Tools Mail List" <techtoolslist at flippers.com>
To: "Technical Tools Mail List" <techtoolslist at flippers.com>
Cc: "John Robertson" <jrr at flippers.com>
Sent: Thursday, December 1, 2022 7:47:51 PM
Subject: [Techtoolslist] Designing a 9010 replacement LED display?

I was looking at my 9005 and grumbling because the tube is missing, then 
I pulled out the 9010a service manual and you know, it looks like it 
would be a pretty easy fix to replace the tube with 32 digit 
alpha-numeric LEDs of the correct size on a small PCB and all that would 
be needed is to replace the UDN6118 fluorescent drivers with suitable 
LED drivers and find a place to grab 5V and ground and then mount the 
new display to the board...

Maybe it would work?

Anyone interested in poking at the KiCAD layout? I have no free time, 
but I know there are folks out there looking for a solution to bad or 
weak tubes...

Here is the page: 
ftp://ftp.flippers.com/TTL/Test_Equipment/Fluke/9010%20Series/9010_Fixture%20PDFs/9010A_Display_Schematic.pdf 
<ftp://ftp.flippers.com/TTL/Test_Equipment/Fluke/9010%20Series/9010_Fixture%20PDFs/9010A_Display_Schematic.pdf>

John :-#)#

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