[Techtoolslist] Designing a 9010 replacement LED display?

[Brad Gass]

I guess I hadn't looked at dot matrix displays because of the cost, but they certainly seem feasible from a technical standpoint.  From UT Source, the 3416 size red displays are still a lot more than an LCD, but at ~$21.14 each, are certainly more reasonable than from Newark.

Although I wouldn't fuss over a red versus green display if red were lower cost, I did put in an inquiry on the DLG3416 (green) Osram version of that display, which would more closely match the Fluke's look.  Awaiting a quote.

So, the question is really - retrofit the existing board with a mezzanine type board (if feasible), or a full-on redesign of the board?  Anyone know if there is enough 5V rail current headroom to support up to another 1A of draw (worst case)?  I suspect the safest bet would be to create a new 5V supply for the character modules from the +55V rail used to provide power to the VFD.

Thanks,

--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: Sunday, December 4, 2022 12:51:39 AM
Subject: Re: [Techtoolslist] Designing a 9010 replacement LED display?

On 2022/12/01 8:37 p.m., Brad Gass wrote:
> 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

I did find what appears to be a suitable LED display module, that will 
fit in the space, but we need 8 of them and they cost around $36US each:

https://www.newark.com/broadcom/hdlo-3416/led-alphanumeric-display-dot-matrix/dp/36AJ9396

8 of them is just over 6.5 inches, and the original space is around 6.75 
inches. Height is 0.274" or close enough to the original 0.3" 
fluorescent digit.

They are ASCII coded, and even have 8 user defined characters available.

Not so cheap, but with a bit of logic glue possibly a worthwhile fix 
considering the 9010 is worthless without a display...

John :-#)#

>
> ----- 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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