Display 3478A

[hnjmkl]

In an attempt to rotate the LCD (DSP1) of my 3478A it went KO, P / N 5061-1166. On YT someone managed to replace the 3457A LCD with different displays, even nixie, do you know a feasible project for this intervention? Is the 3478A's LCD different from the 3457A? In appearance they are identical but in the 3457A Service manual I did not find the P / N of the display.

[rsjsouza]

I think one of the most comprehensive discussions about replacing HP3478A displays is at the following thread:
https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)

It starts with an LED replacement but there is also mention of using small OLED graphical displays.

(edit) found the other OLED thread. https://www.eevblog.com/forum/testgear/hp3548-hp3457-oled-display/

(edit) fixed URL

[ledtester]

I think one of the most comprehensive discussions about replacing HP3478A displays is at the following thread:
https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/

The first link has a paren at the end which doesn't get included as part of the URL by the forum's editor.

Here's a working link:

https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-%29/

[M0HZH]

I used a display from a cheap HP 3488A Switch/Control Unit to restore a HP 5385A Frequency Counter and did some reasearch at the time.

Many of the HP gear of the era use the same displays, there are 3 revisions "groups" where displays are compatible with eachother (so 3478A would work with a 6622A display) but no proof that they're compatible between groups (for example 3478A with 3488A display).

LCD PN: 5061-5212
HP 3478A 
HP 6622A
HP 6630A/B

LCD PN: 5181-2813, 5063-2305 or 5083-3473
HP 3457A
HP 3468A
HP 3488A
HP 3852A
HP 5384A
HP 5385A
HP 5386A
HP 6624A
HP 6645A
HP 6674A

LCD PN: 5065-7075
unknown models, after 1995


I'd still get a cheap 3488A unit off eBay and try its display out on yours, not much to lose.

Some of my pics / comments from when I did the swap:

https://twitter.com/YO9IRF/status/1339663054053789696

[sagias]

Tested oled on 3478

[ZGoode]

Tested oled on 3478

Sagias,
That is awesome!  I'm trying to do something similar to what you have done.  Are you able to post any of the schematics/code for your work?

[Miti]

Tested oled on 3478

Sagias,
That is awesome!  I'm trying to do something similar to what you have done.  Are you able to post any of the schematics/code for your work?

The second link in the second post is what you need.

[kawal]

I used a display from a cheap HP 3488A Switch/Control Unit to restore a HP 5385A Frequency Counter and did some reasearch at the time.

Many of the HP gear of the era use the same displays, there are 3 revisions "groups" where displays are compatible with eachother (so 3478A would work with a 6622A display) but no proof that they're compatible between groups (for example 3478A with 3488A display).

LCD PN: 5061-5212
HP 3478A 
HP 6622A
HP 6630A/B

LCD PN: 5181-2813, 5063-2305 or 5083-3473
HP 3457A
HP 3468A
HP 3488A
HP 3852A
HP 5384A
HP 5385A
HP 5386A
HP 6624A
HP 6645A
HP 6674A

LCD PN: 5065-7075
unknown models, after 1995


I'd still get a cheap 3488A unit off eBay and try its display out on yours, not much to lose.

Some of my pics / comments from when I did the swap:

https://twitter.com/YO9IRF/status/1339663054053789696

I have a few 3852A that came with 5061-5212 displays  Rev A displays.  these have triangular  symbols on the bottom.
I did take a display from 3457A model 5181-2813 and placed it in the 3852A and it works.

I made a few OLED displays that work in the 3457A  but the same OLED display will not work in the 3852A. Very strange.