HP/Agilent 6654A Power Supply: swap LCD for VFD/OLED/... - Page 1
Forum section: electronics / repair

author: fchk
author_rank: Frequent Contributor
timestamp: January 03, 2019, 11:46:41 am
content: I've got a HP 6654A Power Supply, and its LCD is not great at all. No backlight, narrow viewing angles. I've also got an 6632B with VFD, which has excellent readability.I'm wondering if anybody has already reverse engineered the LCD module and made an OLED or whatever replacement.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 04, 2019, 11:37:53 am
content: I dont see any projects .... unless you try to add some led backlight yourself.project:https://www.eevblog.com/forum/projects/hp-3457a-lcd-backlight-mod-(also-for-3478a)/

author: EHT
author_rank: Frequent Contributor
timestamp: January 05, 2019, 06:12:39 pm
content: I have a 3457A DMM and 66xx series PSUs. It is really annoying that there is no backlight but trying to retrofit one seems like a huge amount of effort which may end up breaking the LCD anyway.As they have GPIB i think it would be better to add a nice virtual display on the PC instead. In both cases it could emulate the look and feel but also enhance it with data logging. I got basic data collection from the 3457A working in Python although it was a real fiddle with clashes between the NI & Keysight drivers. I haven't tried the 66xx PSUs yet.I see had a quick look at sigrok. It supports both the 3457A DMM and 6632A PSU. However, i think it didn't have a good UI or support the rear inputs on the 3457A. Does anyone have experience of this or other open source equivalents?Cheers.

author: bitseeker
author_rank: Super Contributor
timestamp: January 05, 2019, 11:20:34 pm
content: Here's an HP 3457A (similar type of LCD) that was converted to LED display. There's some talk of other displays as well.https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/I concur with EHT that, if you have a GPIB interface and PC in your lab, that's an easier way to go.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 06, 2019, 03:13:24 am
content: Thehttps://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/Is a very good project but a very complicated one to achieve if your not equiped with cnc tools etc ... you have to trim the led display casing ...

author: bitseeker
author_rank: Super Contributor
timestamp: January 07, 2019, 03:13:51 am
content: Yes, lots of work, but looks great. The yellow LEDs go well with the beige plastic.

author: fchk
author_rank: Frequent Contributor
timestamp: January 07, 2019, 08:37:57 pm
content: Great! I want this look!While digging the schematics of my power supply I found out that front panel and main controller talk to each other throgh an 5V TTL UART serial connection. I'm thinking of making a T-connection, trying to decode the serial protocol and building an external display. This would solve my problem while avoiding permanent changes to the instrument itself.

author: Armadillo
author_rank: Super Contributor
timestamp: January 07, 2019, 08:54:27 pm
content: Would using the GPIB to PC be even easier and neater in that case, as modeless window that position itself on Top Right of screen, for example.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 07, 2019, 11:19:30 pm
content: It would take an oled project like Qu1ck did for the 34401a, you need to decipher the communications lines between the mainboard and display boardFor the 34401a it's spi based, but tested on the old unobtanium NEC ic ... maybe someone here could do an protocol sniffing ??

author: bitseeker
author_rank: Super Contributor
timestamp: January 07, 2019, 11:35:48 pm
content: Quote from: fchk on January 07, 2019, 08:37:57 pmYes. Have a look at the decoding discussion on the subsequent pages of the 3457A thread.

author: bitseeker
author_rank: Super Contributor
timestamp: January 07, 2019, 11:36:27 pm
content: Quote from: Armadillo on January 07, 2019, 08:54:27 pmYes, it would be easier. It just depends if you have/want a PC in your lab. Some do, some don't.

author: giovannirat
author_rank: Regular Contributor
timestamp: January 08, 2019, 12:09:23 pm
content: Maybe you can have a look on Roberto's project on his 6632B power supply.https://www.eevblog.com/forum/buysellwanted/hp-6632b-power-supply-replacement-oled-screen-(done)/msg743995/#msg743995http://www.rbarrios.com/projects/6632BOLED/

author: coromonadalix
author_rank: Super Contributor
timestamp: January 08, 2019, 02:47:40 pm
content: Nice 16x2 oled, would be perfect with no separation between the rows ?? I think there is 1-2 pixel line of separation ??

author: kawal
author_rank: Frequent Contributor
timestamp: December 26, 2024, 05:23:58 pm
content: Quote from: giovannirat on January 08, 2019, 12:09:23 pmThis project will not work for LCD based 6654A but will work for VFD based displays like 66332A 6632B.I tested the OLED from the HP 3457A project (https://github.com/xyphro/HP3457-OLED-display) and it works and looks great. The issue is the board mechanics.https://www.eevblog.com/forum/index.php?action=dlattach;topic=310658.0;attach=2468233;image