HP/Agilent 6654A Power Supply: swap LCD for VFD/OLED/...

[fchk]

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.

[coromonadalix]

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)/

[EHT]

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.

[bitseeker]

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.

[coromonadalix]

The https://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 ...

[bitseeker]

Yes, lots of work, but looks great. The yellow LEDs go well with the beige plastic.

[fchk]

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.

[Armadillo]

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.

[coromonadalix]

It would take an oled project like Qu1ck did for the 34401a, you need to decipher the communications lines between the mainboard and display board

For the 34401a  it's spi based, but tested on the old unobtanium NEC ic ... maybe someone here could do an protocol sniffing ??

[bitseeker]

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.

Yes. Have a look at the decoding discussion on the subsequent pages of the 3457A thread.

[bitseeker]

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.

Yes, it would be easier. It just depends if you have/want a PC in your lab. Some do, some don't.

[giovannirat]

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/#msg743995

http://www.rbarrios.com/projects/6632BOLED/

[coromonadalix]

Nice 16x2 oled, would be perfect with no separation between the rows ??  I think there is 1-2 pixel line of separation ??