HP 6632B Power Supply replacement OLED screen (DONE)

[eb4eqa]

Hi all,

I have two power supplies with dim and ugly displays. I've been working on this for some time and it is almost finished. The new module is a bit smaller but very crisp and very easy to read.

I am not going to give away the code, I don't want to see how someone else is selling my work AGAIN. But I might sell programmed PICs or complete retrofit kits if there is interest.

Would you be interested in one of these for the right price?

https://www.youtube.com/watch?v=GgQS7ePEFmA&feature=youtu.be

Regards,
Roberto EB4EQA

[matseng]

Very nice, but doesn't the OLEDs have an even worse lifetime than the original displays?

[eb4eqa]

You are right, LCD/LEDs are forever but OLEDS are not. But to age a VFD/OLED you need to leave it on, showing the same data for houndreds/thousands of hours. I wouldn't expect any of us doing that for hobby use. On the other hand, that was the biggest module I could find that would fit where the original glass is.


Regards,
Roberto EB4EQA

[Aodhan145]

What OLED display is this? I don't have the PSU but I really like The display.

[eb4eqa]

This one: http://www.ebay.com/itm/IIC-I2C-1602-16x2-OLED-Module-Display-For-Arduino-PIC-AVR-ARM-/161162845021?hash=item25860ddb5d

Roberto EB4EQA

[HighVoltage]

Very impressive!
I do not have a 6632B.

May be one day you will make a display for the Agilent E364xA ?
I have one that has a very dim display, although it was not used much.

[Aodhan145]

This one: http://www.ebay.com/itm/IIC-I2C-1602-16x2-OLED-Module-Display-For-Arduino-PIC-AVR-ARM-/161162845021?hash=item25860ddb5d

Roberto EB4EQA

[PlainName]

Would you be interested in one of these for the right price?

Yes.

[dundee]

May be one day you will make a display for the Agilent E364xA ?
I have one that has a very dim display, although it was not used much.

+1

Very nice project!

[taemun]

That looks really great.

Unfortunately, all of my 6632B VFD's are in good condition (notwithstanding one of the four tantalums going short on one of them).

Just out of interest - are you tapping off the data lines to the VFD, or somewhere else?

[Neganur]

Does it display the low current mode too?

[linux-works]

Very nice, but doesn't the OLEDs have an even worse lifetime than the original displays?

they should have a screen saver or timeout/blanking.

is your product soldered to the oled display or can that be swapped in/out when its had its run and its time for a replacement?

also, anyone know if an unpowered oled has a shelf life?  I assume its only 'wearing' when its powered on, but its worth asking.

when I have done repairs on things that I know will need it again, I sometimes give an easter egg to the next guy by putting a spare part in a bag, labelling it and putting that, safely, inside the gear.  last time I had to fix a nak cassette deck (wow, long time ago) I bought 2 idler wheels, put the spare inside and maybe someday I or someone else will find that 'egg'   then again, the rubber wears out on its own, use or not, so that gift may have been in vain.

so, I'd consider using an oled that is known to wear out, IFF I can get the part, have it be swappable without wearing the main part down (ie, sockets not soldering) and if I could get the spare part (we already know we can).

nice project, btw.  and while I'm an open-source guy, myself, I don't have a problem with someone developing a thing and deciding not to OS it.  in fact, its mostly how the world works, if you think about it; and releasing source is actually quite rare out in the Real World(tm).

[timb]

You are right, LCD/LEDs are forever but OLEDS are not. But to age a VFD/OLED you need to leave it on, showing the same data for houndreds/thousands of hours. I wouldn't expect any of us doing that for hobby use. On the other hand, that was the biggest module I could find that would fit where the original glass is.


Regards,
Roberto EB4EQA

Actually, LEDs are the closest to forever. Segment LCDs (especially older ones) tend to delaminate over time.

Having that exact problem with a Keithley 197A in fact. Another member figured out the display protocol and replaced it with a character LCD.

I'm working on a 3.2" graphic OLED retrofit right now.

Also, check out BuyDisplay.com, they carry a large range of displays at very good prices. (Might be helpful if you decide to do a kit.)


Sent from my Tablet

[Macbeth]

Nice! If I had a 6632A (with the LCD - is it compatible?) then I would go for it. But there is something I like about VFD displays. I noticed some rejuvi tricks on xdevs for a Keithley VFD. But none of my VFDs are so bad that they bear the risk of "if it 'aint broke, don't fix it!" - despite my natural tinkering "if it ain't brok..., ah feck it... tear it apaaart!"

A link to my daft vid of 6632B with worn out VFD

[linux-works]

if you want long life, avoid the fluorescent displays.  on a lark, I bought one that is hd44780 compat (2x16) and used it for a kitchen espresso DIY build of mine.  ran for 3-5 yrs (can't remember when I built it, but it was at least 3 yrs).  it had an on mode with a few areas in the display that were being written to and an off-mode, where the clock (hh:mm) was up in the top/right corner (at all times).

after that 3-5 yr period, the clock area is now burned in and the other segments bad enough that the display is now useless for anything other than that original app (and I have changed out my espresso machine, too, lol).

I loved how bright the fluor display was and how it could be seen in the kitchen lighting, even thru a smoked plexi front bezel.

but for $25 part price, I could not quite see replacing it every 2-3 yrs.  and even if you run a screen blanker, you are still usually writing the same kinds of data to the screen and so you do get burn-in.

(and while we're at it, I have twice seen nixie cathode poisoining on my clock projects; even one that does cycling of all digits every 5 minutes!)

I'm kind of going back to low-tech ascii LED displays, now.  i2c interface for 4-8 ascii chars - what could be simpler!  and those can take abuse and won't wear out for decades.

[eb4eqa]

Hi.

You may have noticed I also posted this in the Test Equipment forum (actually that is what I wanted to do when I posted it here but I could not remove it) and I got a warning from the moderators because it looked is was trying to sell something. The truth is I am not selling anything yet, and maybe never will. The reason to show it here was to prove it can be done and to see if there was interest to decide if I should install this quickly in my two power supplies and move along or come up with something that can be installed easily by other people. I could always send programmed PICs in the first case for the with the time and skills. And maybe someone will now try to do it too for this or other power supply and decide to share the software. I believe that proving that it can be done is a good contribution in itself and explaining how I do it (without all the details) has value for some people.

I used to share everything I do but I've found people selling in eBay manuals I had scanned and two of my old projects. That is why I am more careful now sharing projects that require no effort to copy/sell while all the hard work is in the idea or the development. Check http://www.rbarrios.com and you'll find I share most of my work.

HighVoltage/dundee: I don´t have a E364xA so I can't try with it. I do have a E363XA but the display is fine, I don't plan replacing it. Maybe if there was enough interest I could get one in the future.

taemun: The original plan was to tap the data going into the VFD controller, but it turns out it uses two VFD drivers (Allegro ICs, I can't check the part number now). The display segments are divided in four groups and each group is on and refreshed one at a time (by the way, the ICs do that again for each segment in each group, even faster). I could not find a way for the PIC to keep up at that speed. Then I found the controller on the main logic board and the controller on the front panel board talk to each other using a serial protocol. The PIC decodes that and drives the OLED.

The hard part was understanding that protocol, using any another type of display should not be difficult as long as it can be controlled quickly.

Neganur: It will display anything, including low current mode too. Even if you show custom text on the VFD by sending GPIB commands, you will get them on the new display. The only thing that can't be presented is the SHIFT segment (you can see that in the video), because that is not sent to the main logic board, it remains internal to the front panel controller and I am not tapping there.

linux-works: There is nothing currently soldered anywhere. I have only a PIC development board and the LED module connected with jumpers. Still lots of things to decide.

I also put replacement parts inside equipment if I know they will eventually fail and are hard to get :-)

timb: I chose the OLED module because it had a similar form factor and was the biggest that could fit. I have some ver nice HDSP LED dotmatrix displays but they are very small (and very, very expensive).

Macbeth: Yes, I do believe it should work with the 6632A.

I already tried that rejuvenation process to the VFD of the Keithley 2000 and all I got was a lot of wasted sweat. After running some current on the filaments, It did not get any better.

dunkemhigh, dundee: Thank you, I Will keep you posted.

Thank you all for the interest and feedback,
Roberto EB4EQA

[bapou]

I would also be interested! (Have a 6632B with a dim display)

[samofab]

It is possible that the same display protocol is used on other HP/Agilent devices (at least the rest of the supplies in this series, possibly much more). I played with the idea of hooking up a logical analyzer when I got a shipping with broken display, but the replacement cost was about 12 EUR.. so really not worth the effort.
Nevertheless, I would be very interested to see the protocol used.. perhaps one day on another, but similar, instrument a replacement display will not be easily available. So +1 on sharing the protocol and +1 on not sharing the completed design that you have:
I'm sure that if you investigate where the same display can also is used and be able to sell the whole package for say < 30 EUR, you'll find buyers.. if not here, you can market on other sites.
Also try to differentiate between two possible users: the ones that just want the damn thing working and are happy with LCD (and want to pay as little as possible) and the ones that want to make the whole thing much better (one might even replace a working LCD on 6632 to see if over the room).

[Macbeth]

To be fair, OP has shown that it can be done and is a simple protocol hack rather than a behind the display pins hack which is much more onerous (usually the amount of pins for a start, and then the voltage levels and frequencies - like LCD's use an AC triple voltage kind of PWM scheme, I haven't looked at VFD's).

But I understand OP when it comes to people ripping you off without attribution. A simple acknowledgement is all that's needed

However, the cats out the bag. Just publishing the protocol should be enough.  I'm sure others may find extras to it in time too.

[artag]

I've got a bunch of instruments with VFDs that are fading. Have had moderate success in boosting heaters and segment voltage but it won't last forever.

I was actually just researching oleds with a view to designing a drop-in replacement when I found this posting. I'd prefer an open-source project, or at least one that publishes the protocols, but I'm happy to capture data off my instruments and help publish the details. If you use that to make complete closed-source modules I don't have a problem with that, just as long as it doesn't prevent anyone else doing their own.

[PioB]

According to the service manual http://cp.literature.agilent.com/litweb/pdf/E3634-90010.pdf, p 91.

The serial register is used to send and receive serial data bytes from the main controller to the DAC system, or to communicate with the front panel controller. The serial register is multiplexed to these two circuits. The transmission rate is selected to 1.5 M bits/second for the DAC system and 93.75 k bits/second for communication with the front panel controller. The general serial interface is a 3-bit interface as shown below.

U20 Internal Signal    Configuration Signals   Front Panel Signals
Serial Clock                SERCK                        XFPSK
Data OUT (send)         SERDAT                      FPDI
Data IN (receive)        SERRBK                      FPDO

Serial data is received simultaneously as serial data is clocked out. Front panel data is exchanged in both directions whenever a byte is sent from U20.

Schematics are on this site, relevant pages: 132 "floating logic" and 135, front panel:https://www.eevblog.com/forum/beginners/did-i-kill-my-e3633a/?action=dlattach;attach=40934


So I have a 'stupid' question: As the logic is "floating", what kind of precautions would one have to take to analyze the signals? Can one just connect a computer with a logic analyzer to DGND and FPDI (And XFPSK) or would that lead to trouble? Would one need to rig up an optocoupler-system to galvanically isolate the DUT from earth?

I am following the thread interestedly, but am going on vacations for the next two weeks, away from my home lab with the e3633a.

[PTR_1275]

I know this is quite a old thread, however I came across it while searching for 6632b displays.

I recently purchased a 6632b and the seller packed it fantastically (bubble wrapped, foam protection, box in another box with more foam protection), and yet the couriers still managed to drop it hard enough to force the knob backwards, bend the PCB and smash the VFD.

The seller has been fantastic and refunded me the money as it isn't worth the freight back. I contacted keysight and they wanted $2275 for the front PCA (Yes, you read that correctly, more than 2 thousand dollars!!!!).

I am very interested in this display as an alternative. It is such a shame to have a brilliant power supply sitting there in my "useless" heap, just because I cannot buy a new display for a reasonable price.

If you are interested in making a kit and selling it to me, please let me know. To be honest I am far from clever enough to do this myself. I am happy if you want to PM me so we can discuss details.

[samofab]

Try contacting ebay seller veehifreq, he sometimes has replacement LCD's.
PM for his email.

[KJDS]

I'll have a rummage in my spares pile and see if I have any.

[PTR_1275]

I'll have a rummage in my spares pile and see if I have any.

That would be fantastic if you could.

I will test the power supply and see if the front panel is still working or if the whole front panel is gone. There was a pretty big bulge, so I am not 100% sure if other damage has been done to the front PCA.