HP 6632B Power Supply replacement OLED screen (DONE) - Page 1
Forum section: electronics / general

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 31, 2015, 09:03:13 am
content: 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.beRegards,Roberto EB4EQA

author: matseng
author_rank: Frequent Contributor
timestamp: August 31, 2015, 09:13:03 am
content: Very nice, but doesn't the OLEDs have an even worse lifetime than the original displays?

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 31, 2015, 09:34:31 am
content: 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

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 31, 2015, 10:33:04 am
content: What OLED display is this? I don't have the PSU but I really like The display.

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 31, 2015, 10:35:14 am
content: This one:http://www.ebay.com/itm/IIC-I2C-1602-16x2-OLED-Module-Display-For-Arduino-PIC-AVR-ARM-/161162845021?hash=item25860ddb5dRoberto EB4EQA

author: HighVoltage
author_rank: Super Contributor
timestamp: August 31, 2015, 10:39:45 am
content: 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.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 31, 2015, 10:40:06 am
content: Quote from: eb4eqa on August 31, 2015, 10:35:14 am

author: PlainName
author_rank: Super Contributor
timestamp: August 31, 2015, 11:38:19 am
content: QuoteYes.

author: dundee
author_rank: Regular Contributor
timestamp: August 31, 2015, 12:01:04 pm
content: Quote from: HighVoltage on August 31, 2015, 10:39:45 am+1Very nice project!

author: taemun
author_rank: Regular Contributor
timestamp: August 31, 2015, 02:46:37 pm
content: 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?

author: Neganur
author_rank: Unknown
timestamp: August 31, 2015, 03:09:42 pm
content: Does it display the low current mode too?

author: linux-works
author_rank: Super Contributor
timestamp: August 31, 2015, 10:52:30 pm
content: Quote from: matseng on August 31, 2015, 09:13:03 amthey 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).

author: timb
author_rank: Super Contributor
timestamp: August 31, 2015, 11:43:38 pm
content: Quote from: eb4eqa on August 31, 2015, 09:34:31 amActually, 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

author: Macbeth
author_rank: Super Contributor
timestamp: September 01, 2015, 12:11:48 am
content: 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

author: linux-works
author_rank: Super Contributor
timestamp: September 01, 2015, 12:55:14 am
content: 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.

author: eb4eqa
author_rank: Regular Contributor
timestamp: September 01, 2015, 07:48:38 am
content: 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. Checkhttp://www.rbarrios.comand 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

author: bapou
author_rank: Contributor
timestamp: September 01, 2015, 11:48:40 am
content: I would also be interested! (Have a 6632B with a dim display)

author: samofab
author_rank: Regular Contributor
timestamp: September 01, 2015, 09:23:20 pm
content: 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).

author: Macbeth
author_rank: Super Contributor
timestamp: September 01, 2015, 11:01:03 pm
content: 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 neededHowever, the cats out the bag. Just publishing the protocol should be enough.I'm sure others may find extras to it in time too.

author: artag
author_rank: Super Contributor
timestamp: September 02, 2015, 11:51:54 am
content: 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.

author: PioB
author_rank: Regular Contributor
timestamp: September 02, 2015, 05:31:53 pm
content: According to the service manualhttp://cp.literature.agilent.com/litweb/pdf/E3634-90010.pdf, p 91.QuoteSchematics 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=40934So 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.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 09, 2016, 11:10:45 am
content: 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.

author: samofab
author_rank: Regular Contributor
timestamp: September 09, 2016, 05:58:28 pm
content: Try contacting ebay seller veehifreq, he sometimes has replacement LCD's.PM for his email.

author: KJDS
author_rank: Super Contributor
timestamp: September 09, 2016, 06:13:42 pm
content: I'll have a rummage in my spares pile and see if I have any.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 10, 2016, 12:19:50 am
content: Quote from: KJDS on September 09, 2016, 06:13:42 pmThat 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.

author: PlainName
author_rank: Super Contributor
timestamp: September 10, 2016, 12:32:12 am
content: If it's just the display, you could control it via the serial port and build a remote display/controller. Some small micro, 40x2 LCD, five buttons, bosh.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 26, 2016, 08:59:39 am
content: Quote from: KJDS on September 09, 2016, 06:13:42 pmHave you had a chance to look through your pile and see if you have parts available?I have plugged the front PCA from my 66332a into the broken 6632b and it works fine, if I use the broken PCA I can get all the buttons to work, so there doesn't appear to be any damage further than the VFD being shattered.Further more to that, if the OP is willing to sell me a display kit with the OLED display I would be interested also. I know that it is possible to make one myself, but I do not posses the skills or time currently to make up a serial controller to control the PSU, or a display driver to take the serial feed to the display and run another display.

author: KJDS
author_rank: Super Contributor
timestamp: September 26, 2016, 05:04:52 pm
content: I've got a pile of units waiting to be fixed, so I'll take a look at the recent repair thread and see if that fix can be applied to any of my broken units to make them good. If that doesn't work, then I won't have the time to sort them out and won't mind selling them for parts.No idea when I'll get round to it.

author: senseless
author_rank: Contributor
timestamp: September 26, 2016, 05:44:28 pm
content: Quote from: KJDS on September 26, 2016, 05:04:52 pmI searched for the mentioned thread and guess this one is the correct:https://www.eevblog.com/forum/repair/agilent-6632b-fault-repair-and-several-design-flaws/msg1018796/#msg1018796Just for reference.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 27, 2016, 06:38:28 am
content: Quote from: KJDS on September 26, 2016, 05:04:52 pmNot a problem, Roberto has gotten in contact with me (He doesn't check the forum very often) and we are talking about the OLED conversion, so I will probably not need the VFD after all.

author: kjk24
author_rank: Regular Contributor
timestamp: May 11, 2019, 06:48:29 pm
content: I used a led backlight from a old mobile cut it to the right size and use it with a curentconstant regulator, only two transistors and two resistors.https://photos.app.goo.gl/pih2mcSkGtk2ALkh9A finished picture will follow , the viewing angel is for mobile phones so you have to think about thathttps://photos.app.goo.gl/4V9NmTR8WsNtbGms5