8753 Screen Upgrade / Replacement - Page 1
Forum section: electronics / testgear

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 02, 2017, 11:55:52 am
content: I have an HP 8753E VNA that has a gloomy screen - a common problem it would seem. I've actually gone into similar pieces of equipment and replaced the ccfl tube with reasonable success in improving the brightness. However, I feel that it should not be that big a deal to upgrade the display with a newer alternative that: a) uses an LED backlight and b) has better technology LCD that is clearer.This is the basic project idea - engineer a plug-and-play solution to upgrade the display by removing the old LCD unit and replacing it with a readily available one. Ideally that would mean finding a display that had the same connector (I can dream can't I?) or (more likely) come up with a design that's some kind of interface board - I am an embedded design engineer so I will do this bit if it's needed. Help me and we can all share in the delights of better displays for those aging HP/Agilent VNAs (and probably a load of other stuff using the same display). If you guys on EEVblog help me by finding datasheets etc. we can help the community. Get the stuff to me and I'll update this first post with what we have discovered. I imagine there's a few of you out there that would like to join me as Beta testers?Let's get started with what I know about the display in my HP8753E* HP Part number: 08753-60325 LCD Replacement Assembly* Display used: Sharp LQD340H 8.4 inch 640x480* The backlight is run from an inverter that takes 5V at around 0.5 A and converts it to 380 Vac at around 5 mA - this should be plenty of power for an LED backlight alternative* The brightness control is done by an analog feed from the main unit where 0V = 100% intensity and 4.5V = 50% intensity - some kind of interface to an LED backlight brightness control will be needed hereAction List:1. Find a data sheet for the LQD340H (some say that the LQ9D340H is compatible too)2. Find a newer, affordable, available, better display that uses the same signals (ideally the same connector) and will fit in the same spaceGO!

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 02, 2017, 01:29:11 pm
content: Someone asked if I have looked at the Simmconn kits. I have, and even contacted them but their kits are only to upgrade from CRTs to LCDs, the 8753D, E, ES, and ET are all LCDs as standard, it's just that the LCD is very old technology, poor contrast, muddy colors, and gloomy backlight.

author: Howardlong
author_rank: Super Contributor
timestamp: February 02, 2017, 03:48:38 pm
content: Does the 8753E have a VGA output? If so you could purchase an 8.4" VGA screen and appropriate adapter board.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 02, 2017, 04:07:20 pm
content: Quote from: Howardlong on February 02, 2017, 03:48:38 pmYes it does and I am in process of hooking up an old VGA monitor to it but what I really want is to create a professional looking solution that can be used universally to do an internal upgrade of the old murky LCD display.I don't yet have a datasheet for the standard LQD340H (or LQ9D340H) display. I have reached out via my Avnet contacts to see what Sharp can do to help me.

author: simmconn
author_rank: Regular Contributor
timestamp: February 03, 2017, 01:31:23 am
content: I expect this to be more of a mechanical problem than an electrical one. If the short-form LQ9D340 datasheet on the internet is true about the interface being 6-bit RGB, chances are it follows the industrial standard pinout that's still being used today. Also, Sharp seems to maintain the LQ9D form factor in their LQ084V1 series panels except for the depth. The latest one is the LQ084V1DG43, which is supposed to be in production. I would not expect it to be cheap, though.Have fun!

author: TheSteve
author_rank: Unknown
timestamp: February 03, 2017, 01:38:50 am
content: The LQ084V1DG21 might just be the best option. They aren't crazy money at least and are easy to get.Data sheet here:http://www.sharpsma.com/download/LQ084V1DG21-PB-020905pdf250:1 contrast300cd/m26 bit RGB

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 03, 2017, 02:30:42 am
content: Hi Steve & Simmconn,Thanks for the input. It sure looks like the LQ084V1DG21 may well be a plug-in replacement but, having never seen a datasheet for the LQD340H, I don't know whether the LQ084V1DG21 will be any better. I can get a LQ084V1DG21 on eBay for $130 including shipping which is very reasonable but I could also do what I did to my Sig Gene and take the old one apart and replace the ccfl tube for $10. maybe that's what I'll do.A better datasheet for the LQ084V1DG21is hereThoughts? I cross-checked the pictures and even read through the 8753E service manual to check the voltages, the LQ084V1DG21 appears to have the same connector and uses the same voltages and, at least from a top view, appears to have the same mounting holes. I have just ordered a new LQ084V1DG21 on eBay that ships from the USA for $128 including $13 shipping. I'll update this post once I get it.

author: simmconn
author_rank: Regular Contributor
timestamp: February 03, 2017, 07:21:44 pm
content: Like I said, watch the depth (thickness). I don't have an 8753E and I'm not sure if the thickness is critical in mounting the panel properly. The LQ084V1DG21 is much thicker than the LQ9D340.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 04, 2017, 01:44:32 am
content: Quote from: simmconn on February 03, 2017, 07:21:44 pmWhen you say "The LQ084V1DG21 is much thicker than the LQ9D340." how much thicker is it? Is it twice as thick? I have some room I believe and I can alter the mounting system to allow for a thicker display. I have the datasheet for the LQ084V1DG21 which is now on its way, do you have the datasheet for the LQ9D340 or can you measure one?I've included a picture from the 8753E service guide, as you can see there's quite a big cavity behind the front panel.Thanks.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 04, 2017, 02:39:57 am
content: I think I've answered my previous question. From drawings I found online, the LQ9D340 is 7.3 mm thick and the LQ084V1DG21 is 12 mm thick. So yes, the new one is 60% thicker than the old one but it's actually only 4.7 mm thicker. That indicates that the display will probably fit although the plastic backing will probably need to be re-engineered. Sounds like a job for my 3D printer.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 07, 2017, 08:11:31 pm
content: Well I got the new display and fitted it today. The pictures show the process. The new LQ084V1DG21 display fits in the place of the LQ9D340 (which was the one fitted in my 8753E). I had to cut out the 'spring' holders from the nylon backing piece and also trim off a ridge on the new display using a box cutter and it was still a biit tight. My new display had 1 stuck on pixel that's slightly right of center near the top but I can live with that. The end result is really so much better than what I started with as you can see.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 07, 2017, 08:15:20 pm
content: Missing Pictures

author: rfspezi
author_rank: Regular Contributor
timestamp: February 14, 2018, 02:47:21 pm
content: The LQ084V1DG43 seems to be an alternative that's in production right now.But what makes it even more interesting is the LED Backlight.

author: EE-digger
author_rank: Frequent Contributor
timestamp: February 15, 2018, 02:53:15 am
content: The unit looks fantastic. Great job !I'll just throw this out because the title was a generic 8753. On my 8753C, since replaced by PNA but waiting to go on Ebay when I get a chance, I wanted to replace the Sony Trinitron display module with an LCD.The screen format is somewhat odd, like 512x384 (from my memory), which actually turns out being an old Apple format. Horizontal sweep was also not quite a today standard.I ended up, temporarily, wiring up a GB8220 arcade type conversion board ($20 on ebay), a sync separator chip with a few passive parts, and a VGA input, 1024x768 LED backlight display.The setup was tricky but when it worked, it was quite lovely. Your graphics obviously are not going to be re-painted at the higher res but it looked great.This was far less effort than my alternative which was going to be a quick re-education on FPGA/RAM as a DIY buffer/format converter. Others on this forum have taken the latter approach quite successfully on a Tek Nu-Color LCD replacement (I think).At that point I came upon some NOS Sony monitors and dropped the project. It's still good to keep in mind for older equipment, especially with an oddball video and sync capability.The 8753C/85047A are in great shape if anyone has interest north of Boston. This is just reference information since this is not a for sale thread

author: KE5FX
author_rank: Super Contributor
timestamp: February 15, 2018, 05:24:31 am
content: Looks good. I wonder if this is the same LCD panel that the 8510C used? If so, I can definitely see swapping mine out for an LQ084V1DG43.

author: rfspezi
author_rank: Regular Contributor
timestamp: February 15, 2018, 08:06:48 am
content: Unfortunately the LQ084V1DG43 is a bit pricy.Price at Digikey is around € 250,-.

author: rfspezi
author_rank: Regular Contributor
timestamp: February 25, 2018, 05:46:22 pm
content: I did a quick test replacing the old CCFL of my 8753E with a LED strip from another, smaller LCD.The result is a nice, bright LCD screen.See the picture below how i installed the strip.Later on, I will replace the strip with a longer one that also reaches the corners.A tip for all of you who also got an old CCFL tube.When i removed the old CCFL tube, i noticed that the CCFL melted the edge of the transparent plastic light distribution plate.So i polished it to get maximum transparency again.

author: rfspezi
author_rank: Regular Contributor
timestamp: February 28, 2018, 08:05:26 pm
content: Just found this page describing a LED-backlight mod for the LQ084V1DG21.http://www.rbarrios.com/projects/LCD2LED/

author: TheSteve
author_rank: Unknown
timestamp: December 16, 2018, 06:35:53 am
content: Picked up an 8753E the other day. The LCD was crazy dim. I thought I'd give an LED upgrade a try before replacing the entire LCD unit.I started with a standard LED strip designed for monitor back lighting which has sets of 3 LED's in series(9+ volts minimum). The 8753E original back light CCFL inverter runs on 5 volts. I decided to mod the LED strip to have all of the LED's running in parallel so I could run them from the original 5 volt source. This was pretty simple, just cut the traces between the LED's and then run tiny 30 gauge jumpers from the positive and ground lines on the back side of the PCB to each of the LED's. Current limiting is handled by 3 20 ohm resistors in parallel. Drive current ended up about 280 mAh.The downside to an always on back light is that the 8753E screen will be bright white until it finishes booting, it will also be bright white when you perform a preset. The original CCFL driver has an enable line which is toggled by the 8753E processor to prevent this. It seemed only right so to have the same feature I added a small P channel FET and few resistors. The LED's are now turned on/off as the original CCFL was. This means you never see any bright white screen at boot, and you can't even tell it was modified. So far I am very pleased with the result.Now, if I only had some APC7 to N or SMA/3.5mm adapters!

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: December 17, 2018, 09:47:26 pm
content: Great job Steve, looks good.

author: TiN
author_rank: Super Contributor
timestamp: December 17, 2018, 11:39:11 pm
content: Why you kept that high-voltage supply module after swap to LED backlight?

author: TheSteve
author_rank: Unknown
timestamp: December 17, 2018, 11:41:54 pm
content: Quote from: TiN on December 17, 2018, 11:39:11 pmIt is disconnected but left in place. Maybe down the road someone will want to convert it back to CCFL.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: December 18, 2018, 12:32:51 pm
content: I ordered some LED strip but, rather than modify it, isn't there a 12V supply available somewhere? Maybe a 5 to 12V converter circuit would be neater? Can you share the circuit for enabling the light in more detail? How about brightness control?

author: TheSteve
author_rank: Unknown
timestamp: December 18, 2018, 05:12:22 pm
content: The various howto's I found around the net indicated there is 24 volts from another board and that you can run it to the front panel. I liked the idea of a fully linear solution and of using the original 5 volt supply.The brightness control is an analog voltage, it is located on the other end of the 5 position connector used to drive the backlight driver. It would be nice to incorporate but was a lower priority for me.The enable/disable switch is pretty simple. It is a SOT23 logic level P channel FET connected in series with the positive line. The enable/disable signal is low for off, high for on. I used a series 10 ohm resistor to the gate and a 4.7 k pullup to the 5 volt line. It is connected using the yellow wire in my picture. If you change to using 12/24 volts you'd probably want to switch to an N channel on the negative supply with a transistor inverter driving the gate.The stock LCD in my unit only had a single 140mm long CCFL tube so it was replaced with 17 LED's. Some of the newer LCD's have a tube which goes along one side and the top of the LCD so it would need quite a few more LED's.

author: syau
author_rank: Frequent Contributor
timestamp: July 06, 2021, 11:58:31 pm
content: Sorry for digging up this old thread. Just want to share my experience for screen replacement.Scored a 8753ES with Opt 006, seller confirmed the display is dead. Hooked up a VGA monitor and it works with self test passed. Open up found the LCD CCFL inverter fuse open circuit. Replaced the fuse and the display work fine but very dim. Got a replacement display (LQ084V1DG21) from Taobao for USD $80 and it is now sharp and clear. The display fitted perfectly without any work but the reviewable areas is 1/8” less from the top

author: mauro
author_rank: Newbie
timestamp: August 28, 2025, 10:36:17 am
content: Good morning, The Steve,Congratulations on your work. Could you please send me the schematic with the parts list, as I want to do the same job for my new display?Thanks.Best regards.

author: TheSteve
author_rank: Unknown
timestamp: August 28, 2025, 03:26:52 pm
content: I'm sorry I don't have a schematic and I sold the unit several years ago. The basic design is described in my posts though.

author: mauro
author_rank: Newbie
timestamp: August 28, 2025, 03:56:45 pm
content: OK, thanks. I'll look for the description. I'm using a translator. A diagram would have been much simpler.Regards