IWATSU DS-8710 Oscilloscope LCD display repair help(complete) - Page 1
Forum section: electronics / repair

author: daisizhou
author_rank: Super Contributor
timestamp: August 30, 2025, 11:31:16 am
content: This is an IWATSU DS-8710 100MHZ digital oscilloscope.The LCD display is a 320*240 screen,The exact model is: TW2294V-0 or G321E.https://www.alldatasheet.com/datasheet-pdf/view/80509/SII/G321EV.htmlIt seems that the failure is caused by aging or oxidation of the transparent adhesive used to bond the screen.I'm not planning on buying the same model of display because it's only a matter of time before this model suffers from the same burn-in shadow failure.I'd like to know if there is a compatible model that can be a perfect replacement, because I measured the installation dimensions and the screen of this model seems to be special.If you have a better solution, please tell me, thank you

author: coromonadalix
author_rank: Super Contributor
timestamp: August 30, 2025, 12:16:12 pm
content: mm unless im wrong this is a controller less display, only row and coloumn drivers ?you need to find the one(s) compatible with your display controller, you could face timing issue, characters codes compatibility, physical size, power issues, contrast etc ...you need to find a display with the same drivers chips ??me if i was able to find another identical one, i would put a new one in there ... i understand the problems,but once repaired i would try on the old one to see if it is fixable, but the foil / flex is very fragileif you search : 1/240 duty 320x240 lcd will give many google results, check the pinouts and physical sizes, AND it is a 4bit data parallel inputthis one came up a few time ?https://www.raystar-optronics.com/graphic-lcd-display-module/lcd-display-320x240.htmlRG320240A

author: daisizhou
author_rank: Super Contributor
timestamp: August 30, 2025, 12:26:41 pm
content: Simply put, I don't want to use a monitor like the G321E again, because see the picture below.It is a layer of row and column displays glued together,A transparent glue is used,After a long time, this layer of transparent glue will undergo a chemical reaction.The obstruction is caused by the oxidation of this layer of transparent glue.If I continue to buy this type of display, it is only a matter of time before the same problem occurs again.

author: daisizhou
author_rank: Super Contributor
timestamp: August 30, 2025, 01:01:45 pm
content: really Installing physical dimensions is a headache.Is there a perfectly compatible and suitable solution?The original layer of obstruction has been expanding, and I have endured it for a long time.I used it normally and didn't directly expose this screen to sunlightThere seem to be many specifications for a 320 * 240 screen, and I am not a professional expert in this field, so I need your help. Thank you

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 30, 2025, 02:00:55 pm
content: Quote from: daisizhou on August 30, 2025, 12:26:41 pmnot a glue. it is filled with liquid crystal. That is why it is called a liquid crystal panel.Looks like it's just the polarizer degrading.Did you try peeling off the polarizer?as an alternative, it would be a 4.7", 320x240, STN or FSTN, 4-bit parallel, and CCFL backlighting. among these, search for a compatible replacement by reviewing the datasheets.https://www.panelook.com/modelsearch.php?op=advancedsearch&order=panel_id&panel_type_main=STN&inch_low=470&inch_high=470&resolution_pixels=21550&touch_screen_main=No&display_colors_amount=MN&backlight_type=63

author: daisizhou
author_rank: Super Contributor
timestamp: August 30, 2025, 06:48:12 pm
content: Quote from: squadchannel on August 30, 2025, 02:00:55 pmpolarizer?Are you referring to the thin film used for polarization? Can it be torn off?

author: daisizhou
author_rank: Super Contributor
timestamp: August 30, 2025, 10:16:01 pm
content: Are you referring to this layer?I used a blade to gently lift this layer.As far as I know, polarizing films have degrees. Do you know what degree my polarizing film is?

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 31, 2025, 12:32:53 am
content: Purchase polarizers from Taobao or any other source.Since there are polarizers on both the front and back sides of the LCD glass, replace both. (if the condition is good, only one side)Do not attempt to peel both at once. Instead, peel one side, turn on the power, place the purchased polarizer on top, and find the optimal angle while checking the visibility.make sure the adhesive side of the polarizer faces the glass. once you find the angle, mark it to avoid mistakes, then just cut and attach it.once one side is applied, proceed to the other.avoid touching the backlight unit. if BEF film are used, and touch it, it'll be a hassle.also careful with the film cable. if it peels off, it's difficult to repair. they're sold on Taobao for calculator repairs, but I don't know if they'll work.PS:replacing the back side might be tricky. connected by zebra contacts, but how do they determine the position? take it off, you might not be able to put it back.

author: daisizhou
author_rank: Super Contributor
timestamp: August 31, 2025, 01:01:29 am
content: ThanksHow can I determine the degree of polarization of my polarizing film? 0 degrees? 90 degrees? 45 degrees? ..........The Y-axis of the LCD screen is in contact with the PCB through a conductive rubber, and the X-axis is through a zebra strip, which is hot pressed on the PCB. The conductive rubber seems to be removable and can be separated from the PCB.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 31, 2025, 01:11:09 am
content: 0 degrees, 90 degrees, or 45 degrees, it doesn't matter.It's simply the angle at which it was cut (manufactured). angled a 90-degree piece 90 degrees makes it the same as a 0-degree piece.Quote from: daisizhou on August 31, 2025, 01:01:29 amunlike DMM's Zebra, there's no positioning frame, the pitch is fine, and while you can it off, I don't think you can put it back.

author: daisizhou
author_rank: Super Contributor
timestamp: August 31, 2025, 01:23:35 am
content: Quote from: squadchannel on August 31, 2025, 01:11:09 amI don't understand what you mean.There is an iron frame outside for installing the LCD panel and conductive rubber.The conductive rubber is installed in a fixed position between the backlight guide plate and the iron frame.

author: daisizhou
author_rank: Super Contributor
timestamp: August 31, 2025, 10:34:53 pm
content: Hi squadchannelThere seems to be a film on the back of the LCD screen and in front of the backlight panel.Is it the same as the polarizing film in front?I chose a 265mm*200mm polarizing film with a 90-degree angle.I actually need to use 107mm*83mm,I plan to cut the polarizing film I purchased into 4 pieces,If everything goes well, I need to use 2 copies.Is this the right choice for me?Thanks

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 01, 2025, 01:09:54 am
content: this type of LCD panel, the front and back use the same polarizer.You'll need to test the cutting angle. Whether it's 0 degrees, 90 degrees, 45 degrees, or some other angle varies depending on the LCD panel.

author: daisizhou
author_rank: Super Contributor
timestamp: September 01, 2025, 01:31:33 am
content: Quote from: squadchannel on September 01, 2025, 01:09:54 amhttps://www.alldatasheet.com/datasheet-pdf/view/80509/SII/G321EV.htmlThe link above is the data sheet for this LCD screen,Can I confirm in this data sheet whether it is 0 degrees, 90 degrees or 45 degrees?The LCD panel appears to be of STN type

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 01, 2025, 01:42:48 am
content: not specified in datasheet.

author: daisizhou
author_rank: Super Contributor
timestamp: September 04, 2025, 07:58:27 am
content: Please see my video above, I bought a new polarizing film, but the new polarizing film does not seem to have the ideal contrast.I conducted a comparison test between the new and old polarizing films.There seems to be no accurate model or contrast index for polarizing film, and I don't know how to buy it correctly

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 04, 2025, 08:46:31 am
content: Is the adhesive surface of the polarizer facing the lcd?polarizer angle between the front and back is also important, so it may be impossible to replace it without replace the back polarizer.

author: daisizhou
author_rank: Super Contributor
timestamp: September 04, 2025, 10:22:21 am
content: Quote from: squadchannel on September 04, 2025, 08:46:31 amI tested the polarizer with the adhesive side facing the LCD screen or not, but the effect was still not good.Comparison with original polarizer,Very light color concentration,It looks like low resolutionI haven't disassembled the rear polarizer yet.STN or FSTN is called pseudo color screen in Chinese. It seems to require special polarizer. I don’t know how to buy it. Now this is the most common general polarizer.

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 04, 2025, 10:26:16 am
content: it shouldn't be FSTN, a special polarizer shouldn't be necessary.if it's FSTN, special polarizer sell here. "点阵570偏光片"https://item.taobao.com/item.htm?_u=43s8grt66f1f9&id=610116223737

author: daisizhou
author_rank: Super Contributor
timestamp: September 04, 2025, 11:45:59 pm
content: Please see the pictures below, I took pictures of the front and back of the membraneFrom the mark "G321EV5B" on the back of the PCB, it corresponds to "G321EV5B000" on the datasheet, see picture "99"I can never find the model or type of any polarizing film in the data sheet.

author: daisizhou
author_rank: Super Contributor
timestamp: September 05, 2025, 01:17:59 am
content: I conducted a comparative test on the universal polarizing film and the original polarizing film,I found that the color concentration of the universal polarizing film is not as good as the original polarizing film. Please see the picture.(The best angle has been adjusted)I accidentally discovered that the 3D glasses worn for 3D movies, the lens on the right, has a display effect very similar to the original polarized film, please see the picture

author: daisizhou
author_rank: Super Contributor
timestamp: September 05, 2025, 02:22:33 pm
content: After 9981 difficulties, I finally got it done. The only regret is that the bottom of the polarizing film was not thoroughly cleaned. When I applied it, a few air bubbles entered and I couldn't get them clean. Forget it, imperfection is beautiful. Thank you all for your help.Close this post

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 05, 2025, 03:17:55 pm
content: rubber roller does a good job.