Iiyama XB2474HS-B2 LCD monitor no input signal - Page 1
Forum section: electronics / repair

author: RandomPotato
author_rank: Newbie
timestamp: February 09, 2025, 03:02:02 pm
content: Hi !I am trying to repair a IIYAMA XB2474HS-B2 monitor which shows no input signal on HDMI or VGA inputs.The Display Port input works fine.When plugged to HDMI or VGA, the screen displays "No input found" for a couple of seconds, then turns off (sleep mode). Multiple HDMI/VGA cables tested (which are working fine with other monitors).Looking at the main controller board, I don't see any physical damage or components where the magic smoke would have escaped.I've also looked for cracked solder joints, but could not see any - Although, I don't have a microscope, and many of the solder joints are tiny.The caps look good, both on the main controller board and on the power supply (I think we can exclude that one since the DP input works fine.)I've also checked the HDMI hotplug input diode (D501), inspired by Dave's recent video (), which appears to be working fine.I've looked for service schematics for this monitor series, but could not find one. The closest I've found is for a PL2409HDS monitor (https://www.manualslib.com/manual/832312/Iiyama-Plb2409hds-B1.html).This was somehow helpful to understand the general board design, but did not help me understand where my issue could come from.I find interesting that the issue affects both VGA and HDMI, but not Display Port. Looking at the PCB traces for those, they appear to go directly from the port to the main RTD2525AR chip, which might be the culprit - See the PCB pictures. [EDIT: HDMI is left next to the VGA port]I've received a quote from Iiyama's Germany service center of 86euros for a replacement board, which I find quite expensive for this monitor, so I am trying to exhaust other options prior to byte the bullet, (also local second hand market for the board PN or monitor model did not show much success)Long story short, I am looking for ideas for the cause or tests that I could run to identify it.If you also happen to know of a place where I could get the correct service manual for this monitor, that'd be verify much appreciated.Thanks!

author: benj38
author_rank: Frequent Contributor
timestamp: February 09, 2025, 08:24:42 pm
content: I suggest you read the RTD2525AR datasheet and try to understand how it works and the difference between how it processes HDMI and VGA, Vs. display port. This should be the key to how you should proceed.Please forgive me if I am stating the obvious.

author: tunk
author_rank: Super Contributor
timestamp: February 09, 2025, 09:14:47 pm
content: Don't know if this is the case here, but on some Dellmonitors you have to manually select the input port.

author: benj38
author_rank: Frequent Contributor
timestamp: February 09, 2025, 10:09:32 pm
content: Quote from: tunk on February 09, 2025, 09:14:47 pmThis monitor has an "input" button that, once pressed, gives four options to select from: "Auto", "VGA", "HDMI", "DP".

author: RandomPotato
author_rank: Newbie
timestamp: February 10, 2025, 09:38:22 pm
content: Quote from: benj38 on February 09, 2025, 08:24:42 pmThanks. Found the datasheet on rtddisplay.com - relevant block diagram included.From what I can tell, DP and HDMI are handled together (kinda makes sense, as they're both digital), and VGA is handled separately until all 3 inputs are sent to the same processing unit.So, this would indicate that the issue is outside the RTD2525 chip itself right?

author: benj38
author_rank: Frequent Contributor
timestamp: February 10, 2025, 11:26:13 pm
content: Quote from: RandomPotato on February 10, 2025, 09:38:22 pmNot necessarily, since the RTD2525 is responsible for the auto detection of input source (we are assuming that you have set the monitor input option to "auto"!).If you include a link to the datasheet, it may help.

author: RandomPotato
author_rank: Newbie
timestamp: February 12, 2025, 05:48:41 pm
content: Here is the datasheet:http://rtddisplay.com/upload/20231121161929.pdfIt's for the -BR version, not -AR and it's a short datasheet only, but that's the closest I could find. Looking at other chips of the same family (RTD25xx), they all appear to have a similar design - I don't think the -AR will vary a lot.Regarding the auto detect, yes, you're right - though in my case, having it on auto or manual input does not make a difference.

author: benj38
author_rank: Frequent Contributor
timestamp: February 13, 2025, 05:52:55 pm
content: Looking at this (partial) datasheet, I must say that it seems like nothing external is involved in selecting between HDMI and DP. Thus, if only DP works, my main suspect would be the RTD2525 itself.I would thus suggest that you inspect carefully the soldering of the RTD2525 IC, and if you see no problem there, I guess the 86 Euro offer for a replacement board is not a bad deal after all.In fact (ignoring your desire to fix it yourself, which I fully share), the fact that they are willing to send you a full replacement board, and at a very reasonable price, is very commendable!