snclawson

I was able to find a board schematic from a YouTube channel that was linked from a post on forum.sorinelectronics.com. I'm using OpenBoardView to look at the .cad file, but it's been a long time since I've messed with hardware much so I'm still trying to find my way around. So far it is interesting to see how things are connected though!

Has anyone ever dealt with repairing a 7740 motherboard? More specifically, one that has an `LCD power rail failure'? (That is, two amber blinks, then eight white blinks at boot)? I finally got my nearly dream 7740 with an 9980HK and a RTX4000, but wanted to upgrade to a UHD panel. I didn't want to pay an arm and a leg so thought I'd be clever and buy an Alienware LCD Display Assembly (Dell part 74D90, for an Area-51m R2) for only about $70. Well, the panel has a high-density 0.4mm pitch 40-pin edp connector and the cable I have for the 7740 as a 0.5mm pitch 40-pin edp connector. I bought an adapter off of aliexpress to convert between them thinking that would be fine. Well... After disassembling the system, swapping the cable and hooking it up, nothing seemed to happen. The power light lit up, but the LCD panel never did and then the power light just went off. =( At first I thought that the panel was bad, but after swapping everything back to the original cable and panel it continued to do the same thing. That's when I noticed the LED error blinks, which specified `LCD power rail failure.' =( I'm not sure just what's at fault. The video cable I was using is the G11GD/DAP20_EDP_CABLE_UHD, which AFAIK should be the right cable (ie. not a 40-pin touchscreen cable; from what I can tell Dell didn't sell a 7730/7740 with a touchscreen?). Could be that 40-pin edp adapter is bad, since the panel itself was brand new, but it's as likely that I didn't get the connection quite right and shorted something when I connected it. At this point I don't really feel like trying to test the adapter/panel in another one of my other systems though! The Dell Service Manual just says `replace motherboard', but it was already hard enough to find _this_ one with an 9980HK! Is there a repair schematic available anywhere? Hopefully if it was a short then there should be an obvious blown capacitor or something in the LCD power rail area that could be replaced (although I don't see any damage on any of the connectors or on the motherboard!). I did swap out the RTX4000 for an RTX3000 I had in the hopes that the power circuit was there, but of course there's no change. I tried clearing the CMOS (both by holding down the power button and by pulling the CMOS battery), but that didn't help either. Thanks!

Anyone know of somewhere to get a reasonably priced heatsink (<=$40?) compatible with the RTX 4000/5000 series cards in a 7740? It looks like the only model that fits is the FHD64 (AT2KA005ZAL/NV-256) and even banged up models are over $50 on eBay, new ones are $90 and up! =( For whatever reason (late night looking at too many pictures on eBay I think) I had come to the conclusion that the 7730's 7JV64 heatsink (also labeled `nv-256') had the same screw layout as the FHD64, but after buying one it's definitely not. =( What I'm trying to do is upgrade a 7730 that I just bought that came with a P3200 and the D1HY2 `nv-192' heatsink. I was initially really excited to get an RTX 4000 for about the same price as an RTX 3000, until I went to install it and noticed the difference in the mounting screw locations. =( I did see that someone on notebookreview modified their old heatsink to work, but I couldn't tell if all that meant was that they only screwed in the two mounting screws that line up! Anyhow...I shifted from Lenovo to Dell (from a W530 to an M6700) because of the upgradability of the GPU and the fact that they also had a trackpoint (I'm old enough that I got used to using one _before_ trackpads existed! So that's a problem...). But I seem to have run into the end of the line for both now with Dell. =(