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Need picture or pin-out of inverter cable from logic board 20" G4

I replaced the inverter on my 20" G4 and switched the wires from the logic board. I didn't write down the configuration and now wish I had?

Can anyone give me a pic or cable configuration (or color) of the inverter cable? I looked at several PDF's but they are too grainy.

Thanks much

Imac G4 1.25Ghz (USB 2.) 20", 500Gb HD, 1.25gb ramm G5 LCD

Posted on Feb 15, 2009 6:42 PM

32 replies

garrettpf Author

Level 1

14 points

Mar 1, 2009 8:58 AM in response to MisterDNA

anywho. Spudnuty thinks that the inductor which is my avatar at the elctro forums is why I am not getting 12v to my inverter.

Right now I am running the inverter 2-12v supply and gnd directly from the power supply connector on the logic board. I placed some small pins in there and just pushed the inverter cable ends onto them and taped them up.

As for brightness control I believe I have the orange wire hooked up for brightness control. I do not remember what pin it is as I would have to take the mac apart again to figure it out. The brightness does work however backwards as apple uses .88v-3.3v for brightness with 3.3v being the brightest. The after market inverter I have in there now uses 0v as a default brightness (makes sense).

I also know that the yellow cable is what turns the inverter on and off. There is only one more cable (brown i think) that i think is the return from the brightness PWM from the inverter.

Man, if we could get Apple to step up to the plate and help out with a simple schematic lol.

Oh, also check out my post in "using your imac" as there is usefull info there and an almost pretty good pic of the inverter connector.

Wait a minute, can you get a pin out of the inverter cable for me lol. what imac are you working on?

Message was edited by: garrettpf

Mar 1, 2009 9:12 AM in response to garrettpf

I am working on a 20" iMac G4. What pinout do you need? I had been using your pinout description and photos at ETO. I don't see a brown cable. All I see other than the Vcc and Ground wires are the yellow, purple and orange at pins 6, 7, and 8 at the inverter board.

I do have the iMac G4 taken apart. If the pinout you want me to check is the motherboard connector to see if the inductor is connected to the inverter Vcc, for example, that's easy.

I can also test the PWM return theory with an oscilloscope.

garrettpf Author

Level 1

14 points

Mar 1, 2009 9:51 AM in response to MisterDNA

ok, then purple lol. I cannot remember. I know it has not been long but I have a home show coming up so my head is spinning.

as for the inductor, i fear replacing mine as I am sure the logic board is multi-layer and who knows what caused it or what damage was done. I would like to try as i just hate leaving things be 😉

And if you could get me either a pin out or pic of both sides of the inverter connector that would be awesome. I believe that yellow would be next to the purple but not totally sure.

As for the TMDS connector on the LCD. first off, I have an LVDS LCD in my mac right now. I believe that the imac decides which type of signal to send dependent on LVDS or TMDS LCD technology. I have a PDF of the LM201W01-SLA1 but a little cinfirmation on what channel goes to what on the DVI would be helpful. I have not had time to lay it out myself but I would like the display running for the home show 😟

the LCD panel I have now is the LM201W01-SLA3 but I would think there is no difference in the pin config. Below is a link to the PDF I found on it.

http://www.beyondinfinite.com/lcd/Library/LG-Philips/LM201W01-SLA1.pdf

I hope that help and also if you could, post a link to what you found.

Oh, and as for the PMW control, it would help others but I am not using the OEM inverter so I cannot verify any of that myself 😟

Thanks for your help,
Garrett

Mar 1, 2009 10:52 AM in response to garrettpf

You may be in luck with the logic board damage. At work, I have access to the x-ray machine we use for inspecting circuit boards and solder.

I have a pinout for the TMDS connector as it relates to the logic board connector and the panel module connector. I mapped it out last night pin-by-pin with the continuity setting on my meter. I'll post it as soon as I can get out to my workshop since I didn't save it to the shared folder.

The panel is supposed to be DVI-compliant. The only thing I lack is the supply voltage for the LCD panel (carried on pins 1 and 2 of the TMDS connector at the logic board side). It's supposed to be a 12VDC +-5% supply according to the datasheet, but since it doesn't appear to be directly connected to the power supply and checking it would require a working machine, I can't check it on mine. I'll have to try the variable DC supply at work since the panel is supposed to prevent power-on with a voltage below 10.8V or something like that.

Mar 1, 2009 11:01 AM in response to garrettpf

iMac G4 panel to motherboard connector map-out for verbatim:

Panel Lead Motherboard side
1 GND Pin 3,4
2 SHLD2 Pin 3,4
3 RX2+ Pin 5
4 RX2- Pin 6
5 SHLD1 Pin 3,4
6 RX1+ Pin 8
7 RX1- Pin 9
8 SHLD0 Pin 3,4
9 RX0+ Pin 11
10 RX0- ` Pin 12
11 SHLD C Pin 3,4
12 RXC+ Pin 14
13 RXC- Pin 15
14 GND Pin 16
15 V-EDID Pin 17
16 AGING N/C
17 CLK-EDID Pin 19
18 Data-EDID Pin 20
19 GND Pin 3,4
20 GND Pin 3,4
21 GND N/C
22 Vcc Pin 1,2
23 Vcc Pin 1,2
24 Vcc Pin 1,2
The rest are not connected

Mar 1, 2009 1:06 PM in response to MisterDNA

I just tested L103 to see if it is, in fact, in series with the inverter VCC leads and it most definitely is. Also, it appears to be built in such a way that it has a chance of acting as a fuse before the real fuse would. Maybe what happened was your original inverter was bad.

garrettpf Author

Level 1

14 points

Mar 3, 2009 12:32 AM in response to MisterDNA

well, maybe when i get back in there to straighten out the inverter cables I will replace the inductor. The inductor was melted but I was still getting inverter 12v. When i noticed it was burnt I touched it and it came right off.

MisterDNA, a few things I would like you to help me with: 1- can you still get a pic of the inverter connector logic board side? 2- help me figure out what pin goes where on the LCD to DVI. In the PDF it lists pin as "data0" thru "data3 but on DVI's its lists it as "data0" thru "data5" here is what I mean.

From the LM201W01 data sheet

And a DVI

confusing to you too? I would have a better shot just looking at the PCB of the LCD and praying lol.

let me know if you can help me and thanks for the help so far.
g

Mar 3, 2009 5:27 AM in response to garrettpf

The biggest problem is you have LVDS listed there with DVI. DVI is TMDS and the two protocols are incompatible. There are, however, TMDS to LVDS converters. That's what's inside of the stock iMac G4 panel, specifically, a TI TFP403 chip. I don't know whether you discussed it in the thread or not, but what happened to the original LCD that was in the iMac? You should be using that.

You may be wondering why Apple even used a TMDS cable when LVDS is so much more common. It's because of a lower wire-count, better signal quality over distance, reduced RF noise and the easy availability of the TMDS output directly from the GPU.

"In the PDF it lists pin as "data0" thru "data3 but on DVI's its lists it as "data0" thru "data5"."

It's not confusing at all, but you have to be looking at the datasheet for the original iMac panel, which is where I sourced the display side of the pinout I mapped out at the logic board. Your everyday DVI connector is Dual-Channel. Very few displays use both channels, but Apple's 30" panel comes to mind as one example. Since the panel in the iMac only needs one channel, that's all it has. When using a single-channel display on a Dual-Channel connector, you use data pairs 0-2 and leave 3-5 unconnected. There is only one clock channel pair so you use that in all cases.

I can still get a photo of the inverter connector at logic board side. The photo will take time as I'm busy all day, but I could get you a pinout this morning if that would help. The same connector carries a few other signals like the microphone and standby LED. Are you after just the inverter pins for the time being?

garrettpf Author

Level 1

14 points

Mar 3, 2009 11:18 AM in response to MisterDNA

I have a panel from an iMac G5. It is the LG-Philips LM201W01(SL)(A3). I want to use this as a monitor for my gaming PC with DVI. The vid card in my PC (GTX280) should have the converter built into it as well. I have data sheets up the ying yang for TMDS and LVDS but was kind of hoping you would just say oh, pin bla goes to pin blabla 😉. I have the data sheet for a TMDS to LVDS converter so I will have to look on that.

As for my iMac G4 I do have a LVDS LCD panel in it right now. It is also from a G5 and is the same LM201W01 (A5)(K2). here is the link to what I have

I guess I assumed I could simply hook the LVDS to a DVI connector and plug it into my GTX280 and be good to go. At first when I looked at the TMDS data sheet it seemed a lot easier 😉

Message was edited by: garrettpf

Mar 3, 2009 4:07 PM in response to garrettpf

The panel in my iMac G4 is an IDTech M201Z2-M01, full-on DVI-compliant.

I thought you were working on the original panel.

garrettpf Author

Level 1

14 points

Mar 3, 2009 6:17 PM in response to MisterDNA

Well, I was under the assumption that I could hook this up to DVI and allow the GTX280 to do the switching. I guess I didn't do the right searching. I have all kinds of data sheets on DVI and LVDS and never put the correlation that it will not work through DVI 😟. I had it all in front of me but never looked at it 😟

Well, I get what you are saying now. And now that it is so close to the home show and I did want to use it in the show, I wish I would have taken more time doing research and just not assumed.

Well, I will look for a LVDS to DVI/VGA converter. I have data sheets on them already lol. The nice thing with the converters is they have on/off and inverter with brightness control too 🙂 for around $40 that solves a lot of messing around.

BTW, I still have the perfectly working IDtech 20" from my G4 but I ripped the small ribbon cable from the side as I was putting back together 😟.

garrettpf Author

Level 1

14 points

Mar 3, 2009 7:08 PM in response to garrettpf

hey, can you send me the datasheet for your IDtech. I have one but it does not show the pin assignment. Maybe I can do some sort of crossref. with that and see if I can get this to work as is with out an add-on card.

I still think that the GTX280 should have the LVDS chip on it and it should be through DVI. I will have to send nVidia an e-mail and see if I can get a reply.

garrettpf Author

Level 1

14 points

Mar 3, 2009 7:55 PM in response to garrettpf

Let me explain my theory a little better. I put an LVDS display in place of a TMDS display. The same cable was used. Since the logic board contains a chip that does the switch, it works. So, if I can connect a DVI cable the same way the TMDS would connect, my GTX280 should as well know the switch. Since it works on the iMac would lead me to believe that the cable connections are the same whether it be TMDS or LVDS.

So, if you can get me a pinout of either the IDtech or the connector on the logic board I can then hook my LVDS display to a DVI and hopefully that will be all I need to do 🙂

I hope I explained that in a way that is understandable. If you can send me an e-mail at the address below I would appreciate it.

Thanks,

garrettpf Author

Level 1

14 points

Mar 3, 2009 10:16 PM in response to garrettpf

Forget my post about the IDtech datasheet. I looked at mine again and must not have went all the way to the bottom most pages, it has what I need to know (mostly anyway).

Check out the pic below. It is of the IDtech PCB on top of the LG PCB. pretty interesting and makes it even more interesting that the two monitors can be swapped out.

pic here

GavinD

Level 1

15 points

May 20, 2009 12:08 PM in response to MisterDNA

After stumbling on this conversation, I'm really hoping you guys can help with a question I have since I'm looking for similar information regarding inverter pinouts on a macbook -

Just before the plug on the logic board that leads to the inverter, the inductor that feeds the 12V signal into the inverter blew. Is there a way to tell what size that inductor was and, if not, is there a range of sizes that would serve the same function if I soldered it in to that spot (or connected it in-line in the inverter cable? My LCD backlight is obviously not working, but it does work when I bridge that gap with a screwdriver. And with that, what would the fate of my inverter/LCD backlight be if I were to just drop a dot of solder on the board to bridge the gap and forget the inductor?

Thanks for any insight you could offer!

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Need picture or pin-out of inverter cable from logic board 20" G4