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[Dallas186]

QUOTE(thedominor @ Oct 25 2005, 09:04 PM)

I'm really glad to hear progress has been made, thanks Dallas and Pimple especially for doing so much testing.  I think I have some 3904s in my 'kit,' so I might bust out my old mobo and see if this works.  It sounds like maybe I should get a small tip though, and I'm glad to hear an explanation of a soldering iron that makes sense; in my own words, hotter irons melt that shit faster = less waiting and uncertainty.  Dallas, do you think you could do some ms paint over that pic you posted with the two Ts, to show which is EBC?  I know which was the board is facing because of the traces.  That would be appreciated so i don't have to figure it out myself 

Hi,

sure, in fact i'll work out a better way of soldering these on that will be a lot easier to install. the obvious way that springs to mind is to make use of the 'ground' pad that's at the side of the LPC, so doing away with soldering to pin 1&4 of the place where the MA used to reside. that only leaves 3 other points to solder to as pins 2&3 are tied anyway. piece of cake  

i'll try to do this tonight for you, wife permitting of course..lol

I'm reliably informed by RS that the 50 x MA IC's (dual 2N 3904's) that i ordered are arriving in the UK today from the US (what a laugh eh??) so should get these tomorrow. PimpleX ~ i'll mail you a few hopefully tomorrow. ok?

now if i could just figure out how to flash this Aladdin XT Pro then i would be happy....hehehe

Rich

[ferrari_rulz_02]

QUOTE(Dallas186 @ Nov 1 2005, 01:37 AM)

i'll try to do this tonight for you, wife permitting of course..lol

allways the limiting factor.  

well if you get the time, let us know how they go.

cheers
 

[fr_dr]

Hi all,
I just want to let you all know that i found someone that sell these dual smt transistor (3904 NPN) on ebay. The name is bob-ke6f (http://search.ebay.ca/_W0QQsassZbob-ke6fQQhtZ-1) and the good news is that he sell pak of 100 for only 5-6 $. I won one auction and there's still another one ending in 2 days, so be fast    but there will probably be more in the future.

I'll try this fix as soon as i receive these transistor and ill let you know what are the results.

[PimpleX]

I received my trannies off Dallas (many thanks for those Dallas!)

Results:

Now I have a smaller tip and some desolder wick things are a whole lot easier to do.....

Fitting the trannie corrects the 0.196v (0.2v) problem on LPC pin 5 on both my boards (v1.0 and v1.1), they now show 3.3v as normal ......BUT they both boot 3 times then FRAG and have 0.0V on the MPCX. The LPC is all good, but both still frag. During the 3 boot attempts the volts on the MCPX do hit 3.3v, then are 0.0v when it's running and flashing red and green though.  

Possible scenarios:

1.The dual trannie does two jobs, one for the LPC pin 5 and one for the MPCX and I fried the MCPX half of the trannie on install...but that's doubtful on two boards and careful and neat install.

2.My MCPXs have died

3.On my boards there's another fault besides the dual trannie killing power to the MCPX.

I have double checked my soldering.

Cheers,

PimpleX

[PimpleX]

Just to correct the above post: (edit time ran out)

I received my trannies off Dallas (many thanks for those Dallas!)

Results:

Now I have a smaller tip and some desolder wick things are a whole lot easier to do.....

Fitting the trannie corrects the 0.196v (0.2v) problem on LPC pin 5 on both my boards (v1.0 and v1.1), they now show 3.3v as normal ......BUT they both boot 3 times then FRAG and have 0.0V on the MPCX.

Now I've got hooked up on this 0.0V thing on the MCPX and it turns out to irrelavent as all FRAGing board do that!!! I just tested it by earthing D0 on a working board and it does exactly the same thing, funny I'm sure I tried this before and got 3.3V ...anyway I now think 0.0v on the MCPX doesn't matter as long as it hits 3.3v during the 3 boot attempts then the MCPX part of the circuit looks good. (that's my now theory anyway!!)

So I'm back to fragging board with good LPC volts,....I have double checked my soldering.

Suggestions?

Cheers,

PimpleX

[ferrari_rulz_02]

QUOTE(PimpleX @ Nov 3 2005, 01:15 AM)

So I'm back to fragging board with good LPC volts,....I have double checked my soldering.

Suggestions?

this may be a bit dangerous, but the MCPX need 3.3v all the time, right?

then solder a wire from a 3.3v source on the mobo across.

but before you try that, back track thge trace that should have teh 3.3v to teh MCPX on it, and see if you can find another dud component

[Dallas186]

np mate, glad that you received them so quickly.

ok, the original MA was clearly duff as at least now you have 3.3v on pin 5 which has gotta be a move in the right direction.

i'm not convinced that this particular component is responsible for powering the MCPX chip anyway, primarily because at 200ma (MAX forward I) it wouldn't have the guts to drive it.

IMHO you need to be looking at something more like the MTD3302 NFET transistor but i really am NOT an expert on Xbox hardware, (i'm learning so please bear with me) so i really could be talking b0llocks.

I assume that you have another working board from which to take some comparative readings, if not i have a breadboarded v1 on the bench at the moment, let me know if you need any data from various points on the board.

I'm sorry that replacing this dual tranny didn't solve your problem, but just to confirm that it IS the right IC for the job i soldered one in place of those 2 BC337's on a V1.4 board (from earlier in the thread) and voila! it worked perfectly, though obviously this board had no other serious problems.

Rich

[PimpleX]

Right, just thought I'd share this little enlightenment with you. ...this may at 1st appear to be off the FRAO topic, but bare with me it isn't...

I got a 1.3 mobo today and replaced some missing resistors and away she went...so i flashed the TSOP and unlocked the hard disk and was 1/2 way thru FTPing the hard disk to my standard Evox setup and then it froze and the FTP failed.

On reboot and it boots 3 times and FRAGs (yes flashing RED and GREEN)

I am gutted I can tell you, WTF??? I measure the LPC volts and they several are off, I didn't write them down, but Pin 1 and pin 5 were defo miles off

So I take the last dual transistor I had left from Dallas186 and decided to try that....

Well it worked, volts are normal and it's working fine again.

Soooo, what does this mean I hear you ask?

Well, I'd say it rules out the Q7R1 dual transistor as being the SOLE cause of FRAO motherboards, as my boards' Q7R1 had clearly failed and it was FRAGing. replacing the Q7R1 trannie fixed it.

****************************************************************
On a secondary note: I've also confirmed 0.0V on the MCPX on FRAGing boards, so that measurement is now totally irelavent and needs to be ignored as misinformation (started by me LOL) when looking for FRAO board solutions. So drop the 0.0v on MCPX now please, I have.
****************************************************************

Cheers,

PimpleX

[ferrari_rulz_02]

so basically what were looking for is the underlying problem that is causing this dual trannie to die.

well it could really be one of two things:
 
 a) - too much current being drawn through it

  - the voltage is too high (caused by another failing component elsewhere)

does anyone agree with that?

[Dallas186]

ummmm, i need to think about this a little more then.

bad news. i killed my only working version 1 mobo yesterday trying to take voltage readings off of the SC1186CSW 24pin programmable DC/DC voltage regulator (the one on the underside of the board). completely my fault, i got as far as pin 12 when the probe slipped of the leg and shorted pins 12 and 13. a tiny puff of smoke and that was that. what was previously 6.xx volts out pin 12 became 0 and the board fragged... AAGGGGHHH!!

seems this IC is now obsolete just to add insult to injury so can't even procure a replacement. a board for the parts bin unless i can scrounge this particular IC from another board..any volunteers to sell me this IC??? lol

Rich

[ferrari_rulz_02]

bump for a thread in need of more exposure

[edbtz123]

Has anyone tried to bypass the NPN transistor, by instead of replacing it, connect the emitter to the collector?  I think this will fix the problem, as long as there is not anything else wrong.  Read on before attempting this.

I think the transistor is used as a fuse (a 200mA fuse), to protect the circuitry on the board.  When people start adding a bunch of things (Modchops), it increases the current needed making this fuse more suceptible to blowing.  Another reason this fuse may blow is that people accidently cause a short when doing some work on the board (i think this is what I did when installing some RAM).  As for the unmoded xbox's with blown transistors, this can happen over time just like it can for a fuse.

To verify this Follow the base (aka gate)  lines of the transistor and see if they are always wired to an on logic (i think it would be 0 volts, or a low voltage for this transistor).

If this is the problem I would recomend replacing the transistor with a transistor rated at a higher current (say 300 mA instead of 200 mA) especially if you have added components to your board (like a modchip or extra RAM).

For people who replace the transistors and fixed a FRAO and is now FRAG, I bet you did something to the board (maybe u made a short) which then blew the transistor, and then when you replaced the transistor the initial problem (possibly a short) is still  there.

I am going to probe my mobo a bit and check to see if the base is hardwired to a certain logic level.

-Mike

[ferrari_rulz_02]

edbtz123, you might be right.

this would be a good one for people with frao'ing board to try. just make sure that you make lots of multimeter mesurments before you do this.

i like the changing it to a 300ma rated tranny, its probably the best idea

[grifface]

i have read thru quit a bit of this thread.. can somebody explain to me the difference between FRAG and FRAO .. My xbox jus started this stuff like 2 days ago when i put the lid on and hooked up the usb ports on the front of the control panel  i unhooked that wire and thru it away (oops) and still have the lid off, i took the power unit out and looked it over , but found nothing. i have a v1.6 MB and my light flashes red and green.. can some1 jus point me in the right direction ?

This post has been edited by grifface: Nov 22 2005, 04:56 PM

[PimpleX]

QUOTE(edbtz123 @ Nov 21 2005, 05:47 PM)

Has anyone tried to bypass the NPN transistor, by instead of replacing it, connect the emitter to the collector?  I think this will fix the problem, as long as there is not anything else wrong.  Read on before attempting this.

I think the transistor is used as a fuse (a 200mA fuse), to protect the circuitry on the board.  When people start adding a bunch of things (Modchops), it increases the current needed making this fuse more suceptible to blowing.  Another reason this fuse may blow is that people accidently cause a short when doing some work on the board (i think this is what I did when installing some RAM).  As for the unmoded xbox's with blown transistors, this can happen over time just like it can for a fuse.

To verify this Follow the base (aka gate)  lines of the transistor and see if they are always wired to an on logic (i think it would be 0 volts, or a low voltage for this transistor).

If this is the problem I would recomend replacing the transistor with a transistor rated at a higher current (say 300 mA instead of 200 mA) especially if you have added components to your board (like a modchip or extra RAM).

For people who replace the transistors and fixed a FRAO and is now FRAG, I bet you did something to the board (maybe u made a short) which then blew the transistor, and then when you replaced the transistor the initial problem (possibly a short) is still  there.

I am going to probe my mobo a bit and check to see if the base is hardwired to a certain logic level.

-Mike

I'll try it as long as you tell me which pins do what again LOL...I have many mobos now as I bought a load of faulty ones off Ebay and have found at least 6 v1.0 and v1.1s among them with classic FRAO pin 1 (0.0v)and pin 5 (<0.2v) voltages showing (despite they ALL FRAG non are FRAO!!) so look good candidates for the q7r1 dual tansistor.

This is how it is on the XBOX which pins do I join? (red line is those pins joined on the XBOX already, Pin 1 and 4 are on Ground (that's Earth for us UK peeps) :

(IMG:http://www.meltdown.fsnet.co.uk/pics/XBOX/q7r1pins.jpg)

Cheers,

PimpleX

This post has been edited by PimpleX: Nov 22 2005, 06:49 PM