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Lpc Diagnostics (V0.1)


barnito
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On 7/24/2020 at 2:28 AM, HDShadow said:

I've tested all of them now and apart from that one they're all correct.

What is annoying, for me, is that all my pins/soldering are showing continuity so why I can't get the Aladdin chip working correctly is a bit of a mystery.

Pin 5 is still showing only 0.15v so I'm going to redo that but otherwise I'm running out of ideas as to what is wrong.

I really think you need to post a picture of the solder work on the affected Xbox LPC

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.

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Hate mobile 'phones so likewise no camera that way either.

Ironically I have plenty of film based cameras around and, old but good quality close up gear too...........................problem is haven't bought film or taken a photo in 25 years and don't have a scanner to be able to convert it into digital form anyway.

I doubt that the pics would be much use in identifying the problem, it can really only be pin 5 and pin 1 anyway. They have to be redone and I'm going to take the pins out and clean the LPC contacts and test them before redoing the soldering.

However if the actual LPC voltage readings are problematic ie. LPC mount 5 doesn't show 3.3.v and I can't get any voltage reading from LPC mount 1 then I'm going to need some more advice. Can I, for instance, use a wire to connect pin 5 to one of the unused LPC 3.3v pin mounts ie. 15?  

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8 hours ago, HDShadow said:

Can I, for instance, use a wire to connect pin 5 to one of the unused LPC 3.3v pin mounts ie. 15?  

scrap that I was low on caffeine when I said yes 

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.

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8 hours ago, HDShadow said:

Hate mobile 'phones so likewise no camera that way either.

Ironically I have plenty of film based cameras around and, old but good quality close up gear too...........................problem is haven't bought film or taken a photo in 25 years and don't have a scanner to be able to convert it into digital form anyway.

I doubt that the pics would be much use in identifying the problem, it can really only be pin 5 and pin 1 anyway. They have to be redone and I'm going to take the pins out and clean the LPC contacts and test them before redoing the soldering.

However if the actual LPC voltage readings are problematic ie. LPC mount 5 doesn't show 3.3.v and I can't get any voltage reading from LPC mount 1 then I'm going to need some more advice. Can I, for instance, use a wire to connect pin 5 to one of the unused LPC 3.3v pin mounts ie. 15?  

Pin 1 is actually a 33MHz clock signal.  Your multimeter may not translate it into a voltage level of any kind as it is not one.

Pin 5 at 0.15Vdc ??? appears there may be a pull-up resistor missing/broken on the motherboard near the LPC Debug port.  Won't work with the LRESET# always LOW. The LPC bus is stuck in a reset mode.

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What does pin 5 test with the IDE connector disconnected as on all versions on boards I get 33 Ohm to the reset for the IDE device (pin 1).

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.

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I'll try to answer some of these question tomorrow.

I was wondering about that pin 1 voltage as I know it is clock signal. That would explain the variable voltage readings I was getting from the LPC on the other v1.1. But the fact is I'm getting nothing on this 'problem' v1.1 surely means there is a problem with it.

With pin 5 how would I identify the precise resistor if it is that? Nothing looks broken or bad on the the MB that I can see. If there is a faulty resistor it must be local because, as said, up until I decided to chip this Xbox it was working fine as a softmod. I've not knowingly damaged anything and I even checked after the first failure to get the chip to work that with the old HDD that it still booted as a softmod , and it did.   

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15 minutes ago, HDShadow said:

With pin 5 how would I identify the precise resistor if it is that? Nothing looks broken or bad on the the MB that I can see. If there is a faulty resistor it must be local because, as said, up until I decided to chip this Xbox it was working fine as a softmod. I've not knowingly damaged anything and I even checked after the first failure to get the chip to work that with the old HDD that it still booted as a softmod , and it did.

I've been trying to track down a pull-up resistor connected to pin 5, LRESET#, of the LPC Debug port but have not had much luck.  I haven't found one like I see connected to the LAD[0..3] lines.

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9 hours ago, SS_Dave said:

Pin 1 is approx 1.5 volt.

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.

 

When I tested it on the other v1.1 that is, roughly, what it reported once it had settled down. But it took a little time to actually do that.

There should be a measurable voltage on pin 1 that is for sure and I'm not getting anything on the problem v1.1.

What about the pin 5 question? Whether caused by a faulty resistor or not could it be connected to another 3.3v source ie. LPC pin contact 15?   

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From what has been reported, it seems that the MCPX doesn't output a the LPC clock (pin 1) on the LPC Debug port if pin 5 of it is LOW.  Something somewhere on the motherboard is keeping this RESET line pulled LOW instead of allowing it to go high after initial power on.

 

Is pin 1 of the IDE connector also at 0.15 Vdc?

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R7R5 one side tests 0 ohm to the 3.3 volt on the power connector

the other side tests 0 ohm to pin 5 of the LPC and 33 ohm to pin 1 of the IDE connector.

It's a big SMD 100 ohm resistor to damage.

 

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.
 

 

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Update: Q7R1's generating the stronger PCI_RST* signal to drive many other chips on the motherboard.  The MCPX can't drive them all without it.

Edit: There's must (may) be another transistor pack to generate the SDRAMs CKE (clock enable) line from the MCPX's active low output PCI_RST*.  I just haven't tracked it down yet.

PCI_RST* is held low after the console is powered on to reset all of the PCI attached devices.  Once Power_Good is received from the power supply to indicate that all voltages are present, the PCI_RST* line is released (goes HIGH) to allow the system to exit the RESET state.  There's also a similar RESET line (CPU_RST*) from the NV2A that's released after the PCI_RST* is released to allow the CPU to start working.  

Q7R1 is most likely an MBT3904DW1T1G dual NPN general-purpose transistor pack.  From the lableing on other transistors (Q id'd parts) on the motherboard which are MMBT3904s - general purpose NPN transistors.  There's also the MMBT3906 on a v1.6 motherboard - general purpose PNP transistor.

package labeling should read MA followed by the date code letter(s).

On-Semi datasheet: https://www.onsemi.com/pub/Collateral/MBT3904DW1T1-D.PDF

Update 2: The two vias where pin 4 would be in the LPC Debug port are the PCI_RST* signal, via closest to pin 2, from the MCPX chip and the buffered/strengthened Buffered_PCI_RST* output, the via closest to LPC Debug port pin 6,, from Q7R1's pin 6. 

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I hate tracking down traces on these motherboard images.  I need to print out some 2 or 4 x sized acetates of the top and bottom side of the motherboard images since my laptop monitor isn't very big to see a large enough region of the motherboard when blown up.

 

Line up the two acetates so I can see through from the top to bottom side of the motherboard.

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From my updated post a couple entries up, measure the voltage present on the tiny via closest to pin 2 of the LPC Debug port, is it 3.3Vdc?

You've already measured the level present on the other via or at least it should still read 0.15Vdc. There's a trace going from that second via to pin 5 of the LPC Debug port.

Edit: What voltage level do you read for the PSU connector's Power OK pin?  I believe it's the white wire.

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Managed to get some of the reading requested but not sure how to do the others from a practical point of view as they on the underside of the MB and appear to need the thing powered up. But the other info is as as follows:-

1). Pin 5 to pin 1 of the IDE connector : 33 Ohms.

2). Is that 0.15v too? No, it is reading 0v.

3). ICQR7 no obvious evidence of damage - looks cleans and in good condition.

4). R7R5: this one I couldn't work out how to test with power but I measured 100 Ohms on one side to pin 5 and 33 Ohms from the other side to pin 1 of the IDE connector.

5). Could get any reading under power from the two vias ("pin 4") but the contacts are so small I'm not confident of anything. The one nearest pin 2 has a trace to a larger contact pad which I tried to get a reading from but again - nothing.

6). PSU Power OK (White wire) reports as 3.3v

I think that is everything.

I'm beginning to think I'm flogging a dead horse here. If the LPC has a problem with the output from pin 1 and pin 5 there must be something wrong. I do not see how I could have damaged anything myself despite the chip apparently, partially, working at some point. I'm minded to remove the pin header entirely so I can measure the LPC voltages without any interference from my possibly dodgy soldering.

If the voltage to the pin 5 contact is still just 0.17v and I'm getting nothing from the pin contact 1 (LCLK)  then that must be evidence of a component failure or other problem.

If that is the case then I'll hopefully restore it to its previous softmodded state and think instead about TSOPing. I wanted to do another TSOP on a different version Xbox from the v1.4 I did six months ago and this Xbox was bought earmarked for either that or chipping. 

Problem is what to do with the chip - I have my original softmodded v1.0 I'm not keen on using due to its age but the only other alternatives are both v1.6 which means rebuildng the LPC. Whether my soldering skills are up to doing that is questionable.

   

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All moot now. Thanks for all the help, info and suggestions.

Decided to try to revert it back to softmod with the idea of TSOPing it instead and whatever the problems were caused by turned out to be more serious than just dodgy LPC soldering.

Removed the D0 ground but left the pin-header in place, put the Xbox back together again, tested it with the softmodded  HDD and it was still fragging. Took it apart again and removed the pin-header (messy but did not do too much damage) but pin-header itself a write off. Checked everything, traces, solder splashes etc, nothing obvious so reassembled it and...............................................fragging.

I checked pin 5, the one only reporting 0.17v - same and pin 1 still nothing.

Obviously a serious problem somewhere - maybe caused by something I did but the fact is the chip did appear to be working initially after reflowing the solder early on but after shutdown the next day on restart the Xbox started fragging again and has done so ever since. I suspect component failure.

Annoying waste of three weeks effort trying to get it work but I bought that Xbox knowing it might get crocked so its no big problem. The parts should ensure my other v1.1 lives for longer.

I realised I do have another Xbox suitable for chipping as it was bought with as a non-working softmod and so no eeprom available. A v1.2 or v1.3 but it has some bad caps that need replacing first and I now need to get a new pin-header for the LPC too.

The LPC has been tested and its all good. Using contact 2 or 12 as ground unlike the v1.1 Xbox contact 5 is definitely reporting 3.3v and contact 1 around 1.5v as they're supposed too.   

 

 

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  • 5 months later...

The original numbering from baldbouncer, and incorrect placement of the checkpoint for Pin 7 was driving me crazy when I checked my own board, so I tossed this together. 

This leverages work from baldbouncer, livefast9986, a board photo from bunnie, and a graphic posted by HDShadow.

Hopefully this is a helpful companion to the original guide barnito put together above. I've kept the source PSD in case anyone notices anything I should be correcting.

On a side note, if anyone can help me track down the checkpoints for pins 13-16, I'd be happy to update this.

xbox LPC.png

Edited by Supa
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11 hours ago, Supa said:

On a side note, if anyone can help me track down the checkpoints for pins 13-16, I'd be happy to update this.

Pin 15 is the same as Pin 9 (3.3 volt)

Pin 14 0f the LPC is Pin 5 (SDA) of the EEprom

Pin 13 of the LPC is Pin 6 (SCL) of the EEprom

 

Cheers

SS Dave


Soft modding is like masturbating, It gets the job done but it's nothing like the real thing.

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