Power Issue, Ram Install

[wikati 91]

Curious question

in a furious rush i harvested 2 ram chips off a working board, now id like to re-install these and get it working again because as far as i can remember this unit worked just fine prior.

the replacement ram came from a friend with a broken console. one chip had 2 twisted pins which laid down pretty nice with gentle persuasion. 

now that they are installed (2 on the bottom) the unit will not power on?

power button does nothing, any ideas how ram affects the power process?

could this be a separate issue? 

very interested to hear thoughts/theories. 

the extent of my troubleshooting was testing a working consoles psu on this board which yielded identical results (power button does nothing, i can 'hear' the psu working there is a subtle discharge sound).

i have 1 more chip to try in place of the twisted one. 

there are no bridges on the install and contact is made on each pad as far as continuity is concerned.

[Frank D'Agostino 40]

When doing a ram upgrade aren't you supposed to install for chips? Two on top two on bottom?

[wikati 91]

3 minutes ago, Frank D'Agostino said:

When doing a ram upgrade aren't you supposed to install for chips? Two on top two on bottom?

correct.
The board in question was robbed of half its ram during an upgrade i did on a different one (it was something i regret but always thought i could just re-install and have this working again)

so now that i have the parts im attempting to re-install the 2 missing chips to bring it back to stock. 
so, currently this board is missing 2 chips. and i have just installed them finding out i cant get power.
Frank i've seen you change capacitors in youtube videos etc... i wonder what you know about what affects the xbox powering on, its strange, this one just does nothing when i hit the power button. again, its got 64mb ram installed (not an upgrade)

[KaosEngineer 428]

Had the clock cap leaked on this console? 

There could be damaged traces. The 4 very thin traces along the front edge on the solder side of the motherboard. (Please login or register to see this link. ) Two of these traces carry power and eject button control signals from the front panel, I really need to take the time to label which is which, to the System Management Processor (PIC processor) at location U7B2.  The PIC controls the state of the power supply: either standby or full on.

Check them for tiny breaks (trace corrosion) in grid 7V on the solder side along the front edge of the motherboard.   Even better, test continuity as shown Please login or register to see this link. .

Edited March 7, 2018 by KaosEngineer

[wikati 91]

35 minutes ago, KaosEngineer said:

Had the clock cap leaked on this console? 

There could be damaged traces. The 4 very thin traces along the front edge on the solder side of the motherboard. (Please login or register to see this link. ) Two of these traces carry power and eject button control signals from the front panel, I really need to take the time to label which is which, to the System Management Processor (PIC processor) at location U7B2.  The PIC controls the state of the power supply: either standby or full on.

Check them for tiny breaks (trace corrosion) in grid 7V on the solder side along the front edge of the motherboard.   Even better, test continuity as shown Please login or register to see this link. .

thank you KE
i found this at TIZ 
Please login or register to see this link.

I find it very strange this just all of a sudden happened.... i swear this was a functional unit only a few short weeks ago... although i JUST removed the clock cap. i suppose it could be the case
KE, any idea if bad ram can cause no power?

[KaosEngineer 428]

1 hour ago, wikati said:

thank you KE
i found this at TIZ 
Please login or register to see this link.

I find it very strange this just all of a sudden happened.... i swear this was a functional unit only a few short weeks ago... although i JUST removed the clock cap. i suppose it could be the case
KE, any idea if bad ram can cause no power?

If there's a short somewhere, the power supply protection circuitry could be preventing it from turning on. Ass-u-me-ing the Xbox power supply has over-current protection built-in.

Removing the board from the case may have been the last straw that broke the trace carrying the power control signal to the SMC (System Management Controller - PIC processor). 

Check for continuity between the two violet (power) end-points then the two cyan (eject) end-points indicated on the P/E Continuity Trace diagram for your version of Xbox.

Edited March 7, 2018 by KaosEngineer

[wikati 91]

oh man, you are awesome. i cant wait to try this out.

[wikati 91]

1 hour ago, KaosEngineer said:

If there's a short somewhere, the power supply protection circuitry could be preventing it from turning on. Ass-u-me-ing the Xbox power supply has over-current protection built-in.

Removing the board from the case may have been the last straw that broke the trace carrying the power control signal to the SMC (System Management Controller - PIC processor). 

Check for continuity between the two violet (power) end-points then the two cyan (eject) end-points indicated on the P/E Continuity Trace diagram for your version of Xbox.

KE, Thank you so much. looking forward to giving this a go.

[wikati 91]

so.
it was my soldering (of course it was)
found the problem cleaned it up (its just too late at night once i get to this... not enough patience)

anyways, i've got power. there must be some kind of short protection built in... i cant confirm that. do not assume there is. anyone reading. triple check, there are pins that test as bridged and arent. i use the stock chips as reference when testing continuity for bridged pins. i also foolishly work without a magnifying glass (strained eyes and a headache)