FRAG Red Green LED (Xbox Original)
The hardest issue to fix on the Xbox original I have found is the FRAG.
The Flashing Red And Green error is generated by the SMC (the PIC16LC63A-04/SO), when it does not receive the watchdog timer response from the NVIDA MCPX, or the encoded data signature between the EEPROM and MCPX do not match, or various other issues on the SM Bus.
This means if you are swapping out the NVIDIA MCPX or EEPROM and SMC PIC chip between boards, you must swap them in sets as they are encoded together.
The SMC isn't present on the v1.6 models. That model uses a custom Xyclops chip above the LPC port to replace the SMC.
The FRAG is very specifically:
- Power on with green light and fan spin for 1 second
- Power off
- Power on with green light and fan spin for 1 second
- Power Off
- Power on full fan spin and flashing red/green LED where red and green are on for equal amounts of time (not red staying on longer for example)
If you also have a temperature sensor issue then instead of flashing between green and red, it would be flashing orange but with the power-on-off twice.
Here are the following things I have confirmed can cause it (not guessing or might, I've actually found and fixed these exact issues).
If the SMC, EEPROM and MCPX are not paired (from the same motherboard) you will get FRAG.
I think perhaps SMC is not required to be paired, but the EEPROM and MCPX are for sure.
Also to confirm is if using a mod chip is this EEPROM pairing bypassed (surely it has to be?)
If any single RAM chip, or any of the traces between them and the GPU (smaller chip of the two under heat sinks) are bad, it will cause this issue.
A bad GPU can obviously cause it too.
It is known that the SMC needs to talk to the MCPX and receive a paired key as well as a watchdog signal otherwise you get FRAG. So the traces between them must be good.
This is a v1.6 board that worked fully, then after an IPA clean it was FRAG.
In this photo this is before reflowing them. The console would sometimes boot, sometimes FRAG. Placing my finger very lightly over the circles areas made it boot ALMOST every time.
My suspicion is currently a broken trace or failing component. Usually when touching something makes it work and adding IPA prevents it (or vice-versa) it's a poor trace signal.
With the lack of any schematics this is very hard to narrow down but I will update this once I figure more out.
Until then we know this area is crucial for initial boot and valid response between the SMC and MCPX.
Interestingly I could also get it to boot if applying a slight bend in this exact area.
This further supports that it is a broken trace on the left that runs between the SMC and MCPX.
Even after a full reflow of all the chips in the circuit, the FRAG was the same, only going if I touched in that area gently. Then once I did that, I could remove my finger, and it would remain fixed for a long time (and instantly FRAG if I sprayed with IPA again).
I guess the recommendation is to reflow all components around the MCPX including resistor arrays, resistors, capacitors, and small ICs just for good measure, including the EEPROM above it, and if your problem persists see if bending the board near this area helps.
Until I find the exact broken trace or cause though just be aware of this issue and I am not sure how common it is yet. Although I have had multiple (4+) in one day that from just cleaning along can cause FRAG.
So, there are definitely some common causes of broken traces, hopefully in similar areas or causes.
The problem with the Xbox Original is it is a multi-layer board, so traces run inside the PCB and are not easily testable or repairable.
Add to that the MPCX is a BGA component running jumper wires is generally harder too. A broken trace causing FRAG if not in a visible area may well be very hard to repair.
Most often bad traces will be visibly damaged like a darker green.
If you see no trace damage the much more likely suspect is then a via that is bad. These can hairline fracture at the trace connection point with zero-visible damage, or the through-hole plating can be fractured internally.
It is rare to see a visibly damaged via so they are hard to narrow down. Try touching specific vias with your finger to see if the console then boots.
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