Xbox 1537 - Only powers on USB

[marcian0]

Mods: Feel free to delete this ongoing rambling if you prefer. Case is closed.

Hi folks,
I have read through a couple of threads but didn?t really find my direction.
I have a Controller here which worked quite well besides double clicks on dpad. I switched the sticker and contacts which didn?t really help. So I went back and forth until I thought it was ok?ish.
I also switched the four potentiometers while I was at it.
For the whole time the controller worked well.

When I put everything together finally, it wouldn?t turn on any more.
I changed U1, U2 and U3. The controller came back to life.
But it only works on USB. It doesn?t mind the batteries being in the controller.

I don?t really know where to go from there?
I do have a second controller with similar symptoms, where I exchanged one of the diodes, but it still only works wired.
Don?t know how I got so lucky to have two of these Controllers.

I can measure stuff but I don?t understand how the circuit works (even though it is probably pretty basic).

Edit: Sorry. I am a pleb. I seem to have managed to sheer off Q8 including all pads on dismantling and rebuilding. Won?t work without this. I will try to find replacement and fit it with jumper wires. (On the second controller Q8 is still in place).

Edit2: Have now replaced Q8. The controller turns on also on Batteries now, but it doesn?t sync then (after being plugged with cable). Sync button works, but it doesn?t sync. Also it seems like something is always down, probably left analogue stick. When I use the controller wired it always scrolls down on  menu?

Edit3: It is the top board. The mcu board works perfectly with another top board (for which I dismantled my nice working controller.
The voltage on C23 is well below 3Volts, while it is 3.3 on the working one. Don?t know whether the MP3414 is broken again or whether something is dragging the voltage down.

Edit4: So. After another hunting session. I tried another set of IACMs. Then I also had to change R35 because it was 200k instead of 180k. Now it works again on USB and Batteries.
Need to buy some resistors now, perhaps I can also fix the other controller that has been robbed for the resistor and the transistor.

[RDC]

That R35 is a precision Resistor, make sure you get a 1% or better tolerance value one when replacing it. Not that a 5% one wouldn't still work, but R35 and R34 make up the feedback voltage divider that sets the output voltage for U3 there.

[marcian0]

Thanks for the hint. The order is set for 1% type resistors. Still on the way though. Seems to take weeks. Hope to get back at this soon!

[marcian0]

So, today the resistor books arrived.
First I installed just one resistor but the result was 3.5 volt.

Then I checked the schematics in the 1537.
I am not getting my head around it. The U3 is listed with R34 at 340k and R35 at 180K. 340/180 is 1.89. according to the MP3414 datasheet we add one to this and multiply by 1.21 to get the target voltage.. This would give us 3.5 Volts.
But the line is listed as 3.3Volts. To get the 3.3V the R35 could be e.g. 200k.

As the selection I have is only a limited amount of values I know chose 510k and 300k as my feedback pair.

Any thoughts?

P.S.: One Controller I have had a 200k resistor value. I had thought it was starting to fail, but failing resistors probably increase to largely higher resistance, and not the little deviation of 10% between 180 and 200.

[RDC]

I just pulled an R35 from a board here and it measures 190k with a couple of different meters. Plugging that into the MP3414 equation gives 3.37v. I doubt it would hurt anything running it at the 3.5v either, might just run a shade warmer is all. That 180k was probably a typo from way back when it was first made that should have been 190k that I never caught.

[marcian0]

Thanks a lot. For the latest check and for sharing your information in general.

Your schematics helped me a lot to get my controllers working again. (My rambling in the first post is caused by me not usually reading this kind of stuff and taking a lot of time to understand it. )

We have saved the world from two controllers in the e waste.

[RDC]

Welcome.