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2 MHz on MMU clock input would be almost impossible. You are likely measuring the wrong pin.satjanand wrote: 22 Feb 2023 14:34 MMU P5 reads 2 MHz while 16 MHz is expected.
...
I could measure no direct continuity between MMU P5 and Shifter P39, but neither could I in a working ST.
Yes, that's unfortunately the way the schematic goes, and quite normal. You'll need to get a magnifying glass and manually track the traces on the board.satjanand wrote: 22 Feb 2023 14:34Thanks, I've corrected my post.rubber_jonnie wrote: 22 Feb 2023 14:07 That's an inductor not a capacitor, though I'm not sure why it is there, but looks like probably a factory bodge. It looks normal, see the picture of another board here: ST Mainboard
At least 2 mainboards in this section of the forum have the same bodge as yours. Later revisions may not have it, or have it integrated into the PCB.
When I look at the schematics, I see P39 go into an arrow shape saying 16MHz, but no traces after that. I see the same kind of arrow shape saying 16 MHz near MMU P5, connecting to it. But I can't see how it routes in between, what components it passes. How do I find that?rubber_jonnie wrote: 22 Feb 2023 14:07 You can do continuity tests without worrying about damage. You need to go point to point and see if there is anything odd going on.
I could measure no direct continuity between MMU P5 and Shifter P39, but neither could I in a working ST.
ijor wrote: 22 Feb 2023 14:432 MHz on MMU clock input would be almost impossible. You are likely measuring the wrong pin.satjanand wrote: 22 Feb 2023 14:34 MMU P5 reads 2 MHz while 16 MHz is expected.
...
I could measure no direct continuity between MMU P5 and Shifter P39, but neither could I in a working ST.
Oh really? That simple? Let's get some magnifying glasses then!rubber_jonnie wrote: 22 Feb 2023 15:25
Yes, that's unfortunately the way the schematic goes, and quite normal. You'll need to get a magnifying glass and manually track the traces on the board.
Oh dear. I read it as "6", didn't notice the "10" there.rubber_jonnie wrote: 22 Feb 2023 17:57satjanand wrote: 22 Feb 2023 17:46
Well, this is the pin I'm measuring.
IMG_20230222_184510_edit_40200617832927.jpg
You're on pin 8 there, not 5. Pin 9 and 10 are marked on the PCB, the corner of the IC .
We all have to learn sometime, I really wouldn't worry about it if you get something from the process.satjanand wrote: 23 Feb 2023 06:36 Would be incomplete without expressing how much of a clown this makes me feel.
But thankful for all the help we can get here.
Will refrain my next posts to the Noob channel :mrgreen: