Which Falcon reset caps to replace with which

[satjanand]

Hi there,

I figured this would be an easy question to solve, but I've been having a hard time finding the right direction.

My Falcon rev D/C board has an issue with its reset circuit. After installing Exxos PSU, the symptom of not booting after power up untill reset is pressed, shows up. So there are reset caps that need replacing, and their values should be swapped - is what I understand from this forum.

But I'm seeing some different configurations and ambiguous information, which makes me hesitant in which direction to go. So I'm hoping a new post can help me out.

- I have a rev D/C motherboard (CA401332-003)
- C1 is 22uF / 16V
- C3 is on the backside of the motherboard, and I couldn't make out its value
- C7 is 1uF / 50V

So now I would like to know: which cap with which values replaces C1, C7 (and C3 if at all)?

Here are some visuals.

I have added the rev G schematic, because it matches my board for C1 and C7 (not sure about C3).

schematic.JPG (46.57 KiB) Viewed 1398 times

Part number and rev.

rev board.jpg (175.2 KiB) Viewed 1398 times

The reset circuit.

reset circuit.jpg (304 KiB) Viewed 1398 times

C1: 22uF/16V.

C1.jpg (168.78 KiB) Viewed 1398 times

C3: unknown.

C3.jpg (130.34 KiB) Viewed 1398 times

C7: 1uF/50V.

C7.jpg (270.38 KiB) Viewed 1398 times

Thanks in advance!

[exxos]

C1,C7 need replacing. Changing of the same value may work but you may have to update them to the values below.

I don't think I have had chance to look at the Falcon specifically yet, only the STE. circuit is the same but obviously the part numbers are different.

viewtopic.php?f=17&t=2175

I would suggest going with the same values or doubling them, which would probably be better.

[satjanand]

C1,C7 need replacing. Changing of the same value may work but you may have to update them to the values below.

I don't think I have had chance to look at the Falcon specifically yet, only the STE. circuit is the same but obviously the part numbers are different.

viewtopic.php?f=17&t=2175

I would suggest going with the same values or doubling them, which would probably be better.

Yes, I've read that topic before.

Thank you for the advice, will go forward replacing C1 and C7. I checked my stash and found a Panasonic FC 2,2 uF / 50V and a Panasonic FR 47 uF / 25V. Would that do the trick?

[exxos]

Thank you for the advice, will go forward replacing C1 and C7. I checked my stash and found a Panasonic FC 2,2 uF / 50V and a Panasonic FR 47 uF / 25V. Would that do the trick?

Yeah should do.

Let us know how you get on.

[satjanand]

Let us know how you get on.

Well the good news is that the Falcon still boots without explosions. But I still need to reset after power up.

C1 now has 47uF / 25V instead of the old 22uF / 16V
C7 now has 2,2uF / 50V instead of the old 1uF / 50V

Although I am alright with resetting to boot, I still wonder what could be the cause.

[exxos]

Well the good news is that the Falcon still boots without explosions. But I still need to reset after power up.

I would suggest you try a higher value on C7 like 22uF-47uF and see if that solves the problem.

[satjanand]

Well the good news is that the Falcon still boots without explosions. But I still need to reset after power up.

I would suggest you try a higher value on C7 like 22uF-47uF and see if that solves the problem.

OK, will do and post back.

[satjanand]

Well the good news is that the Falcon still boots without explosions. But I still need to reset after power up.

I would suggest you try a higher value on C7 like 22uF-47uF and see if that solves the problem.

I have a 22uF/50V that I can use.

[exxos]

I have a 22uF/50V that I can use.

Should be ok. I would just tack it over the top of the other one first before actually changing it again.

On the STE what it looks like I used 47uF for proper boot up. Don't know why the Falcon uses such a lower value in the first place.

[satjanand]

Well the good news is that the Falcon still boots without explosions. But I still need to reset after power up.

I would suggest you try a higher value on C7 like 22uF-47uF and see if that solves the problem.

Yes that worked. Genius.

I now have:

C1: 47uF/25V
C7: 22uF/50V
And one awesome Exxos PSU.

Thank you.