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Micron Xceed Grayscale Adapter recap
Posted by: JDW on 2018-11-14 01:24:37
I have a functional Xceed grayscale adapter that looks exactly like joethezombie's photo.  There are 4 electrolytic radial capacitors that are old enough to warrant replacing, especially so since they are only temperature rated up to 85°C:

C4: 10uF, 16V

C5: 47uF, 10V

C8: 100uF, 16V

C9: 100uF, 63V

There are numerous 10,000-hour 105°C rated replacements available on Mouser.  Have any of you grayscale adapter owners performed a recap on your adapter?  And more specifically, do any of you understand the function of the adapter well enough to know if replacement caps with significantly lower ESR (than the stock caps) would actually create problems?

Thanks.
Posted by: JDW on 2018-11-18 18:29:42
No replies yet.  I know I am not the only member of this forum who has an Xceed Grayscale setup on their SE/30, but I guess I need to prod you folks a bit more...

Here's a Mouser list of all the 10,000-hour radial 100uF 63V Aluminum Electrolytic caps (C9 replacement candidates), and note that one of them has a low ESR of 170m-ohm.  If that ESR is not considered "too low" for the board design, then it's obviously the best replacement cap to get.  And that is why I posted here originally, to see if any of you would be able to at least intelligently speculate on that.

Mouser also has an Organic Polymer 100uF 63V version with an even lower 32m-ohm ESR (@100kHz).  It's rated at 2000 hours but at 125°C, which means the life in hours is far longer than 10,000 hours at 105°C.  The main caveat (assuming ESR isn't one) is that it's more expensive.

So is there a lower limit to ESR for the grayscale board circuit to be stable in terms of the radial electrolytic capacitors used?  That's my primary question.

For your reference, a schematic of the grayscale "sweep board" is shown on "Sheet 4 of 5" (FIG. 4) in the Micron patent.  And a text description of the FIG.4 schematic is given in columns 4 & 5 of that same patent.
Posted by: Bolle on 2018-11-18 22:51:02
I can check what kind of caps I used for my replica board if that’s any help.

I did not pay close attention when ordering and I think I just went with low ESR as usual.
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