MK3 AGA question

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Don't Panic. Please wash hands.
  • It appears a part may have fallen off of my MK3. Not sure how or when. I'm capable of putting it back on (and probably voiding my warranty). But, I need to know the value.

    I'm assuming it's a capacitor, but it's not really marked. It's on the bottom nere the words "Indivision AGA MK3". There you'll see a C51 with a capacitor above it. The part that is missing is above that. I'm assuming it was also a capacitor based on other images I've seen on the internet. But I don't know what part that would be, I don't see anything in the silkscreen that refers to that part. Around it is L11, L13, L12, R19 and C51. I'm looking for the part on top of what I believe is C51. The part towards the edge of the card above C51.

    If I know the value, I could easily replace it myself. But I just need to know what value. It appears it's a capacitor, size 0805. But what is the value?


    Thanks.

  • The part designator is C55 and I had to remove the silkscreen print because it's just so crowded in that area :-)


    It's a 0805-sized 10µF capacitor, 16V rating. The unit will work without it, as the 1.8V regulator has it's own 10µF cap, and the main goal of L13 is to filter high frequencies going back into the analogue 1.8V supply, which is going through L12, filtered by C51. Naturally, 10µF won't filter high frequencies - the 0201/100nF/10V caps are taking care of that.


    It's on the digital side "for good measure", and because it's in the application circuit of the encoder chip. In other words: It's safe to operate Indivision without it, but should be put back if you have the chance.


    Please also mention the warranty ID of your unit, so I can check if this was missed in QC, or it happened somewhere in transit. We have high-resolution pictures of each unit (both sides).

  • What identifies the warranty ID? I see a "WARRANTY" sticker on the same side that just says &T&0/ but I checked online and other pictures seem to have the same thing. When I scan the QR code it actually says "#p&T&0/"

    The QR on the other side scans as 20239028_20190510_00170_PD2320

  • When I scan the QR code it actually says "#p&T&0/"

    That's the warranty ID: The "#p" is an internal prefix, and "&T&0/" is the ID. More characters of the alphabet allow for a shorter printed ID, yet having a larger number space :-) The other code is from the assembly company - they also have single-unit tracking for possible warranty claims.


    Checking the QC picture, it shows that we did not miss anything in QC: The cap was on at the time the picture was taken (August 10th, 2020, 14:23). Since this is a very early card, probably ordered in the pre-order phase or shortly after release, it may be possible that the CIA adapter was pushed into the bubble foil bag as well, so chances are that the adapter pushed against the cap. We did make sure that all employees are re-instructed not to put the CIA adapter into the bag, so this won't happen again. So at this point, there's nothing to change on our side, but I'm happy to make a note in the database that you've soldered on the cap, and warranty won't be harmed by that (I understand that shipping it from UK is way too much of a hassle).

  • I actually bought it second hand from eBay. So I'm guessing I have no warranty. I am in the US, so shipping would still be a lot.


    I'm still having lots of trouble with this card, and about to go back on eBay and sell it for a loss. I was hoping it was the capacitor so I ended up keeping it, but that didn't fix the issue at all. I did solder a small 16v 10uf cap on, that wasn't a big deal.

    It almost never powers up. If I turn the power off and on again real quick, sometimes the card will power up and show a display. Actually, I think even when it's not showing a display, it's powered up as the card gets warm.


    My A1200 is recapped and the timing caps on the bottom aren't there. I have a 1D4 board. I've tried the recovery disk and it flashed fine (when I was able to get it to find the board), and sometimes works beautifully. But most of the time I get no display. And this is with two different power supplies, one original and one of those newer style that I'm told is Meanwell, that you say is not good for the Amiga. Anyway, it does it with the original power supply too.


    I've checked the pins on the Lisa chip under my microscope - all are soldered fine, no cracks.

    Unfortunately I only have a single A1200 to test with.

    It seems like some timing issue or something.

    Nice board when it works, but hardly ever works. I've read a lot of the other posts in this forum with people troubleshooting their cards and different things to try. But with a single A1200 I'm about out of things to troubleshoot.

  • It almost never powers up. If I turn the power off and on again real quick, sometimes the card will power up and show a display. Actually, I think even when it's not showing a display, it's powered up as the card gets warm.

    This could either be a power supply issue (can you measure voltage/ripple?), or a leaked-capacitor issue in your A1200 (check around the NE555 circuit that generates the reset signal - these are sometimes overlooked when re-capping is done).

    It seems like some timing issue or something.

    All timing issues have been ironed out with the updates that came after release. If you have run the rescue disk, you have the latest firmware installed already, and timing issues are not to be expected.


    But with a single A1200 I'm about out of things to troubleshoot.

    There may be a lot more - please describe the whole system, including all other expansions and your case. Sometimes it's as simple as replacing the shield (even if it's just the lower shield).