Macintosh SE FDHD/SuperDrive Slow Booting with Checkerboard Pattern

Hello all, I picked up an SE SuperDrive last week and been busy restoring it. Cleaned the floppy drive and replaced the eject gear, recapped the analog/logic board and the power supply (it has an astec power supply and all capacitors tested good, but replaced them anyway), also dealt with melting rubber bumpers in the quantum hard drive (wrapped several layers of teflon tape around it as removing the bottom magnet requires taking out the head assembly).

Now after putting everything back together, it greets me with a checkerboard pattern:


Thought it might be a ram issue, i replaced all 4 ram sticks with known good ones (1Mx8, 8 chip, 80ns), but it still boots to checkerboard. However, after about 10 seconds it chimes and booted up as usual, and sees all 4MB ram. Power cycled it several times, it will always get stuck at the checkerboard screen for ~10s before chiming and booting up

Is this normal for an SE FDHD/SuperDrive? All SEs I have chime instantly when power is switched on. Reset is slow too, after pressing reset button it takes about 10s to chime. Otherwise this SE FDHD is fully functional.

Hi all, thanks so much for your input. I double checked the voltage, reseated both rom chips as well as the swim chip, problem persisted. Swapped the motherboard into an SE chassis, same issue. Then I noticed something, I put a 47uf capacitor on C36 by mistake:



Which should have been a 1uf 50V cap. After replacing this cap with a 4.7uf one this mac chimes instantly on powering on.

Digging things a bit further, schematic shows this cap is connected to the sony sound chip directly:



So maybe replacing it with a larger capacitor, it will pull down pin 7 of the sound chip much longer till it charges up, and this somehow prevents the sound chip from releasing RST signal, which explains the checkerboard pattern

Anyway, problem solved and thanks again for your input!