Ok, so I found the service manual and the Memory test is showing to check:
DRAM - IC24(1),23(2)
WAVE ROM - IC14(A),8(B),7(C),6(D)
XP CHIP - IC15

That sounds like there is something wrong with voltage delivery to me. Maybe there are some more bad solder joints. I'll have to work on it some more later but at least I have an idea of what to look at.

In any case, I am attaching the service notes for future reference:

Found a vcfed where somebody was having a somewhat similar issue and in the end it turn out to be a bad connection:
https://www.vcfed.org/forum/forum/collections … work#post770685

I think I will start out checking everything on both main circuit boards.

Took it apart again and took a closer look at the board. There is definitely some corrosion from leaking capacitors... yay. I am starting to not like these SMD electrolytic capacitors.

Also check out how Roland used components that are way smaller than the pad layout suggests was needed.

Seeing the gunk on the chip (3rd pic), maybe something went poof because it destructively failed?

yawetaG wrote on 2021-05-08, 06:33:

Seeing the gunk on the chip (3rd pic), maybe something went poof because it destructively failed?

Nah, I don't think so. It is actually just gunk stuck to the chip. I know what a poofed chip looks like and this isn't it.

I just scratched it off with my fingernail. Chip looks fine.

I believe with a recap and some patching when necessary the unit will work fine again
it's a classic leaking caps symptom

keropi wrote on 2021-05-08, 09:47:

I believe with a recap and some patching when necessary the unit will work fine again
it's a classic leaking caps symptom

I really hope that OP will get his SC-88 to sing again .

This does make me wonder, though, how common are leaky/bad capacitor issues on SC-55 and SC-88 Roland sound modules ?

I am asking from the perspective of whether pro-active re-capping should be considered on still working units,especially if no leakage/corrosion seems to be visually apparent (yet).

These units are all 25 to 30 years old, but I have seen relatively few issues reported. This could either mean that that the "bad" ones are outliers or that we are seeing the beginning of a wave of upcoming cap related failures or that I have been living under a rock and just have not noticed how many issues are cropping up .

One thing to consider is that the problem unit described here is an SC-88, which has an internal PSU, so may be subject to greater heat buildup than, for example, an SC-55 or SC-88VL, that both have external PSUs (though I imagine that all the aforementioned units use an internal linear regulator to derive the voltage actually used).

SC-55 mk1 and mk2 use "old style" electrolytic caps so no leaking like this
everything from that era that uses smd caps is prone to capacitor leaking - it affects everything from home computers to game consoles and everything needs a recap if you care to have it working

keropi wrote on 2021-05-08, 10:25:

SC-55 mk1 and mk2 use "old style" electrolytic caps so no leaking like this
everything from that era that uses smd caps is prone to capacitor leaking - it affects everything from home computers to game consoles and everything needs a recap if you care to have it working

Thank you .

I was aware of the fact that at least some of these early SMD caps were problematic in lots of electronic product of the same vintage, I just had not heard of many SC-88 units with similar issues . So the answer to my question is essentially that it is only a question of time before pretty much anything with SMD caps from that era (EDIT : likely regardless of capacitor brand) needs recapping and possibly corrosion related repairs, if I understand correctly (at least we got a few decades out of these caps, unlike the later "capacitor plague" era stuff)

The photos that I have seen online seem to show the SC-88VL using "old style" through hole caps (I will need to check mine) like the SC-55 variants, so , ironically, the cost reduced SC-88VL may be more maintenance free than the SC-88 .

SC-88VL mainboard photo : https://xn--krketr-jual.com/projects_isa486_e … 32_trimmers.php EDIT : My unit is externally identical to the one pictured .

The VL always was, as AFAIK the internal PSU of the regular 88 is prone to failing more often than the external power brick on the VL.

I've mentioned this in other places here, but even my 2003 Edirol SD-20 had evidence of SMD cap leakage. I only found this when trying to figure out why I wasn't getting any audio from the analog outputs off the module. When I saw the dull grey and crumbly look of the solder at the base of the caps, I knew I needed to replace them out. I did so using standard electrolytics and sure enough, the analog outputs starting working again after that.