Could try this but honestly I've never had much luck trying something like this, especially considering the datecodes are bullshit.
http://www.ic2ic.com/search.jsp?sSearchWord=U … 38-3B9&prefix=U
http://www.icbaibai.com/search.jsp?sSearchWor … 38-3B9&prefix=U

uPD65622 series is a CMOS gate array. It's not necessarily considered to be end-user reprogrammable. The "program" defines which areas become memory and which logic. And it's quite possible there's read protection, meaning even if you had a programmer that could program a blank chip, you wouldn't be able to read it out again.
http://www.datasheetarchive.com/dlmain/Datash … /DSA-434048.pdf

If you can find the exact chip with the exact numbers (UPD65622GF-138-3B9) and if it's working you may be able to fix the device, sure. But you may need another Roland SC-88 to scavenge from to do just that.

Ya I was figuring I was at a dead end without another unit with a working chip.
I am still stuck on a website i found that says the reset line is low for about 5 seconds then goes high..

my unit is always high "5v", granted this website is google translated but idk still has me wondering.

anyways I will probably just break down and buy a working unit at some point.

Hi again, sorry for the late reply...

The status on my SC-88 is still as follows: none of the controls or inputs work, it boots up seemingly normal, but the symptoms after that aren't consistent. Mostly it just forever sits on Piano 1 with default settings, but sometimes it suddenly cycles through instruments and settings all by itself. The only clue right now are the positive ends of C38 and C39 which I have bridged as said in the last post; it's not 100% clear to me from the service manual, but they do seem to be connected from what I can tell from the schematic there.

If there is any method of checking the chips with a reasonably priced probe I'm all up for it, but until then this unit is dead sadly...

Hi, I have joined up to this just to say thank you for providing all this troubleshooting info. I managed to pick up an SC88 Pro for pennies due to it displaying the same issues as you have experienced.

I managed to follow the schematics and your troubleshooting steps as I thought it may have been the same issue.

It looks like there could be a common issue between the units, I checked all the caps all were good a bit crusty but none were leaking and showing the corrrect capacitance.

After spending many hours tracing back the 5v and 3.3v lines with an jewellers Lupe, I noticed that most of the corrosion was below the vent on the main board.

So tested every test point and noticed that even the memory chips were recieving power they were getting 5v not 3.3v they were expecting. I managed to find a broken trace which was directly under the vent and repaired the corroded trace and boom it came to life. I have tested the unit thoroughly and can report it is working perfectly.

It may be worth checking this trace as this seems to be a place that may have been missed but is open to the elements.

Sorry for bringing up a thread from the dead but hopefully this helps someone else out there like this post did for me.

I've still not given up on my broken SC-88. When I pulled it out again I discovered that it does react to adjusting the MIDI switch or not having a battery installed, these differences are listed during the power up sequence. But other than that, it is as I've described in my previous posts, no reaction from the buttons. Still, the fact that it does display correct text gives me some hope that it could be salvageable. After all, it did work initially after I did that recap...

I've now did some voltage measurements on it and it mostly appears normal. The readings from that test point on the analog board were all within 0.1V of rated voltage, reset around 5V, which should be normal from what I can tell from this thread. The positive legs on the electrolytics, which I believe is Vcc, all measure 4.9V. The one thing that seemed off to me was IC12, which is a 2-input NAND according to the manual. Here it says that pin 5 should be 3V and is in parallel to a ceramic, I traced this pin and it reads 4.5V. Pin 4, which goes to the CS pin on each of the SRAMs, reads 3.72V.

I'm guessing it's okay to post here after a few months since others have before.

I'm running into a similar issue as people here; my SC-88 Pro just died all of a sudden and now refuses to start - no display, no sounds, nothing. Just the hum of the transformer. There's no obvious leaky caps, corroded traces, or broken traces here.
I tested what I could with a multimeter (only electronics tool I have besides a soldering iron), and it seems like there is NO voltage going to the main board. Absolutely nothing. I checked the cable going from the analog board to the main board and it doesn't seem like there's any voltage there, either, so nothing is coming off of the board, even though the analog board it self is getting power.
Is there anyone who has repaired these things or other SC units that wants to weigh in on what might be happening? I'm pretty lost here.

I've never cracked into an SC-88 but I would imagine that like most devices. It will have one or more voltage regulators that provide the actual needed DC voltages and current to the various parts of the module. So in situations like this, if you can confirm that voltage is getting to the main boards themselves, then you use your meter to start looking for and measuring voltages at the voltage regulators. Measure the incoming voltage to the VR to make sure it is there and what voltage you have on the output pin of the VR to make sure there is +5 or whatever is required from there. My guess is that a VR somewhere isn't doing its job and they can die and burn out like anything else.

*Edit* So you already confirmed no voltage to the main board at all? Then the issue has to be the AC adapter itself. Doesn't the SC-88 use an adapter just like the SC-55/MT-32...etc? Check the back where the power plugs into and it should list the voltage and amperage needed. Most importantly, it should list the polarity. In the case of the MT-32 and my MT-200 I can use a Sega Genesis or Master System power supply as it has the exact specs needed to operate those modules. So my guess now...is the AC/DC adapter itself.

CrossBow777 wrote:

I've never cracked into an SC-88 but I would imagine that like most devices. It will have one or more voltage regulators that provide the actual needed DC voltages and current to the various parts of the module. So in situations like this, if you can confirm that voltage is getting to the main boards themselves, then you use your meter to start looking for and measuring voltages at the voltage regulators. Measure the incoming voltage to the VR to make sure it is there and what voltage you have on the output pin of the VR to make sure there is +5 or whatever is required from there. My guess is that a VR somewhere isn't doing its job and they can die and burn out like anything else.

Alright, I'll take a peek at those later, thanks. Thankfully synfo has all of the service schematics so I can see exactly what each of those regulators is supposed to be doing...

*Edit* So you already confirmed no voltage to the main board at all? Then the issue has to be the AC adapter itself. Doesn't the SC-88 use an adapter just like the SC-55/MT-32...etc? Check the back where the power plugs into and it should list the voltage and amperage needed. Most importantly, it should list the polarity. In the case of the MT-32 and my MT-200 I can use a Sega Genesis or Master System power supply as it has the exact specs needed to operate those modules. So my guess now...is the AC/DC adapter itself.

Nope, Roland ditched external PSUs for the SC-88, 88 Pro, 8850, and SC-D70. And voltage is getting to the *analog/power* board, which is where power goes first (it goes from the transformer to the transformer board, which gives 5V/12V to the rest of the machine). But it stops there, nothing is coming out of the power board to the main board (which is connected via a few wires on a connector).

So there has to be a transformer stepping down the AC to DC. As such there might not even be normal VRs in there. But you should be able to take similar voltage measurements from the transformer to at least make sure it is good and go from there.

Also is there any kind of fuse in the SC-88 power section. Even something like a small pico fuse or something perhaps?

CrossBow777 wrote:

So there has to be a transformer stepping down the AC to DC. As such there might not even be normal VRs in there. But you should be able to take similar voltage measurements from the transformer to at least make sure it is good and go from there.

Also is there any kind of fuse in the SC-88 power section. Even something like a small pico fuse or something perhaps?

I found no fuse at all.
Also, I took your advice of checking the VRs and I think you're onto something: (for the record, the service manual lists them as ICs) IC105, IC106, and IC107 all read correctly, but IC101 (+5V) reads 0V. IC101 is also the one that's connected to CN102 (with a resistor in the way), which connects the Power board to the Main board, which explains why the connector was reading 0V since... well, IC101 isn't doing anything.

EDIT: I just went back to it today - IC101 is connected back to D102 (S5VB20) which is supposed to be giving out +5v and -5V, but it's doing neither despite continuity on every line. D102 is connected to two capacitors, C119 and C700, which are putting out -9.98V or so and -3.27V respectively. Maybe they're dead? I'm not familiar with reading these type of caps, but I took a pic. I did forget to check continuity from these caps to D102, so I will probably do that later.

EDIT 2: Assuming I'm not misinterpeting things online, I think these are 0.1uF caps. I tried to find the exact replacements on Mouser and they have them... but there's a 28 week wait. Ugh. Also, all the continuity is fine, so either these caps are dead or D102 is dead but I'm betting on the caps. Both of them are going to be a pain to get replacements for anytime soon.

I feel dumb; I think I was measuring the wrong side of the capacitor - both of them have whatever is coming out of the 5V line on the AC on the line that's connected to D102. So, the good news is that I didn't needlessly take stuff off or replace components or break anything, the bad news is that I have absolutely no idea what to do at this point. I'm gonna see if I can get in contact with a friend of a friend that knows way more about electronics repair than I do.